compositor: Generalize output previous damage into per buffer damage
This is a more generic fix for the issue solved in 4f521731 where
damage obscured by overlays could be lost in one of the output buffers
due to rapid move of a surface in an overlay plane.
This changes the renderer so it keeps track of the damage in each
buffer. Every time a new frame is drawn, the damage of the frame is
added to all the buffers and the rendered regions are cleared from
the current buffer's damage.
diff --git a/src/screenshooter.c b/src/screenshooter.c
index ba80ce5..ffcc970 100644
--- a/src/screenshooter.c
+++ b/src/screenshooter.c
@@ -261,7 +261,7 @@
struct weston_output *output = data;
uint32_t msecs = output->frame_time;
pixman_box32_t *r;
- pixman_region32_t damage;
+ pixman_region32_t damage, *previous_damage;
int i, j, k, n, width, height, run, stride;
uint32_t delta, prev, *d, *s, *p, next;
struct {
@@ -270,9 +270,18 @@
} header;
struct iovec v[2];
+ /* When recording, this will be exactly the region that was repainted
+ * in this frame. Since overlays are disabled, the whole primary plane
+ * damage is rendered. For the first frame, the whole output will be
+ * damaged and that damage will be added to both buffers causing the
+ * non-current buffer damage to be while output. Rendering will clear
+ * all the damage in the current buffer so in the next frame (when
+ * that is non-current) the only damage left will be the one added
+ * from the primary plane. */
+ previous_damage = &output->buffer_damage[output->current_buffer ^ 1];
+
pixman_region32_init(&damage);
- pixman_region32_intersect(&damage, &output->region,
- &output->previous_damage);
+ pixman_region32_intersect(&damage, &output->region, previous_damage);
r = pixman_region32_rectangles(&damage, &n);
if (n == 0)