static CanvasBitmap MakeThumbnailPretty(CanvasBitmap capturedBitmap, float thumbnailWidth, float thumbnailHeight, Rect targetRect)
{
var pixelColors = capturedBitmap.GetPixelColors();
// Remove any unused space around the edge of the bitmap, so it will fill the thumbnail.
Rect cropRect = CropCapturedBitmap(capturedBitmap, pixelColors);
// Choose a (hopefully) aesthetically pleasing background color.
Color backgroundColor = ChooseBackgroundColor(pixelColors);
// Apply letterbox scaling to fit the image into the target thumbnail.
Vector2 outputSize = new Vector2((float)targetRect.Width, (float)targetRect.Height);
var sourceSize = new Vector2((float)cropRect.Width, (float)cropRect.Height);
var letterbox = Utils.GetDisplayTransform(outputSize, sourceSize);
var translate = Matrix3x2.CreateTranslation((float)targetRect.X, (float)targetRect.Y);
// Position the image where we want it.
var scaledImage = new Transform2DEffect
{
Source = new AtlasEffect
{
Source = capturedBitmap,
SourceRectangle = cropRect,
},
InterpolationMode = CanvasImageInterpolation.HighQualityCubic,
TransformMatrix = letterbox * translate,
};
// Create the final thumbnail image.
var finalImage = new CompositeEffect
{
Sources =
{
// Blurred shadow.
new ShadowEffect
{
Source = new MorphologyEffect
{
Source = scaledImage,
Mode = MorphologyEffectMode.Dilate,
Width = dilateAmount,
Height = dilateAmount,
},
BlurAmount = blurAmount,
},
// Overlay the image itself.
scaledImage
}
};
// Rasterize the effect into a rendertarget.
CanvasRenderTarget output = new CanvasRenderTarget(capturedBitmap.Device, thumbnailWidth, thumbnailHeight, 96);
using (var ds = output.CreateDrawingSession())
{
ds.Clear(backgroundColor);
ds.DrawImage(finalImage);
}
return(output);
}