Tag Archives: Nuget

Publishing the Nuget of my Color Picker Control for Xamarin.Forms!

March 17, 2020App Development, Coding, Experimentation, Mobile App Development, Programming, SkiaSharp, Uncategorized, Xamarin, Xamarin Android, Xamarin Forms, Xamarin iOS, Xamarin UWPColor Picker, Colors, Design, Element, Gradient Effects, Interactive, Nuget, Responsive, SkiaSharp, Touch Handling, Udara Alwis, UI Control, Xamarin FormsÇøŋfuzëÐ SøurcëÇødë

Let me share the journey of me publishing the Nuget Package of my interactive Color Picker Control for Xamarin.Forms that I built using SkiaSharp.

So some time back I built an Interactive and responsive Color Picker Control for Xamarin.Forms (Android, iOS, UWP) with a whole bunch of awesome features. On a Canvas with a beautiful Color spectrum similar to a rainbow gradient effect spreading across, drag, drop, swipe and pan over the Canvas to pick the Color you need easily, in a fun-to-use interactive experience. Built from pure Xamarin.Forms based on SkiaSharp, lightweight and fast!

Backstory…

In my previous blog post I shared with you guys how I built my interactive Color Picker Control for Xamarin.Forms, https://theconfuzedsourcecode.wordpress.com/2020/02/26/i-built-an-interactive-color-picker-control-for-xamarin-forms/

Since then I had been adding a whole bunch of extra feature to this Color Picker Control I built, so I thought it was a good idea to publish it as a Nuget Package and share with everyone! 😀

So this time, let me share my journey of implementing more advanced features and publishing the Nuget Package of my Color Picker Control for Xamarin.Forms! 😉

Some thought…

So before I isolated my Color Picker Control into a stand alone reusable package, I wanted to make sure that I maintain my philosophy of building Plugins. This would definitely have a big impact on your Users who will will be using these Plugins to build their apps, therefore I’ll share the tick list that I consider as important as follows…

Plug and Play: The plugin should easy to set up with. Do not force Devs to set up any dependencies or property values by themselves. The properties and behaviors of the Plugin should have default values assigned to them.

Customization: It should be easy and straight forward for the Devs to customize the appearance or the behaviors of the Plugin. In some case this might be limited, but you must build the Plugin in a way it make it easy as much as possible.

Embedded: In the case of UI Element Plugins, you should make it easy to be embedded into any Layout structure, being able to inherit the Parent Layout’s behaviors and values, without overriding or disrupting them.

Keep it Light: Make the Plugin as lightweight as possible, give the Dev the chance to choose which assemblies to be included in the plugin. Remove unnecessary references or dependencies from your Plugin core, so it’s light weight as possible.

Performance First: It shouldn’t cause any performance bottleneck, therefore from scratch you must build the Plugin with performance in mind. Constantly check for performance improvements during the development of your Plugin.

So may be go over this list before you build or release a Plugin for the public! 😉 Alright, with all those principles in mind, let’s move ahead…

The Features!

So here are the features that are already available in the Color Picker Control that I built which I had shared from my previous blog post…

Picked Color: The Property that allows Users to retrieve the Color values that’s selected from the Color Picker. This value is only a Get Property.

Picked Color Changed Event: The Event that fires up every time the PickedColor Value is changed during Color selection. You can subscribe to this event and observe the behavior.

Since my venture into this Color Picker Plugin I had a few ideas in mind as improvements or rather add as extra features, rather than just being a UI Element which allows you to pick a color on a beautiful spectrum! 😉 So here are the extra features that I’ll be building up into it..

Change the Available Base Colors List: You can set the primary list of Colors where the gradient spectrum will be rendered from. So choose the base colors you want to be populated as you wish and it will be rendered on the Color Picker.

Change the Color List Flow Direction: You will be able to change the direction of the flow of the colors on the canvas, where it be Horizontal flow or a Vertical flow of the color spectrum. Further more Horizontally being starting off the flow from left to right, and Vertically being top to bottom.

Change the Color Spectrum Style: You will be able to change the style of the Color Spectrum gradient, the rendering combination of base colors (Hue), or lighter colors (Tint) or darker colors (Shade). You’ll be able to set it with different order as well, ex: Hue Colors, Shade Colors, Tint Colors or Tint Colors, Hue Colors, Shade Colors, etc..

Change the Appearance of the Pointer: The white color circle that is used as the Picker Pointer on the Canvas, should be able to customized based on its Diameter or Thickness of the Circle border. Another nice addition would be to allow user to set the position of the Pointer as they wish.

Alright, now that we listed down the new intended feature set that I’m planning to ship out with my Color Picker Control, let’s get down to building it… 😀

Sneak Peek!

Just to give a little glimpse of the awesomeness I ended up building and publishing… 😀 behold the Color Picker Control for Xamarin.Forms!

Pretty awesome eh! 😉 I have moved out of my previous repo to a new standalone repo in github, since I’m publishing this as a package. Therefore all the new development will be done in this repository.

Project hosted on github:
https://github.com/UdaraAlwis/XFColorPickerControl

So feel free to take a look in there before we continue… 😉

Time to Build!

Since I already explained in my previous blog post how I built my Color Picker Control from scratch step by step, I won’t be repeatedly going through same code bits in this post, but rather focus on the new changes and features only.
If you haven’t read that one yet, then I would recommend you take a peek there first, I built an Interactive Color Picker Control for Xamarin.Forms! And continue here…

I named the Solution as Udara.Plugin.XFColorPickerControl, and in return I intend to keep the Package reference with the same naming. I am using Visual Studio 2019 on Windows 10 here as my development environment.

