Category Archives: Hacking

Programmatically access your complete Google Forms skeleton!

So you wanna load the content of your Google Forms programmatically? access all the questions, answer options, field types, submit ids and so on as you wish? 😉 Stick around!

Hope yol remember in my last blog post, SCRIPTfully scrape off your Google Forms Field Ids… I was sharing a neat little script I built to extract the Field identifier IDs from your Google Forms page, so that you can use them with ease for auto filling question answer fields or submitting data using REST API into your Google Forms! So this is the nest step in this series of Google Forms Hacks!

In this post we’re gonna load your Google Forms skeleton programmatically!

What does it mean?

Yes, instead of loading your Google Forms page on the typical web browser, why not load the bare bone content of it as you wish? By this I mean,

  • List of Questions (your question content…)
  • The types of Questions (Short Answer, Paragraph, Checkbox, etc)
  • Available Answer options (Multiple choice answer questions…)
  • Title and Description of your Google Form, etc…
  • And many more details you have added to your Google Form…

Once you get access to those bare bone content or the skeleton structure of your Google Form, then you can do all kinds of stuff with it…

Then  you can render it as you wish and present to your users, re-render it into a Web App or a Desktop app or even a Mobile App with your own custom layouts, filtering, and validations! 😀

So how we gonna do it?

Simply put, we gonna extract the skeleton or the bare bone structure from our Google Forms page. Now as you may have figured out there’s no official API or SDK to access Google Forms services programmatically, therefore we obviously have to hack our way around this!

We’re going to build a little a script which will load the HTML content of our Google Form and perform a magical algorithm to extract our Google Forms structure! All the questions, answer options, validation, and etc the whole deal… 😉

Backstory…

In my last post hope you remember how I shared about scraping through the HTML content of our Google Form page to extract Field identifiers which is used to submit answers or otherwise known as Field Answer identifiers.

Then along that same time I was experimenting with trying to extract the whole structure of the design the same manner. But filtering through the HTML tags to retrieve the complex structure of a given Google Forms Question-Answer field structure seemed quite hectic.

Jackpot!

So while I was  going up and down the HTML of the page, trying to find a better way to extract our Google Forms Question-Answer structure, I came across this interesting piece of script at the end of the page.

As you can see at the bottom there’s java script starting with “FB_PUBLIC_LOAD_DATA_ = [nulll…” with a strange pattern of the content, which I’m not sure what the purpose of it in this page, but you can surely find this in any Google Forms page. This specific script snippet seem to be holding the whole skeleton of our Google Forms page as you can see, it containing the Question Content, Answer Fields and so on!

So there’s our little treasure… 😉

Now finding this bit wasn’t enough at all, I had to figure out how  to parse this properly to extract the data that we’re looking for, as you can see it’s got a little unorthodox structure in its content. Now that’s the next challenge!

Let the hacking begin…

Now for this post also let’s use the same sample questionnaire Google Form that I created for last post’s demo.

https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/viewform

So we’re going to load the HTML content of our Google Forms page, and then we’ll extract that mystery javascript code snippet, and parse the content of it to access the skeleton structure of our Google Forms!

Now first let me walk you through how to parse that mystery FB_PUBLIC_LOAD_DATA_  content! 😉 Let me warn you though, figure this out was no walk in the park but let me share the secret source with yol straight away.

Let me copy and paste it here from my sample Google Form and get started! Below you can clearly see how all the Questions along with Answers and Field identifiers in my sample Google Form are contained in this mystery code snippet.

var FB_PUBLIC_LOAD_DATA_ = [null,["Please fill up the following questions. You need to answer all the fields please! ;) ",[[122249536,"Hello there, this is question 1, could you answer?",null,0,[[1277095329,null,0]]],[1170747525,"Which one would you prefer as the answer from below?",null,2,[[995005981,[["Mango Peach",null,null,null,0],["Banana Plums",null,null,null,0],["Strawberry Pears",null,null,null,0]],1,null,null,null,null,null,0]]],[2147453523,"Well another question here wouldn't hurt now eh?",null,4,[[1155533672,[["Monkeys with hoodies",null,null,null,0],["Dogs with hats",null,null,null,0],["Cats with crowns",null,null,null,0]],1,null,null,null,null,null,0]]],[172187917,"How about this for a change?",null,3,[[1579749043,[["Running Banana",null,null,null,0],["Jumping Apples",null,null,null,0],["Rolling Pears",null,null,null,0]],1,null,null,null,null,null,0]]],[676251522,"What's the date would you like to be today?",null,9,[[815399500,null,1,null,null,null,null,[0,1]]]],[1280585510,"What time would it be right now? ",null,10,[[940653577,null,1,null,null,null,[0]]]]],null,null,null,[0,0],null,null,"Sample questionnaire!",48,[null,null,null,null,0],null,null,null,null,[2]],"/forms","Random Sample Questionnaire",null,null,null,"0",null,0,0,"","",0,"e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA",1];

In order to parse this into a known data structure you need to first remove the “var FB_PUBLIC_LOAD_DATA_ = ” and the “;” at the end if you notice carefully.

However by looking at the content you can make a guess that it should be some JSON based content structure.

So let’s use any online JSON parser tool and you should be able to see the formatted content as follows. ex: jsoneditoronline, codebeautify or jsonformatter

Now you get some readable structure yeah, where you are able to traverse through it’s content by expandable nodes array.

Pattern Recognition and Analysis!

Since we parsed the mystery content into a JSON Array tree, we can now traverse through the data easily and extract the specific data that we’re looking for.

Now since there’s no official documentation regarding the parsing of this data from structure, I guess we’re going to have to figure out ourselves, where to pick what data in this data tree and recognize the pattern.

So basically what we are going to be focusing on retrieving the following data,

  • Google Form Title, Description, Form ID
  • List of Question Fields

And in each question,

  • Question Field Text
  • Question Type
  • If submitting Answer is mandatory or not
  • Available answer list (Multiple answer selection)
  • Question Field Identifier (Field Id) or Answer Submission ID

Now that I believe comprises the complete structural skeleton of any given Google Form! 🙂

– General Google Form data

In the parent root you can see the Google Form Doc’s Name in the [3] index.

Then the Form Id in the index [14] of the array tree. And rest of the important bits seem to be in the [1] index node as you can see it has a lot of child nodes in it. Let’s look into that..

Now this index item seem to be containing a lot of information in child nodes. In its child node index [0] you can see the Description of our Google Form, and index [8] holds the Title.

Next the most important node, that is node index [1] which contains all the Question Fields data, and it looks like this.

Once you expand it you can view the List of child elements that represents the Question Fields in your Google Form!

Now you know you can easily access the Question fields by traversing [1][index of the question field]

Let’s try opening up a child node then! 😉

– Question Field data

Woot! Here you have it, the whole Question Field as expected, and specifically in this sample questionnaire, you can see how it shows all the details regarding the 1st Question Field.

Also notice the value I’m pointing to below, node [1][0][3] to be exact, that index holds the Question Type value “0”, which determines whether it’s a Short Answer, Paragraph, Dropdown, Checkbox field and so on. Then the second arrow, node [1][0][4][0][0], that right there is the unique Field identifier that we need to use when submitting answer to this question field. 😀 Thereby we could consider the value as Answer Submit Id as well.

Now that’s a single answer field, such as Short Answer and Paragraph Question field types in Google Form.

In the node [1][0][4][0][2] holds the value to determine whether Answer Required or not.

So how about we open up a child node of a Multiple Answer field?

Now below I’ve open up the node of a Multiple Answer selection Question Field.

– Multiple Answer Question Field data

Right here you can see in the Question Type value node it has number “2” as the value, which is what Multiple Answer Question Fields are denoted with.

Over here you get an extra child node underneath the Field identifier node as you recognized above.

This has a list of child nodes which as you can see holds the list of Answers Available for the Question Field.

So now we know how to load the list of Answers available for a given question, that we can traverse through.

Next let me dive a bit deep into Question Type identifier values..

– Hunt for Question Field types…

You already know Google Forms provide multiple types of Question Fields that can be added to your Google Form, and you saw above where to grab the Field type value. But how do you know which value maps to what type?

That’s why I had to run a trial and error recognition of trying to match those numeric values to the actual Field types, and I’ve finalized the list as follows…

  • Short Answer Field = 0
  • Paragraph Field = 1,
  • Multiple Choice Field = 2
  • Check Boxes Field = 4
  • Drop Down Field = 3
  • File Upload Field = 13

// File Upload – we’re not going to implement for this right now, because it needs user log in session implementation, a bit complicated. So let’s look into it later!

  • Linear Scale Field = 5
  • Grid Choice Field = 7

//Grid Choice – represents both: Multiple Choice Grid & Checkbox Grid

  • Date Field = 9
  • Time Field = 10

As you can see the assigning of the numeric values for the available types of Fields are not so straight forward and Google Forms tends to mix up or skips some mapping of the values without a proper order.  That’s why I mentioned it was a bit painful trial and error process.

Now we’ve walked through the recognition of the data pathways that we’re hoping to extract, let’s summarize our analysis as follows..

  • The most crucial node is index [1] which holds all the data we need
  • Although Google Form’s Id is in the root node [14]
  • Description is in the node [1][0]
  • Title is in the node [1][8]
  • All the Question Field data is in node [1][1]
  • We need to traverse through this child node list and fetch each item
    • Question Field Text is in  [1]
    • Question Field Type is in [3]
    • Question Field Id is in [4][0][0]
    • Question Field Answer required or not is in [4][0][2]
    • Multiple Answer Options are in [4][0][1]
    • Multiple Answer Options needs to be traversed and loaded
  • We need to create a mapping for numeric values of Question Field Types to readable values, Short Answer Field, Paragraph Field, Multiple Choice Field, etc.

So that’s the complete list of analysis that we have derived from this step, which we need to carry forward to our next level, that is implementing all this logic and retrieving the complete skeleton structure of your Google Forms page!

Let the coding begin!

So just like in the previous article, I’m going to use  dotnet and C# as the language for our little code snippet. And to parse HTML content, I choose HTMLAgilityPack. Then we need Newtonsoft.Json to perform our JSON data structure execution. Also I would be using a Console Project type in dotnet, pretty simple to begin with.

Given you have created the project and added the HTMLAgilityPack and Newtonsoft.Json to your dotnet project, let’s start by creating the model class

Enum mapping class for the Question Field Types that we identified before, so that we can easily cast our scraped out values in code.

Now you might say shouldn’t we create Model classes to represent Google Forms Fields and Google Form parent objects themselves, but I would rather keep that to a future post! 😉 let’s just try to keep things simple in this one!

Then let’s code the method that we’ll be executing the load our Google Form structure! I’m gonna be calling it ScrapeOffFormSkeletonFromGoogleFormsAsync() with a parameter passing in which will carry the URL link to a given Google Form! 😀

Let’s begin by adding the simple LoadFromWebAsync() using the HTMLAgilityPack, which will load the HTML content first.

