gl: Let base transform relay the meta api for us

During allocation query, when this element is not passthrough, it must
relay the overlay compostion meta and it's parameters. Fortunatly, base
transform can do this for us.

https://bugzilla.gnome.org/show_bug.cgi?id=753850

ext/gl/gstglcolorconvertelement.c

@@ -41,6 +41,9 @@ static GstCaps *gst_gl_color_convert_element_transform_caps (GstBaseTransform *
     bt, GstPadDirection direction, GstCaps * caps, GstCaps * filter);
 static gboolean gst_gl_color_convert_element_get_unit_size (GstBaseTransform *
     trans, GstCaps * caps, gsize * size);
+static gboolean
+gst_gl_color_convert_element_filter_meta (GstBaseTransform * trans,
+    GstQuery * query, GType api, const GstStructure * params);
 static gboolean gst_gl_color_convert_element_decide_allocation (GstBaseTransform
     * trans, GstQuery * query);
 static GstFlowReturn
@@ -92,6 +95,7 @@ gst_gl_color_convert_element_class_init (GstGLColorConvertElementClass * klass)
   bt_class->transform_caps = gst_gl_color_convert_element_transform_caps;
   bt_class->set_caps = gst_gl_color_convert_element_set_caps;
   bt_class->get_unit_size = gst_gl_color_convert_element_get_unit_size;
+  bt_class->filter_meta = gst_gl_color_convert_element_filter_meta;
   bt_class->decide_allocation = gst_gl_color_convert_element_decide_allocation;
   bt_class->prepare_output_buffer =
       gst_gl_color_convert_element_prepare_output_buffer;
@@ -159,6 +163,14 @@ gst_gl_color_convert_element_get_unit_size (GstBaseTransform * trans,
   return TRUE;
 }
 
+static gboolean
+gst_gl_color_convert_element_filter_meta (GstBaseTransform * trans,
+    GstQuery * query, GType api, const GstStructure * params)
+{
+  /* propose all metadata upstream */
+  return TRUE;
+}
+
 static gboolean
 gst_gl_color_convert_element_decide_allocation (GstBaseTransform * trans,
     GstQuery * query)

ext/gl/gstgluploadelement.c

@@ -45,6 +45,8 @@ static GstCaps *_gst_gl_upload_element_transform_caps (GstBaseTransform * bt,
     GstPadDirection direction, GstCaps * caps, GstCaps * filter);
 static gboolean _gst_gl_upload_element_set_caps (GstBaseTransform * bt,
     GstCaps * in_caps, GstCaps * out_caps);
+static gboolean gst_gl_upload_element_filter_meta (GstBaseTransform * trans,
+    GstQuery * query, GType api, const GstStructure * params);
 static gboolean _gst_gl_upload_element_propose_allocation (GstBaseTransform *
     bt, GstQuery * decide_query, GstQuery * query);
 static gboolean _gst_gl_upload_element_decide_allocation (GstBaseTransform *
@@ -72,6 +74,7 @@ gst_gl_upload_element_class_init (GstGLUploadElementClass * klass)
   bt_class->query = gst_gl_upload_element_query;
   bt_class->transform_caps = _gst_gl_upload_element_transform_caps;
   bt_class->set_caps = _gst_gl_upload_element_set_caps;
+  bt_class->filter_meta = gst_gl_upload_element_filter_meta;
   bt_class->propose_allocation = _gst_gl_upload_element_propose_allocation;
   bt_class->decide_allocation = _gst_gl_upload_element_decide_allocation;
   bt_class->get_unit_size = gst_gl_upload_element_get_unit_size;
@@ -139,37 +142,29 @@ _gst_gl_upload_element_transform_caps (GstBaseTransform * bt,
   return gst_gl_upload_transform_caps (context, direction, caps, filter);
 }
 
+static gboolean
+gst_gl_upload_element_filter_meta (GstBaseTransform * trans, GstQuery * query,
+    GType api, const GstStructure * params)
+{
+  /* propose all metadata upstream */
+  return TRUE;
+}
+
 static gboolean
 _gst_gl_upload_element_propose_allocation (GstBaseTransform * bt,
     GstQuery * decide_query, GstQuery * query)
 {
-  guint alloc_index;
-  gboolean alloc_has_overlay_meta;
   GstGLUploadElement *upload = GST_GL_UPLOAD_ELEMENT (bt);
+  gboolean ret;
 
   if (!upload->upload)
     return FALSE;
 
-  alloc_has_overlay_meta =
+  ret = GST_BASE_TRANSFORM_CLASS (parent_class)->propose_allocation (bt,
-      gst_query_find_allocation_meta (decide_query,
+      decide_query, query);
-      GST_VIDEO_OVERLAY_COMPOSITION_META_API_TYPE, &alloc_index);
-
-  if (alloc_has_overlay_meta) {
-    const GstStructure *params;
-    GST_DEBUG ("adding allocation meta in upload for textoverlay");
-
-    /* read window size from decide_query */
-    gst_query_parse_nth_allocation_meta (decide_query, alloc_index, &params);
-
-    /* it does not matter if params are NULL (no known window size), forward
-     * the meta in any case */
-    gst_query_add_allocation_meta (query,
-        GST_VIDEO_OVERLAY_COMPOSITION_META_API_TYPE, params);
-  }
-
   gst_gl_upload_propose_allocation (upload->upload, decide_query, query);
 
-  return TRUE;
+  return ret;
 }
 
 static gboolean

gst-libs/gst/gl/gstglbasefilter.c

@@ -69,8 +69,6 @@ static gboolean gst_gl_base_filter_start (GstBaseTransform * bt);
 static gboolean gst_gl_base_filter_stop (GstBaseTransform * bt);
 static gboolean gst_gl_base_filter_decide_allocation (GstBaseTransform * trans,
     GstQuery * query);
-static gboolean gst_gl_base_filter_propose_allocation (GstBaseTransform * trans,
-    GstQuery * decide_query, GstQuery * query);
 
 /* GstGLContextThreadFunc */
 static void gst_gl_base_filter_gl_start (GstGLContext * context, gpointer data);
@@ -95,8 +93,6 @@ gst_gl_base_filter_class_init (GstGLBaseFilterClass * klass)
   GST_BASE_TRANSFORM_CLASS (klass)->stop = gst_gl_base_filter_stop;
   GST_BASE_TRANSFORM_CLASS (klass)->decide_allocation =
       gst_gl_base_filter_decide_allocation;
-  GST_BASE_TRANSFORM_CLASS (klass)->propose_allocation =
-      gst_gl_base_filter_propose_allocation;
 
   element_class->set_context = gst_gl_base_filter_set_context;
   element_class->change_state = gst_gl_base_filter_change_state;
@@ -365,7 +361,8 @@ gst_gl_base_filter_decide_allocation (GstBaseTransform * trans,
       goto error;
   }
 
-  return TRUE;
+  return GST_BASE_TRANSFORM_CLASS (parent_class)->decide_allocation (trans,
+      query);
 
 context_error:
   {
@@ -381,13 +378,6 @@ error:
   }
 }
 
-static gboolean
-gst_gl_base_filter_propose_allocation (GstBaseTransform * trans,
-    GstQuery * decide_query, GstQuery * query)
-{
-  return FALSE;
-}
-
 static GstStateChangeReturn
 gst_gl_base_filter_change_state (GstElement * element,
     GstStateChange transition)