I have created a VS Solution with a .NET Standard 2.0 Library which will hold the UI Control in place, with the naming ColorPicker. You can see I have added the dependencies of the Plugin, with Xamarin.Forms and SkiaSharp.Views.Forms packages. 😉

Notice the pure Xamarin.Forms DemoApp project inside the Demo folder that I have added to the same solution? That is for testing and showcasing the Plugin’s use, also as a reference point for anyone who wants to learn how to use the Plugin in many different ways, this attached DemoApp could come handy. 😀

The ColorPicker.xaml is the UI Element that users will be using under the namespace Udara.Plugin.XFColorPickerControl.ColorPicker in their XAML or C# code for building the UI. Here’s base skeleton implementation of the ColorPicker.xaml.cs, which all the core implementation will be taking place…

namespace Udara.Plugin.XFColorPickerControl
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class ColorPicker : ContentView
    {
        public ColorPicker()
        {
            InitializeComponent();
        }

        // Implementation goes here
    }
}

Next let’s get into the implementation of Features one by one as I discussed before…

Building the Features!

So I’m going to use the same code for the two features that I already implemented in my previous blog post, Picked Color and Picked Color Changed Event feature that’s represented by PickedColor Property and PickedColorChanged Event Handler.

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ColorPicker : ContentView
{
	/// <summary>
	/// Occurs when the Picked Color changes
	/// </summary>
	public event EventHandler<Color> PickedColorChanged;

	public static readonly BindableProperty PickedColorProperty
		= BindableProperty.Create(
			nameof(PickedColor),
			typeof(Color),
			typeof(ColorPicker));

	/// <summary>
	/// Get the current Picked Color
	/// </summary>
	public Color PickedColor
	{
		get { return (Color)GetValue(PickedColorProperty); }
		private set { SetValue(PickedColorProperty, value); }
	}
	
	...
}

Now considering the rest of the features that I discussed in the beginning, all those features can be implemented and exposed via Bendable Properties, and handling the Property Changed events internally to react for any changes requested during run time.

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ColorPicker : ContentView
{
    ...
 
    public static readonly BindableProperty PropertyNameProperty
        = BindableProperty.Create( 
        ... 
        
            validateValue: (bindable, value) =>
            {
                // validate value
                return (..);
            },
            
            propertyChanged: (bindable, value, newValue) =>
            {
                if (newValue != null)
                    // action on value change
                else
                    // handling null values
                    ((ColorPicker)bindable).PropertyNameProperty = default;
            });
        );
 
    public type PropertyName
    { ... }
 
    ...
}

All the Bindable Properties are safeguarded with validations as you see above. I have added an extra layer of protection against unnecessary null values being set up, by defaulting the property value to default of itself. You can check the full implementation of each of these Properties on the github repo itself. github.com/UdaraAlwis/XFColorPickerControl Let’s begin..

Feature: BaseColorList

Bindable Property, BaseColorList: Change the available base Colors on the Color Spectrum, of the Color Picker. This will take a List of strings of Color names or Hex values, which is held in an IEnumerable as show here, also I have set up the fallback default values with the rainbow color spectrum.

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ColorPicker : ContentView
{
    ...

    public static readonly BindableProperty BaseColorListProperty
        = BindableProperty.Create( ... );

    public IEnumerable BaseColorList
    { ... }

    ...
}

This Property is then consumed during the SkiaSharp rendering cycle as follows, where as we’re using the Xamarin.Forms built in ColorTypeConverter to parse the string color values to actual Color objects and then to SKColor objects, which is then used to render the render the color spectrum on the Color Picker Control. 😀

...
    private void SkCanvasView_OnPaintSurface
                   (object sender, SKPaintSurfaceEventArgs  e)
    {
        ...
         
        // Draw gradient rainbow Color spectrum
        using (var paint = new SKPaint())
        {
            paint.IsAntialias = true;
 
            // Initiate the base Color list
            ColorTypeConverter converter = new ColorTypeConverter();
            System.Collections.Generic.List<SKColor> colors = 
                new System.Collections.Generic.List<SKColor>();
            foreach (var color in BaseColorList)
                colors.Add(((Color)converter.
		          ConvertFromInvariantString(color.ToString())).ToSKColor());
				
            ...
        }
    }
...

Pretty straight forward eh! Let’s see how you could use this as a developer.

How to use?

You can easily use this feature in XAML as follows, by accessing ColorPicker.BaseColorList property and setting up the list of color values you prefer as hex values or with pre-defined color value names.

<xfColorPickerControl:ColorPicker
	x:Name="ColorPicker"
	...	>
	<xfColorPickerControl:ColorPicker.BaseColorList>
		<x:Array Type="{x:Type x:String}">
			<!--  Yellow  -->
			<x:String>#ffff00</x:String>
			<!--  Aqua  -->
			<x:String>#00ffff</x:String>
			<!--  Fuchsia  -->
			<x:String>#ff00ff</x:String>
			<!--  Yellow  -->
			<x:String>#ffff00</x:String>
		</x:Array>
	</xfColorPickerControl:ColorPicker.BaseColorList>
</xfColorPickerControl:ColorPicker>

If you prefer in C# code, you can easily do as as well, a list of string values of the colors…

ColorPicker.BaseColorList = new List<string>()
{
	"#00bfff",
	"#0040ff",
	"#8000ff",
	"#ff00ff",
	"#ff0000",
};

Here’s some action…

Feature: ColorFlowDirection

The Bindable Property, ColorFlowDirection: Change the direction in which the Colors are flowing through on the Color Spectrum, of the Color Picker. This will allow you to set whether the Colors are flowing through from left to right, Horizontally or top to bottom, Vertically. I have defined an Enum type which will represent this type of course.

namespace Udara.Plugin.XFColorPickerControl
{
    public enum ColorFlowDirection
    {
        Horizontal,
        Vertical
    }
}

Let’s create our ColorFlowDirection Bindable Property based on that,

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ColorPicker : ContentView
{
    ...

    public static readonly BindableProperty ColorFlowDirectionProperty
        = BindableProperty.Create( ... );

    public ColorFlowDirection ColorFlowDirection
    { ... }

    ...
}

The default value will be set as ColorFlowDirection.Horizontal, and if the User changes value during run time, it will fire up a new SkiaSharp rendering cycle of the Canvas, effectively rendering the spectrum accordingly to the new color value, which is handled in the rendering logic as below…

...
    private void SkCanvasView_OnPaintSurface
                   (object sender, SKPaintSurfaceEventArgs  e)
    {
        ...
        