Next let’s access the FB_PUBLIC_LOAD_DATA_  script content in our HTML doc.

As you can see we are filtering out the html nodes with the “//script” definition which contains “FB_PUBLIC_LOAD_DATA_” value in it. Then we load it into a variable fbPublicLoadDataJsScriptContent which of type string.

Next on, we gotta clean it up by removing the “var FB_PUBLIC_LOAD_DATA_ = ” and the “;” at the end if you notice carefully. So that we can parse the data to a JSON Array structure.

Now we’re ready to parse the content into a JSON Array using Newtonsoft.Json as below.

And also let’s access some basic data of our Google Form, such as Title, Description and the Form ID just like how we discussed in our pattern analysis of this array object structure. Then we load the most important index of the array [1][1] into arrayOfFields variable at the bottom.

Next on we are going to traverse through the list of field data indexes, but here I have added a special filter to identify if the given Field object is an actual Question or a Field placed as a Description Panel or an Image banner, which I have noticed people do to customize their Google Forms. In that case we ignore that object and move on to the next iteration.

There we are looping through each item in arrayOfFields and skipping off the filtered objects. As you can see above, we’re first loading the Field Question text value, then extracting the Question Type value, while using the Enum parser that we build before with mapping the readable Field Type values.

Speaking of accessing Answer Options List for Multiple Choice Questions, we’re handling that next in this code bit.

And we load it up to answerOptionsList object.

Then we load our next Values, Field Answer Submit ID and the value representing if the answer is required to submit or not, with a conversion to boolean which is true or false.

For the IsAnswerRequired value Google gives us “1” or “0” as the representation of true or false, so we need to do that mapping ourselves as you see above.

Then as the last stretch of our loop, let’s print it all out to the Console.

There now the data related to each field is now printed out to the Console nicely.

Let me share the full code snippet that puts it all together below. Strap your seat belts fellas its a long code snippet, therefore I’ll only put a link to it here! 😉

https://gist.github.com/UdaraAlwis/c338a9de4af4509ba0ff67e2c4f37f5c

Yeah click on that Gist link and view the full code snippet over at my Github!

You can use the above method in any of your dot net projects, as long as you have HtmlAgilityPack and Newtonsoft.Json nugets installed and imported in the code. Application is yours to imagine yo, just pass in your Google Forms link text to the method and you’re good to go!

Hit F5 and Run!

Now if you’re on Visual Studio, let’s just run this little snippet of magic eh! 😉

TADAAA! 😀

Here I’m using my simple demo Google Form link, passing it into the method in this little Console dotnet app, and you can see how it nicely loads all the question field data and all the information about my Google Form page.

Here’s a fun side-by-side comparison of programmatically accessing your complete Google Forms skeleton!

Pretty cool eh!

As far as my testing this little script works perfectly for any Google Form that contains the basic main types of Question Fields that are available in Google Forms as of this day!

Imagination is the limit yol! 😉

Well… That’s it!

Who would have thought the FB_PUBLIC_LOAD_DATA_ is such a mysterious yet awesome data snippet hiding in the rendered HTML content of a given Google Forms page! lol 😀

During my experimental research of cracking this mystery, I got some hints from the following python hacks that I derived the same logic into dotnet C# code.

https://gist.github.com/davidbau/8c168b2720eacbf4e68e9e0a9f437838

https://gist.github.com/gcampfield/cb56f05e71c60977ed9917de677f919c

Now keep in mind we do not have precise control whether Google will change these format and data structure patterns in future, so you gotta keep an eye out if you’re planning to use these hacks for a long term solid implementation. My suggestion would be to write up a series of Test cases (TDD yo!)

There you have it, the little magic script to programmatically accessing your complete Google Forms skeleton!

Share the love! 😀 Cheers!

SCRIPTfully scrape off your Google Forms Field Ids…

Y’all wanna scrape off the list of Field IDs of your Google Forms easily? yes programatically through a neat little script! Stick around y’all! 😉

So you remember my last blog posts about my journey of hacking around Google Forms, You may RESTfully submit to your Google Forms… and even in the one before, Let’s auto fill Google Forms with URL parameters… you might remember how crucial it was to hook up to the list of Field Identifiers in your Google Forms which you can use to Submit data to your Form using the REST API or even to populate the Auto filled data in the Form. Now that goes without saying this blog post is a follow up of the above two articles, therefore I would prefer if you took a sneak peak into those before continuing in this article.

So the way we retrieved the list of Field identifiers were by manually reading through the rendered HTML code and looking at the network traffic data. Specifically I introduced three methods as follows…

  • Method 1: Looking up page source HTML content.
  • Method 2: Inspecting HTML code of each field.
  • Method 3: Monitor the network traffic data.

So all those methods are completely manual, shouldn’t there be an easy way? Yes, I’ve been wondering that myself and I continued on experimenting…

Yes.. Scrape em off programmatically!

Wouldn’t it be easier if we could write a little script to retrieve the list of Field IDs in any given Google Form? Just scrape through the rendered HTML content and pick up the Field identifiers automatically! Oh think about how much time you could save! 😀

Well yes, that’s exactly what we’re going to do. Let’s build a simple script that could scrape off the list of Field IDs of your Google Forms without you breaking a sweat!

But to build the script you might have to break some sweat… 😉 Alright, so what this script is going to do is, given the link of a Google Form, it will load the HTML content of it, and scrape through it to find the elements that holds the Field Ids, filter them out and return the results! Quite straight forward eh! 😀

Let the hack begin…

Let’s use a dot net C# to write out script, and yes an absolutely biased choice given my favorite platform! lol But if you can grasp the process and idea behind each step you could easily reproduce the same script from any other language or framework!

It’s all about programming the our method of manually reading through the HTML code and figuring out the IDs, into a self executing code. This requires us understanding the pattern of which the HTML is rendered for each Field element in the Google Form, and I figured this out by repeatedly looking at the rendered HTML content. Once we understand the pattern and where to filter out the data that we need to scrape out, we can easily code it into our script.

Now for this post also let’s use the same sample questionnaire Google Form that I created for last post’s demo.

https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/viewform

So now we got a Google Form, let’s start the little hack by finding the field IDs in the form…

Identify the Pattern..

Now this is the most crucial step, let me walk you through by simply looking into the rendered HTML content of our Google Form.

Now for me though it took a lot of trial and error steps to recognize how all different types of question fields are rendered in Google Forms, where by created a bunch of sample Forms and analyzed their HTML structure continuously, until I was sure. 😉

I’ve explained regarding this pattern in my previous blog post: Let’s auto fill Google Forms with URL parameters… in which I dive into detailed steps of finding the IDs of each question field in your Google Form. If you go through it and focus on the section “Method 2: Inspecting each field” you could easily understand what I’m about to dive into. Therefore let me keep things simple in this article just to avoid repetition. 😀

Assuming you’re using Google Chrome let’s begin, by right clicking on any of the question fields in your Google Form and go to -> Inspect Element menu option.

If you carefully take a look at the rendered HTML node of our Short Answer question Field, it’s actually “input” type element and you can see how the “name” property holds the ID for the Field “entry.1277095329”. Now let’s take another type of an Field, how about Multiple choice selection question Field? 😮

When you’re reading through the parent node of the radio button elements, you can see at the bottom there’s an “input” type element, that’s set to hidden, with the Field ID that we’re looking for. Then how about a Checkbox selection Field? Let’s try the same inspection and see for ourselves… 😉

Now the parent node of it is a bit differently structured, but you can see how it follows the same pattern, of having an “input” type element which holds the ID of the question Field.

Also something to notice is that the same exact child node is repeated in each parent div element containing the ID value. And then just above the child elements, you got another field which carries the same values, but with a “_sentinel” suffix in the “name” property, which sorta creates a repetition of data that needs to be filtered out. So this is something you need to keep in mind, that we will need to filter out in our script. 😀

Next let’s try out a Paragraph question Field of Google Forms, and try to analyze it.

Now this fella got a “textbox” type element rendered, which also includes the “name” property that holds the Field ID, and now we know another element that needs special filtering in our script! 😉

Finally all the other types of Questions Fields in Google Forms follows almost the same pattern of rendered HTML, therefore without further adieu let’s try to analyze the patterns which we seen behind those elements.

Analyze the Pattern…

Now in this step you need to be able to see the full picture of the whole pattern of which those Google Forms question Field elements are rendered in their HTML environment. So after analyzing all those different fields we could draw a few major analysis that we need to keep in mind when we’re thinking of scraping out the Field IDs from the HTML…

  • “input” elements holds the Field IDs in their “name” attribute
  • “textarea” is an exceptional element which is used by Paragraph question type
  • the Field ID value begins with “entry.” prefix in the “name” attribute
  • Checkbox Field elements renderes a repetition of its “input” nodes
  • Also Checkbox Filed generates an extra “input” element with “_sentinel” suffix in ID
  • repeated nodes with same values should be filtered out

Now keeping all those in mind we need to implement the logic into our script, or in other words we need to code the above logic and filtering as rules into our little script that’ll scrap out the HTML of our Google Form to retrieve the Field IDs automatically.

Let the coding begin!

Assuming that you’re already experienced in dotnet, I’m not going to be diving in to spoon feeding details here, and rather focus on the important bits of the code. We’re going be using dotnet and C# as the language for our crawler script. And we need a library that could parse HTML content, and traverse through those content programmatically. Therefore I choose HTMLAgilityPack which is a well known and stable HTML parser for dotnet projects.

So the project type that you’re going to implement is totally up to you, but for this demo I would be using a Console Project in dotnet, pretty simple to begin with.

Given you have added the HTMLAgilityPack to your dotnet project, let’s create the method definition with a string parameter that will represent the URL link of our Google Form that we need to scrape off and it will be returning the list of Field IDs of the given Google Form!

Oh and make sure to make it an async method, hence we will need that for our web call that’ll load the HTML content.

Let’s use the HtmlWeb class which allows us to load an HTML content from a given url string asynchronously.

There we’re executing the LoadFromWebAsync() upon the given Google Forms Link and load it into memory. Next we need to implement out first line of filtering on top of the HTML content that we loaded into memory.

There we’re scooping off the “input” and “textarea” elements from the HTML content,  into a List object of type IEnumerable<HtmlNode>, given the DocumentNode which contains all the HTML elements of the Google Form that we just parsed into memory.

Like I said before we’re basically implementing the logic that we learned in the Pattern Analysis step, therefore next we go on to the next layer of filtering.

There we’re filtering the list of data based on the predicament, that we retrieve all the HTML elements which contains the “entry.” prefix in their “name” attribute, thus securing out Field ID values. Then we exclude all the elements that contains “_sentinel” suffix in their “name” attributes which governs the cleaning up of Checkbox field element repetition.

