void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs e)
{
SKImageInfo info = e.Info;
SKCanvas canvas = e.Surface.Canvas;
canvas.Clear();
if (image != null)
{
if (kernelSelected)
{
using (SKPaint paint = new SKPaint())
{
paint.FilterQuality = SKFilterQuality.High;
paint.IsAntialias = false;
paint.IsDither = false;
paint.ImageFilter = SKImageFilter.CreateMatrixConvolution(
sizeI, kernel, 1f, 0f, new SKPointI(1, 1),
SKMatrixConvolutionTileMode.Clamp, false);
canvas.DrawImage(image, info.Rect, ImageStretch.Uniform, paint: paint);
image = e.Surface.Snapshot();
kernel = null;
kernelSelected = false;
}
}
else
{
canvas.DrawImage(image, info.Rect, ImageStretch.Uniform);
}
}
}
[Arguments("t.jpg", "t2.jpg")] // SkiaSharp doesn't have TIFF support
public void SkiaSharp(string input, string output)
{
using (var bitmap = SKBitmap.Decode(input))
{
bitmap.ExtractSubset(bitmap, SKRectI.Create(100, 100, bitmap.Width - 200, bitmap.Height - 200));
var targetWidth = (int)Math.Round(bitmap.Width * .9F);
var targetHeight = (int)Math.Round(bitmap.Height * .9F);
// bitmap.Resize(new SKImageInfo(targetWidth, targetHeight), SKBitmapResizeMethod.Triangle)
// is deprecated, so we use `SKFilterQuality.Low` instead, see:
// https://github.com/mono/SkiaSharp/blob/1527bf392ebc7b4b57c992ef8bfe14c9899f76a3/binding/Binding/SKBitmap.cs#L24
using (var resized = bitmap.Resize(new SKImageInfo(targetWidth, targetHeight), SKFilterQuality.Low))
{
using (var surface = SKSurface.Create(new SKImageInfo(targetWidth, targetHeight, bitmap.ColorType,
bitmap.AlphaType)))
using (var canvas = surface.Canvas)
using (var paint = new SKPaint {
FilterQuality = SKFilterQuality.High
})
{
var kernel = new[]
{
-1f, -1f, -1f,
-1f, 16f, -1f,
-1f, -1f, -1f
};
var kernelSize = new SKSizeI(3, 3);
var kernelOffset = new SKPointI(1, 1);
paint.ImageFilter = SKImageFilter.CreateMatrixConvolution(kernelSize, kernel, 0.125f, 0f,
kernelOffset, SKMatrixConvolutionTileMode.Repeat, false);
canvas.DrawBitmap(resized, 0, 0, paint);
canvas.Flush();
using (var fileStream = File.OpenWrite(output))
{
surface.Snapshot()
.Encode(SKEncodedImageFormat.Jpeg, Quality)
.SaveTo(fileStream);
}
}
}
}
}
