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wayland: Fix damage of infinite regions

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To avoid integer overflow when scaling "infinite" regions (0, 0)
(INT32_MAX, INT32_MAX), intersect with the surface rect before scaling,
instead of intersecting with the buffer rect afterwards.

https://bugzilla.gnome.org/show_bug.cgi?id=746510
This commit is contained in:
Jonas Ådahl 2015-03-20 15:09:37 +08:00
parent 939f7ce781
commit dbca3337b2
1 changed files with 13 additions and 7 deletions
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20
src/wayland/meta-wayland-surface.c
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@ -121,24 +121,30 @@ static void
surface_process_damage (MetaWaylandSurface *surface,
cairo_region_t *region)
{
unsigned int buffer_width;
unsigned int buffer_height;
cairo_rectangle_int_t surface_rect;
cairo_region_t *scaled_region;
cairo_rectangle_int_t buffer_rect;
int i, n_rectangles;
if (!surface->buffer)
return;
buffer_rect.x = 0;
buffer_rect.y = 0;
buffer_rect.width = cogl_texture_get_width (surface->buffer->texture);
buffer_rect.height = cogl_texture_get_height (surface->buffer->texture);
/* Intersect the damage region with the surface region before scaling in
* order to avoid integer overflow when scaling a damage region is too large
* (for example INT32_MAX which mesa passes). */
buffer_width = cogl_texture_get_width (surface->buffer->texture);
buffer_height = cogl_texture_get_height (surface->buffer->texture);
surface_rect = (cairo_rectangle_int_t) {
.width = buffer_width / surface->scale,
.height = buffer_height / surface->scale,
};
cairo_region_intersect_rectangle (region, &surface_rect);
/* The damage region must be in the same coordinate space as the buffer,
* i.e. scaled with surface->scale. */
scaled_region = meta_region_scale (region, surface->scale);
cairo_region_intersect_rectangle (scaled_region, &buffer_rect);
/* First update the buffer. */
meta_wayland_buffer_process_damage (surface->buffer, scaled_region);