As you see above we’ve singled out the HTML elements that we’re targeting. Next we gotta do some final clean up of our scraped nodes.

We need to clean up any existing duplicate elements in the list, therefore we’re gonna group similar items, and pick the first element into a list of type List<HtmlNode>, which will eliminate the repetition nodes probably caused by Checkbox fields.

And finally we’re going to access the each Node’s “name” attribute, load it into a List.

And return the results. Oh just an add-on I’m printing out the scraped off Field ID elements into the Console.

Let me share the whole script down here…

Let’s try it out shall we! 😉

Hit F5!

Now I’m gonna use the sample Google Form that I created for this demo, pass its URL link into this little script, and hit F5 in Visual Studio!

Look at that beauty! 😉 The complete list of Question Field identifiers in my sample Google Forms just like we expected.

As far as my testing this little script works perfectly for any Google Form that contains the basic main types of Question Fields that are available in Google Forms as of this day!

Well… That’s it!

Basically you can scrape off any data from a given HTML content as long as you understand the pattern of which the HTML rendered targeting the pieces of data that you’re looking for! Likewise there could be many different types of Google Forms that contains different types Question Fields even with custom content in them, but at the end they all follow a certain HTML rendering pattern, which is just a matter of figuring out.

I would like to remind you again, the reason I considered this as a “SCRIPT” is due to the possibility of converting the same HTML scraping steps into any other language or framework easily, as long as you understand the pattern of the rendered HTML of your Google Form!

Now keep in mind all these are simple hacks and tricks derived by careful observation of rendered HTML content of any given Google Forms page, and we do not have precise control whether Google will change these format and rendering patterns in future, so you gotta keep an eye out if you’re planning to use these hacks for a long term solid implementation.
My suggestion would be to write up a series of Test cases (TDD yo!) which would test for the above process flows to make sure they’re working as expected and notify you in case of any changes from Google. 😉

There you have it, the little magic script to scrape off the list of Field IDs from your Google Forms page!

Share the love! 😀 Cheers!

You may RESTfully submit to your Google Forms…

You wanna submit responses to your Google Forms in a REST-ful API call, or rather programmatically in code or easily from a Postman-like tool? Then you’re welcome to stick around here… 😉

So you remember my last post on my journey of hacking around Google Forms, trying to be a smart-ass eh! Let’s auto fill Google Forms with URL parameters… Oh yeah that one right there, well that was just the tip of the ice berg of me playing around with Google Forms! Let me share the next set of cool tricks I figured out here! 😀

This little trick of submitting data RESTfully to your Google form, could become very handy if you wanted to build your own improved custom UI for submitting data to your Google Form, along with your own validations for the fields or even to quickly populate a bunch of sample data from your Form for experimental reason. Them awesome possibilities are endless! 😉

Well.. Google Forms with RESTful ?!?

So during my adventures into messing around with Google Forms, I figured out that we can submit data into our Google Forms using their REST API endpoint! So how cool is that eh, we can directly post data into our form RESTfully, from whatever the medium you prefer, programmatically, or Postman like tool! 😉

So in this post lemme share that cool trickery bits with you…

Let the hack begin…

Now keep in mind unlike the last post, this is a bit advanced trick which requires some experience on HTML and web development, well it could easily help at least.

We’re gonna get the REST endpoint source of our Google Form, package our question-field-answer data into a request object and submit it to the REST endpoint directly, using Postman or Programmatically in code.

Now for this post also let’s use the same sample questionnaire Google Form that I created for last post’s demo.

https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/viewform

Little sneak peak:

So now we got a Google Form, let’s start the little hack by finding the field IDs in the form…

Yes, you still gotta hook up the fields!

Remember in my last post I explained about the Fields in our Google Form having unique identifiers (or IDs) that we can use to attach data into for submission? well you still need em! 😛

Now for this you could still use the methods we discussed in the previous post to get the list of ID of the fields in your Google Form, but this time I’ll introduce some easier ways, since we’re moving to a bit advance trick…

Hooking up to the fields and Endpoint…

Keep in mind this requires a little bit experience in web dev! 😉 Basically we’re going to get the list of Field IDs by tracing the submission request call in our Google Form, which will also help us figure out the REST endpoint link.

So open up your Google Form in Chrome browser and open up developer tools by using the browser menu or on Windows click “Ctrl+Shift+I keys” in the keyboard.

Now to make the magic work, go to “Network” tab in the menu list which will allow us monitor the network trace that’s going to be sent from browser to Google Form submission REST endpoint.

Next, you need to fill up all the question fields in your Google Form and hit submit button. Carefully watch what happens in the developer console!

Yep a whole bunch of logs pops up, which shows you the traces of all the network calls that occurred in the last “Submit” button click. And in there the most important request log is the “formResponse” log as you seen above.

Click on formResponse log which will bring up all the details on it.

Now this is quite awesome, it will show you in 4 separate sections all the details about the Google Form submission data endpoint that just occurred.

https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/formResponse

The Request URL is the endpoint we’re going to be using to submit our form data and the Form Data section is where you’ll find the list of field identifiers of your Google Form.

Now that your holy grail of list of field identifiers in bulk. So go ahead, highlight that chunk of text and copy it up to some notepad to be used later.

Now if you noticed the ID with the “entry.1155533672_sentinel” is something that you can ignore, since its a repeated field coming from the Check box question field in your Google Form!

Just like that you can easily extract the list of IDs of the fields in your Google Form! 😀

entry.1277095329: Bibimbap Turtles
entry.995005981: Banana Plums
entry.1155533672: Dogs with hats
entry.1579749043: Jumping Apples
entry.815399500_year: 2019
entry.815399500_month: 11
entry.815399500_day: 11
entry.940653577_hour: 00
entry.940653577_minute: 30

Now that’s the form data sample from my Google Form! 😉

Shove it up into a Postman!

Or any of the web dev tools you prefer to make a simple REST api call. Up to you! lol. Let’s create a POST call with our Google Forms submission API endpoint which we retrieved in the above step.

https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/formResponse

Actually this URL you could easily make up using your Google Form publish url, just by replacing viewform with formResponse suffix.

So make sure to add the Body parameters of type x-www-form-urlencoded, and list out all the question field IDs and their values you’d like to inject in to the submission. Since then you need to apply header Content-Type as application/x-www-form-urlencoded which will enable our body parameters object.

Assuming you have set up all the body form fields properly, let’s fire it up! 😀

Fire it up!

Let’s go ahead and execute the REST posting! Hit “Send“, and bam!

You should get a successful 200 Status Code response with the above success message “Your Response has been recorded.” inside a whole bunch of HTML content and if you move to the “Preview” tab, you can see how the rendered UI being returned as well.

Now let’s say if you missed adding any specific field in the request body, that was already marked as “Required” in your Google Forms template, and you had hit “Send”. In that case it would return a bad request 400 Status Code with the error in HTML content, “This is a required question”, or with whatever the custom error message you configured your Google Form with.

Yeah you can even view in the Preview tab with the rendered HTML content.

Pretty neat eh! the same way it would behave in a browser environment you can duplicate in a RESTful environment such as Postman! 😀

Now let’s see how easy it is to push that into some code and execute this programatically!

Shove it up into a Code snippet!

Alright let’s shove that into a simple C# snippet where we could POST a simple HTTP request with the body parameters of our Google Form! Basically replicating the same execution as Postman you saw above! 😀

Above we’re using a simple dotnet HttpClient to execute our Google Form submission REST post call, by adding the body values dictionary into the request.

And then we’re printing the Status Code and the HTTP content response we get.

Hit F5!

If you hit F5 on the above code in Visual Studio, you should get the following.

We are successfully submitting our Google Form data to the REST endpoint and getting the success code, along with the usual HTML content, same as how got in Postman. 😉

Now let’s say if something went wrong, or you missed a required field in your request body,

It will show up the same error handling we got in Postman, as 400 Bad Request! And if you dive into the HTML content, you can see how the error message was also delivered back.

So now you know how to programmatically submit data to your Google Forms in code! 😉

Imagination is the limit yol! 😉

Well… That’s it!

It’s quite straightforward how Google has built these forms in such a simple manner for you to handle them easily as you wish. Kudos Google!

Now keep in mind all these are simple hacks and tricks derived by careful observation of html code and network traffic, and we do not have precise control whether Google will change these format and rendering patterns in future, so you gotta keep an eye out if you’re planning to use these hacks for a long term solid implementation.
My suggestion would be to write up a series of Test cases (TDD yo!) which would test for the above process flows to make sure they’re working as expected and notify you in case of any changes from Google. 😉

You can do all kinds of cool stuff with it! So there you have it, how you may RESTfully submit to your Google Forms!

Share the love! 😀 Cheers!

Let’s auto fill Google Forms with URL parameters…

Wanna auto fill and populate your Google Forms with data by injecting values from the URL itself? Then you’re at the right spot. 😉

So I happened to be playing around with Google Forms recently and came across this requirement to pre-populate some data in my Google Form, which led me to come across this simple solution to automatically fill data in the fields of the Google Form by injecting values in the URL targeting the required fields.

Google Forms, a secret?!

Google Forms are simply, nothing but just a list of fields where the user is required to enter data into and submit.

To my surprise when I was hacking around with it, I noticed that Google Forms allows us to attach URL parameters that could target the fields in the form, and pre-populate them with the given parameters. This is probably a not so well known fact, and works like a charm as long as you scrape out the unique identifiers of the fields.

but many types of Fields..?!

There are many different types of fields that could consist in a Google Form, Text fields, Multiple Choice, Check boxes, Drop down, Date and Time selection fields… and so on. But one thing in common among all those different types of fields is that they all have a specific unique identifiers that represents them, so as long as we nicely grab those unique IDs we’ve got the hook to attach values to them on the loading of the page! 😉

Let the hack begin…

For this simple hack I have created a simple Google Form with a bunch of fields in it to enter data and submit. Just another regular Google Form, containing several fields in different types, to demonstrate how to successfully pass values into them no matter the type of each field.

https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/viewform

Little sneak peak:

So now we got a Google Form, let’s start the little hack by finding the field IDs in the form…

Hooking up to the fields…

In order to understand this little hack, you need to treat each question in the Google Form as a field of its own existence, which can be represented by a unique identification that we can use to call upon to attach data into it.

Now let’s try to hook up to the fields of our Google Form by looking up their IDs. There are few ways to hack around to find the IDs, whichever you’re most comfortable you may proceed with…

Method 1: Looking up page source HTML content

One way is to look into the HTML content of our Google Form and manually search for our field identifiers. So open up your Google Form in a web browser and right click on the page -> click on “View Source” option.

Then it will open up the HTML code of the page. Alright now we got the access to the HTML content of our Google Form, let’s hunt for our IDs of question fields. The IDs you’ll find are in the format of, entry.XXXXXXXXX.

So now we know the format of the IDs, let’s search for them using the suffix “entry.”, so click “Ctrl + F” on your keyboard, and type “entry.” which will then highlight all the ID values in the HTML content of the page.

