diff --git a/clutter/clutter-stage-window.c b/clutter/clutter-stage-window.c
index c704854ea..ce88a5d34 100644
--- a/clutter/clutter-stage-window.c
+++ b/clutter/clutter-stage-window.c
@@ -124,6 +124,14 @@ _clutter_stage_window_add_redraw_clip (ClutterStageWindow *window,
iface->add_redraw_clip (window, stage_clip);
}
+/* Determines if the backend will clip the rendering of the next
+ * frame.
+ *
+ * Note: at the start of each new frame there is an implied clip that
+ * clips everything (i.e. nothing would be drawn) so this function
+ * will return True at the start of a new frame if the backend
+ * supports clipped redraws.
+ */
gboolean
_clutter_stage_window_has_redraw_clips (ClutterStageWindow *window)
{
@@ -138,6 +146,14 @@ _clutter_stage_window_has_redraw_clips (ClutterStageWindow *window)
return FALSE;
}
+/* Determines if the backend will discard any additional redraw clips
+ * and instead promote them to a full stage redraw.
+ *
+ * The ideas is that backend may have some heuristics that cause it to
+ * give up tracking redraw clips so this can be used to avoid the cost
+ * of calculating a redraw clip when we know it's going to be ignored
+ * anyway.
+ */
gboolean
_clutter_stage_window_ignoring_redraw_clips (ClutterStageWindow *window)
{
diff --git a/clutter/egl/clutter-stage-egl.c b/clutter/egl/clutter-stage-egl.c
index 16c561d98..859a87740 100644
--- a/clutter/egl/clutter-stage-egl.c
+++ b/clutter/egl/clutter-stage-egl.c
@@ -278,9 +278,16 @@ clutter_stage_egl_has_redraw_clips (ClutterStageWindow *stage_window)
{
ClutterStageEGL *stage_egl = CLUTTER_STAGE_EGL (stage_window);
- /* NB: a degenerate clip means a full stage redraw is required */
- if (stage_egl->initialized_redraw_clip &&
- stage_egl->bounding_redraw_clip.width != 0)
+ /* NB: at the start of each new frame there is an implied clip that
+ * clips everything (i.e. nothing would be drawn) so we need to make
+ * sure we return True in the un-initialized case here.
+ *
+ * NB: a clip width of 0 means a full stage redraw has been queued
+ * so we effectively don't have any redraw clips in that case.
+ */
+ if (!stage_egl->initialized_redraw_clip ||
+ (stage_egl->initialized_redraw_clip &&
+ stage_egl->bounding_redraw_clip.width != 0))
return TRUE;
else
return FALSE;
@@ -291,7 +298,7 @@ clutter_stage_egl_ignoring_redraw_clips (ClutterStageWindow *stage_window)
{
ClutterStageEGL *stage_egl = CLUTTER_STAGE_EGL (stage_window);
- /* NB: a degenerate clip means a full stage redraw is required */
+ /* NB: a clip width of 0 means a full stage redraw is required */
if (stage_egl->initialized_redraw_clip &&
stage_egl->bounding_redraw_clip.width == 0)
return TRUE;
@@ -324,7 +331,7 @@ clutter_stage_egl_add_redraw_clip (ClutterStageWindow *stage_window,
return;
/* A NULL stage clip means a full stage redraw has been queued and
- * we keep track of this by setting a degenerate
+ * we keep track of this by setting a zero width
* stage_egl->bounding_redraw_clip */
if (stage_clip == NULL)
{
@@ -444,7 +451,7 @@ _clutter_stage_egl_redraw (ClutterStageEGL *stage_egl,
#endif
if (G_LIKELY (backend_egl->can_blit_sub_buffer) &&
- /* NB: a degenerate redraw clip width == full stage redraw */
+ /* NB: a zero width clip == full stage redraw */
stage_egl->bounding_redraw_clip.width != 0 &&
/* some drivers struggle to get going and produce some junk
* frames when starting up... */
diff --git a/clutter/glx/clutter-stage-glx.c b/clutter/glx/clutter-stage-glx.c
index 42b29fe81..ae3c8cda1 100644
--- a/clutter/glx/clutter-stage-glx.c
+++ b/clutter/glx/clutter-stage-glx.c
@@ -291,9 +291,16 @@ clutter_stage_glx_has_redraw_clips (ClutterStageWindow *stage_window)
{
ClutterStageGLX *stage_glx = CLUTTER_STAGE_GLX (stage_window);
- /* NB: a degenerate clip means a full stage redraw is required */
- if (stage_glx->initialized_redraw_clip &&
- stage_glx->bounding_redraw_clip.width != 0)
+ /* NB: at the start of each new frame there is an implied clip that
+ * clips everything (i.e. nothing would be drawn) so we need to make
+ * sure we return True in the un-initialized case here.
+ *
+ * NB: a clip width of 0 means a full stage redraw has been queued
+ * so we effectively don't have any redraw clips in that case.
+ */
+ if (!stage_glx->initialized_redraw_clip ||
+ (stage_glx->initialized_redraw_clip &&
+ stage_glx->bounding_redraw_clip.width != 0))
return TRUE;
else
return FALSE;
@@ -304,7 +311,7 @@ clutter_stage_glx_ignoring_redraw_clips (ClutterStageWindow *stage_window)
{
ClutterStageGLX *stage_glx = CLUTTER_STAGE_GLX (stage_window);
- /* NB: a degenerate clip means a full stage redraw is required */
+ /* NB: a clip width of 0 means a full stage redraw is required */
if (stage_glx->initialized_redraw_clip &&
stage_glx->bounding_redraw_clip.width == 0)
return TRUE;
@@ -369,7 +376,7 @@ clutter_stage_glx_add_redraw_clip (ClutterStageWindow *stage_window,
return;
/* A NULL stage clip means a full stage redraw has been queued and
- * we keep track of this by setting a degenerate
+ * we keep track of this by setting a zero width
* stage_glx->bounding_redraw_clip */
if (stage_clip == NULL)
{
@@ -408,7 +415,7 @@ clutter_stage_glx_add_redraw_clip (ClutterStageWindow *stage_window,
if (redraw_area > (stage_area * 0.7f))
{
g_print ("DEBUG: clipped redraw too big, forcing full redraw\n");
- /* Set a degenerate clip to force a full redraw */
+ /* Set a zero width clip to force a full redraw */
stage_glx->bounding_redraw_clip.width = 0;
}
#endif
@@ -519,7 +526,7 @@ _clutter_stage_glx_redraw (ClutterStageGLX *stage_glx,
CLUTTER_TIMER_START (_clutter_uprof_context, painting_timer);
if (G_LIKELY (backend_glx->can_blit_sub_buffer) &&
- /* NB: a degenerate redraw clip width == full stage redraw */
+ /* NB: a zero width redraw clip == full stage redraw */
stage_glx->bounding_redraw_clip.width != 0 &&
/* some drivers struggle to get going and produce some junk
* frames when starting up... */