tree 508d9911d05510b9e8e737f730aaa3e2c96ea3fc
parent a4a9743a983dfccd6e7cc16fa3cb0f6d468041c1
author Sam Lantinga <slouken@libsdl.org> 1499786160 -0700
committer Sam Lantinga <slouken@libsdl.org> 1499786160 -0700

Fixed bug 3699 - Shaped windows are distorted unless width is divisible by 8

Bogomancer

On X11, windows created using the shaped window API appear distorted unless the width of the shape surface is divisible by 8.

Steps to reproduce:

    1) Use your favorite image editor to resize one of the images in test/shapes/ to a width that's not a multiple of 8.
    2) Compile and run test/testshape.c on the image you edited.
    3) The shaped window will appear twisted and distorted.

It appears the bug was not caught sooner because all the test images are either 640 or 256 pixels wide.

I tracked down the bug to SDL_CalculateShapeBitmap() in SDL_shape.c. The shape surface is reduced to a 1-bit-per-pixel mask, but the original code doesn't take into account that X11 apparently wants each scanline to begin on a new byte.