            // create the gradient shader between base Colors
            using (var shader = SKShader.CreateLinearGradient(
                new SKPoint(0, 0),
                ColorFlowDirection == ColorFlowDirection.Horizontal ?
                    new SKPoint(skCanvasWidth, 0) : 
                    new SKPoint(0, skCanvasHeight),
                colors.ToArray(),
                null,
                SKShaderTileMode.Clamp))
            {
                paint.Shader = shader;
                skCanvas.DrawPaint(paint);
            }
            
        ...
    }
...

The trick here is to configure the SKShader.CreateLinearGradient() method’s start and end coordinate parameters, which governs the direction in which the gradient effect will be drawn with the list of colors, thus rendering the color list from left to right or top to bottom. As you can see for Horizontal effect, we use SKPoint (0,0) to SKPoint(<canvasWidth>, 0) by using the corner most value on the X axis for the end coordinates, the same pattern is used for Vertical effect with bottom most value on the Y axis.

Here how to consume this feature as a developer…

How to use?

You can easily use this feature in XAML, by accessing ColorPicker.ColorFlowDirection property and setting Horizontal or Vertical option as you prefer…

<xfColorPickerControl:ColorPicker
	x:Name="ColorPicker"
	ColorFlowDirection="Horizontal"
	...	>
</xfColorPickerControl:ColorPicker>

If you prefer in C# code, use the ColorFlowDirection.Horizontal or Vertical option…

ColorPicker.ColorFlowDirection =
	Udara.Plugin.XFColorPickerControl.ColorFlowDirection.Horizontal;

Here’s some action…

Feature: ColorSpectrumStyle

The Bindable Property, ColorSpectrumStyle: Change the Color Spectrum gradient style, with the rendering combination of base colors (Hue), or lighter colors (Tint) or darker colors (Shade). If you’re not familiar with these technical terms, here’s a clear illustration of comparison of Hue, Shade, and Tint of Colors.

We need to make sure our Color Picker is able to deliver to this kind of requirement, having darker or lighter colors of the given base colors on the Color Picker Spectrum. So I’ve created an Enum type which will consist of all the possible combinations of Hue, Shade and Tint colors based on the available Base Colors, that would facilitate this feature.

namespace Udara.Plugin.XFColorPickerControl
{
    public enum ColorSpectrumStyle
    {
        HueOnlyStyle,
        HueToShadeStyle,
        ShadeToHueStyle,
        HueToTintStyle,
        TintToHueStyle,
        TintToHueToShadeStyle,
        ShadeToHueToTintStyle
    }
}

Let’s create our ColorSpectrumStyle Bindable Property based on that,

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ColorPicker : ContentView
{
    ...

    public static readonly BindableProperty ColorSpectrumStyleProperty
        = BindableProperty.Create( ... );

    public ColorSpectrumStyle ColorSpectrumStyle
    { ... }

    ...
}

I will be setting ColorSpectrumStyle.HueToShadeStyle as the default value for this property, any changes to this value during run time will kick start a new refresh draw on the Color Spectrum, which is handled in the rendering logic as below…

...
    private void SkCanvasView_OnPaintSurface
                   (object sender, SKPaintSurfaceEventArgs  e)
    {
        ...
         
        // Draw secondary gradient color spectrum
        using (var paint = new SKPaint())
        {
            paint.IsAntialias = true;
 
            // Initiate gradient color spectrum style layer
            var colors = GetSecondaryLayerColors(ColorSpectrumStyle);
			
            ...
        }
    }
...

Over here, we’re retrieving the list of colors based on the ColorSpectrumStyle value, which is a combination of Transparent, Black and White colors, which will be used to draw the secondary gradient layer. GetSecondaryLayerColors() will be returning the appropriate list of secondary colors that matches the ColorSpectrumStyle requested as follows.

...
    private SKColor[] GetSecondaryLayerColors(ColorSpectrumStyle colorSpectrumStyle)
    {
        ...
        
        if (colorSpectrumStyle == GradientColorStyle.DarkToColorsToLightStyle)
        {
            return new SKColor[]
            {
                SKColors.Black,
                SKColors.Transparent,
                SKColors.White
            };
        }
        
        ...
    }
...

I’m maintaining a simple If-else block chain which will check for the ColorSpectrumStyle value available and return the appropriate list of colors back. Quite straight forward! 😉

Now here’s how you use this awesome feature…

How to use?

You can easily use this feature in XAML, by accessing ColorPicker.ColorSpectrumStyle property and setting the appropriate Style option as you prefer…

<xfColorPickerControl:ColorPicker
	x:Name="ColorPicker"
	ColorSpectrumStyle="TintToHueToShadeStyle"
	...	>
</xfColorPickerControl:ColorPicker>

If you prefer in C# code…

ColorPicker.ColorSpectrumStyle =
	Udara.Plugin.XFColorPickerControl.ColorSpectrumStyle.TintToHueToShadeStyle;

Here’s some action…

Feature: PointerRing Styling

As you can see there’s a pretty neat Pointer Ring that’s pointing the picked color position on the Color Picker, it would be nice to be able to customized this too eh! 😉

Therefore I have introduced four features for this,

PointerRingDiameterUnits
PointerRingBorderUnits
PointerRingPositionXUnits
PointerRingPositionYUnits

Alright, let’s walk through them one by one..

