Sanitize image drawing API.

- Remove opacity parameter - should push an opacity instead
- Add a WPF-compatible overload of `DrawImage` to `DrawingContext`

samples/RenderDemo/Pages/RenderTargetBitmapPage.cs

@@ -39,7 +39,7 @@ namespace RenderDemo.Pages
                 ctx.FillRectangle(Brushes.Fuchsia, new Rect(50, 50, 100, 100));
             }
 
-            context.DrawImage(_bitmap, 1, 
+            context.DrawImage(_bitmap,
                 new Rect(0, 0, 200, 200), 
                 new Rect(0, 0, 200, 200));
             Dispatcher.UIThread.Post(InvalidateVisual, DispatcherPriority.Background);

src/Avalonia.Controls/Image.cs

@@ -86,7 +86,7 @@ namespace Avalonia.Controls
 
                 var interpolationMode = RenderOptions.GetBitmapInterpolationMode(this);
 
-                context.DrawImage(source, 1, sourceRect, destRect, interpolationMode);
+                context.DrawImage(source, sourceRect, destRect, interpolationMode);
             }
         }
 

src/Avalonia.Controls/Remote/RemoteWidget.cs

@@ -83,7 +83,7 @@ namespace Avalonia.Controls.Remote
                         Marshal.Copy(_lastFrame.Data, y * _lastFrame.Stride,
                             new IntPtr(l.Address.ToInt64() + l.RowBytes * y), lineLen);
                 }
-                context.DrawImage(_bitmap, 1, new Rect(0, 0, _bitmap.PixelSize.Width, _bitmap.PixelSize.Height),
+                context.DrawImage(_bitmap, new Rect(0, 0, _bitmap.PixelSize.Width, _bitmap.PixelSize.Height),
                     new Rect(Bounds.Size));
             }
             base.Render(context);

src/Avalonia.Visuals/Media/DrawingContext.cs

@@ -77,15 +77,26 @@ namespace Avalonia.Media
         /// Draws an image.
         /// </summary>
         /// <param name="source">The image.</param>
-        /// <param name="opacity">The opacity to draw with.</param>
+        /// <param name="rect">The rect in the output to draw to.</param>
+        public void DrawImage(IImage source, Rect rect)
+        {
+            Contract.Requires<ArgumentNullException>(source != null);
+
+            DrawImage(source, new Rect(source.Size), rect);
+        }
+
+        /// <summary>
+        /// Draws an image.
+        /// </summary>
+        /// <param name="source">The image.</param>
         /// <param name="sourceRect">The rect in the image to draw.</param>
         /// <param name="destRect">The rect in the output to draw to.</param>
         /// <param name="bitmapInterpolationMode">The bitmap interpolation mode.</param>
-        public void DrawImage(IImage source, double opacity, Rect sourceRect, Rect destRect, BitmapInterpolationMode bitmapInterpolationMode = default)
+        public void DrawImage(IImage source, Rect sourceRect, Rect destRect, BitmapInterpolationMode bitmapInterpolationMode = default)
         {
             Contract.Requires<ArgumentNullException>(source != null);
 
-            source.Draw(this, opacity, sourceRect, destRect, bitmapInterpolationMode);
+            source.Draw(this, sourceRect, destRect, bitmapInterpolationMode);
         }
 
         /// <summary>

src/Avalonia.Visuals/Media/DrawingImage.cs

@@ -20,7 +20,6 @@ namespace Avalonia.Media
 
         public void Draw(
             DrawingContext context,
-            double opacity,
             Rect sourceRect,
             Rect destRect,
             BitmapInterpolationMode bitmapInterpolationMode)

src/Avalonia.Visuals/Media/IImage.cs

@@ -17,13 +17,11 @@ namespace Avalonia.Media
         /// Draws the image to a <see cref="DrawingContext"/>.
         /// </summary>
         /// <param name="context">The drawing context.</param>
-        /// <param name="opacity">The opacity to draw with.</param>
         /// <param name="sourceRect">The rect in the image to draw.</param>
         /// <param name="destRect">The rect in the output to draw to.</param>
         /// <param name="bitmapInterpolationMode">The bitmap interpolation mode.</param>
         void Draw(
             DrawingContext context,
-            double opacity,
             Rect sourceRect,
             Rect destRect,
             BitmapInterpolationMode bitmapInterpolationMode);

src/Avalonia.Visuals/Media/Imaging/Bitmap.cs

@@ -107,14 +107,13 @@ namespace Avalonia.Media.Imaging
         /// <inheritdoc/>
         void IImage.Draw(
             DrawingContext context,
-            double opacity,
             Rect sourceRect,
             Rect destRect,
             BitmapInterpolationMode bitmapInterpolationMode)
         {
             context.PlatformImpl.DrawBitmap(
                 PlatformImpl,
-                opacity,
+                1,
                 sourceRect,
                 destRect,
                 bitmapInterpolationMode);