问Xamrin.Android加图像水印

EN

var filename = System.IO.Path.Combine(Environment.GetExternalStoragePublicDirectory(Environment.DirectoryDownloads).ToString(), "filename.png");

Bitmap newBitmap;
using (var aBitmapToApplyWaterMarkTo = await BitmapFactory.DecodeResourceAsync(Resources, Resource.Drawable.Alexina))
using (var waterMarkBitmap = await BitmapFactory.DecodeResourceAsync(Resources, Resource.Drawable.watermark))
{
    newBitmap = aBitmapToApplyWaterMarkTo.Copy(aBitmapToApplyWaterMarkTo.GetConfig(), true);
    using (var canvas = new Canvas(newBitmap))
    {
        canvas.DrawBitmap(waterMarkBitmap, newBitmap.Width - 100, newBitmap.Height - 100, null);
    }
}
using (var fileStream = new FileStream(filename, FileMode.OpenOrCreate, FileAccess.Write))
{
    await newBitmap.CompressAsync(Bitmap.CompressFormat.Png, 100, fileStream);
}
newBitmap.Dispose();