Feature: PointerRingDiameterUnits

The Bindable Property, PointerRingDiameter: Changes the Diameter size of the Pointer Ring on the Color Picker. It accepts values between 0 and 1, as a representation of numerical units which is compared to the 1/10th of the longest length of the Color Picker Canvas. By default this value is set to 0.6 units.

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ColorPicker : ContentView
{
    ...
 
    public static readonly BindableProperty PointerRingDiameterUnitsProperty
        = BindableProperty.Create( ... );
 
    public double PointerRingDiameterUnits
    { ... }
    
    ...
}

This will be calculated against the longest length of Color Picker’s Canvas, whether it be Width or Height. The reason for adding another 1/10th of the value is to maintain the maximum size of the Pointer Ring, avoiding ridiculous sizing of the element. lol So the Precise calculation is as, Canvas Size (Height or Width) x PointerRingDiameterUnits x (1/10)
This value will render exactly to the same proportion against different screen sizes and DPs.

...
    private void SkCanvasView_OnPaintSurface
                   (object sender, SKPaintSurfaceEventArgs  e)
    {
        ...
         
        // Painting the Touch point
        using (var paint = new SKPaint())
        {
            ...
 
            var canvasLongestLength = (skCanvasWidth > skCanvasHeight) 
                    ? skCanvasWidth : skCanvasHeight;

            // Calculate 1/10th of the units value for scaling
            var pointerRingDiameterUnitsScaled = (float)PointerRingDiameterUnits / 10f;
            // Calculate against Longest Length of Canvas 
            var pointerRingDiameter = (float)canvasLongestLength 
                                                    * pointerRingDiameterUnitsScaled;

            // Outer circle of the Pointer (Ring)
            skCanvas.DrawCircle(
                _lastTouchPoint.X,
                _lastTouchPoint.Y,
                (pointerRingDiameter / 2), paintTouchPoint);

            ...
        }
    }
...

I’ve set up the skCanvas.DrawCircle() with the (pointerRingDiameter / 2) since it accepts radius value only for drawing the circle.

How to use?

You can easily use this feature in XAML, by accessing ColorPicker.PointerRingDiameterUnits property and setting the value against your Color Picker’s Width and Height.

<xfColorPickerControl:ColorPicker
    x:Name="ColorPicker"
    PointerRingDiameterUnits="0.6"
    ...    >
</xfColorPickerControl:ColorPicker>

If you prefer in C# code…

ColorPicker.PointerRingDiameterUnits = 0.6;

Here’s some action…

Feature: PointerRingBorderUnits

The Bindable Property, PointerRingBorderUnits: Changes the Border Thickness size of the Pointer Ring on the Color Picker. It accepts values between 0 and 1, as a representation of numerical units which is calculated against the diameter of the Pointer Ring. By default this value is set to 0.3 units.

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ColorPicker : ContentView
{
    ...
 
    public static readonly BindableProperty PointerRingBorderUnitsProperty
        = BindableProperty.Create( ... );
 
    public double PointerRingBorderUnits
    { ... }
    
    ...
}

This calculation executes against the Pointer Ring’s pixel diameter value as, (Pointer Ring Diameter in Pixels) x PointerRingBorderUnits, since this is dependent on the Pointer Ring’s diameter, we thickens the border inside that circle only. Basic technique here is to draw a Circle inside the Parent Circle, with the picked pixel point’s color, emulating the visual of a Ring.

...
    private void SkCanvasView_OnPaintSurface
                   (object sender, SKPaintSurfaceEventArgs  e)
    {
        ...
         
        // Painting the Touch point
        using (var paint = new SKPaint())
        {
            ...
 
            // Draw inner circle with picked color
            paintTouchPoint.Color = touchPointColor;

            // Calculate against Pointer Circle
            var pointerRingInnerCircleDiameter 
                          = (float)pointerRingDiameter 
                              * (float)PointerRingBorderUnits; 

            // Inner circle of the Pointer (Ring)
            skCanvas.DrawCircle(
                _lastTouchPoint.X,
                _lastTouchPoint.Y,
                ((pointerRingDiameter 
                        - pointerRingInnerCircleDiameter) / 2), paintTouchPoint);
            ...
        }
    }
...

I’ve set up the skCanvas.DrawCircle() with the calculation, ((pointerRingDiameter – pointerRingInnerCircleDiameter) / 2) since it accepts radius value only for drawing the circle.

How to use?

You can easily use this feature in XAML, by accessing ColorPicker.PointerRingBorderUnits property and setting the value against PointerRingDiameterUnits you have used.

<xfColorPickerControl:ColorPicker
    x:Name="ColorPicker"
    PointerRingBorderUnits="0.3"
    ...    >
</xfColorPickerControl:ColorPicker>

If you prefer in C# code…

ColorPicker.PointerRingBorderUnits = 0.3;

Here’s some action…

Feature: PointerRingPosition<X,Y>Units

The Bindable Property, PointerRingPosition<X,Y>Units: Changes the Pointer Ring’s position on the Color Picker Canvas programmatically. There are of two bindable properties PointerRingPositionXUnits and PointerRingPositionYUnits, which represents X and Y coordinates on the Color Picker Canvas. It accepts values between 0 and 1, as a presentation of numerical units which is calculated against the Color Picker Canvas’s actual pixel Width and Height. By default both the values are set to 0.5 units, which positions the Pointer Ring in the center of the Color Picker.

