async void Redraw(bool recreateSurface = true)
{
if (_compositor == null)
{
_compositor = Window.Current.Compositor;
_generator = _compositor.CreateCompositionGenerator();
_defaultSize = new Vector2(GridWidth, GridWidth);
// Create the original output image visual
_originalImageVisual = _compositor.CreateSpriteVisual();
_originalImageVisual.Size = _defaultSize;
_imageSurface = await _generator.CreateImageSurfaceAsync(new Uri("ms-appx:///Assets/Images/cat.png"), _defaultSize.ToSize(), ImageSurfaceOptions.Default);
_originalImageVisual.Brush = _compositor.CreateSurfaceBrush(_imageSurface);
ElementCompositionPreview.SetElementChildVisual(OriginalOutputGrid, _originalImageVisual);
// Create the source image visual
_sourceImageVisual = _compositor.CreateSpriteVisual();
_sourceImageVisual.Size = _defaultSize;
ElementCompositionPreview.SetElementChildVisual(ImageGrid, _sourceImageVisual);
//Create the mask visual
_maskVisual = _compositor.CreateSpriteVisual();
_maskVisual.Size = _defaultSize;
ElementCompositionPreview.SetElementChildVisual(MaskGrid, _maskVisual);
// Create the output visual
_outputVisual = _compositor.CreateSpriteVisual();
_outputVisual.Size = _defaultSize;
ElementCompositionPreview.SetElementChildVisual(OutputGrid, _outputVisual);
}
var selIndex = ImageList.SelectedIndex;
if (selIndex == -1)
{
return;
}
var uri = _images.Values.ElementAt(selIndex);
if (uri == null)
{
return;
}
var offset = OffsetSlider.Value.ToSingle();
var padding = new Thickness(offset);
if (recreateSurface)
{
_sourceImageSurface =
await _generator.CreateImageSurfaceAsync(uri, _defaultSize.ToSize(), ImageSurfaceOptions.Default);
_imageMaskSurface = _generator.CreateImageMaskSurface(_sourceImageSurface, _defaultSize.ToSize(),
padding, ImageSurfaceOptions.GetDefaultImageMaskOptionsForBlur(_blurRadius));
}
else
{
_imageMaskSurface.Resize(_defaultSize.ToSize(), padding, ImageSurfaceOptions.GetDefaultImageMaskOptionsForBlur(_blurRadius));
}
_sourceImageVisual.Brush = _compositor.CreateSurfaceBrush(_sourceImageSurface);
_maskVisual.Brush = _compositor.CreateSurfaceBrush(_imageMaskSurface);
var maskedBrush = _compositor.CreateMaskBrush();
maskedBrush.Source = _originalImageVisual.Brush;
maskedBrush.Mask = _compositor.CreateSurfaceBrush(_imageMaskSurface);
_outputVisual.Brush = maskedBrush;
}
