On 27.10.16 21:43, Semyon Sadetsky wrote:
As you mention above background of the window will be always cleared
by the window itself, and we can get double alpha in the background
when we blit the backbuffer to the window. What composite is used when
we draw backbuffer to the window?
It is src-over.
If it is src-over mean that in the window you will get a composite of
colors, which was drawn to the backbuffer and the colors which was drawn
in the window(which was drawn by the window itself). And in this case
you will get a different results when you paint via backbuffer or when
you skip it.
Should the previous composite be restored after the rect filling?
SRC should be the default composite type.
default composite type should be srcOver, and it should be restored
before call paintToOffscreen().
--
Best regards, Sergey.