[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class ColorPicker : ContentView
{
    ...
 
    public static readonly BindableProperty PointerRingPositionXUnitsProperty
        = BindableProperty.Create( ... );
 
    public double PointerRingPositionXUnits
    { ... }
	
    public static readonly BindableProperty PointerRingPositionYUnitsProperty
        = BindableProperty.Create( ... );
 
    public double PointerRingPositionYUnits
    { ... }
 
    ...
}

This calculation executes against the Color Picker Canvas’s actual pixel Width and Height as, (Color Picker Canvas Width in Pixels) x PointerRingPositionXUnits and (Color Picker Canvas Height in Pixels) x PointerRingPositionYUnits
Up on invoke of the PropertyChanged on those Properties, we make a call to the following SetPointerRingPosition() with the new X and Y position units requested from User.

...
    private void SetPointerRingPosition
                      (double xPositionUnits, double yPositionUnits)
    {
        // Calculate actual X Position
        var xPosition = SkCanvasView.CanvasSize.Width
                                 * xPositionUnits; 
        // Calculate actual Y Position
        var yPosition = SkCanvasView.CanvasSize.Height
                                 * yPositionUnits; 

        // Update as last touch Position on Canvas
        _lastTouchPoint = new SKPoint(Convert.ToSingle(xPosition), Convert.ToSingle(yPosition));
        SkCanvasView.InvalidateSurface();
    }
...

We’re calculating the actual X and Y coordinates against the Canvas pixel size and setting up the _lastTouchPoint with those values, for keeping the Pointer Ring position on canvas in sync with touch inputs positioning and programmatical positioning, then at the end we fire up the SkiaSharp rendering cycle with SkCanvasView.InvalidateSurface();

Handling Pointer Ring Position on Initialization!

We need to handle the positioning of the Pointer Ring on the initialisation or on the rendering of the element during run time. We can achieve this by a one-time execution with a boolean flag, that executes this logic. So upon the first SkiaSharp canvas rendering cycle, we hook up to the PointerRingPositionXUnits and PointerRingPositionYUnits properties and render the Pointer Ring Position to the set value.

...    
    private bool _checkPointerInitPositionDone = false;

...
    private void SkCanvasView_OnPaintSurface
                   (object sender, SKPaintSurfaceEventArgs  e)
    {
        ...
          
        if (!_checkPointerInitPositionDone)
        {
            var x = ((float)skCanvasWidth * (float)PointerRingPositionXUnits);
            var y = ((float)skCanvasHeight * (float)PointerRingPositionYUnits);

            _lastTouchPoint = new SKPoint(x, y);

            _checkPointerInitPositionDone = true;
        }
    }
...

We use _lastTouchPoint variable which is used by the drawing functions for rendering the Pointer Ring on Color Picker’s Canvas.

How to use?

You can easily use this feature in XAML, by accessing ColorPicker.PointerRingPositionXUnits property and ColorPicker.PointerRingPositionYUnits setting the values against your Color Picker’s Width and Height.

<xfColorPickerControl:ColorPicker
    x:Name="ColorPicker"
    PointerRingPositionXUnits="0.3"
    PointerRingPositionYUnits="0.7"
    ...    >
</xfColorPickerControl:ColorPicker>

If you prefer in C# code…

ColorPicker.PointerRingPositionXUnits = 0.3;
ColorPicker.PointerRingPositionYUnits = 0.7;

Here’s some action…

UWP Bug Fix!

One issue I noticed was on UWP run time, where the SkiaSharp’s Canvas touch event behaves differently than iOS and Android. The touch event would get activated even if you hover over the canvas using your mouse pointer, and this was causing the PickedColor property to fire up.
The Touch event should occur only if you actually click on the canvas and drag and drop on the Canvas, so in order to fix this I used the InContact property SKTouchEventArgs inside the touch event to validate on UWP run time.

...
    private void SkCanvasView_OnTouch
                (object sender, SKTouchEventArgs e)
    {
        // to fix the UWP touch behavior
        if (Device.RuntimePlatform == Device.UWP)
        {
            // avoid mouse over touch events
            if (!e.InContact)
                return;
        }

        _lastTouchPoint = e.Location;
        
        ...
    }
...

This fixed the bug on UWP, making sure the touch event is validated before executing the rest of the logic.

Nugetizing!

Alright then, its time to set up our beautiful Color Picker Control for Xamarin.Forms as a Nuget Package using Visual Studio. I’m going first set the Nuget package properties first, then build the package, and finally publish it to Nuget, allowing it to be shared with everyone out there! 😀

Set up package properties…

You could do this straight from Visual Studio Project Properties, or directly from a Nuspec file added to the project itself. For now I would prefer setting up properties in VS Project -> Properties – Package tab, making sure to add all the necessary properties and information about the package as shown below…

Make sure to click on “Generate Nuget package on build” tick, which will enable all the property fields. You could also do this by editing .csproj file of the package project as well, if you require any fine tuned editing…

Now we’re ready to build the package of our Udara.Plugin.XFColorPicker library.

Building the Package…

We need to create the Publish Profile for the package.
Right click on Library project node -> Publish

If this was your first time, it will navigate you to create new Publish Profile tab as shown below…

It is easier to set up a Publish Profile, since you don’t have to manually change your build configuration to Release and then launch a build. Therefore I have set it up now, and next time I publish it will straightaway handle all the configuration for you! 😀

Click Publish, and it nicely builds…

Once we navigate to the folder location mentioned in the above build output…

There we have our nupkg package file, which we can then use to directly upload to Nuget!

Upload to Nuget…

Grab that nupkg file and drag and drop into the upload page of nuget.org and you’re done!

Here you’ll be able to add a short marked down documentation for the users, I would highly recommend you do that since it will increase the support and visibility.

Well that’s all it takes, and the package will be available in a few hours on Nuget!

Updating Package…

Now how do we update our package? if you have noticed around nuget, there’s no update option in in the page where you manage the package. You can update your package by using the NuGet command-line utility or directly uploading an increment build, in which I have opted for the end option to keep it easy.