Each and every one of those highlighted search results represents a field that you need to enter data into in the Google Form. If you just read through the surrounding content of those IDs, you’ll see that they’re mapping to each question field in our Google Form.

You can just take a note of the list of entry values popping up in that search result to prepare for our next step.

There’s also another way…

Method 2: Inspecting each field.

Right click on any field -> Click on “Inspect” option, which will open up the HTML code of the specific element that you focused on.

As an example, in the above Text field, when we inspect its HTML content, it shows the “input” element. If you carefully read the HTML code there, you can see how that node has a property called “name” which has the value “entry.1277095329” as you can see above. TADAA! there you have the ID of that specific field.

You can easily find all the identifiers or IDs of the Fields easily in either ways above, so go ahead with whichever you find easier. 😉

Oh, different types of field eh! 😮

So in Google Forms we have many different types of Question Fields that are provided,  such as Drop down selection fields or Check box selection fields, etc. Therefore something to keep in mind is that all those different types of fields, may have their IDs assigned to them differently, because their HTML content is differently structured and rendered.

As you can see above, in the Google Forms designer console, you can see the different types of Question Fields it provides for the users.

Let me show some examples which might help you to track down their IDs! 😉

How to find the ID of a Multiple Choice field?

So one of the tricky fields is the Multiple Choice field in a Google Form. You gotta right click -> Inspect element, where you’ll see a list of Radio button elements attached to the parent “div” element.

Then at the bottom of the parent “div”, you have a hidden “input” field with the ID that we are looking for, that we can use to target in our little hack! 😉

How to find the ID of a Drop down field?

Well this one is quite the same for previous one where you’ll the hidden “input” field at the bottom of the parent “div” element.

You can see in the HTML content how the checkbox options at the top of the list and the bottom containing the ID field with “entry.xxxxxxxx” similarly.

How to find the ID of a Check Boxes field?

Sam as before you have to inspect HTML content of each element of the Check boxes field to get the ID. This will be attached to the “div” as a hidden “input” field, being assigned the same ID for each Checkbox element in the question. Which sorta makes it easier for us to take out the Field ID just by inspecting a single Checkbox element in the question.

As you can see same ID value is assigned to each Check boxes field in the question. 😉 Easy peasy eh!

How to find the ID of a Date selection field?

Well this is a little unique, just go ahead right click to “Inspect” the element as usual in your Chrome. Here you’ll see somewhat similar to the above but with three hidden input fields.

There’s going to be three “input” hidden fields with the ID for each “Year”, “Month”, “Day” selection in a Date selection field. So you need to keep a track of those three IDs, “entry.xxxxxxx_year”, “entry.xxxxxxx_month”, and “entry.xxxxxxx_day” to send a complete data to fill the date selection field.

How to find the ID of a Time selection field?

This is very much similar to Date selection where as you got IDs assigned for “Hour” and “Minute” fields of a Time selection field.

But you need to keep in mind each of those two nodes are inside two separate parent “div” elements as shown above. Anyhow take a note of the “entry.xxxxxxx_hour”, and “entry.xxxxxxx_minute” fields above which are the IDs you’re going to require to set the values for your Time selection.

Well I assume that’s plenty of examples on how to hunt down the field identifiers in your Google Form. Any other given type of field should somewhat follow the same pattern with their hidden fields with the IDs, and it should be easy to figure out as long as you’re comfortable with reading simple HTML content!

Now according to my sample Google Form, following are the IDs of the fields available..

  • entry.1277095329
  • entry.995005981
  • entry.1155533672
  • entry.1579749043
  • entry.815399500_year
  • entry.815399500_month
  • entry.815399500_day
  • entry.940653577_hour
  • entry.940653577_minute

Off to next step then…

Then let’s fill the data…

Alright now we got all the field identifiers in our Google Form, next let’s move on to generating the URL that allows us to inject all those data into the fields. It’s actually quite easy as follows…

entry.xxxxxxxx1=This is answer 1

Given our Google Form link…

https://docs.google.com/forms/d/e/XxxxXXXxxxXXXx/viewform

We shall attach the all the field ID’s and their injected answers as follows…

https://docs.google.com/forms/d/e/XxxxXXXxxxXXXx/viewform?entry.xxxxxxxx1=This is answer 1&entry.xxxxxxxx2=This is answer2

We just have to pass the value assigning it to the question field ID, and attach it to the link of the Google Form. Navigating to the above link will present your Google Form with all the fields pre-filled with answers you parsed. More about it below..

Pass the values targeting the fields…

This is something you need to pay extra attention when it comes to the syntax of the URL, making sure to pass the proper field ID’s and their answers, and separating them properly in the URL without a mistake.

Let’s first take a look at how we’re assigning values to the list of fields in my sample Google Form…

  • entry.1277095329=Jumping Beans
  • entry.995005981=Banana Plums
  • entry.1155533672=Dogs with hats
  • entry.1579749043=Running Banana
  • entry.815399500_year=2019
  • entry.815399500_month=10
  • entry.815399500_day=28
  • entry.940653577_hour=03
  • entry.940653577_minute=04

Now those field IDs and their targeted answers should be merged into a URL. So let’s add the separation tag with ‘&’ and put them together accordingly.

https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/viewform?
entry.1277095329=Jumping Beans&
entry.995005981=Banana Plums&
entry.1155533672=Dogs with hats&
entry.1579749043=Running Banana&
entry.815399500_year=2019&
entry.815399500_month=10&
entry.815399500_day=28&
entry.940653577_hour=03&
entry.940653577_minute=04

You can see how the fields value assigning nodes are separated with the ‘&’ separation to be merged into a single URL and the complete URL should be formed as follows…

https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/viewform?entry.1277095329=Jumping Beans&entry.995005981=Banana Plums&entry.1155533672=Dogs with hats&entry.1579749043=Running Banana&entry.815399500_year=2019&entry.815399500_month=10&entry.815399500_day=28&entry.940653577_hour=03&entry.940653577_minute=04

Now if you click on the above link, it will show how my sample Google Form is pre-filled with all the answers I passed in the URL targeting each field.

Fire it up!

TADAAA! 😀 Pretty cool eh!

You can cross check with the values I have passed in the URL with the values that are auto-filled in the Google Form! 😉

Something about multiple choice fields…

One thing to keep in mind is that, when it comes to fields that you have to select values, such as Multiple choice fields, Drop down selection fields and so on, they need to be assigned with exact values already given in their list of answers. 😉 Otherwise the values injected will be ignored by the form, and rendered as empty. 😦

Well… That’s it!

You don’t have to set values for all your fields in the URL parameters, just include the ones you’re intending to fill up is enough. This could become very handy if you want to auto fill fields like “date and time fields” for the ease of your users or if you want to populate pre-set default values in your Form for your targeted users. Another aspect this could be handy is when you need an easy and quick way to generate some sample data from your Google Form submissions. 😉

So there you have it, how to easily pre-populate data in your Google Forms!

Share the love! 😀 Cheers!

XFHACKS-009 Frame with Border Image!

Ever wanted to have a Xamarin.Forms.Frame with a Border Image? Or have a Border Image around any of your Xamarin.Forms Elements? Welcome to another lightening short post of me hacking around Xamarin.Forms elements!

The Xamarin.Forms.Frame by default only has a boring BorderColor property without even letting you to set the Width of the Border or even set an Image as the Border.

So I thought of making use of my own crazy imagination and hack my way around to get this to work right from Xamarin.Forms itself!

No custom renderers, no platform specific code and no third party libraries! Just by using pure out of the box Xamarin.Forms! 😉

Sneak Peak!

That’s what we gonna be build yol! A Frame with a Border Image property along with the Border Width! 😉

XFHACKS Recipe!

Buckle up fellas, its recipe time! 😉 I’ve been writing quite a few hacks around Xamarin.Forms Frame element, and this recipe is also going to be based on my previous posts, XFHACKS-007 Frame with a Border Width! I would rather recommend you read up on that before continuing here, regardless I would explain the same concept in short here as well. Basically we’re placing a Frame element (child) inside another Frame element (parent) with a Margin value which will create visually a single frame with a Border as our choice of the Margin.

Now keeping that in mind for our Border Image we’re simply going to add Grid into the parent Frame and place an Image in it, while using the IsClippedToBounds=”True” property in both parent Frame and Grid Layout to avoid the Image element rendering itself outside the bounds of the parent Frame. Then on top of that Image inside the same Grid we’re placing our child Frame that I mentioned before with the Margin property that renders the Border aspect of the whole view.

Just like that you get the entire custom element put together which you could use as a single Frame element with a Border Image! 😉

Code!

Behold the golden XAML code!

<!--  Frame with Border Image  -->
<Frame
    Padding="0"
    CornerRadius="7"
    HasShadow="False"
    IsClippedToBounds="True">
    <Grid HeightRequest="50" IsClippedToBounds="True">
        <Image Aspect="AspectFill" 
            Source="{extensions:ImageResource   
            XFHacks.Resources.abstractbackground1.jpg}" />
        <Frame
            Margin="5"
            Padding="0"
            BackgroundColor="White"
            CornerRadius="5"
            HasShadow="False"
            IsClippedToBounds="True">
            <!--
                Whatever the content you want to
                place inside the Frame goes in here
            -->
        </Frame>
    </Grid>
</Frame>

 

There you have the Frame with Border Image in XAML just like I explained earlier. We have the parent Frame with IsClippedToBounds and CornerRadius property, the Grid and the Image with form the Border Image. Notice the Padding=”0″, since we want the Image with the Grid to spread across the parent Frame. You could change the CornerRadius as you wish to control the curved corner of the Frame.

I have given a HeightRequest value to the Grid just to make sure it renders to the exact size I need, or you could even let the whole element freely size itself according to the Element inside the whole custom Frame.  Then on top of that we have the child Frame with the Margin property cropping our the center of the Image element that’s placed under it, thus forming the Border Image as we wanted! 😀

Now let’s put it together and build something awesome! 😀

Fire it up!

Let me showcase the awesomeness of this with something fun!

 

There you go! 😀 Running side by side Android, iOS and UWP.

Grab it on Github!

https://github.com/UdaraAlwis/XFHacks

Well then, that’s it for now. More awesome stuff on the way!

Cheers! 😀 share the love!

XFHACKS-008 Label with Border and Background!

Ever wanted to have a Xamarin.Forms.Label, with a Border, or even better with a Background, or with a Corner Radius customization? Welcome to another lightening short post of me hacking around Xamarin.Forms elements!

By default Xamarin.Forms.Label doesn’t have a Border, Background neither a Corner Radius property, the only possible way to achieve that is by resorting to custom renderers. So I thought of making use of my own crazy imagination and hack my way around to get this to work right from Xamarin.Forms itself!

