author Sam Lantinga <>
Wed, 30 Nov 2016 22:06:05 -0800
changeset 10668 1889c850fafc
parent 10474 e723c663ba58
child 13520 d62544e5fa7a
permissions -rw-r--r--
Fixed bug 3340 - SDL_BlitScaled causes access violation in some cases.

Simon Hug

The SDL_BlitScaled function runs into an access violation for specific blit coordinates and surface sizes. The attached testcase blits a 800x600 surface to a 1280x720 surface at the coordinates -640,-345 scaled to 1280x720. The blit function that moves the data then runs over and reads after the pixel data from the src surface causing an access violation.

I can't say where exactly it goes wrong, but I think it could have something to do with the rounding in SDL_UpperBlitScaled. final_src.y is 288 and final_src.h is 313. Together that's 601, which I believe is one too much, but I just don't know the code enough to make sure that's the problem.


I think this patch fix the issue, but maybe it's worth re-writing "SDL_UpperBlitScaled" using SDL_FRect.
     1 # sdl2 cmake project-config input for ./configure scripts
     3 set(prefix "@prefix@") 
     4 set(exec_prefix "@exec_prefix@")
     5 set(libdir "@libdir@")
     6 set(SDL2_PREFIX "@prefix@")
     7 set(SDL2_EXEC_PREFIX "@prefix@")
     8 set(SDL2_LIBDIR "@libdir@")
     9 set(SDL2_INCLUDE_DIRS "@includedir@/SDL2")