public void transform_pixel_rectangle (ref Rectangle? rect)
First transforms the
rect using this, then calculates the bounding box of the transformed
The rectangle should be in device units (pixels).
This function is useful for example when you want to draw a rotated
PangoLayout to an image buffer, and want to know how large the
image should be and how much you should shift the layout when rendering.
a Matrix, or
in/out bounding box in device units, or