video-overlay-composition: Allow empty overlay compositions

Allowing to pass NULL to the constructor removes the need to
special-case the first rectangle in calling code and generally
simplifies application code.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/1256>
This commit is contained in:
Sebastian Dröge 2021-08-16 10:19:07 +03:00 committed by Nicolas Dufresne
parent 535c02c73b
commit a14f4f48c4

View file

@ -327,12 +327,14 @@ gst_video_overlay_composition_free (GstMiniObject * mini_obj)
/**
* gst_video_overlay_composition_new:
* @rectangle: (transfer none): a #GstVideoOverlayRectangle to add to the
* @rectangle: (transfer none) (nullable): a #GstVideoOverlayRectangle to add to the
* composition
*
* Creates a new video overlay composition object to hold one or more
* overlay rectangles.
*
* Note that since 1.20 this allows to pass %NULL for @rectangle.
*
* Returns: (transfer full): a new #GstVideoOverlayComposition. Unref with
* gst_video_overlay_composition_unref() when no longer needed.
*/
@ -341,11 +343,8 @@ gst_video_overlay_composition_new (GstVideoOverlayRectangle * rectangle)
{
GstVideoOverlayComposition *comp;
/* FIXME: should we allow empty compositions? Could also be expressed as
* buffer without a composition on it. Maybe there are cases where doing
* an empty new + _add() in a loop is easier? */
g_return_val_if_fail (GST_IS_VIDEO_OVERLAY_RECTANGLE (rectangle), NULL);
g_return_val_if_fail (GST_IS_VIDEO_OVERLAY_RECTANGLE (rectangle)
|| NULL, NULL);
comp = g_slice_new0 (GstVideoOverlayComposition);
@ -355,18 +354,16 @@ gst_video_overlay_composition_new (GstVideoOverlayRectangle * rectangle)
NULL, (GstMiniObjectFreeFunction) gst_video_overlay_composition_free);
comp->rectangles = g_new0 (GstVideoOverlayRectangle *, RECTANGLE_ARRAY_STEP);
comp->rectangles[0] = gst_video_overlay_rectangle_ref (rectangle);
gst_mini_object_add_parent (GST_MINI_OBJECT_CAST (rectangle),
GST_MINI_OBJECT_CAST (comp));
comp->num_rectangles = 1;
comp->seq_num = gst_video_overlay_get_seqnum ();
/* since the rectangle was created earlier, its seqnum is smaller than ours */
comp->min_seq_num_used = rectangle->seq_num;
GST_LOG ("new composition %p: seq_num %u with rectangle %p", comp,
comp->seq_num, rectangle);
GST_LOG ("new composition %p: seq_num %u", comp, comp->seq_num);
if (rectangle)
gst_video_overlay_composition_add_rectangle (comp, rectangle);
return comp;
}