Ability to set backgroundColor of a image

Author: dimonovdd

ImageFromXamarinUI/ImageFromXamarinUI.csproj

@@ -13,33 +13,30 @@
     <AssemblyVersion>1.0.0.0</AssemblyVersion>
     <AssemblyFileVersion>1.0.0.0</AssemblyFileVersion>
     <Version>1.0.0</Version>
-    <PackageVersion>1.0.0-pre1</PackageVersion>
+    <PackageVersion>1.0.0-pre2</PackageVersion>
     <Authors>dimonovdd</Authors>
     <Owners>dimonovdd</Owners>
     <RepositoryUrl>https://github.com/dimonovdd/ImageFromXamarinUI</RepositoryUrl>
     <PackageReleaseNotes>See: https://github.com/dimonovdd/ImageFromXamarinUI/releases</PackageReleaseNotes>
     <DefineConstants>$(DefineConstants);</DefineConstants>
-    <UseFullSemVerForNuGet>false</UseFullSemVerForNuGet>
     <EnableDefaultCompileItems>false</EnableDefaultCompileItems>
     <PackageLicenseFile>LICENSE</PackageLicenseFile>
     <PackageRequireLicenseAcceptance>true</PackageRequireLicenseAcceptance>
     <PackageProjectUrl>https://github.com/dimonovdd/ImageFromXamarinUI</PackageProjectUrl>
     <DebugType>portable</DebugType>
-    <Configurations>Debug;Release</Configurations>
+    <Configurations>Debug;Release</Configurations>    
+    <LangVersion>8.0</LangVersion>
  </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)'=='Debug' ">
     <DebugSymbols>true</DebugSymbols>
   </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <DocumentationFile>bin\Debug\netstandard2.0\ImageFromXamarinUI.xml</DocumentationFile>
-  </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
     <DocumentationFile>bin\Release\netstandard2.0\ImageFromXamarinUI.xml</DocumentationFile>
   </PropertyGroup>
   <ItemGroup>
     <None Include="..\LICENSE" PackagePath="" Pack="true" />
     <None Include="..\icon.png" PackagePath="" Pack="true" />
-    <PackageReference Include="Xamarin.Build.TypeRedirector" Version="0.1.2-preview" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All" />
     <PackageReference Include="Xamarin.Forms" Version="4.4.0.991864" />
     <Compile Include="**\*.shared.cs" />
     <Compile Include="**\*.shared.*.cs" />

ImageFromXamarinUI/VisualElementExtension.android.cs

@@ -9,9 +9,9 @@ namespace ImageFromXamarinUI
 {
     public static partial class VisualElementExtension
     {
-        static async Task<Stream> PlatformCaptureImageAsync(VisualElement view)
+        static async Task<Stream> PlatformCaptureImageAsync(VisualElement view, Xamarin.Forms.Color backgroundColor)
         {
-            using var bitmap = ViewToBitMap(GetNativeView(view));
+            using var bitmap = ViewToBitMap(GetNativeView(view), backgroundColor);
             var stream = await BitMapToStream(bitmap);
             bitmap.Recycle();
             return stream;
@@ -27,11 +27,11 @@ static Android.Views.View GetNativeView(VisualElement view)
             return render.View;
         }
 
-        static Bitmap ViewToBitMap(Android.Views.View view)
+        static Bitmap ViewToBitMap(Android.Views.View view, Xamarin.Forms.Color backgroundColor)
         {
             var bitmap = Bitmap.CreateBitmap(view.Width, view.Height, Bitmap.Config.Argb8888);
             using var canvas = new Canvas(bitmap);
-            canvas.DrawColor(Android.Graphics.Color.Transparent);
+            canvas.DrawColor(backgroundColor.ToAndroid());
             view.Draw(canvas);
 
             return bitmap;

ImageFromXamarinUI/VisualElementExtension.ios.cs

@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using System.Threading.Tasks;
+using CoreGraphics;
 using UIKit;
 using Xamarin.Forms;
 using Xamarin.Forms.Platform.iOS;
@@ -9,10 +10,10 @@ namespace ImageFromXamarinUI
 {
     public static partial class VisualElementExtension
     {
-        static Task<Stream> PlatformCaptureImageAsync(VisualElement view)
+        static Task<Stream> PlatformCaptureImageAsync(VisualElement view, Color backgroundColor)
         {
             Stream stream = null;
-            using (var image = ViewToUIImage(GetNativeView(view)))
+            using (var image = ViewToUIImage(GetNativeView(view), backgroundColor))
                 stream = ImageToStream(image);
             return Task.FromResult(stream);
         }
@@ -27,10 +28,19 @@ static UIView GetNativeView(VisualElement view)
             return render.NativeView;
         }
 
