How to draw directly on an Image?

Question

I've a little program to draw in pixels. It actually works fine, but every time it updates the image via my timer, I notice a flicker. I think that's due to always setting a new source, so my question is: if there is a way to draw directly on the image instead of setting a new source?

Here is my draw method:

private void SetPixel(int x, int y)
{
    WriteableBitmap wrb = new WriteableBitmap((BitmapSource)image.Source);

    byte[] color = new byte[] { b, g, r, a };

    wrb.WritePixels(new Int32Rect(x, y, 1, 1), color, 4, 0);

    image.Source = wrb;
}

Answer 1

You could try to cast the Source property to a WriteableBitmap instead of setting it to a new WriteableBitmap each time:

private void SetPixel(int x, int y)
{
    WriteableBitmap wrb = image.Source as WriteableBitmap;
    if (wrb == null)
    {
        wrb = new WriteableBitmap((BitmapSource)image.Source);
        image.Source = wrb;
    }
    byte[] color = new byte[] { b, g, r, a };
    wrb.WritePixels(new Int32Rect(x, y, 1, 1), color, 4, 0);
}