So when you want to push an update to your package, make sure to update the package properties in Visual Studio to reflect the next immediate version, as shown below where I’m updating from version 1.0.2 to version 1.0.3…

Also do no forget the assembly versioning as well…

Now build your package and directly go to nuget upload page, drag and drop the file…

Make sure to add the nuget documentation and Submit!

Done and dusted, just like that, the updating is done! 😀

Published on nuget:
nuget.org/Udara.Plugin.XFColorPickerControl/

Now anyone can use my Color Picker Control for Xamarin.Forms by setting up this nuget package in their project…

Demoing it up!

As you saw at the beginning I have attached a Demo project into the same parent Solution of Udara.Plugin.XFColorPickerControl, which I have used for testing during development, and to maintain as a demonstration of all the awesome features this plugin provides! 😉

Since this plugin is meant to be compatible on a cross platform environment its impeccable do continuous testing on all the platforms. Anyhow here’s a sneak peek of the demo app…

I have created separate pages to demonstrate awesomeness of each special feature…

BaseColorList Demo:

Android, UWP and iOS…

ColorFlowDirection Demo:

Android, UWP and iOS…

ColorSpectrumStyle Demo:

Android, UWP and iOS…

PointerRingStyling Demo:

Android, UWP and iOS…

Since it’s a pure Xamarin.Forms and can be deployed directly to all three platforms, Android, iOS and Windows UWP, you can do the same with my plugin. Feel free to take a look at the demo app in case if you need trouble shooting.

Conclusion!

There you have it my Color Picker Control for Xamarin.Forms, now published to nuget as a package, with a whole bunch of awesome features, and anyone can easily use it in their own Xamarin.Forms projects! 😀 Pheww… What a joy! Sharing something you’ve been working so hard for a long time. So feel free to give a try, contribute, and any feedback is always welcome…

hosted on github:
github.com/UdaraAlwis/XFColorPickerControl
published on nuget:
nuget.org/Udara.Plugin.XFColorPickerControl/

Well that was fun! So keep in mind I’m going to be implementing more and more features for this plugin in future, and might end up changing some of those features or implementations as well. This blog post will not be constantly updated against them, so many sure to keep in touch with the docs in the github repo itself for future references.

Imagination is the limit yol! 😉

Share the love! 😀 Cheers!

UPDATE: Guess what yol? My little Color Picker Control got featured at the .NET Conf: Focus on Xamarin event by Microsoft!

WOOT! WOOT! Thanks @James Montemagno!

I built a Google Forms Toolkit Library for .NET!

December 17, 2019Coding, Experimentation, Programming, Uncategorized, Web Crawling.NET Standard, c#, Google Forms, Google Forms Hacks, Google Forms Tricks, GoogleFormsToolkitLibrary, Library, Nuget, REST API, Submit Form Data, ToolkitÇøŋfuzëÐ SøurcëÇødë

Watch me building the soon-to-be-famous (lol) my GoogleFormsToolkitLibrary for .NET C#, a nuget library that will help you easily access your Google Forms programmatically in dotnet, letting you load Field Question data, Submit Form data and so on! 😉

In my previous blog article, Programmatically access your complete Google Forms skeleton! where I shared about my adventure into working out a little hack to access your Google Forms page content programatically, I realized it was a solid implementation, and could be used with almost all kinds of openly accessible Google Forms.

So following up on that, this time I will be building a complete .NET library that will consist of all the awesome hacks and tricks that I built around playing with Google Forms myself, which I have also continuously written blog articles as well!

Backstory…

So far we have come across…

And then in my previous blog article, Programmatically access your complete Google Forms skeleton! I shared how we retrieving the following data on a given Google Form extensively,

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

And in each Question Field,

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

Then we analyzed the data structure of the FB_PUBLIC_LOAD_DATA_ script that we scraped out of the rendered HTML content, and even managed to parse it into a meaningful data structure which could be mapped to the data we are looking for.

So using that knowledge and expertise, let’s step up the game and build a solid library tool, which we can reuse easily in anywhere to access our Google Forms programmatically to perform all kinds of awesomeness as we wish! 😉

However if you haven’t gone through my previous blog articles in this Google Forms Hacks series, please do so before continuing to avoid any confusion, since I might not be diving into all the details.

Behold GoogleFormsToolkitLibrary v1!

So this library that I’m building will be on .NET Standards, which will allow you to use it in almost any kind of a .NET project. From Console apps, Desktop, Web and even to Mobile Apps in Xamarin!

It will provide you with the following awesome features!

Load information on your Google Form
Load Question Field data on your Google Form
Submit Form data to your Google Form

At least for now, I will be adding more features as I go along my journey of hacking around Google Forms! 😉

I will be publishing this library to Nuget, so that you can easily grab it into your .NET projects, also let’s add some fancy Test Driven goodness to it, using xUnit Tests! 😀

Project Solution Set up…

So I created a .NET Stanard version 2.0 library in Visual Studio, naming it GoogleFormsToolkitLibrary of course! 😉 The I added a Test folder into the Solution which will hold the xUnit Unit Test project, which I named .Tests!

Then don’t forget to add the HTMLAgilityPack and Newtonsoft.Json nugets to the Library solution which will allow us to scrape out the HTML content in a Google Form and use the Json content parsing logic!

Now the basic set up is done, let’s move on to the code!

Let the coding begin…

We need to model the data objects that we’re going to handle when it comes to the perspective of a Google Form. Basically following are the main entities of a Google Form as far as we have recognized in our previous blog articles!

A Google Form
A Google Form Question Field
The Google Form Field Type

Then as of the functionality I would be adding two public methods that we can call upon to execute.

Load Google Form Structure, data, and form fields
Submit form data to a given Google Form

Crafting the Models…

So we let’s start by building Model classes that will represent the entities we need.

GoogleFormsFieldTypeEnum

Let’s start with the simplest Model we could build that is the Google Form Field Type object, which will represent the type of a given Question Field. I basically described in detail about this entity and how I build the entity model myself through trial and error in my previous blog article:

Let’s create an enum model class giving it the name GoogleFormsFieldTypeEnum.

