Add gst_vaapi_display_{sync,flush}() helpers.

docs/reference/libs/libs-sections.txt

@@ -133,6 +133,8 @@ GstVaapiDisplayClass
 gst_vaapi_display_new_with_display
 gst_vaapi_display_lock
 gst_vaapi_display_unlock
+gst_vaapi_display_sync
+gst_vaapi_display_flush
 gst_vaapi_display_get_display
 gst_vaapi_display_get_width
 gst_vaapi_display_get_height

gst-libs/gst/vaapi/gstvaapidisplay.c

@@ -48,10 +48,10 @@ struct _GstVaapiDisplayPrivate {
     guint               height_mm;
     guint               par_n;
     guint               par_d;
-    gboolean            create_display;
     GArray             *profiles;
     GArray             *image_formats;
     GArray             *subpicture_formats;
+    guint               create_display  : 1;
 };
 
 enum {
@@ -504,10 +504,10 @@ gst_vaapi_display_init(GstVaapiDisplay *display)
     priv->height_mm             = 0;
     priv->par_n                 = 1;
     priv->par_d                 = 1;
-    priv->create_display        = TRUE;
     priv->profiles              = NULL;
     priv->image_formats         = NULL;
     priv->subpicture_formats    = NULL;
+    priv->create_display        = TRUE;
 
     g_static_mutex_init(&priv->mutex);
 }
@@ -569,6 +569,52 @@ gst_vaapi_display_unlock(GstVaapiDisplay *display)
         klass->unlock(display);
 }
 
+/**
+ * gst_vaapi_display_sync:
+ * @display: a #GstVaapiDisplay
+ *
+ * Flushes any requests queued for the windowing system and waits until
+ * all requests have been handled. This is often used for making sure
+ * that the display is synchronized with the current state of the program.
+ *
+ * This is most useful for X11. On windowing systems where requests are
+ * handled synchronously, this function will do nothing.
+ */
+void
+gst_vaapi_display_sync(GstVaapiDisplay *display)
+{
+    GstVaapiDisplayClass *klass;
+
+    g_return_if_fail(GST_VAAPI_IS_DISPLAY(display));
+
+    klass = GST_VAAPI_DISPLAY_GET_CLASS(display);
+    if (klass->sync)
+        klass->sync(display);
+    else if (klass->flush)
+        klass->flush(display);
+}
+
+/**
+ * gst_vaapi_display_sync:
+ * @display: a #GstVaapiDisplay
+ *
+ * Flushes any requests queued for the windowing system.
+ *
+ * This is most useful for X11. On windowing systems where requests
+ * are handled synchronously, this function will do nothing.
+ */
+void
+gst_vaapi_display_flush(GstVaapiDisplay *display)
+{
+    GstVaapiDisplayClass *klass;
+
+    g_return_if_fail(GST_VAAPI_IS_DISPLAY(display));
+
+    klass = GST_VAAPI_DISPLAY_GET_CLASS(display);
+    if (klass->flush)
+        klass->flush(display);
+}
+
 /**
  * gst_vaapi_display_get_display:
  * @display: a #GstVaapiDisplay

gst-libs/gst/vaapi/gstvaapidisplay.h

@@ -103,8 +103,10 @@ struct _GstVaapiDisplay {
  * GstVaapiDisplayClass:
  * @open_display: virtual function to open a display
  * @close_display: virtual function to close a display
- * @lock: virtual function to lock a display
+ * @lock: (optional) virtual function to lock a display
- * @unlock: virtual function to unlock a display
+ * @unlock: (optional) virtual function to unlock a display
+ * @sync: (optional) virtual function to sync a display
+ * @flush: (optional) virtual function to flush pending requests of a display
  * @get_display: virtual function to retrieve the #VADisplay
  * @get_size: virtual function to retrieve the display dimensions, in pixels
  * @get_size_mm: virtual function to retrieve the display dimensions, in millimeters
@@ -120,6 +122,8 @@ struct _GstVaapiDisplayClass {
     void       (*close_display) (GstVaapiDisplay *display);
     void       (*lock)          (GstVaapiDisplay *display);
     void       (*unlock)        (GstVaapiDisplay *display);
+    void       (*sync)          (GstVaapiDisplay *display);
+    void       (*flush)         (GstVaapiDisplay *display);
     VADisplay  (*get_display)   (GstVaapiDisplay *display);
     void       (*get_size)      (GstVaapiDisplay *display,
                                  guint *pwidth, guint *pheight);
@@ -139,6 +143,12 @@ gst_vaapi_display_lock(GstVaapiDisplay *display);
 void
 gst_vaapi_display_unlock(GstVaapiDisplay *display);
 
+void
+gst_vaapi_display_sync(GstVaapiDisplay *display);
+
+void
+gst_vaapi_display_flush(GstVaapiDisplay *display);
+
 VADisplay
 gst_vaapi_display_get_display(GstVaapiDisplay *display);
 

gst-libs/gst/vaapi/gstvaapidisplay_x11.c

@@ -192,6 +192,26 @@ gst_vaapi_display_x11_close_display(GstVaapiDisplay *display)
     }
 }
 
+static void
+gst_vaapi_display_x11_sync(GstVaapiDisplay *display)
+{
+    GstVaapiDisplayX11Private * const priv =
+        GST_VAAPI_DISPLAY_X11(display)->priv;
+
+    if (priv->x11_display)
+        XSync(priv->x11_display, False);
+}
+
+static void
+gst_vaapi_display_x11_flush(GstVaapiDisplay *display)
+{
+    GstVaapiDisplayX11Private * const priv =
+        GST_VAAPI_DISPLAY_X11(display)->priv;
+
+    if (priv->x11_display)
+        XFlush(priv->x11_display);
+}
+
 static VADisplay
 gst_vaapi_display_x11_get_va_display(GstVaapiDisplay *display)
 {
@@ -253,6 +273,8 @@ gst_vaapi_display_x11_class_init(GstVaapiDisplayX11Class *klass)
 
     dpy_class->open_display     = gst_vaapi_display_x11_open_display;
     dpy_class->close_display    = gst_vaapi_display_x11_close_display;
+    dpy_class->sync             = gst_vaapi_display_x11_sync;
+    dpy_class->flush            = gst_vaapi_display_x11_flush;
     dpy_class->get_display      = gst_vaapi_display_x11_get_va_display;
     dpy_class->get_size         = gst_vaapi_display_x11_get_size;
     dpy_class->get_size_mm      = gst_vaapi_display_x11_get_size_mm;