No custom renderers, no platform specific code and no third party libraries! Just by using pure out of the box Xamarin.Forms! 😉

Sneak Peak!

That’s what we gonna be build yol!

A Label with a Border and a Background, none other than with Corner Radius customization, a true dream come true for Xamarin.Forms developers! lol kidding! 😉

XFHACKS Recipe!

Buckle up fellas, its recipe time! 😉 Now this hack basically has mostly to do with my previous post, XFHACKS-007 Frame with a Border Width! If you would like to read more on detail about it then please check that article and come back here, but let me explain it in short form here though. Basically we’re placing a Frame element inside another Frame element with a Margin value which will create visually a single frame with a Border as our choice of the Margin.

Now for our Label, we’re going to place it inside that custom Frame we just built, giving it a nicely rendered border around it. You have the complete control over the Border Width property as explained in my previous article.

And the best part of it is that this Frame will resize itself according to the Label inside of it, since we’re not restricting it to any static values, whatever the Height or Width property you set to the Label, the border will follow it. Talking of Alignment of the Label you can freely use the Margin, HorizontalOptions and VerticalOptions to easily align the Label inside the Border. 😉

Code!

Behold the golden XAML code!

<!--  Label with a Border  -->
<Frame
    Padding="0"
    BackgroundColor="#2196F3"
    CornerRadius="7"
    HasShadow="False">
    <Frame
        Margin="2"
        Padding="5"
        BackgroundColor="White"
        CornerRadius="5"
        HasShadow="False">
        <Label
            BackgroundColor="Transparent"
            HorizontalOptions="Center"
            Text="Border with curved corners"
            TextColor="Black" />
    </Frame>
</Frame>

 

There you have the Label with a Border in XAML! Just like I explained above the two Frames rendering the Border around it. Feel free to change the Margin value of the child Frame element to increase or decrease the Border-Width. And both Frames CornerRadius are used to give a curved corners effect to the Border. Let’s see it in actions:

If you want to have curved sides for the Label Border, then simply increase the CornerRadius=”16″ parent Frame and CornerRadius=”14″ for the child Frame.

Now Imagine if you want to Align the Label inside the Border, then simply use the HorizontalOptions property as you wish, for example HorizontalOptions=”Start” and just to avoid the Label crashing with the border use the Margin property of the Label in whichever the direction you’re aligning your Label to, as an example Margin=”5,0,0,0″

How about that Background I promised earlier, well then simply set the child Frame’s background Color as you wish, and if you prefer to have a different Color for Border and Background, just make sure to set different colors to parent Frame’s Background color and child Frame’s background color.

Now how about having a Background Image, what you need to do is simply add an Image behind the Label using a Grid Layout by laying down both the elements on top of each other.

<!--  Label with a Background  -->
<Frame
    Padding="0"
    BackgroundColor="#2196F3"
    CornerRadius="7"
    HasShadow="False">
    <Frame
        Margin="2"
        Padding="0"
        BackgroundColor="White"
        CornerRadius="5"
        IsClippedToBounds="True"
        HasShadow="False">
        <Grid HeightRequest="30" IsClippedToBounds="True">
            <Image Aspect="AspectFill" Source="{extensions:ImageResource XFHacks.Resources.abstractbackground.jpg}" />
            <Label
                BackgroundColor="Transparent"
                FontAttributes="Bold"
                HorizontalOptions="Center"
                Text="With a Cool Background!"
                TextColor="White"
                VerticalOptions="Center" />
        </Grid>
    </Frame>
</Frame>

 

There you have it, the golden XAML! So what we have done here is basically the same concept but with a bit more icing on top, by removing the padding inside the child Frame allowing the Image background to stretch to on to the edge of the border. Then inside the child Frame we have a Grid Layout, and its got a HeightRequest property which determines the Height of the Label, meanwhile cropping out using IsClippedToBounds property, the excessive rendering of the Image inside that’s acting as the Background.

Now let’s put it together and fire it up! 😉

Fire it up!

Load your cannons, fire it up!

 

There you go! 😀 Running side by side Android, iOS and UWP.

A little Trick! 😉

Just like how I’ve implemented the Border and Background for the Label element, you could follow the same pattern and use this for any UI Element in Xamarin.Forms as you wish, such as Image, Editor, Slider, ListView, etc whichever you wish! 😉 Just replace that Label with the UI element of your choice! 😀

Grab it on Github!

https://github.com/UdaraAlwis/XFHacks

Well then, that’s it for now. More awesome stuff on the way!

Cheers! 😀 share the love!

XFHACKS-006 Password Entry with show/hide Text feature!

Ever wished if your Xamarin.Forms Password Entry control had the option to reveal, or show the Password text that the User types on demand, instead of the black dots? 😉  Even better, without any Custom Renderers or Platform Specific code? Welcome to another lightening short post of me hacking around Xamarin.Forms elements!

So in Xamarin.Forms to enable this feature usually you need to resort to creating Custom Renderers or some platform specific implementation, which is a tedious process and a complicated implementation. So I thought of making use of my own crazy imagination and hack my way around to get this to work right from Xamarin.Forms itself!

No custom renderers, no platform specific code and no third party libraries! Just by using pure out of the box Xamarin.Forms! 😉

Sneak Peak!

That’s what we gonna be build yol!

XFHACKS Recipe!

Let the recipe begin! So basically the idea here is to have two Entry elements which represents the Entry with IsPassword enabled and another Entry with IsPassword disabled, laid on top of each other inside a Grid layout. Also we’re going to switch the visibility of these two Entry controls on a Button click event which will also be laid on top of both the Entry elements, aligned to the right most corner of the whole Grid layout. Just to add some cheery to the icing, let’s have a Button with an Icon Image inside of it, which implementation I’ll be extracting from one of my previous XFHACKS articles, XFHACKS-005 Button with full control on Text and Icon! ! Give it a read if you’re curious! 😉

Since we’re maintaining two Entry elements, we need to make sure both of them have the same Text value at any point of the user’s interaction. So to make this happen we’re going use Element to Element binding in Xamarin.Forms, where as we are binding the Text field properties of both Entry controls to eachother. Thereby one Entry’s Text changes immediately reflects on the other one and so on.

Just to show some love for my architectural practices, I’m going to move the whole Button click event and the handling of the behavior logic of this control into a TriggerAction, aha! separation of concern or loosely coupled and no direct code behind dependency allowing for more re-usability! 😀

Code!

Behold the golden XAML code!

<Grid
   Grid.Row="1"
   Grid.Column="0"
   HeightRequest="45"
   HorizontalOptions="FillAndExpand"
   IsClippedToBounds="True">

   <!--  Entry Password  -->
   <Entry
      x:Name="EntryPassword"
      Grid.Row="0"
      Grid.Column="0"
      FontSize="Medium"
      IsPassword="True"
      IsVisible="True"
      Keyboard="Plain"
      Placeholder="Password"
      Text="{Binding Source={x:Reference EntryText}, Path=Text, Mode=TwoWay}" />

   <!--  Entry Text  -->
   <Entry
      x:Name="EntryText"
      Grid.Row="0"
      Grid.Column="0"
      FontSize="Medium"
      IsPassword="False"
      IsVisible="False"
      Keyboard="Plain"
      Placeholder="Password"
      Text="{Binding Source={x:Reference EntryPassword}, Path=Text, Mode=TwoWay}" />

   <!--  Button with Icon  -->
   <Grid
      Grid.Row="0"
      Grid.Column="0"
      Padding="0,0,3,0"
      HeightRequest="27"
      HorizontalOptions="End"
      IsClippedToBounds="True"
      VerticalOptions="Center"
      WidthRequest="35">

      <!--  Button Control  -->
      <Button x:Name="ShowPasswordButton" BackgroundColor="White">
         <Button.Margin>
            <OnPlatform x:TypeArguments="Thickness">
               <On Platform="Android" Value="-4,-6,-4,-6" />
               <On Platform="iOS" Value="0" />
            </OnPlatform>
         </Button.Margin>
         <Button.Triggers>
            <EventTrigger Event="Clicked">
               <triggers:ShowPasswordTriggerAction
                  EntryPasswordName="EntryPassword"
                  EntryTextName="EntryText"
                  IconImageName="ShowPasswordButtonIcon" />
            </EventTrigger>
         </Button.Triggers>
      </Button>

      <!--  Icon Image  -->
      <Image
         x:Name="ShowPasswordButtonIcon"
         HeightRequest="25"
         HorizontalOptions="Fill"
         InputTransparent="True"
         Source="{extensions:ImageResource XFHacks.Resources.showpasswordicon.png}"
         VerticalOptions="Fill"
         WidthRequest="25" />
   </Grid>

</Grid>

 

Here we go, explanation time! So the two Entry elements are laying on top of each other and bound to each other’s Text properties, while having one Entry as IsPassword=true and the other opposite. I have given names for the Elements because we need references of them to handle the behaviour inside our TriggerAction which I will show next.

Then the Button with the Icon Image Element is aligned to the very right corner of Parent layout, laying on top of both Entry elements. I have added some padding to it to avoid it conflicting with the border of the Entry in iOS and UWP, then for Android it shouldn’t really matter visually. There’s a HeightRequest=”27″ and WidthRequest=”35″ given to this Element group because I needed to have some horizontal space besides the Image icon visually. For the Image we’re using a EmbeddedResource type image, which makes things really easy for managing the Images.

Then for the Parent Grid Layout that holds all of these Elements together,is using IsClippedToBounds property to make sure everything holds inside the Bounds of the Grid as a single UI Element.

This is the most crucial part where inside the Button click event we’re invoking a TrigerAction called ShowPasswordTriggerAction which handles all the logic and behaviour of this custom control. And we’re passing in the names of the Elements we have assigned, into the Trigger so that we can look it up inside the TriggerAction, retrieve their runtime references and handle the behavior as we need. Pretty straightforward implementation there 😉

Next let’s look into the golden TriggerAction!

/// <summary>
/// The Trigger Action that will handle
/// the Show/Hide Passeword text
/// </summary>
public class ShowPasswordTriggerAction : TriggerAction<Button>
{
    public string IconImageName { get; set; }

    public string EntryPasswordName { get; set; }

    public string EntryTextName { get; set; }

    protected override void Invoke(Button sender)
    {
        // get the runtime references 
        // for our Elements from our custom control
        var imageIconView = ((Grid) sender.Parent)
                  .FindByName<Image>(IconImageName);
        var entryPasswordView = ((Grid) ((Grid) sender.Parent).Parent).FindByName<Entry>(EntryPasswordName);
        var entryTextView = ((Grid)((Grid)sender.Parent).Parent).FindByName<Entry>(EntryTextName);

        // Switch visibility of Password 
        // Entry field and Text Entry fields
        entryPasswordView.IsVisible =     
                       !entryPasswordView.IsVisible;
        entryTextView.IsVisible = 
                       !entryTextView.IsVisible;

        // update the Show/Hide button Icon states 
        if (entryPasswordView.IsVisible)
        {
            // Password is not Visible state
            imageIconView.Source = ImageSource.FromResource(
                "XFHacks.Resources.showpasswordicon.png",
                Assembly.GetExecutingAssembly());

            // Setting up Entry curser focus
            entryPasswordView.Focus();
            entryPasswordView.Text = entryTextView.Text;
        }
        else
        {
            // Password is Visible state
            imageIconView.Source = ImageSource.FromResource(
                "XFHacks.Resources.hidepasswordicon.png",
                Assembly.GetExecutingAssembly());

            // Setting up Entry curser focus
            entryTextView.Focus();
            entryTextView.Text = entryPasswordView.Text;
        }
    }
}

 

Here’s the most important bit where we’re handling the behaviour logic of our awesome Password Entry Control! At the moment of Invoking the Button click we’re doing a simple FindByName<T> look up for our required Elements, that are the EntryPassword field, EntryText field, and the IconImage.

