Polygon Shape doesn't work with DynamicResource color binding

[bdgza]

Description

Updating to XF 4.8 from 4.7 the DynamicResource fill color binding on the Polygon shape is no longer recognized. It still works with a fixed color.

Steps to Reproduce

1. Bind a DynamicResource color to the fill color on a Polygon shape in XAML.

Expected Behavior

The DynamicResource color binding is used to fill the Polygon.

Actual Behavior

The Polygon is not drawn at all.

Basic Information

• Version with issue: Xamarin Forms 4.8.0.1269
• Last known good version: 4.7.0.1260
• IDE: Visual Studio for Mac 8.7
• Platform Target Frameworks:
  • iOS: 13.6 (13.20.2.2)
  • Android: 10 (10.3.1.4)
• Affected Devices: iOS Simulator, Samsung SM-T395

Screenshots

4.7:

4.8:

Reproduction Link

PolygonDynamicColor.zip

[PureWeen]

@StephaneDelcroix or @jsuarezruiz ?

[jsuarezruiz]

The type supported by the Shapes Fill and Stroke properties in Xamarin.Forms 4.8 is a Brush (SolidColorBrush, LinearGradientBrush, or RadialGradientBrush) instead of a Color.
The first case works because there is a TypeConverter, but in the second, using a Color type, it is not working. Changing the Color resource by a SolidColorBrush fixes the problem.

[StephaneDelcroix]

@jsuarezruiz so you'd like TypeConverters to be applied with DynamicResource, or any kind of Binding too ?

[bdgza]

I define a SolidColorBrush entry in my App.xaml and reference this Brush in my Polygon Fill instead of the Color. But then setting the Color for my SolidColorBrush has the same problem as setting the Color directly.

I can only use a fixed color or StaticResource Color, as soon as I change the Brush Color to a DynamicResource Color it doesn't render the Polygon.

[jsuarezruiz]

Could you take a look to this modified sample:
PolygonDynamicColor.zip
?

[bdgza]

I took a look, but what if I wanted to do it like how it is in this modified modified sample:
PolygonDynamicColor.zip

[jsuarezruiz]

@bdgza Thanks for the new modified sample. Now I see the issue!. Will answer here when I have the fix.

[BurkusCat]

I think this needs reopened @rmarinho. I've posted a comment on #12836 describing more but if the color dynamically changes the polygon shape does not change color. It is behaving like a StaticResource instead of a DynamicResource.

[jsuarezruiz]

@BurkusCat Thanks for the feedback, I will review the issue changing the DynamicResource.

[AdrianoRochedo]

Xamarin.Forms 5.0.0.1931

• Works on Android
• Does not work on UWP
• Not tested on IOS

[Juansero29]

I'm having issues with the brush not changing using <PackageReference Include="Xamarin.Forms" Version="5.0.0.2012" /> when using a static brush that defines its Color property via a DynamicResource expression. Here's what my code looks like.

In DarkTheme.xaml

<?xml version="1.0" encoding="UTF-8" ?>
<ResourceDictionary
    x:Class="EnigmatiKreations.Framework.Controls.DarkTheme"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:d="http://xamarin.com/schemas/2014/forms/design"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <Color x:Key="PrimaryColor">Black</Color>
    <Color x:Key="AccentColor">WhiteSmoke</Color>
    <Color x:Key="TertiaryColor">#484848</Color>
    <Color x:Key="CardEvenColor">#212121</Color>
</ResourceDictionary>

In LightTheme.xaml

<?xml version="1.0" encoding="UTF-8" ?>
<ResourceDictionary
    x:Class="EnigmatiKreations.Framework.Controls.LightTheme"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:d="http://xamarin.com/schemas/2014/forms/design"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <Color x:Key="PrimaryColor">WhiteSmoke</Color>
    <Color x:Key="AccentColor">Black</Color>
    <Color x:Key="TertiaryColor">DarkGray</Color>
    <Color x:Key="CardEvenColor">GhostWhite</Color>
</ResourceDictionary>

In Themes.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ResourceDictionary
    x:Class="EnigmatiKreations.Framework.Controls.Themes"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:d="http://xamarin.com/schemas/2014/forms/design"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <!--  https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/theming/theming  -->
    <SolidColorBrush x:Key="PrimaryBrush" Color="{DynamicResource PrimaryColor}" />
    <SolidColorBrush x:Key="AccentBrush" Color="{DynamicResource AccentColor}" />
    <SolidColorBrush x:Key="TertiaryBrush" Color="{DynamicResource TertiaryColor}" />
    <SolidColorBrush x:Key="QuaternaryBrush" Color="{DynamicResource CardEvenColor}" />

    [.... more styles here using the brushes and colors ...]
    
