public static void DrawBitmap(this SKCanvas canvas, SKBitmap bitmap, SKRect source, SKRect dest,
BitmapStretch stretch,
BitmapAlignment horizontal = BitmapAlignment.Center,
BitmapAlignment vertical = BitmapAlignment.Center,
SKPaint paint = null)
{
if (stretch == BitmapStretch.Fill)
{
canvas.DrawBitmap(bitmap, source, dest, paint);
}
else
{
float scale = 1;
switch (stretch)
{
case BitmapStretch.None:
break;
case BitmapStretch.Uniform:
scale = Math.Min(dest.Width / source.Width, dest.Height / source.Height);
break;
case BitmapStretch.UniformToFill:
scale = Math.Max(dest.Width / source.Width, dest.Height / source.Height);
break;
}
SKRect display = CalculateDisplayRect(dest, scale * source.Width, scale * source.Height,
horizontal, vertical);
canvas.DrawBitmap(bitmap, source, display, paint);
}
}
void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs args)
{
SKImageInfo info = args.Info;
SKSurface surface = args.Surface;
SKCanvas canvas = surface.Canvas;
canvas.Clear();
SKRect dest = new SKRect(0, 0, info.Width, info.Height);
BitmapStretch stretch = (BitmapStretch)stretchPicker.SelectedItem;
BitmapAlignment horizontal = (BitmapAlignment)horizontalPicker.SelectedItem;
BitmapAlignment vertical = (BitmapAlignment)verticalPicker.SelectedItem;
canvas.DrawBitmap(bitmap, SOURCE, dest, stretch, horizontal, vertical);
}
static SKRect CalculateDisplayRect(SKRect dest, float bmpWidth, float bmpHeight,
BitmapAlignment horizontal, BitmapAlignment vertical)
{
float x = 0;
float y = 0;
switch (horizontal)
{
case BitmapAlignment.Center:
x = (dest.Width - bmpWidth) / 2;
break;
case BitmapAlignment.Start:
break;
case BitmapAlignment.End:
x = dest.Width - bmpWidth;
break;
}
switch (vertical)
{
case BitmapAlignment.Center:
y = (dest.Height - bmpHeight) / 2;
break;
case BitmapAlignment.Start:
break;
case BitmapAlignment.End:
y = dest.Height - bmpHeight;
break;
}
x += dest.Left;
y += dest.Top;
return(new SKRect(x, y, x + bmpWidth, y + bmpHeight));
}