First of all we’re setting the visibility of the two Entry Elements opposite for each other, as in if the User clicks on Show Password state, then the Entry with Text property will be displayed, and the user clicks on Hide Password state then the Entry with Password property (black dots) will be displayed.

Then based on the state, we’re updating the button icon’s Image source, as you can see we’re setting the showpasswordicon.png and hidepasswordicon.png respectively depending on the current state.

Finally we’re doing something extra to make sure whatever the visible the Entry element is still on Focus after the switching of the Password visibility state.

There we go, pretty straight forward yeah!

 Important: You could also move that whole piece of XAML to a separate XAML file, so that you could set it up as a reusable Control in your project! 😉

Fire it up!

Alright let’s see this in action!

 

There you have it running on Android, iOS and UWP like a charm! 😀

NO CUSTOM RENDERERS! NO NATIVE CODE! MORE AWESOME! xD

Grab it on Github!

https://github.com/UdaraAlwis/XFHacks

Well then, that’s it for now. More awesome stuff on the way!

Cheers! 😀 share the love!

Improvement suggestion: I was discussing this with one of my colleagues and he pointed out an awesome tweak for a much better improvement, that is to use the same implementation with trigger and all but with a single Entry element with the IsPassword true and false state on demand instead of using two Entry elements. This is a great idea yet so simple, which will drastically improve the rendering performance. So if you wanna give it a crack please go ahead! And here’s a shout out to an awesome developer Akshay Kulkarni – ak47akshaykulkarnimake sure to check out his Github repo! 😉

XFHACKS-005 Button with full control on Text and Icon!

Ever came across an instance where you wished if you had more control or customization over the Text and Icon properties of your Xamarin.Forms Button? even better even without any Custom Renderers or Platform Specific code? Welcome to another lightening short post of me hacking around Xamarin.Forms elements!

Uh oh, in Xamarin.Forms?!

The default Xamarin.Forms Button has it’s own limitations for customisation, specially in the Text and Icon, there’s not much control over those properties in terms of,

  • Alignment of Text and Icon
  • Positioning of Text and Icon 
  • Default upper case Text in Android
  • Icon Image Size and Aspect Property
  • Icon Source only limited for Local Images

Talking of the Icon Source, you can only use Platform Specific Local Images for it, you cannot use Embedded Resources for it.

So I thought of making use of my own crazy imagination and hack my way around to fix all those limitations!

No custom renderers, no platform specific code and no third party libraries! Just by using pure out of the box Xamarin.Forms! 😉

Usual approach…

Now as an out of the box solution for this we could avoid using Xamarin.Forms Button totally and switch to a Xamarin.Forms Label or Image control with a Tap gesture recognizer attached to it. But then it wouldn’t actually give that nice look and feel of a button does it, specially in Android that nice ripple effects and on iOS the fade out effect on the button click is something really nice to have on your UI.

So… wait for it….

XFHACKS Receipe!

Here’s my awesome solution, we’re still going to stick to Xamarin.Forms Button button, and we’ll be laying down a Label or an Image on top of our Button view inside a Grid layout. This is actually very common hack of mine if you had gone through previous XFHACKS articles of my blog.

Yep sounds super simple, yet solves all of the issues I just mentioned above. Basically we’re constructing our own Custom Button control right from Xamarin.Forms elements, properties and behaviours without any custom renderers or platform code.

So getting into more details, here’s how we’re going to solve the above talked issues. For Alignment of the Text and Icon in the button, we are going to use the HorizontalOption of both Image and Label element that we’re placing on top of the Button. Then the Position of those elements, we shall resort to the Margin property of each. Since we’re using the Image control itself the Source property issue is automatically solved. Then as an added advantage you could also have the control over the Aspect property of the Image Icon you want to display in your button.

Now on top of all that one might wonder when you place a Label or Image on top of a Button, wouldn’t it obstruct the Clickable touch area of the Button? That’s where InputTransparent comes into rescue, passing down the touch even down to the Button straight away!

To add some cherry on top of the icing, we’re going to use the IsClippedToBounds property to crop out any areas of the inner elements of the Grid being rendered outside the View bounds of the Grid itself, so everything comes together as a single Element on UI.

Now all these comes together solving the issues that I have pointed out at the beginning! 😉

Sneak Peak!

That’s what we gonna be build yol!

Code and Run!

Behold the golden XAML code!

<!--  Button with Text and Icon  -->
<Grid
    Grid.Row="1"
    Grid.Column="0"
    HeightRequest="40"
    HorizontalOptions="Fill"
    IsClippedToBounds="True"
    VerticalOptions="Center">

    <!--  Button Control  -->
    <Button BackgroundColor="#2196F3">
        <Button.Margin>
            <OnPlatform x:TypeArguments="Thickness">
                <On Platform="Android" Value="-4,-6,-4,-5" />
                <On Platform="iOS" Value="0" />
            </OnPlatform>
        </Button.Margin>
    </Button>

    <!--  Text Label  -->
    <Label
        Margin="10,0,0,0"
        FontAttributes="Bold"
        FontSize="Small"
        HorizontalOptions="Start"
        HorizontalTextAlignment="Center"
        InputTransparent="True"
        Text="go next"
        TextColor="White"
        VerticalOptions="Center"
        VerticalTextAlignment="Center" />

    <!--  Icon Image  -->
    <Image
        Margin="0,0,5,0"
        HeightRequest="30"
        HorizontalOptions="End"
        InputTransparent="True"
        Source="{extensions:ImageResource XFHacks.Resources.rightarrowicon.png}"
        VerticalOptions="Center"
        WidthRequest="30" />
</Grid>

 

There you have it as we discussed earlier, our empty Button and on top of that the Label and the Image elements inside a Grid. As you can see the Button has some Margin value added for Android run time of, “-4,-6,-4,-5” which is to get rid of the default empty space that’s rendered around the Button at Android run time. The button will be spread across the whole Grid in background with its default HorizontalOptions=”Fill” property.

The Grid’s IsClippedToBounds=”True” property value makes sure it will cut off any inner elements that will render themselves out of the bounds of Grid. You can set whatever the HeightRequest or WidthRequest as you wish if you want to customize this even further.

Now speaking of the Label and Image you can see how I’m using the advantage of HorizontalOptions to align the elements as whatever the way I wish along with the Margin property of them, adding space wherever I wish. In here we have pushed the Label to the beginning of the Button and the Icon to the End of the Button horizontally.

Next the  InputTransparent=”True” comes in solving the touch issue, which will pass the touch action down to the Button element when the user clicks on it, giving the exact effect of a Button. The use of Image element we can now set whatever the size we wish for our Icon inside the button and adjust its Aspect property and so on.

And let’s try something else as well! Lets have a Button which has its Text and Icons aligned to the Right most corner.

<!--  Button with Text and Icon  -->
<Grid
    Grid.Row="0"
    Grid.Column="1"
    HeightRequest="40"
    HorizontalOptions="Fill"
    IsClippedToBounds="True"
    VerticalOptions="Center">

    <!--  Button Control  -->
    <Button Grid.ColumnSpan="2" BackgroundColor="#2196F3">
        <Button.Margin>
            <OnPlatform x:TypeArguments="Thickness">
                <On Platform="Android" Value="-4,-6,-4,-5" />
                <On Platform="iOS" Value="0" />
            </OnPlatform>
        </Button.Margin>
    </Button>

    <!--  Text Label  -->
    <Label
        Grid.Column="0"
        Margin="0,0,5,0"
        FontAttributes="Bold"
        FontSize="Small"
        HorizontalOptions="End"
        HorizontalTextAlignment="End"
        InputTransparent="True"
        Text="favs"
        TextColor="White"
        VerticalOptions="Center"
        VerticalTextAlignment="Center" />

    <!--  Icon Image  -->
    <Image
        Grid.Column="1"
        Margin="0,0,10,0"
        HeightRequest="30"
        HorizontalOptions="End"
        InputTransparent="True"
        Source="{extensions:ImageResource XFHacks.Resources.staricon.png}"
        VerticalOptions="Center"
        WidthRequest="30" />

    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="Auto" />
    </Grid.ColumnDefinitions>
</Grid>

 

Here’s another example where I have pushed the Image Icon to the End of the Button and the Label to be following it horizontally.

You can follow the same implementation and have our Button’s Text and Icon aligned t other Left most corner.

Now just like that you can customize all the aspects of a Button using this hack I just shared, just set up the Label and Icon with whatever the properties and customization as you wish on top of a Button. That’s it!

 Important: You could also move that whole piece of XAML to a separate XAML file, so that you could set it up as a reusable Control in your project! 😉

Fire it up!

Let me share some examples I’ve built using this awesomeness!

There you go our awesome Custom Button control running on Android, as you can see with all the preserved Button click effect! 😀

 

Since its completely out of the box Xamarin.Forms, you can run it across all the native platforms and expect the same results! 😉

Grab it on Github!

https://github.com/UdaraAlwis/XFHacks

Well then, that’s it for now. More awesome stuff on the way!

Cheers! 😀 share the love!

Simple Segmented Button Control in pure Xamarin.Forms!

A Segmented Control, or as some call it Grouped Button Control, or Tabbed Button Control or some even call the Rocker Control, is what I’m gonna share with yol today, built 100% from Xamarin.Forms!

Yeah such a platform specific UI element, right out of Xamarin.Forms without a single line of native code, how’s that even? Well if you’ve been following my blog for a while, you know that I’m all about pushing them limits of any given platform and achieve the impossibru! 😉

Whut whut in Xamarin.Forms?

So there’s many different interpretations of this UI elements and also different use cases. Specifically you can see this in native Tabbed Page views in both Android and iOS. And in native platforms they actually have their own Segmented button controls, that allows you to have a set of buttons in a single segment, that allows you to have a selected state, which will let you perform a certain operation, change a value or load a certain View to another element.

