Improve performance of copyArea(), especially relevant for mobile devices.

vigra::copyImage89 does not handle copy areas in the same image so the
code checks whether the src and dst are same buffer and directs it to
scaleImage() which is very slow. The whole concept of pixel accessors
is a huge overhead in the case of direct pixel copy (vigra::copyImage
is also using pixel accessors). The idea here is to identify when
direct memory copy is applicable (when the format is an integral
number of bytes per pixel, src.size==dst.size, and
src.format==dst.format) and use direct memory block copy and not
pixel-wise copy. The result is 100x faster than the vigra
implementation. This direct copy is also handling the case when the
src and dst are same buffer by copy it from bottom to top when needed
and using memmove() instead of memcpy().

Change-Id: I8ec589463d6386db82777a916371a5ebbf9e2d50
Reviewed-on: https://gerrit.libreoffice.org/5707
Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>

0 files changed, 0 insertions, 0 deletions