</ResourceDictionary>

In App.xaml

<?xml version="1.0" encoding="utf-8" ?>
<Application
    x:Class="ControlsGallery.App"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:Controls="clr-namespace:EnigmatiKreations.Framework.Controls;assembly=EnigmatiKreations.Framework.Controls">
    <Application.Resources>

        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>

                <!--  Imports the app themes (color palettes, and default styles for native controls)  -->
                <!--  Every other template and control depends on this import  -->
                <Controls:Themes />

                <!--  Imports data templates and templates to be reused across the app  -->
                <!--  They themselves make use of themes  -->
                <Controls:Templates />

                <!--  Imports XAML styles and templates for custom controls, templated controls and inherited controls from the app  -->
                <!--  They themselves make use of templates and themes  -->
                <Controls:GenericControls />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>

        <!--  Default is set apart to identify it easily when changing it dynamically with switch  -->
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <Controls:DarkTheme />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>

In MainPage.xaml

                    <!--  (changing the Fill expression to Fill="{StaticResource AccentBrush}" to shows the same behavior -->
                    <Path
                        Aspect="UniformToFill"
                        Data="M19,13H13V19H11V13H5V11H11V5H13V11H19V13Z"
                        Fill="{DynamicResource AccentBrush}"         
                        HeightRequest="64"
                        HorizontalOptions="Center"
                        VerticalOptions="Center"
                        WidthRequest="64" />

In MainPage.xaml.cs, the code that dynamically changes the app's theme for Xamarin.Forms

        public MainPage()
        {
            InitializeComponent();
            BindingContext = this;
        }

        private void Switch_Toggled(object sender, ToggledEventArgs e)
        {
            var themeMergedDictionary = Application.Current.Resources.MergedDictionaries.Where(d => d.MergedDictionaries.Count == 1).FirstOrDefault();
            if (themeMergedDictionary != null) themeMergedDictionary.MergedDictionaries.Clear();
            if (e.Value)
            {
                Application.Current.UserAppTheme = OSAppTheme.Light;
                themeMergedDictionary.MergedDictionaries.Add(new LightTheme());
            }
            else
            {
                Application.Current.UserAppTheme = OSAppTheme.Dark;
                themeMergedDictionary.MergedDictionaries.Add(new DarkTheme());
            }
        }

It only works if I declare the brushes directly with static color values in LightTheme.xaml and DarkTheme.xaml like this:

Working LightTheme.xaml

<?xml version="1.0" encoding="UTF-8" ?>
<ResourceDictionary
    x:Class="EnigmatiKreations.Framework.Controls.LightTheme"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:d="http://xamarin.com/schemas/2014/forms/design"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <Color x:Key="PrimaryColor">WhiteSmoke</Color>
    <Color x:Key="AccentColor">Black</Color>
    <Color x:Key="TertiaryColor">DarkGray</Color>
    <Color x:Key="CardEvenColor">GhostWhite</Color>

    <SolidColorBrush x:Key="PrimaryBrush" Color="WhiteSmoke" />
    <SolidColorBrush x:Key="AccentBrush" Color="Black" />
    <SolidColorBrush x:Key="TertiaryBrush" Color="DarkGray" />
    <SolidColorBrush x:Key="QuaternaryBrush" Color="GhostWhite" />
</ResourceDictionary>

Working DarkTheme.xaml

<?xml version="1.0" encoding="UTF-8" ?>
<ResourceDictionary
    x:Class="EnigmatiKreations.Framework.Controls.DarkTheme"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:d="http://xamarin.com/schemas/2014/forms/design"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <Color x:Key="PrimaryColor">Black</Color>
    <Color x:Key="AccentColor">WhiteSmoke</Color>
    <Color x:Key="TertiaryColor">#484848</Color>
    <Color x:Key="CardEvenColor">#212121</Color>


    <SolidColorBrush x:Key="PrimaryBrush" Color="Black" />
    <SolidColorBrush x:Key="AccentBrush" Color="WhiteSmoke" />
    <SolidColorBrush x:Key="TertiaryBrush" Color="#484848" />
    <SolidColorBrush x:Key="QuaternaryBrush" Color="#212121" />
</ResourceDictionary>

Is this a normal behaviour? If so, why? Can someone please explain?