Background gradients fixes (#25194)

* Background gradients fixes

* Add test snapshots

* Pending snapshot

---------

Co-authored-by: Javier Suárez <[email protected]>

src/Controls/tests/TestCases.HostApp/Issues/Issue25193.xaml

@@ -0,0 +1,77 @@
+<?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.Issue25193">
+    <VerticalStackLayout>
+        <Label Text="Label: "/>
+        <Label
+            Text="Hello, Maui!"
+            AutomationId="label">
+            <Label.Background>
+                <LinearGradientBrush EndPoint="1,0">
+                    <GradientStop Color="Red"
+                                  Offset="0.7"/>
+                    <GradientStop Color="Green"
+                                  Offset="1.0"/>
+                </LinearGradientBrush>
+            </Label.Background>
+        </Label>
+
+        <Label Text="Button: "/>
+        <Button Text="Hello, Maui!">
+            <Button.Background>
+                <LinearGradientBrush EndPoint="1,0">
+                    <GradientStop Color="Blue"
+                                  Offset="0.7"/>
+                    <GradientStop Color="Yellow"
+                                  Offset="1.0"/>
+                </LinearGradientBrush>
+            </Button.Background>
+        </Button>
+
+        <Label Text="Entry: "/>
+        <Entry Text="Hello, Maui!">
+            <Entry.Background>
+                <LinearGradientBrush EndPoint="1,0">
+                    <GradientStop Color="Pink"
+                                  Offset="0.7"/>
+                    <GradientStop Color="Lime"
+                                  Offset="1.0"/>
+                </LinearGradientBrush>
+            </Entry.Background>
+        </Entry>
+
+        <Label Text="Picker: "/>
+        <Picker
+            Title="Hello, Maui!">
+            <Picker.Background>
+                <LinearGradientBrush EndPoint="1,0">
+                    <GradientStop Color="Brown"
+                                  Offset="0.7"/>
+                    <GradientStop Color="Gold"
+                                  Offset="1.0"/>
+                </LinearGradientBrush>
+            </Picker.Background>
+        </Picker>
+
+
+        <Label Text="Scroll view: "/>
+        <ScrollView Orientation="Horizontal"
+                    HeightRequest="100">
+            <ScrollView.Background>
+                <LinearGradientBrush StartPoint="0,0.5"
+                                     EndPoint="1,0.5">
+                    <LinearGradientBrush.GradientStops>
+                        <GradientStop Color="Orange"
+                                      Offset="0.75"/>
+                        <GradientStop Color="Purple"
+                                      Offset="1"/>
+                    </LinearGradientBrush.GradientStops>
+                </LinearGradientBrush>
+            </ScrollView.Background>
+
+            <Border WidthRequest="1200"/>
+        </ScrollView>
+
+    </VerticalStackLayout>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue25193.xaml.cs

@@ -0,0 +1,12 @@
+namespace Maui.Controls.Sample.Issues
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Issue(IssueTracker.Github, 25193, "Background gradients don't work for some views", PlatformAffected.iOS)]
+	public partial class Issue25193 : ContentPage
+	{
+		public Issue25193()
+		{
+			InitializeComponent();
+		}
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue25193.cs

@@ -0,0 +1,24 @@
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue25193 : _IssuesUITest
+{
+	public Issue25193(TestDevice device) : base(device) { }
+
+	public override string Issue => "Background gradients don't work for some views";
+
+	[Test]
+	[Category(UITestCategories.Label)]
+	[Category(UITestCategories.ScrollView)]
+	[Category(UITestCategories.Button)]
+	[Category(UITestCategories.Entry)]
+	[Category(UITestCategories.Picker)]
+	public void BackgroundGradientsShouldRenderCorrectly()
+	{
+		App.WaitForElement("label");
+		VerifyScreenshot();
+	}
+}

src/Core/src/Handlers/View/ViewHandler.iOS.cs

@@ -55,7 +55,8 @@ internal static void MapContextFlyout(IElementHandler handler, IContextFlyoutEle
 		static partial void MappingFrame(IViewHandler handler, IView view)
 		{
 			UpdateTransformation(handler, view);
-			handler.ToPlatform().UpdateBackgroundLayerFrame();
+			if (handler.VirtualView?.Background is not null)
+				handler.ToPlatform().UpdateBackgroundLayerFrame();
 		}
 
 		public static void MapTranslationX(IViewHandler handler, IView view)