	// using System.ComponentModel;

	/// <summary>
	/// Found the Field type representation values with trial
	/// and error try out of blood sweat and tears lol! 😉
	/// </summary>
	public enum GoogleFormsFieldTypeEnum
	{
	[Description("Short Answer Field")]
	ShortAnswerField = 0,
	[Description("Paragraph Field")]
	ParagraphField = 1,

	[Description("Multiple Choice Field")]
	MultipleChoiceField = 2,
	[Description("Check Boxes Field")]
	CheckBoxesField = 4,
	[Description("Drop Down Field")]
	DropDownField = 3,

	// FileUpload – Not supported (needs user log in session)
	[Description("File Upload Field")]
	FileUploadField = 13,

	[Description("Linear Scale Field")]
	LinearScaleField = 5,
	// represents both: Multiple Choice Grid \| Checkbox Grid
	[Description("Grid Choice Field")]
	GridChoiceField = 7,

	[Description("Date Field")]
	DateField = 9,
	[Description("Time Field")]
	TimeField = 10,
	}

view raw

GoogleFormsFieldTypeEnum.cs

hosted with ❤ by GitHub

We’re adding the Description tags to hold the human readable value of each type.

GoogleFormField

Now this fella right here is a big deal, that is the Google Form Question Field object, which will represent a single Question Field in a given Google Form. A whole list of these fields comprises in every Google Form.

Let’s create a model class giving it the name GoogleFormField.

	// using System.Collections.Generic;

	/// <summary>
	/// A Question Field in a Google Form
	/// </summary>
	public class GoogleFormField
	{
	/// <summary>
	/// Type of the Question Field
	/// </summary>
	public GoogleFormsFieldTypeEnum QuestionType { get; set; }

	/// <summary>
	/// Question text of the Field
	/// </summary>
	public string QuestionText { get; set; }

	/// <summary>
	/// The unique Id need to be used
	/// when submitting the answer
	/// I also refer to this as: Field Id
	/// </summary>
	public string AnswerSubmissionId { get; set; }

	/// <summary>
	/// Available Answer List for any kind of
	/// multiple answer selection field
	/// </summary>
	public List<string> AnswerOptionList { get; set; } = new List<string>();

	/// <summary>
	/// If the answer is required to Submit
	/// </summary>
	public bool IsAnswerRequired { get; set; }
	}

view raw

GoogleFormField.cs

hosted with ❤ by GitHub

As you can see we have created properties inside this model that will hold all the values that we discussed previously, that could consist in a given Google Form Question Field.

GoogleForm

Now here’s the top entity, representing a whole Google Form page content. Let’s create a model class giving it the name GoogleForm.

	/// <summary>
	/// A model representing a Google Form structure
	/// consist of main the properties of a Google Form
	/// </summary>
	public class GoogleForm
	{
	/// <summary>
	/// Document Name of your Google Form
	/// </summary>
	public string FormDocName { get; set; }

	/// <summary>
	/// Form ID of your Google Form
	/// </summary>
	public string FormId { get; set; }

	/// <summary>
	/// Title of your Google Form
	/// </summary>
	public string Title { get; set; }

	/// <summary>
	/// Description of your Google Form
	/// </summary>
	public string Description { get; set; }

	/// <summary>
	/// List of Question Fields in your Google Form
	/// </summary>
	public List<GoogleFormField> QuestionFieldList { get; set; }
	}

view raw

GoogleForm.cs

hosted with ❤ by GitHub

Pretty straight forward set of properties that would usually contain in any Google Form as you can see above. Now make sure to add those Model classes to the Models directory in your project.

Alrighto, we got the model classes done, then let’s move on to the actual functional coding!

Implementing the core features…

We’re going add two main functionality to this library, for now as following! 😉

LoadGoogleFormStructureAsync

Now this method will intake a string parameter that will carry your Google Forms link, and it will return an object of type GoogleForm that we define above. Which obviously contains the given Google Form’s generic information and Question Field list data including Question Type, Answer Options, Submission Id, etc. Now that’s quite a handful eh! 😉

Task<GoogleForm> 
LoadGoogleFormStructureAsync(string yourGoogleFormsUrl)

So this fella will make Http Async call to load the rendered HTML of the Google Form into memory, run through my magical data scraping algorithm, build the GoogleForm object and return it! Sounds pretty simple but don’t let the implementation confuse you, take a look here! 😉

https://gist.github.com/UdaraAlwis/dcb473f9f07d5024376f1289c1b08ace

Please feel free to take a look at the full implementation on Gist link.

This method is more of an extension of the ScrapeOffFormSkeletonFromGoogleFormsAsync() method that I shared with you all in my last blog post, which I gotten into in depth details about explaining each step of the code.

So to reduce repetition I’m not going to repeat the same here, rather I would share the important bits to explain that are improvements on top of the previous implementation.

One of the differences I would say is that now we’re injecting the data that we scraped out into our model objects, as you can see we’re initializing out GoogleForm and GoogleFormField data objects here, and then loading the GoogleForm data object values.

Then inside the loop we’re loading the GoogleFormField object values as well, and then each object will then be added to the QuestionFormFieldList property of the GoogleForm. That’s pretty much it! 😉

SubmitToGoogleFormAsync

This method will intake a string parameter that will carry your Google Forms link, and a Dictionary object containing the Form field answer submission id and answer values mapping. As a result it will return a boolean value denoting the success or failure of the submission task.

Task<bool> SubmitToGoogleFormAsync
(string yourGoogleFormsUrl, Dictionary<string, string> formData)

It will make a Http Async call the Google Forms REST API endpoint with the given data and await for the response code, upon receiving the response it will return true or false based on it.

https://gist.github.com/UdaraAlwis/8d547f68ae3f629d40b2184f51acd43e

Please feel free to take a look at the full implementation on Gist link.