So when it comes to Xamarin.Forms, there’s no out of the box UI element that provides this view, unless you use Xamarin.Forms TappedPage control, in which case is impractical if you’re not in need of a Tabbed Page, or worse case in a Content element area where you absolutely can’t use a Page element.

Le Solucioano!

So here’s my solution for this, a Segmented Control in pure Xamarin.Forms, that allows you to have the same exact look and feel and behavior of a native Segmented Control, or a Tabbed Button Control or a Rocker Control or whatever. Lol

Specially no custom renderers, no native code or whatever, just simple and pure Xamarin.Forms! 😉

Sneak Peak

Here’s a sneak peak of what I built, on iOS..

And on Android..

Look at the eh, just like a native control with all the looks and feels and behaviours…

This whole awesome project is hosted up in my Github repo : https://github.com/UdaraAlwis/XFSegmentedControl 

Recipe time…

Buckle up, contains a whole bunch of me hacking around pushing the limits of Xamarin.Forms to achieve some impossibru! 😉

So first thing, we need to keep in mind the aspect of having the same look and feel of a native Segmented control, in aspect of both Android and iOS, therefore we’re going to be using a lot of platform specific properties in XAML and code behind.

We are going to have two Buttons inside a Layout, to emulate the two segmented Buttons. The layout is going to be a Xamarin.Forms Frame, since it has the property CornerRadius, which is vital to gain the curved corners appearance for iOS, and Border property, which we can use to draw the border around the element for iOS. As of Android we can disregard both of those properties. Also don’t forget about the IsClippedToBounds property which all the Layout elements has in Xamarin.Forms, allowing you to crop out of bounds elements inside the layout, which will allow us to have that curved corners in iOS without the button borders popping out of it.

So you might say as of the Button we could use a Label or something and then use a Tap Gesture to handle the click event. Nope! I like the perfection of whatever I’m building! 😉 Therefore we’re going to use actual Xamarin.Forms Button control, now hold on…

Now speaking of the Buttons, we can’t use Buttons with text inside, since the default behaviour of a button restricts the visibility of Text inside it. Therefore we’re going to use a little hack I have always used, that is placing one element over another inside a Grid view. So we are going to use a Button without text inside of it, and then a Label on top of it that represents the Text of the Segmented Button. So you’re probably worries about the Button click behaviour since we’re laying out a Label on top of it, but hello don’t worry, that’s where InputTransparent comes into rescue, passing down the touch even down to the Button straight away! So on selection of the Button we shall do the necessary changes to show the IsSelected status.

We are going to assign name identifiers to our elements in this control to handle some of the code behind magic as well, in case you wondered when you see the code! 😀

Also not to mention that we’re going to maintain properties inside the custom control, like Colors, Text, Selected Button Index properties and also an EventHandler to inform the changes of the Segment button selection.

Well that’s pretty much it, with a bit more details to be gotten into later.

XAML time…

We’re going to create a custom control elements that’s going to be independent and reusable anywhere in the project. Let’s call it SimSegmentedControl, thus denoting “Simple Segmented Control”!

<?xml version="1.0" encoding="UTF-8" ?>
<ContentView
    x:Class="XFSegmentedControl.Simple.Controls.SimegmentedControl"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:system="clr-namespace:System;assembly=netstandard">
    <ContentView.Content>
	
	<!--  Rest of content goes here (Next code snippet) -->
	
    </ContentView.Content>
</ContentView>

 

Now let’s get into the inside elements of our SimSegmentedControl, which is basically the Frame Layout that I explained before.

<Frame
    x:Name="FrameView"
    Padding="0"
    IsClippedToBounds="True">
    <!--  Platform specific customization values for the border  -->
    <Frame.HasShadow>
        <OnPlatform x:TypeArguments="system:Boolean">
            <On Platform="Android" Value="False" />
            <On Platform="iOS" Value="True" />
        </OnPlatform>
    </Frame.HasShadow>
    <Frame.CornerRadius>
        <OnPlatform x:TypeArguments="system:Single">
            <On Platform="Android" Value="0" />
            <On Platform="iOS" Value="5" />
        </OnPlatform>
    </Frame.CornerRadius>
    <Frame.HeightRequest>
        <OnPlatform x:TypeArguments="system:Double">
            <On Platform="Android" Value="50" />
            <On Platform="iOS" Value="35" />
        </OnPlatform>
    </Frame.HeightRequest>
    <!--  Platform specific customization values for the border  -->

    
    <!--  Segmented Buttons go in here (Next code snippet)  -->
    
</Frame>

 

As you can see I have added a whole bunch of platform specific customization values for Android and iOS to achieve the design we’re targeting for, such as CornerRadius and Height.

Then let’s add our Segmented Button elements, just to make it easier let’s identify each of them as “Tab Button” element.

<Grid ColumnSpacing="0">

    <!--  Tab button 1  -->
    <Grid Grid.Column="0" IsClippedToBounds="True">
        <Button
            x:Name="Tab1ButtonView"
            Margin="-2,-3,-2,0"
            Clicked="Tab1Button_OnClicked" />
        <Label
            x:Name="Tab1LabelView"
            FontAttributes="Bold"
            FontSize="Medium"
            HorizontalOptions="CenterAndExpand"
            InputTransparent="True"
            Text="Tab 1"
            VerticalOptions="CenterAndExpand" />
        <BoxView
            x:Name="Tab1BoxView"
            HeightRequest="2"
            InputTransparent="True"
            IsVisible="False"
            VerticalOptions="End" />
    </Grid>
    <!--  Tab button 1  -->

    <!--  Tab button 2  -->
    <Grid Grid.Column="1" IsClippedToBounds="True">
        <Button
            x:Name="Tab2ButtonView"
            Margin="-2,-3,-2,0"
            Clicked="Tab2Button_OnClicked" />
        <Label
            x:Name="Tab2LabelView"
            FontAttributes="Bold"
            FontSize="Medium"
            HorizontalOptions="CenterAndExpand"
            InputTransparent="True"
            Text="Tab 2"
            VerticalOptions="CenterAndExpand" />
        <BoxView
            x:Name="Tab2BoxView"
            HeightRequest="2"
            InputTransparent="True"
            IsVisible="False"
            VerticalOptions="End" />
    </Grid>
    <!--  Tab button 2  -->

    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>
</Grid>

 

Voila! behold the two button elements, with all the platform specific customizations, just like how I explained before, Label on top of a Button inside a Grid layout. Also you may have noticed the Margin property that I have used with “-2,-3,-2,0”, which is to stretch out the empty border line of the buttons out of the Grid so it crops out with the IsClippedToBounds property.

And the BoxView is to emulate the bottom line we have in Android look and feel of the Segmented Control.

Code-behind time…

Now this is where we’re basically going to handle all the action in our SegmentedControl!

So I’m not going to spoon feed the whole code in this blog post, since its going to be a pretty lengthy one, so I’ll be cutting out most of the repetitive code which you can easily figure out yourself or just check out on my github repo where I have committed this whole project code.

So like I explained at beginning we’re going to have a bunch of properties that are going to handle all the customization values such as Color, Text, SelectedIndex, EventHandler and so on. And then apply a whole bunch of code behind customization for platform specific look and feels, along with the handling of Segment button click event behavior.

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class SimSegmentedControl : ContentView
{
    public static readonly BindableProperty PrimaryColorProperty
        = BindableProperty.Create(
            nameof(PrimaryColor),
            typeof(Color),
            typeof(SimSegmentedControl),
            Color.CornflowerBlue);

    public Color PrimaryColor
    {
        get { return (Color)GetValue(PrimaryColorProperty); }
        set { SetValue(PrimaryColorProperty, value); }
    }

    // SecondaryColorProperty

    // Tab1TextProperty

    // Tab2TextProperty

    // SelectedTabIndexProperty
    
    public event EventHandler<SelectedTabIndexEventArgs> SelectedTabIndexChanged;

    public SimSegmentedControl()
    {
        InitializeComponent();
    }

    /// <summary>
    /// load up the customizations and applying
    /// properties when the element has rendered
    /// </summary>
    protected override void OnParentSet()
    {
        base.OnParentSet();
        
        // Setting up platform specific properties for Android and iOS
        if (Device.RuntimePlatform == Device.Android)
        {
            Tab1LabelView.FontSize
                = Device.GetNamedSize(NamedSize.Medium, Tab1LabelView);
            Tab2LabelView.FontSize
                = Device.GetNamedSize(NamedSize.Medium, Tab1LabelView);

            Tab1ButtonView.BackgroundColor = PrimaryColor;
            Tab2ButtonView.BackgroundColor = PrimaryColor;

            Tab1BoxView.Color =
            Tab2BoxView.Color =
            Tab1LabelView.TextColor =
            Tab2LabelView.TextColor = SecondaryColor;
        }
        else if (Device.RuntimePlatform == Device.iOS)
        {
            Tab1LabelView.FontSize
                = Device.GetNamedSize(NamedSize.Small, Tab1LabelView);
            Tab2LabelView.FontSize
                = Device.GetNamedSize(NamedSize.Small, Tab1LabelView);

            Tab1ButtonView.BackgroundColor =
            Tab2ButtonView.BackgroundColor = PrimaryColor;

            FrameView.BorderColor =
            Tab1LabelView.TextColor =
            Tab2LabelView.TextColor = SecondaryColor;
        }

        Tab1LabelView.Text = Tab1Text;
        Tab2LabelView.Text = Tab2Text;

        // setting up default values
        SelectTab1();
        SelectedTabIndex = 1;
        SendSelectedTabIndexChangedEvent();
    }

    private void Tab1Button_OnClicked(object sender, EventArgs e)
    {
        SelectTab1();
        SelectedTabIndex = 1;
        SendSelectedTabIndexChangedEvent();
    }

    private void Tab2Button_OnClicked(object sender, EventArgs e)
    {
        SelectTab2();
        SelectedTabIndex = 2;
        SendSelectedTabIndexChangedEvent();
    }
    
    // SelectTab1()
    
    // SelectTab2()
    
    // SendSelectedTabIndexChangedEvent()
}

 

So we PrimaryColor and SecondaryColor which handles the two main colors that is styling our SimSegmentedControl, which is exactly how it being used in native version of this control as well, just two simple Colors styling the whole element.

Then Tab1Text and Tab2Text property to handle the Text that needs to be displayed in the Segmented buttons.

As you can see OnParentSet (this is when the View is rendered in memory and just about to be displayed on the Page) we’re applying all the platform specific customization for the elements in our SimSegmentedControl. Then you can see we’re setting the Tab1 and Tab2 text properties to our Labels, which is not actually good practice, but I was too lazy to add that in the PropertyChangedEvent handler of those respective bindable properties. After that at the end you can see we’re setting the default values.

Also the SelectedTabIndexChanged EventHandler is there to notify any outside element who wants to be aware of the selected Tab in our SimSegmentedControl, so they can perform whatever the action based on it.

