Pekka Paalanen authored Jun 13, 2022 and Pekka Paalanen committed Jun 16, 2022

Simplify the code by using ready-made helpers.

This also change the loop to draw the image row by row rather than
column by column. Row by row is more natural as it is linear with the
memory layout. No other change in behaviour.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>