This methods is actually an improvement of one of my previous posts, You may RESTfully submit to your Google Forms… where I explain in depth how I hacked around to figure this out and what each line of code is meant to handle. Please look into that article if you’re keep for more details.

We’re basically looking for the 200 StatusCode value that determines successful submission to the Google Forms REST API endpoint.

Now our Core Library is ready to go!

Unit Test it yo!

Yep but its not done until we implement a proper set of test cases isn’t it! So let’s add some Unit Tests that will test the functionalities that we built into our Library.

Like I mentioned in the Project set up, we have added a xUnit Unit Test project into the solution, and make sure to add a reference of our Library project GoogleFormsToolkitLibrary into it.

Let’s start by adding a Tests.cs class to it, which we will use to implement the tests. For now, I will add two test cases,

RetrieveGoogleFormStructure_Success

This will test for LoadGoogleFormStructureAsync() feature and make sure we get a valid response and the expected data of the given Google Form page.

SubmitDataToGoogleForm_Success

Now this case will test for the SubmitToGoogleFormAsync() feature and make sure we get a successful boolean response, with the given Google Form link, and the form data dictionary object.

Oh let’s not forget to make sure they’re passing in the Test Runner! 😀 lol

All good to go it seems! for now at least lol 😛

This is really a great practice because if I ever break anything in the code during any new implementation or existing modifications, I would be able to notice it here in the tests.

Nugetting it!

Let’s not forget to publish the beauty to Nuget eh! Let’s make sure all the nuget properties are added to the package before uploading…

And you may find it on nuget right now!

Nuget: nuget.org/packages/GoogleFormsToolkitLibrary/

This whole project is open sourced and published to Github as well if you’re interested in looking at the code, or track the improvements I’m adding in the future!

Github: github.com/GoogleFormsToolkitLibrary

So that’s done!

Let’s try it out!

Now the beauty of this is that you can easily add this to any of your .NET projects as the whole library is based on .NET Standard.

Go ahead and add it to your .NET project from Nuget using either the Package Manager Console or the Nuget Package Manager.

Install-Package GoogleFormsToolkitLibrary

Use of GoogleFormsToolkitLibrary is pretty simple, just instantiate it and call upon the method you wanna use.

// Retrieve the structure of my sample Google Forms page
// https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/viewform

var googleFormLink =
"https://docs.google.com/forms/d/e/" +
"1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA" +
"/viewform";

var googleFormsToolkitLibrary = new GoogleFormsToolkitLibrary();
var result = await googleFormsToolkitLibrary.
                    LoadGoogleFormStructureAsync(googleFormLink);

That should work like a charm! Make sure to pass your Google Form’s link properly and make sure it is openly accessible, you should be able to see the magic pretty easily!

// Submit data to my sample Google Forms page
// https://docs.google.com/forms/d/e/1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA/viewform

var googleFormLink =
	"https://docs.google.com/forms/d/e/" +
	"1FAIpQLSeuZiyN-uQBbmmSLxT81xGUfgjMQpUFyJ4D7r-0zjegTy_0HA" +
	"/formResponse";

Dictionary<string,string> formData = new Dictionary<string, string>
{
	// Question Field 1
	{"entry.1277095329", "Moon Rockets Launching"}, 

	// Question Field 2
	{"entry.995005981","Banana Plums"},

	// Question Field 3
	{"entry.1155533672","Monkeys with hoodies"},

	// Question Field 4
	{"entry.1579749043","Jumping Apples"},

	// Question Field 5
	{"entry.815399500_year","2019"},
	{"entry.815399500_month","11"},
	{"entry.815399500_day","11"},

	// Question Field 6
	{"entry.940653577_hour","04"},
	{"entry.940653577_minute","12"},
};

var googleFormsToolkitLibrary = new GoogleFormsToolkitLibrary();
var result = await googleFormsToolkitLibrary
                .SubmitToGoogleFormAsync(googleFormLink, formData);

The above should nicely respond with a successful true value! 😉

Something to keep in mind here is that you need to make sure you’re setting the correct Field Answer Submission ID properly, and when it comes to Multiple Answer selection fields, make sure the provided answers matches the available list of answers. Date Time fields should be carefully treated with their additional year,month,day suffixed fields and hour,minute respectively. Just go through my past few blog posts on Google Forms hacking, you’ll see for yourself!

What’s next?

Well building this and publishing it openly is just the first step, I’m going to continue building this further adding more features and performance improvements.

Then I will be building some demo Client apps which will use this library to implement some cool features… 😀

So keep an eye out!

There you have it, how I built a Google Forms Toolkit Library for .NET!

Share the love! 😀 Cheers!

Backstory…

Some thought…

The Features!

Sneak Peek!

Time to Build!

Building the Features!

Feature: BaseColorList

How to use?

Feature: ColorFlowDirection

How to use?

Feature: ColorSpectrumStyle

How to use?

Feature: PointerRing Styling

Feature: PointerRingDiameterUnits

How to use?

Feature: PointerRingBorderUnits

How to use?

Feature: PointerRingPosition<X,Y>Units

Handling Pointer Ring Position on Initialization!

How to use?

UWP Bug Fix!

Nugetizing!

Set up package properties…

Building the Package…

Upload to Nuget…

Updating Package…

Demoing it up!

BaseColorList Demo:

ColorFlowDirection Demo:

ColorSpectrumStyle Demo:

PointerRingStyling Demo:

Conclusion!

Share this:

Backstory…

Behold GoogleFormsToolkitLibrary v1!

Project Solution Set up…

Let the coding begin…

Crafting the Models…

Implementing the core features…

Unit Test it yo!

Nugetting it!

Let’s try it out!

What’s next?

Share this: