From e2101e4ea4471ff682525f52d2e393830a03db10 Mon Sep 17 00:00:00 2001
From: Pieter Nijs <pieternijs@live.be>
Date: Tue, 29 Oct 2019 15:09:19 +0100
Subject: [PATCH] iOS: Frame with HasShadow set to true and BackgroundColor
 alpha < 1 casts shadow on all child views (#7518)

* Updated renderer with additional ShadowView

* Added buttons to test some behavior

* ShadowLayer background color tweaks

* Resolved flawed merge, restored _Template page

* Apply suggestions from code review

Co-Authored-By: Gerald Versluis <github@geraldversluis.nl>

* Added more descriptive issue Title

* Updated Issue5108.xml's properties

* Update Xamarin.Forms.Controls.Issues.Shared.projitems

Fixed missing closing tags

* Updated projitems

* Removed eventhandlers from XAML

* Update Issue5108.xaml.cs

Added eventhandlers in code + surrounded code-behind with APP preprocessor directive to avoid issues when building for UITEST
---
 .../Issue5108.xaml                                 | 31 ++++++++
 .../Issue5108.xaml.cs                              | 62 +++++++++++++++
 .../Xamarin.Forms.Controls.Issues.Shared.projitems | 18 ++++-
 .../_TemplateMarkup.xaml.cs                        |  4 +-
 .../Renderers/FrameRenderer.cs                     | 91 +++++++++++++++++++---
 5 files changed, 192 insertions(+), 14 deletions(-)
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5108.xaml
 create mode 100644 Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5108.xaml.cs

diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5108.xaml b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5108.xaml
new file mode 100644
index 0000000..f97917d
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5108.xaml
@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<controls:TestContentPage
+    xmlns="http://xamarin.com/schemas/2014/forms"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:controls="clr-namespace:Xamarin.Forms.Controls"
+    x:Class="Xamarin.Forms.Controls.Issues.Issue5108">
+    <ScrollView>
+        <StackLayout>
+            <Frame BackgroundColor="#2257BABE" BorderColor="#57BABE" CornerRadius="10" Margin="20" x:Name="myframe">
+                <StackLayout Spacing="0">
+                    <StackLayout Orientation="Horizontal" Margin="0, 5, 0, 20">
+                        <Label class="RadioText" HorizontalOptions="StartAndExpand" VerticalTextAlignment="Start" FontAttributes="Bold">Please review and confirm that you agree to our terms and conditions before continuing.</Label>
+                        <Button Text="View" class="Primary" HorizontalOptions="End" VerticalOptions="Start" BorderRadius="8" WidthRequest="80"></Button>
+                    </StackLayout>
+                    <StackLayout Orientation="Horizontal" Margin="0, 5, 0, 5">
+                        <Label class="RadioText" FontAttributes="Bold" VerticalTextAlignment="Center">I agree</Label>
+                        <Switch x:Name="rbTerms" HorizontalOptions="StartAndExpand" />
+                        <Button x:Name="btnContinue" StyleClass="Primary" Text="Continue" HorizontalOptions="Center" BorderRadius="8" IsEnabled="False" WidthRequest="150"></Button>
+                    </StackLayout>
+                </StackLayout>
+            </Frame>
+            <Label Text="Toggle the HasShadow property of the frame:" Style="{DynamicResource CaptionStyle}" />
+            <Button Text="Toggle HasShadow" x:Name="HasShadowButton" />
+            <Label Text="Check if the Shadow layer updates its properties following the 'shadowee' layer:" Style="{DynamicResource CaptionStyle}" />
+            <Button Text="Update Margin" x:Name="MarginButton" />
+            <Button Text="Update Corner Radius" x:Name="RadiusButton" />
+            <Label Text="Toggle the Frame's Background to see how the shadow layer reacts. A background with alpha == 1, the shadow should be darker." Style="{DynamicResource CaptionStyle}" />
+            <Button Text="Update Background" x:Name="BackgroundButton" />
+        </StackLayout>
+    </ScrollView>
+</controls:TestContentPage>
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5108.xaml.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5108.xaml.cs
new file mode 100644
index 0000000..96185d1
--- /dev/null
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Issue5108.xaml.cs
@@ -0,0 +1,62 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using Xamarin.Forms.Xaml;
+using System;
+
+namespace Xamarin.Forms.Controls.Issues
+{
+#if APP
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Github, 5108, "iOS: Frame with HasShadow set to true and BackgroundColor alpha < 1 casts shadow on all child views", PlatformAffected.iOS)]
+	public partial class Issue5108 : TestContentPage
+	{
+		public Issue5108()
+		{
+			InitializeComponent();
+			MarginButton.Clicked += MarginButton_Clicked;
+			HasShadowButton.Clicked += HasShadowButton_Clicked;
+			RadiusButton.Clicked += RadiusButton_Clicked;
+			BackgroundButton.Clicked += BackgroundButton_Clicked;
+		}
+
+		protected override void Init()
+		{
+		}
+
+
+		void MarginButton_Clicked(object sender, EventArgs e)
+		{
+			if (myframe.Margin.Top == 20)
+				myframe.Margin = new Thickness(5);
+			else
+				myframe.Margin = new Thickness(20);
+		}
+
+		void HasShadowButton_Clicked(object sender, EventArgs e)
+		{
+			myframe.HasShadow = !myframe.HasShadow;
+		}
+
+		void RadiusButton_Clicked(object sender, EventArgs e)
+		{
+			if (myframe.CornerRadius == 10)
+				myframe.CornerRadius = 20;
+			else
+				myframe.CornerRadius = 10;
+		}
+
+		Color? initialColor = null;
+		void BackgroundButton_Clicked(object sender, EventArgs e)
+		{
+			if (!initialColor.HasValue)
+				initialColor = myframe.BackgroundColor;
+
+			if (myframe.BackgroundColor == initialColor.Value)
+				myframe.BackgroundColor = Color.HotPink;
+			else
+				myframe.BackgroundColor = initialColor.Value;
+		}
+	}
+#endif
+}
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
index 83ef723..baee0a0 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems
@@ -46,6 +46,9 @@
     <Compile Include="$(MSBuildThisFileDirectory)Issue8008.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue6640.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7556.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Issue5108.xaml.cs">
+      <SubType>Code</SubType>
+    </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Issue7329.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7290.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Issue7240.cs" />
@@ -1457,6 +1460,9 @@
     <Compile Update="$(MSBuildThisFileDirectory)Issue6254.xaml.cs">
       <DependentUpon>Issue6254.xaml</DependentUpon>
     </Compile>
+	<Compile Update="$(MSBuildThisFileDirectory)Issue5108.xaml.cs">
+      <DependentUpon>Issue5108.xaml</DependentUpon>
+	</Compile>
     <Compile Update="$(MSBuildThisFileDirectory)Issue7357.xaml.cs">
       <DependentUpon>Issue7357.xaml</DependentUpon>
     </Compile>
@@ -1498,7 +1504,7 @@
     </Compile>
     <Compile Update="$(MSBuildThisFileDirectory)Issue7865.xaml.cs">
       <DependentUpon>Issue7865.xaml</DependentUpon>
-    </Compile>
+	</Compile>
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue1455.xaml">
@@ -1525,6 +1531,12 @@
     </EmbeddedResource>
   </ItemGroup>
   <ItemGroup>
+    <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue5108.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+	</EmbeddedResource>
+  </ItemGroup>
+  <ItemGroup>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue7357.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
@@ -1600,7 +1612,7 @@
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue7803.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
-    </EmbeddedResource>
+	  </EmbeddedResource>
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="$(MSBuildThisFileDirectory)Issue7048.xaml">
@@ -1608,4 +1620,4 @@
       <Generator>MSBuild:Compile</Generator>
     </EmbeddedResource>
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/_TemplateMarkup.xaml.cs b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/_TemplateMarkup.xaml.cs
index e9b25fb..5c48b25 100644
--- a/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/_TemplateMarkup.xaml.cs
+++ b/Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/_TemplateMarkup.xaml.cs
@@ -49,7 +49,7 @@ namespace Xamarin.Forms.Controls.Issues
 	{
 		public ViewModelIssue2()
 		{
-			
+
 		}
 	}
 
@@ -58,7 +58,7 @@ namespace Xamarin.Forms.Controls.Issues
 	{
 		public ModelIssue2()
 		{
-			
+
 		}
 	}
 }
\ No newline at end of file
diff --git a/Xamarin.Forms.Platform.iOS/Renderers/FrameRenderer.cs b/Xamarin.Forms.Platform.iOS/Renderers/FrameRenderer.cs
index 656f369..f07d1d2 100644
--- a/Xamarin.Forms.Platform.iOS/Renderers/FrameRenderer.cs
+++ b/Xamarin.Forms.Platform.iOS/Renderers/FrameRenderer.cs
@@ -1,11 +1,15 @@
 using System.ComponentModel;
 using System.Drawing;
+using CoreAnimation;
+using CoreGraphics;
 using UIKit;
 
 namespace Xamarin.Forms.Platform.iOS
 {
 	public class FrameRenderer : VisualElementRenderer<Frame>
 	{
+		ShadowView _shadowView;
+
 		protected override void OnElementChanged(ElementChangedEventArgs<Frame> e)
 		{
 			base.OnElementChanged(e);
@@ -39,26 +43,95 @@ namespace Xamarin.Forms.Platform.iOS
 			else
 				Layer.BackgroundColor = Element.BackgroundColor.ToCGColor();
 
+			if (Element.BorderColor == Color.Default)
+				Layer.BorderColor = UIColor.Clear.CGColor;
+			else
+			{
+				Layer.BorderColor = Element.BorderColor.ToCGColor();
+				Layer.BorderWidth = 1;
+			}
+
 			if (Element.HasShadow)
 			{
+				if (_shadowView == null)
+				{
+					_shadowView = new ShadowView(Layer);
+					SetNeedsLayout();
+				}
+				_shadowView.UpdateBackgroundColor();
+				_shadowView.Layer.CornerRadius = Layer.CornerRadius;
+				_shadowView.Layer.BorderColor = Layer.BorderColor;
+			}
+			else
+			{
+				if (_shadowView != null)
+				{
+					_shadowView.RemoveFromSuperview();
+					_shadowView.Dispose();
+					_shadowView = null;
+				}
+			}
+
+			Layer.RasterizationScale = UIScreen.MainScreen.Scale;
+			Layer.ShouldRasterize = true;
+		}
+
+		public override void LayoutSubviews()
+		{
+			if (_shadowView != null)
+			{
+				if (_shadowView.Superview == null)
+					Superview.InsertSubviewBelow(_shadowView, this);
+
+				_shadowView?.SetNeedsLayout();
+			}
+			base.LayoutSubviews();
+		}
+
+		class ShadowView : UIView
+		{
+			CALayer _shadowee;
+			CGRect _previousBounds;
+			CGRect _previousFrame;
+
+			public ShadowView(CALayer shadowee)
+			{
+				_shadowee = shadowee;
 				Layer.ShadowRadius = 5;
 				Layer.ShadowColor = UIColor.Black.CGColor;
 				Layer.ShadowOpacity = 0.8f;
 				Layer.ShadowOffset = new SizeF();
+				Layer.BorderWidth = 1;
 			}
-			else
-				Layer.ShadowOpacity = 0;
 
-			if (Element.BorderColor == Color.Default)
-				Layer.BorderColor = UIColor.Clear.CGColor;
-			else
+			public void UpdateBackgroundColor()
 			{
-				Layer.BorderColor = Element.BorderColor.ToCGColor();
-				Layer.BorderWidth = 1;
+				//Putting a transparent background under any shadowee having a background with alpha < 1
+				//Giving the Shadow a background of the same color when shadowee background == 1.
+				//The latter will result in a 'darker' shadow as you would expect from something that 
+				//isn't transparent. This also mimics the look as it was before with non-transparent Frames.
+				if (_shadowee.BackgroundColor.Alpha < 1) 
+					BackgroundColor = UIColor.Clear;
+				else
+					BackgroundColor = new UIColor(_shadowee.BackgroundColor);
 			}
 
-			Layer.RasterizationScale = UIScreen.MainScreen.Scale;
-			Layer.ShouldRasterize = true;
+			public override void LayoutSubviews()
+			{
+				if (_shadowee.Bounds != _previousBounds || _shadowee.Frame != _previousFrame)
+				{
+					base.LayoutSubviews();
+					SetBounds();
+				}
+			}
+
+			void SetBounds()
+			{
+				Layer.Frame = _shadowee.Frame;
+				Layer.Bounds = _shadowee.Bounds;
+				_previousBounds = _shadowee.Bounds;
+				_previousFrame = _shadowee.Frame;
+			}
 		}
 	}
 }
\ No newline at end of file
-- 
2.7.4