-        static UIImage ViewToUIImage(UIView view)
+        static UIImage ViewToUIImage(UIView view, Color backgroundColor)
         {
-            UIGraphics.BeginImageContextWithOptions(view.Frame.Size, false, UIScreen.MainScreen.Scale);
-            view.Layer.RenderInContext(UIGraphics.GetCurrentContext());
+            var size = view.Frame.Size;
+            UIGraphics.BeginImageContextWithOptions(size, false, UIScreen.MainScreen.Scale);
+            using var context = UIGraphics.GetCurrentContext();
+
+            if(backgroundColor != Color.Transparent)
+            {
+                context.SetFillColor(backgroundColor.ToCGColor());
+                context.FillRect(new CGRect(0, 0, size.Width, size.Height));
+            }
+            
+            view.Layer.RenderInContext(context);
             var image = UIGraphics.GetImageFromCurrentImageContext();
             UIGraphics.EndImageContext();
 

ImageFromXamarinUI/VisualElementExtension.netstandard.cs

@@ -7,7 +7,7 @@ namespace ImageFromXamarinUI
 {
     public static partial class VisualElementExtension
     {
-        static Task<Stream> PlatformCaptureImageAsync(VisualElement view)
+        static Task<Stream> PlatformCaptureImageAsync(VisualElement view, Color backgroundColor)
                => throw new NotImplementedException($"{nameof(CaptureImageAsync)} not supported on netstandart project");
 
     }

ImageFromXamarinUI/VisualElementExtension.shared.cs

@@ -4,12 +4,14 @@
 
 namespace ImageFromXamarinUI
 {
+    /// <summary>The extension class with methods for creating images</summary>
     public static partial class VisualElementExtension
     {
         /// <summary>Captures an image from the current state of <paramref name="element"/></summary>
         /// <param name="element">element to which the render was assigned</param>
+        /// <param name="backgroundColor"></param>
         /// <returns>Stream an image as png with transparency</returns>
-        public static async Task<Stream> CaptureImageAsync(this VisualElement element)
-            => await PlatformCaptureImageAsync(element);
+        public static async Task<Stream> CaptureImageAsync(this VisualElement element, Color? backgroundColor = null)
+            => await PlatformCaptureImageAsync(element, backgroundColor ?? Color.Transparent);
     }
 }

README.md

@@ -27,7 +27,7 @@ async void OnCapture(Xamarin.Forms.VisualElement element)
 {
     try
     {
-        var stream = await element.CaptureImageAsync();
+        var stream = await element.CaptureImageAsync(Color.White);
         ResultImageSource = ImageSource.FromStream(() => stream);
     }
     catch (Exception)

Sample/Sample/MainPage.xaml

@@ -10,7 +10,7 @@
         <sample:MainViewModel />
     </ContentPage.BindingContext>
     <ScrollView >
-        <StackLayout Background="Red" >
+        <StackLayout Background="Green" >
             <Frame BackgroundColor="#2196F3" Padding="24" CornerRadius="0">
                 <Label Text="Welcome to Xamarin.Forms!" HorizontalTextAlignment="Center" TextColor="White" FontSize="36"/>
             </Frame>
@@ -27,8 +27,11 @@
                 </Label.FormattedText>
             </Label>
 
-            <Button Text="Capture" Background="#990000ff" 
-                Command="{Binding CaptureCommand}" CommandParameter="{x:Reference rootView}"/>
+            <ContentView x:Name="button">
+                <Button Text="Capture" Background="#990000ff" Margin="10"
+                Command="{Binding CaptureCommand}" CommandParameter="{x:Reference button}"/>
+            </ContentView>
+            
 
             <Image Source="{Binding ResultImageSource}"/>
 

Sample/Sample/MainViewModel.cs

@@ -1,5 +1,7 @@
-using System.Windows.Input;
+using System.IO;
+using System.Windows.Input;
 using ImageFromXamarinUI;
+using Xamarin.Essentials;
 using Xamarin.Forms;
 
 namespace Sample
@@ -27,8 +29,21 @@ public ImageSource ResultImageSource
 
         async void OnCapture(VisualElement element)
         {
-            var stream = await element.CaptureImageAsync();
+            var stream = await element.CaptureImageAsync(Color.Red.MultiplyAlpha(0.4));
             ResultImageSource = ImageSource.FromStream(() => stream);
+
+
+            //var dir = FileSystem.CacheDirectory;
+            //var filepath = Path.Combine(dir, "image.jpg");
+
+            //if (File.Exists(filepath))
+            //    File.Delete(filepath);
+
+            //var fileStream = File.OpenWrite(filepath);
+            //stream.CopyTo(fileStream);
+            //fileStream.Close();
+
+            //await Share.RequestAsync(new ShareFileRequest(new ShareFile(filepath)));
         }
     }
 }