Then let me get into the SelectTab1(), SelectTab2() and SendSelectedTabIndexChangedEvent methods.

private void SelectTab1()
{
    // set up platform specific
    // properties for SelectTab1 event
    if (Device.RuntimePlatform == Device.Android)
    {
        Tab1BoxView.IsVisible = true;
        Tab2BoxView.IsVisible = false;
    }
    else if (Device.RuntimePlatform == Device.iOS)
    {
        Tab1ButtonView.BackgroundColor = SecondaryColor;
        Tab2ButtonView.BackgroundColor = PrimaryColor;

        Tab1LabelView.TextColor = PrimaryColor;
        Tab2LabelView.TextColor = SecondaryColor;
    }
}

private void SelectTab2()
{
    // set up platform specific
    // properties for SelectTab2 event
    if (Device.RuntimePlatform == Device.Android)
    {
        Tab1BoxView.IsVisible = false;
        Tab2BoxView.IsVisible = true;
    }
    else if (Device.RuntimePlatform == Device.iOS)
    {
        Tab1ButtonView.BackgroundColor = PrimaryColor;
        Tab2ButtonView.BackgroundColor = SecondaryColor;

        Tab1LabelView.TextColor = SecondaryColor;
        Tab2LabelView.TextColor = PrimaryColor;
    }
}

/// <summary>
/// Invoke the SelectedTabIndexChanged event
/// for whoever has subscribed so they can
/// use it for any reative action
/// </summary>
private void SendSelectedTabIndexChangedEvent()
{
    var eventArgs = new SelectedTabIndexEventArgs();
    eventArgs.SelectedTabIndex = SelectedTabIndex;

    SelectedTabIndexChanged?.Invoke(this, eventArgs);
}

--------------

public class SelectedTabIndexEventArgs : EventArgs
{
    public int SelectedTabIndex { get; set; }
}

 

So there you can see in SelectTab1() we’re setting up the necessary customization for the Selected state of our Segmented Button for both Android and iOS, such as the BackgroundColor, TextColor and whatnot. And then in SelectTab2() we’re doing the exact opposite customization, Button 1 -> Unselected and Button 2 -> Selected appearance.

Then in the SendSelectedTabIndexChangedEvent we’re basically broadcasting the selected Tab index of our SimSegmentedControl with the SelectedTabIndex property value.

Time to consume!

Let’s use this awesome SimSegmentedControl in our Page shall we?!!! 😀

<local:SimSegmentedControl
	x:Name="SegmentedControlView"
	PrimaryColor="CornflowerBlue"
	SecondaryColor="White"
	SelectedTabIndexChanged="SegmentedControlView_SelectedTabIndexChanged"
	Tab1Text="Monkeys"
	Tab2Text="Minions">
	<local:SimSegmentedControl.Padding>
		<OnPlatform x:TypeArguments="Thickness">
			<On Platform="Android" Value="0" />
			<On Platform="iOS" Value="10,0,10,10" />
		</OnPlatform>
	</local:SimSegmentedControl.Padding>
</local:SimSegmentedControl>

 

Easy peasy, you just set the property values such as PriaryColor, SecondaryColor and so on that we created in our SimSegmentedControl and do a bit of customization if you wish to 😉 like I’ve added some padding for iOS!

In case if you’re wondering how to use the SelectedTabIndexChanged, you basically subscribe to that event and perform whatever the action you desire, whether it be changing some values, or swapping some Views or whatever your requirement is!

private void SegmentedControlView_SelectedTabIndexChanged
			(object sender, SelectedTabIndexEventArgs e)
{
	if (e.SelectedTabIndex == 1)
	{
		ContentView1.IsVisible = true;
		ContentView2.IsVisible = false;
	}
	else if (e.SelectedTabIndex == 2)
	{
		ContentView1.IsVisible = false;
		ContentView2.IsVisible = true;
	}
}

 

Just like that!

Let’s fire it up!

Let’s see this beauty in action now! 😀

Here we go baby! iOS and Android running side by side…

 

Let’s change up a bit of the colors shall we!

Woot, whatever the color combination you wish! 😉

Improvement suggestions..

Well if you ask me this is not the exact implementation I used for my actual requirement, this is more of a very simple implementation of it.

But there’s many ways to improve this. One would be adding Command for the selected Tab Index changed property handling. Also add both way handling of SelectedTabIndex so that we can set the default selected Tab on the go. Specially add dynamic Tab Buttons to the SimSegmentedControl at run time without just limiting to 2 buttons. 😉

Well your imagination is the limit fellas! 😀

This whole awesome project is hosted up in my Github repo : https://github.com/UdaraAlwis/XFSegmentedControl 

Check out the Part 2 of this article: Advanced Segmented Button Control in pure Xamarin.Forms!

Cheers! 😀 Keep on going my fellow devs!

Spread the love…

XFHACKS-004 Editor with a Placeholder!

Ever wanted to have a Placeholder property for your Xamarin.Forms.Editor control? Welcome to another lightening short post of me hacking around Xamarin.Forms elements to build cool stuff and get sh*t done! 😉

By Default Xamarin.Forms.Editor is a pretty boring control with not much room for customization, but is a very useful control. So I had always wondered why it didn’t have a Placeholder property like we have to the Entry control.

So I thought of build an Editor with a Placeholder by myself, without any custom renderers or native code or third party libraries. 😉

Sneak Peak!

That’s what we gonna be build yol!

XFHACKS Recipe!

So this recipe is going to be a bit advanced one, although the basic here is also going to be what we’ve been using last few XFHACK articles, the stacking of Elements on top of each other! my favorite! 😀 lol

Let me begin with the concept of Placeholder, which is a text display that is visible in any Text Editable element until the user starts typing their input, and if the user clears his input the Placeholder comes back to visibility.

In simple terms we are going to stack a Label underneath our Editor control which will act as the “Placeholder” element and then we’re going to do some external handling to make that given Label to be set visible or invisible based on users text input typing event. The first part is pretty straightforward but the second part needs more explaining I assume. To do that we’re going to make use of the awesome Triggers in Xamarin.Forms, we’re going to implement a simple TriggerAction which will react to the event of Text field change of our Editor control. So inside the trigger execution we will set the Placeholder Label to be visible or invisible.

The Golden Triggers: So we’re going to use DataTriggers of Xamarin.Forms that allows us to listen to changes in a Data Field and react up on it, in this case the changes of the Text property of our Editor control. We’ll attach the DataTriggers to the Label and bind them to the Editor.Text property, then reacting on that our TriggerAction will hide or visible the Placeholder Label.

How easy is that eh!

Code!

Let’s start off by implementing our awesomely simple TriggerAction which will be handling the event of Editor’s text field change.

/// <summary>
/// A simple trigger to change a
/// View's visibility dynamically
/// </summary>
public class VisibilityTriggerAction
			: TriggerAction<View>
{
	public bool IsViewVisible { get; set; }

	protected override void Invoke(View sender)
	{
		sender.IsVisible = IsViewVisible;
	}
}

 

So we have a TriggerAction which can be reused anywhere to set a given View’s Visibility on demand, the reason I made it as a “View” type is exactly for the reason of reusability. So inside our Trigger we will be changing the value of IsViewVisible property to change the visibility of the Placeholder Label.

Behold the golden XAML code!

<!--  Editor with a Placeholder  -->
<Grid
      BackgroundColor="#b3ddff"
      HeightRequest="100"
      HorizontalOptions="Center"
      WidthRequest="250">

      <Label
            InputTransparent="True"
            Text="Type anything here..."
            TextColor="Gray">
            <Label.FontSize>
                  <OnPlatform x:TypeArguments="x:Double">
                        <On Platform="Android" Value="17" />
                        <On Platform="iOS" Value="17" />
                        <On Platform="UWP" Value="15" />
                  </OnPlatform>
            </Label.FontSize>
            <Label.Margin>
                  <OnPlatform x:TypeArguments="Thickness">
                        <On Platform="Android" Value="5,11,0,0" />
                        <On Platform="iOS" Value="4,9,0,0" />
                        <On Platform="UWP" Value="11,5,0,0" />
                  </OnPlatform>
            </Label.Margin>
            <Label.Triggers>
                  <!-- the DataTriggers 
                           reacts to Editor.Text changes -->
            </Label.Triggers>
      </Label>
      <Editor
            x:Name="editor"
            BackgroundColor="Transparent"
            TextColor="Black" />

</Grid>

 

There you have the Editor and the Label stacked on top of each other acting like a Placeholder for the Editor. Something important to note here is that, you can see the Margin property being set up in a bunch precise values, this was to align the Label’s text field with the text field of the Editor, so that they superpose each other nicely, which in returns gives the exact look and feel of a Placeholder property. 😉 In addition to that I have very carefully adjusted the default FontSize of the Label to match to the Editor’s! Smart eh!

So with that note, if you want to customize the Editor’s FontSize or Font itself, you need to make sure to do the similar changes accordingly to the underlying Label’s property to match the same appearance.

Now here’s the important bit, the golden Trigger. So we’re going to attach two DataTriggers, one for listening to the Editor.Text property’s null value instance (this is to be safe of null values in certain different platforms) and the other is for Editor.Text.Length property value changes. Based on those two instances we’re activating our Triggers accordingly with passing in the IsViewVisible value to it.

So here are the XAML of the DataTriggers we just spoke about, which you should plug into the above code!

<!--  the DataTriggers reacts to Editor.Text changes  -->
<DataTrigger
      Binding="{Binding Source={x:Reference editor}, Path=Text.Length}"
      TargetType="Label"
      Value="0">
      <DataTrigger.EnterActions>
          <triggers:VisibilityTriggerAction IsViewVisible="True" />
      </DataTrigger.EnterActions>
      <DataTrigger.ExitActions>
          <triggers:VisibilityTriggerAction IsViewVisible="False" />
      </DataTrigger.ExitActions>
</DataTrigger>
<DataTrigger
      Binding="{Binding Source={x:Reference editor}, Path=Text}"
      TargetType="Label"
      Value="{x:Null}">
      <DataTrigger.EnterActions>
          <triggers:VisibilityTriggerAction IsViewVisible="True" />
      </DataTrigger.EnterActions>
      <DataTrigger.ExitActions>
          <triggers:VisibilityTriggerAction IsViewVisible="False" />
      </DataTrigger.ExitActions>
</DataTrigger>

 

There you have it, we’re binding our DataTriggers to the Editor’s Text property according to the two instances we discussed of, and setting the VisibilityTriggerAction‘s value to hide or visible our Placeholder Label.

Now as usualy could also move that whole piece of XAML to a separate XAML file, so that you could set it up as a reusable Control in your project! 😉

Pretty straight forward eh!

Fire it up!

 

There you have it running on Android, iOS and UWP like a charm! 😀

Grab it on Github!

https://github.com/UdaraAlwis/XFHacks

Well then, that’s it for now. More awesome stuff on the way!

Cheers! 😀 share the love!