[Android] invalidate shadows on parent's size change

src/Controls/tests/TestCases.HostApp/Issues/Issue24034.cs

@@ -0,0 +1,16 @@
+namespace Maui.Controls.Sample.Issues;
+
+[XamlCompilation(XamlCompilationOptions.Compile)]
+[Issue(IssueTracker.Github, 24034, "Shadow is not updating on change of parent control", PlatformAffected.All)]
+public partial class Issue24034 : ContentPage
+{
+ public Issue24034()
+ {
+ InitializeComponent();
+ }
+
+ private void Button_Clicked(object sender, EventArgs e)
+ {
+ GridView.IsVisible = !GridView.IsVisible;
+ }
+}

src/Controls/tests/TestCases.HostApp/Issues/Issue24034.xaml

@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+ xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+ x:Class="Maui.Controls.Sample.Issues.Issue24034">
+ <Grid RowDefinitions="300,Auto" Margin="10" ColumnSpacing="0" Padding="5,0" ColumnDefinitions="*,*,Auto">
+
+ <Border 
+ Grid.Column="0" 
+ HeightRequest="150"
+ Grid.Row="0"
+ StrokeShape="RoundRectangle 16,16,16,16"
+ Margin="5,0">
+ <Border.Shadow>
+ <Shadow Brush="Red"
+ Offset="2,10"
+ Radius="{OnPlatform Android=9, iOS=12}"
+ Opacity="1" />
+ </Border.Shadow>
+ <BoxView BackgroundColor="Green"/>
+ </Border>
+
+ <Border 
+ Grid.Column="1" Grid.Row="0"
+ HeightRequest="150"
+ StrokeShape="RoundRectangle 16,16,16,16"
+ Margin="5,0">
+ <Border.Shadow>
+ <Shadow Brush="Red"
+ Offset="2,10"
+ Radius="{OnPlatform Android=9, iOS=12}"
+ Opacity="1" />
+ </Border.Shadow>
+
+ <BoxView BackgroundColor="Green"/>
+ </Border>
+
+ <Grid x:Name="GridView" Margin="5,0"
+ Padding="0, 5, 0, 0"
+ Grid.Column="2">
+ <BoxView WidthRequest="100" Height="100"/>
+ </Grid>
+
+ <Button Grid.Row="1" Grid.ColumnSpan="3" AutomationId="button" Text="Click" Clicked="Button_Clicked"/>
+ </Grid>
+</ContentPage>

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue24034.cs

@@ -0,0 +1,20 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue24034(TestDevice device) : _IssuesUITest(device)
+{
+ public override string Issue => "Shadow is not updating on change of parent control"; 
+
+ [Test]
+ [Category(UITestCategories.Border)]
+ public void ShadowShouldUpdate()
+ {
+ App.WaitForElement("button");
+ App.Click("button");
+
+ VerifyScreenshot();
+ }
+}

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

@@ -23,6 +23,9 @@ public partial class WrapperView : PlatformWrapperView
  Android.Graphics.Paint _shadowPaint;
  bool _invalidateShadow;
 
+ int _currentViewWidth;
+ int _currentViewHeight;
+
  AView _borderView;
 
  public bool InputTransparent { get; set; }
@@ -148,11 +151,13 @@ protected override void DrawShadow(Canvas canvas, int viewWidth, int viewHeight)
  Graphics.Color solidColor = null;
 
  // If need to redraw shadow
- if (_invalidateShadow)
+ if (_invalidateShadow || DidViewSizeChange(viewWidth, viewHeight))
  {
  // If bounds is zero
  if (viewHeight != 0 && viewWidth != 0)
  {
+ _currentViewWidth = viewWidth;
+ _currentViewHeight = viewHeight;
  var bitmapHeight = viewHeight + MaximumRadius;
  var bitmapWidth = viewWidth + MaximumRadius;
 
@@ -246,6 +251,11 @@ protected override void DrawShadow(Canvas canvas, int viewWidth, int viewHeight)
  canvas.DrawBitmap(_shadowBitmap, 0.0F, 0.0F, _shadowPaint);
  }
 
+ bool DidViewSizeChange(int viewWidth, int viewHeight)
+ {
+ return _currentViewWidth != viewWidth || _currentViewHeight != viewHeight; 
+ }
+
  void ClearShadowResources()
  {
  _shadowCanvas?.Dispose();