static void
gst_gl_display_context_prepare (GstElement * element,
GstGLDisplay ** display_ptr)
{
GstContext *ctxt;
GstQuery *query;
if (!GST_CAT_CONTEXT)
GST_DEBUG_CATEGORY_GET (GST_CAT_CONTEXT, "GST_CONTEXT");
/* 2a) Query downstream with GST_QUERY_CONTEXT for the context and
* check if downstream already has a context of the specific type
* 2b) Query upstream as above.
*/
ctxt = NULL;
query = gst_query_new_context (GST_GL_DISPLAY_CONTEXT_TYPE);
if (run_context_query (element, query, GST_PAD_SRC)) {
GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
"found context (%p) in downstream query", ctxt);
gst_query_parse_context (query, &ctxt);
} else if (run_context_query (element, query, GST_PAD_SINK)) {
GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
"found context (%p) in upstream query", ctxt);
gst_query_parse_context (query, &ctxt);
} else {
/* 3) Post a GST_MESSAGE_NEED_CONTEXT message on the bus with
* the required context type and afterwards check if a
* usable context was set now as in 1). The message could
* be handled by the parent bins of the element and the
* application.
*/
GstMessage *msg;
GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
"posting need context message");
msg = gst_message_new_need_context (GST_OBJECT_CAST (element),
GST_GL_DISPLAY_CONTEXT_TYPE);
gst_element_post_message (element, msg);
}
/*
* Whomever responds to the need-context message performs a
* GstElement::set_context() with the required context in which the element
* is required to update the display_ptr or call gst_gl_handle_set_context().
*/
if (ctxt) {
if (gst_context_has_context_type (ctxt, GST_GL_DISPLAY_CONTEXT_TYPE)) {
gst_context_get_gl_display (ctxt, display_ptr);
}
}
gst_query_unref (query);
}
static GstQuery *
_gst_context_query (GstElement * element,
gpointer ptr, const gchar * display_type)
{
GstQuery *query;
GstContext *ctxt;
/* 2a) Query downstream with GST_QUERY_CONTEXT for the context and
* check if downstream already has a context of the specific type
* 2b) Query upstream as above.
*/
query = gst_query_new_context (display_type);
if (run_context_query (element, query, GST_PAD_SRC)) {
gst_query_parse_context (query, &ctxt);
GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
"found context (%p) in downstream query", ctxt);
} else if (run_context_query (element, query, GST_PAD_SINK)) {
gst_query_parse_context (query, &ctxt);
GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
"found context (%p) in upstream query", ctxt);
} else {
/* 3) Post a GST_MESSAGE_NEED_CONTEXT message on the bus with
* the required context type and afterwards check if a
* usable context was set now as in 1). The message could
* be handled by the parent bins of the element and the
* application.
*/
GstMessage *msg;
GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
"posting need context message");
msg = gst_message_new_need_context (GST_OBJECT_CAST (element),
display_type);
gst_element_post_message (element, msg);
}
/*
* Whomever responds to the need-context message performs a
* GstElement::set_context() with the required context in which the element
* is required to update the display_ptr or call gst_gl_handle_set_context().
*/
return query;
}
