Create a Composite BitmapImage in WPF

Question

I have three BitmapImages that I would like to stitch together to create a composite image. The three images to be stitched together are aligned in the following way:

The images are of a type System.Windows.Media.Imaging.BitmapImage. I have looked at the following solution, but it uses System.Drawing.Graphics to perform stitching. I find it unintuitive to convert my BitmapImage to System.Drawing.Bitmap everytime I want to stich them together.

Is there a simple way to stitch three images of type System.Windows.Media.Imaging.BitmapImage together?

Answer 1

In addition to the options described in the other answer, the code below stitches three BitmapSource together into a single WriteableBitmap:

public BitmapSource StitchBitmaps(BitmapSource b1, BitmapSource b2, BitmapSource b3)
{
    if (b1.Format != b2.Format || b1.Format != b3.Format)
    {
        throw new ArgumentException("All input bitmaps must have the same pixel format");
    }

    var width = Math.Max(b1.PixelWidth, b2.PixelWidth + b3.PixelWidth);
    var height = b1.PixelHeight + Math.Max(b2.PixelHeight, b3.PixelHeight);
    var wb = new WriteableBitmap(width, height, 96, 96, b1.Format, null);
    var stride1 = (b1.PixelWidth * b1.Format.BitsPerPixel + 7) / 8;
    var stride2 = (b2.PixelWidth * b2.Format.BitsPerPixel + 7) / 8;
    var stride3 = (b3.PixelWidth * b3.Format.BitsPerPixel + 7) / 8;
    var size = b1.PixelHeight * stride1;
    size = Math.Max(size, b2.PixelHeight * stride2);
    size = Math.Max(size, b3.PixelHeight * stride3);

    var buffer = new byte[size];
    b1.CopyPixels(buffer, stride1, 0);
    wb.WritePixels(
        new Int32Rect(0, 0, b1.PixelWidth, b1.PixelHeight),
        buffer, stride1, 0);

    b2.CopyPixels(buffer, stride2, 0);
    wb.WritePixels(
        new Int32Rect(0, b1.PixelHeight, b2.PixelWidth, b2.PixelHeight),
        buffer, stride2, 0);

    b3.CopyPixels(buffer, stride3, 0);
    wb.WritePixels(
        new Int32Rect(b2.PixelWidth, b1.PixelHeight, b3.PixelWidth, b3.PixelHeight),
        buffer, stride3, 0);

    return wb;
}