use default arguments for bitmap decoder options in platform backends.

src/Avalonia.Visuals/Platform/IPlatformRenderInterface.cs

@@ -85,23 +85,21 @@ namespace Avalonia.Platform
         /// <returns>An <see cref="IWriteableBitmapImpl"/>.</returns>
         IWriteableBitmapImpl CreateWriteableBitmap(PixelSize size, Vector dpi, PixelFormat? format = null);
 
-        IBitmapImpl LoadBitmap(string fileName, BitmapDecodeOptions decodeOptions);
-
-        IBitmapImpl LoadBitmap(Stream stream, BitmapDecodeOptions decodeOptions);
-
         /// <summary>
         /// Loads a bitmap implementation from a file..
         /// </summary>
         /// <param name="fileName">The filename of the bitmap.</param>
+        /// <param name="decodeOptions">Decode options that specify the size of the decoded bitmap.</param>
         /// <returns>An <see cref="IBitmapImpl"/>.</returns>
-        IBitmapImpl LoadBitmap(string fileName);
+        IBitmapImpl LoadBitmap(string fileName, BitmapDecodeOptions? decodeOptions = null);
 
         /// <summary>
         /// Loads a bitmap implementation from a file..
         /// </summary>
         /// <param name="stream">The stream to read the bitmap from.</param>
+        /// <param name="decodeOptions">Decode options that specify the size of the decoded bitmap.</param>
         /// <returns>An <see cref="IBitmapImpl"/>.</returns>
-        IBitmapImpl LoadBitmap(Stream stream);
+        IBitmapImpl LoadBitmap(Stream stream, BitmapDecodeOptions? decodeOptions = null);
 
         /// <summary>
         /// Loads a bitmap implementation from a pixels in memory.

src/Skia/Avalonia.Skia/PlatformRenderInterface.cs

@@ -78,40 +78,36 @@ namespace Avalonia.Skia
             return new StreamGeometryImpl();
         }
 
-        public IBitmapImpl LoadBitmap(string fileName, BitmapDecodeOptions decodeOptions)
-        {
-            using (var stream = File.OpenRead(fileName))
+        /// <inheritdoc />
+        public unsafe IBitmapImpl LoadBitmap(Stream stream, BitmapDecodeOptions? decodeOptions = null)
+        {            
+            if (decodeOptions is null)
             {
-                return LoadBitmap(stream, decodeOptions);
+                return new ImmutableBitmap(stream);
             }
-        }
+            else
+            {
+                var options = decodeOptions.Value;
 
-        public unsafe IBitmapImpl LoadBitmap(Stream stream, BitmapDecodeOptions decodeOptions)
-        {
-            var skBitmap = SKBitmap.Decode(stream);
+                var skBitmap = SKBitmap.Decode(stream);
 
-            skBitmap = skBitmap.Resize(new SKImageInfo(decodeOptions.DecodePixelSize.Width, decodeOptions.DecodePixelSize.Height), decodeOptions.InterpolationMode.ToSKFilterQuality());
+                skBitmap = skBitmap.Resize(new SKImageInfo(options.DecodePixelSize.Width, options.DecodePixelSize.Height), options.InterpolationMode.ToSKFilterQuality());
 
-            fixed (byte* p = skBitmap.Bytes)
-            {
-                IntPtr ptr = (IntPtr)p;
+                fixed (byte* p = skBitmap.Bytes)
+                {
+                    IntPtr ptr = (IntPtr)p;
 
-                return LoadBitmap(PixelFormat.Bgra8888, ptr, new PixelSize(skBitmap.Width, skBitmap.Height), new Vector(96, 96), skBitmap.RowBytes);                
+                    return LoadBitmap(PixelFormat.Bgra8888, ptr, new PixelSize(skBitmap.Width, skBitmap.Height), new Vector(96, 96), skBitmap.RowBytes);
+                }
             }
         }
 
         /// <inheritdoc />
-        public IBitmapImpl LoadBitmap(Stream stream)
-        {
-            return new ImmutableBitmap(stream);
-        }
-
-        /// <inheritdoc />
-        public IBitmapImpl LoadBitmap(string fileName)
+        public IBitmapImpl LoadBitmap(string fileName, BitmapDecodeOptions? decodeOptions)
         {
             using (var stream = File.OpenRead(fileName))
             {
-                return LoadBitmap(stream);
+                return LoadBitmap(stream, decodeOptions);
             }
         }
 

src/Windows/Avalonia.Direct2D1/Direct2D1Platform.cs

@@ -180,12 +180,12 @@ namespace Avalonia.Direct2D1
         public IGeometryImpl CreateRectangleGeometry(Rect rect) => new RectangleGeometryImpl(rect);
         public IStreamGeometryImpl CreateStreamGeometry() => new StreamGeometryImpl();
 
-        public IBitmapImpl LoadBitmap(string fileName)
+        public IBitmapImpl LoadBitmap(string fileName, BitmapDecodeOptions? options = null)
         {
             return new WicBitmapImpl(fileName);
         }
 
-        public IBitmapImpl LoadBitmap(Stream stream)
+        public IBitmapImpl LoadBitmap(Stream stream, BitmapDecodeOptions? options = null)
         {
             return new WicBitmapImpl(stream);
         }
@@ -195,16 +195,6 @@ namespace Avalonia.Direct2D1
             return new WicBitmapImpl(format, data, size, dpi, stride);
         }
 
-        public IBitmapImpl LoadBitmap(string fileName, BitmapDecodeOptions decodeOptions)
-        {
-            throw new NotImplementedException();
-        }
-
-        public IBitmapImpl LoadBitmap(Stream stream, BitmapDecodeOptions decodeOptions)
-        {
-            throw new NotImplementedException();
-        }
-
         public IGlyphRunImpl CreateGlyphRun(GlyphRun glyphRun, out double width)
         {
             var glyphTypeface = (GlyphTypefaceImpl)glyphRun.GlyphTypeface.PlatformImpl;