cmksoftdev / animatedpngcreator Goto Github PK

    public unsafe Image BlackoutImage(Image newImage, out bool equal)
    {
        equal = false;
        if (newImage == null)
        {
            return null;
        }
        // Make sure we have a bitmap
        var newImageBmp = new Bitmap(newImage);
        // Copy of new image
        var copy_new_image = new Bitmap(newImageBmp);
        // Dimensions
        var x = newImage.Width;            
        var y = newImage.Height;
        var x4 = 4 * x; // argb format

        // Something to do?
        if (oldImage != null)
        {
            // Lock bits of old and new image
            var o_img = oldImage.LockBits(new Rectangle(0, 0, x, y), System.Drawing.Imaging.ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
            var n_img = newImageBmp.LockBits(new Rectangle(0, 0, x, y), System.Drawing.Imaging.ImageLockMode.ReadWrite, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
            // To track equality
            bool is_equal = true;

            for (int j = 0; j < y; j++)
            {
                byte* o_row = ((byte *) o_img.Scan0) + o_img.Stride * j;
                byte* n_row = ((byte * )n_img.Scan0) + n_img.Stride * j;
                for (int i = 0; i < x4; i+=4)
                {                    
                    // Compare b, g, and r values (+0, +1, +2)
                    if (o_row[i+0] == n_row[i+0] && o_row[i+1] == n_row[i+1] && o_row[i+2] == n_row[i+2])
                    {   
                        // For compatibility with tests
                        n_row[i + 0] = 255;
                        n_row[i + 1] = 255;
                        n_row[i + 2] = 255;
                        // Set 'A' value(+3) of new image to 0: fully transparent (whatever the other colors!)
                        n_row[i + 3] = 0;
                    }
                    else
                    {
                        is_equal = false;
                    }
                }
            }
            // Unlock bits
            oldImage.UnlockBits(o_img);
            newImageBmp.UnlockBits(n_img);
            // Update equality
            equal = is_equal;
        }
        // old image is current new image (but without our transparancy changes, so use copy0
        oldImage = copy_new_image;            
        // Return bitmap with transparance changes
        return newImageBmp;
    }

}