Calculating the required buffer size for the WriteableBitmap.WritePixels method

Question

How do I calculate the required buffer size for the WriteableBitmap.WritePixels method?

I am using the overload taking four parameters, the first is an Int32Rect, th

Answer 1

The stride value is calculated as the number of bytes per "pixel line" in the write rectangle:

var stride = (rect.Width * bitmap.Format.BitsPerPixel + 7) / 8;

The required buffer size is the number of bytes per line multiplied by the number of lines:

var bufferSize = rect.Height * stride;

Provided that you have a 2x2 write rectangle and a 32-bits-per-pixel format, e.g. PixelFormats.Pbgra32, you get stride as 8 and bufferSize as 16.