[Windows] Allow to remove shadows at runtime #31452

MartyIX · 2025-09-02T09:40:25Z

Note

Are you waiting for the changes in this PR to be merged?
It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Description of Change

This PR attempts to address https://github.com/dotnet/maui/pull/18337/files#r2314339635. That is, it makes sure that shadow is removed from Border when Border.Shadow = null is assigned.

I took inspiration in Android implementation:

maui/src/Core/src/Platform/Android/WrapperView.cs

Lines 61 to 110 in 718adb7

    
           partial void ShadowChanged() 
        
           { 
        
           	if (Shadow?.Paint is { } shadowPaint) 
        
           	{ 
        
           		var context = Context; 
        
           		var shadowOpacity = Shadow.Opacity; 
        
           		float radius = context.ToPixels(Shadow.Radius); 
        
           		float offsetX = context.ToPixels(Shadow.Offset.X); 
        
           		float offsetY = context.ToPixels(Shadow.Offset.Y); 
        
           		int paintType; 
        
           		int[] colors; 
        
           		float[] positions; 
        
           		float[] bounds; 
        
           		switch (shadowPaint) 
        
           		{ 
        
           			case LinearGradientPaint linearGradientPaint: 
        
           				var linearGradientData = linearGradientPaint.GetGradientData(shadowOpacity); 
        
           				paintType = PlatformPaintType.Linear; 
        
           				colors = linearGradientData.Colors; 
        
           				positions = linearGradientData.Offsets; 
        
           				bounds = [linearGradientData.X1, linearGradientData.Y1, linearGradientData.X2, linearGradientData.Y2]; 
        
           				break; 
        
           			case RadialGradientPaint radialGradientPaint: 
        
           				var radialGradientData = radialGradientPaint.GetGradientData(shadowOpacity); 
        
           				paintType = PlatformPaintType.Radial; 
        
           				colors = radialGradientData.Colors; 
        
           				positions = radialGradientData.Offsets; 
        
           				bounds = [radialGradientData.CenterX, radialGradientData.CenterY, radialGradientData.Radius]; 
        
           				break; 
        
           			case SolidPaint solidPaint: 
        
           				paintType = PlatformPaintType.Solid; 
        
           				// If the alpha is set in the color value, the shadow transparency is applied based on that alpha.  
        
           				// If the Opacity property is set directly, the shadow transparency is applied based on the Opacity.  
        
           				// If both values are provided, the color alpha is combined with the Opacity to apply a unified transparency effect to the shadow, ensuring consistent behavior across platforms. 
        
           				colors = [solidPaint.Color.WithAlpha(solidPaint.Color.Alpha * shadowOpacity).ToPlatform().ToArgb()]; 
        
           				positions = null; 
        
           				bounds = null; 
        
           				break; 
        
           			default: 
        
           				throw new NotSupportedException("Unsupported shadow paint type."); 
        
           		} 
        
           		UpdateShadow(paintType, radius, offsetX, offsetY, colors, positions, bounds); 
        
           	} 
        
           	else 
        
           	{ 
        
           		UpdateShadow(PlatformPaintType.None, 0, 0, 0, null, null, null); 
        
           	} 
        
           }

Test effect

My src\Controls\tests\TestCases.WinUI.Tests\snapshots\windows\Issue24414Test_5.png changes like this:

Before	After

dotnet-policy-service · 2025-09-02T09:40:48Z

Hey there @@MartyIX! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

PureWeen · 2025-09-02T14:26:47Z

/azp run

azure-pipelines · 2025-09-02T14:27:17Z

Azure Pipelines successfully started running 3 pipeline(s).

MartyIX · 2025-09-02T18:29:08Z

src/Core/src/Platform/Windows/WrapperView.cs

 		partial void ShadowChanged()
 		{
-			if (HasShadow)
+			if (Shadow?.Paint is { })


note: You can compare the new snapshot in this PR with the Android one: https://github.com/dotnet/maui/blob/main/src/Controls/tests/TestCases.Android.Tests/snapshots/android/Issue24414Test_5.png. There should be no shadow visible in Issue24414Test_5.png snapshots.

jsuarezruiz · 2025-09-03T06:39:38Z

/azp run

azure-pipelines · 2025-09-03T06:39:58Z

Azure Pipelines successfully started running 3 pipeline(s).

