Pin to 0 and 255. Don't roll over.
Or is there something else?
On Tue, Feb 10, 2009 at 11:11 AM, Lenard Lindstrom <len-l@xxxxxxxxx
<mailto:len-l@xxxxxxxxx>> wrote:
Hi,
I am trying to write unit tests for the blit blend operations and
am running into problems. There are no formal definitions as to
what exactly a BLEND_ADD, BLEND_SUB and BLEND_MULT do. Sure they
are add, subtract and multiply. But what happens with overflow and
underflow. Do they truncate or just return maximum or minimum
values. I will not look as the source for the answers because then
I would just write the tests to pass rather than making tests that
reflect the original intent of the operations.