Hi,
was looking at usage of SPICE_UNALIGNED_CAST and I found this code:
/* round down X to even 32 pixels (i.e. uint32_t) */
extents.x1 = extents.x1 & ~(0x1f);
mask_data_src = (uint8_t *)mask_data + mask_stride * extents.y1 + extents.x1 / 32;
mask_data = SPICE_UNALIGNED_CAST(uint32_t *, mask_data_src);
mask_x -= extents.x1;
mask_y -= extents.y1;
mask_width = extents.x2 - extents.x1;
mask_height = extents.y2 - extents.y1;
subimage = pixman_image_create_bits(PIXMAN_a1, mask_width, mask_height,
mask_data, mask_stride);
pixman_region32_init_from_image(&mask_region,
subimage);
pixman_image_unref(subimage);
the mask_data_src computation seems wrong to me however there seem no reports of rendering
issues. Particularly the "extents.x1 / 32" part.
The mask_data pointer is used to build a 1 bit image (PIXMAN_a1) used later to initialize
a region (pixman_region32_init_from_image).
The initial mask_data (before mask_data_src computation) points to a uint32_t which is the
image raw data start. The fact that this data is used as a 1 bit image raw data seems to
indicate that the image is 1 bit too. mask_stride is expressed in bytes (OT and always
4 multiple) and mask_data is cast to uint8_t* computing mask_data_src so it seems that
the "extents.x1 / 32" offset should be in bytes however is is a pointer to 1 bit raw data
should be "extents.x1 / 8".
Are we just lucky and issues never happens for some reasons (like very rare rendering)
or the computation is wrong?
Frediano
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