MartyIX · 2025-09-03T12:35:06Z

It looks like the tests passed. The failing tests are related to Android.

MartyIX requested a review from a team as a code owner September 2, 2025 09:40

MartyIX requested review from StephaneDelcroix and jfversluis September 2, 2025 09:40

dotnet-policy-service bot added the community ✨ Community Contribution label Sep 2, 2025

MartyIX added platform/windows area-drawing Shapes, Borders, Shadows, Graphics, BoxView, custom drawing labels Sep 2, 2025

MartyIX changed the title ~~[Windows] Allow to remove shadows on runtime~~ [Windows] Allow to remove shadows at runtime Sep 2, 2025

MartyIX commented Sep 2, 2025

View reviewed changes

MartyIX mentioned this pull request Sep 3, 2025

[Windows] Fix performance issue using Shadows (test) #31440

Closed

jsuarezruiz approved these changes Sep 3, 2025

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jfversluis approved these changes Sep 4, 2025

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jfversluis changed the base branch from main to inflight/current September 4, 2025 11:24

MartyIX added 2 commits September 4, 2025 13:26

WIP

cde8526

Update snapshot

326ee2b

jfversluis force-pushed the feature/2025-09-02-Windows-remove-shadows branch from 7583191 to 326ee2b Compare September 4, 2025 11:26

jfversluis added this to the .NET 9 SR11 milestone Sep 4, 2025

jfversluis merged commit cc498be into dotnet:inflight/current Sep 4, 2025
1 check passed

MartyIX deleted the feature/2025-09-02-Windows-remove-shadows branch September 4, 2025 11:27

MartyIX mentioned this pull request Sep 5, 2025

[Windows] Allow to remove clip at runtime #31488

Merged

bronteq mentioned this pull request Sep 19, 2025

[Windows] Fix performance issue using Shadows #18337

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[Windows] Allow to remove shadows at runtime #31452

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	partial void ShadowChanged()
	{
	if (Shadow?.Paint is { } shadowPaint)
	{
	var context = Context;
	var shadowOpacity = Shadow.Opacity;
	float radius = context.ToPixels(Shadow.Radius);
	float offsetX = context.ToPixels(Shadow.Offset.X);
	float offsetY = context.ToPixels(Shadow.Offset.Y);
	int paintType;
	int[] colors;
	float[] positions;
	float[] bounds;

	switch (shadowPaint)
	{
	case LinearGradientPaint linearGradientPaint:
	var linearGradientData = linearGradientPaint.GetGradientData(shadowOpacity);
	paintType = PlatformPaintType.Linear;
	colors = linearGradientData.Colors;
	positions = linearGradientData.Offsets;
	bounds = [linearGradientData.X1, linearGradientData.Y1, linearGradientData.X2, linearGradientData.Y2];
	break;
	case RadialGradientPaint radialGradientPaint:
	var radialGradientData = radialGradientPaint.GetGradientData(shadowOpacity);
	paintType = PlatformPaintType.Radial;
	colors = radialGradientData.Colors;
	positions = radialGradientData.Offsets;
	bounds = [radialGradientData.CenterX, radialGradientData.CenterY, radialGradientData.Radius];
	break;
	case SolidPaint solidPaint:
	paintType = PlatformPaintType.Solid;
	// If the alpha is set in the color value, the shadow transparency is applied based on that alpha.
	// If the Opacity property is set directly, the shadow transparency is applied based on the Opacity.
	// If both values are provided, the color alpha is combined with the Opacity to apply a unified transparency effect to the shadow, ensuring consistent behavior across platforms.
	colors = [solidPaint.Color.WithAlpha(solidPaint.Color.Alpha * shadowOpacity).ToPlatform().ToArgb()];
	positions = null;
	bounds = null;
	break;
	default:
	throw new NotSupportedException("Unsupported shadow paint type.");
	}

	UpdateShadow(paintType, radius, offsetX, offsetY, colors, positions, bounds);
	}
	else
	{
	UpdateShadow(PlatformPaintType.None, 0, 0, 0, null, null, null);
	}
	}

[Windows] Allow to remove shadows at runtime #31452

[Windows] Allow to remove shadows at runtime #31452

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MartyIX commented Sep 2, 2025

Description of Change

Test effect

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