LinearGradientBrush GradientStop with Transparent Color is not transparent, but black

[mitschman]

Description

The LinearGradientBrush GradientStop with Transparent Color is not transparent, but black

Steps to Reproduce

Prepare the LinearGradientBrush resources with Transparent Color GradientStop:

    <Color x:Key="Primary">#512BD4</Color>
    <LinearGradientBrush x:Key="PrimaryToTransparentRightToLeftGradientBrush" StartPoint="1,0" EndPoint="0,0">
        <GradientStop Color="{DynamicResource Primary}" Offset="0"/>
        <GradientStop Color="Transparent" Offset="1"/>
    </LinearGradientBrush>

and/or

    <Color x:Key="PrimaryDark">#ac99ea</Color>
    <LinearGradientBrush x:Key="PrimaryDarkToTransparentRightToLeftGradientBrush" StartPoint="1,0" EndPoint="0,0">
        <GradientStop Color="{DynamicResource PrimaryDark}" Offset="0"/>
        <GradientStop Color="Transparent" Offset="1"/>
    </LinearGradientBrush>

Place the Border on the colored page, set up the Background to the prepared brushes:

                                <Border HorizontalOptions="Start"
                                        Background="{AppThemeBinding Light={DynamicResource PrimaryToTransparentRightToLeftGradientBrush}, Dark={DynamicResource PrimaryDarkToTransparentRightToLeftGradientBrush}}"
                                        Stroke="Transparent" StrokeThickness="1">
                                    <Border.StrokeShape>
                                        <RoundRectangle CornerRadius="{Binding Settings.Layout.ToolsFrame.ItemMediaCornerRadius}" />
                                    </Border.StrokeShape>
                                    <Border.WidthRequest>
                                        <MultiBinding Converter="{StaticResource MultiMathExpressionConverter}" ConverterParameter="x0 * x1">
                                            <Binding Path="Width" x:DataType="Border" Source="{x:Reference MediaProgressControlRect}" />
                                            <Binding Path="CurrentMediaPlaybackProgress" FallbackValue="0" />
                                        </MultiBinding>
                                    </Border.WidthRequest>
                                </Border>

The 'transparent' places are black, not transparent:

Note that the same code worked well on the version before (10.0.51):

Link to public reproduction project repository

No response

Version with bug

10.0.60

Is this a regression from previous behavior?

Yes, this used to work in .NET MAUI

Last version that worked well

10.0.50

Affected platforms

Android

Affected platform versions

Android 10.0 (API 29.0)

Did you find any workaround?

No response

Relevant log output

[MihuBot]

I'm a bot. Here are possible related and/or duplicate issues (I may be wrong):

• [Regression] LinearGradientBrush broken on Android in 10.0.60 #35280
• 10.0.60 breaks transparency on Brushes (on Android?) #35354

[HarishKumarSF4517]

This issue has been validated in Visual Studio Code 1.120.0 with .NET MAUI versions 10.0.51 and 10.0.60. The issue was reproducible from 10.0.60(latest version) on Android platform. I have attached the sample(AndroidBrushIssue.zip) and output for reference:

10.0.51(Issue not reproduced)	10.0.60(Issue reproduced)

[SyedAbdulAzeemSF4852]

This is fixed by PR #35299.