Commit 5ad727f9 authored by Thibault Saunier's avatar Thibault Saunier 🌵

compositor: Frames where we introduce alpha can't obscure anything

When a pad has alpha != 1.0 it means that the resulting frames will
contain alpha and thus can't fully obscure with a lower zorder.

Also simplifies the other checks as blending with an OVER or on a
transparent is not a no-op as previously assumed.

Part-of: <!764>
parent 2faeb7d3
Pipeline #184965 waiting for manual action with stages
in 1 minute and 11 seconds
......@@ -338,7 +338,7 @@ clamp_rectangle (gint x, gint y, gint w, gint h, gint outer_width,
/* Call this with the lock taken */
static gboolean
_pad_obscures_rectangle (GstVideoAggregator * vagg, GstVideoAggregatorPad * pad,
const GstVideoRectangle rect, gboolean rect_transparent)
const GstVideoRectangle rect)
GstVideoRectangle pad_rect;
GstCompositorPad *cpad = GST_COMPOSITOR_PAD (pad);
......@@ -347,13 +347,11 @@ _pad_obscures_rectangle (GstVideoAggregator * vagg, GstVideoAggregatorPad * pad,
if (!gst_video_aggregator_pad_has_current_buffer (pad))
return FALSE;
/* Can't obscure if it's transparent and if the format has an alpha
* component we'd have to inspect every pixel to know if the frame is
* opaque, so assume it doesn't obscure unless it uses the SOURCE operator.
* As a bonus, if the rectangle is fully transparent, we can also obscure it
* if we have alpha components on the pad */
if (cpad->op != COMPOSITOR_OPERATOR_SOURCE && !rect_transparent &&
(cpad->alpha != 1.0 || GST_VIDEO_INFO_HAS_ALPHA (&pad->info)))
/* Can't obscure if we introduce alpha or if the format has an alpha
* component as we'd have to inspect every pixel to know if the frame is
* opaque, so assume it doesn't obscure
if (cpad->alpha != 1.0 || GST_VIDEO_INFO_HAS_ALPHA (&pad->info))
return FALSE;
pad_rect.x = cpad->xpos;
......@@ -420,7 +418,7 @@ gst_compositor_pad_prepare_frame (GstVideoAggregatorPad * pad,
* higher-zorder frames */
l = g_list_find (GST_ELEMENT (vagg)->sinkpads, pad)->next;
for (; l; l = l->next) {
if (_pad_obscures_rectangle (vagg, l->data, frame_rect, FALSE)) {
if (_pad_obscures_rectangle (vagg, l->data, frame_rect)) {
frame_obscured = TRUE;
......@@ -848,7 +846,7 @@ _negotiated_caps (GstAggregator * agg, GstCaps * caps)
static gboolean
_should_draw_background (GstVideoAggregator * vagg, gboolean bg_transparent)
_should_draw_background (GstVideoAggregator * vagg)
GstVideoRectangle bg_rect;
gboolean draw = TRUE;
......@@ -862,7 +860,7 @@ _should_draw_background (GstVideoAggregator * vagg, gboolean bg_transparent)
/* Check if the background is completely obscured by a pad
* TODO: Also skip if it's obscured by a combination of pads */
for (l = GST_ELEMENT (vagg)->sinkpads; l; l = l->next) {
if (_pad_obscures_rectangle (vagg, l->data, bg_rect, bg_transparent)) {
if (_pad_obscures_rectangle (vagg, l->data, bg_rect)) {
draw = FALSE;
......@@ -882,8 +880,7 @@ _draw_background (GstVideoAggregator * vagg, GstVideoFrame * outframe,
* don't bother drawing the background at all. We can also always use the
* 'blend' BlendFunction in that case because it only changes if we have to
* overlay on top of a transparent background. */
if (!_should_draw_background (vagg,
if (!_should_draw_background (vagg))
return FALSE;
switch (comp->background) {
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