libobs: Add ability to disable displays

Sometimes it can be useful to turn off rendering to the display in order
to reduce the number of draw calls and present calls.

libobs/obs-display.c

@@ -41,6 +41,7 @@ bool obs_display_init(struct obs_display *display,
 		return false;
 	}
 
+	display->enabled = true;
 	return true;
 }
 
@@ -170,7 +171,7 @@ static inline void render_display_end()
 
 void render_display(struct obs_display *display)
 {
-	if (!display) return;
+	if (!display || !display->enabled) return;
 
 	render_display_begin(display);
 
@@ -187,3 +188,14 @@ void render_display(struct obs_display *display)
 
 	render_display_end();
 }
+
+void obs_display_set_enabled(obs_display_t *display, bool enable)
+{
+	if (display)
+		display->enabled = enable;
+}
+
+bool obs_display_enabled(obs_display_t *display)
+{
+	return display ? display->enabled : false;
+}

libobs/obs-internal.h

@@ -112,6 +112,7 @@ extern void obs_view_free(struct obs_view *view);
 
 struct obs_display {
 	bool                            size_changed;
+	bool                            enabled;
 	uint32_t                        cx, cy;
 	gs_swapchain_t                  *swap;
 	pthread_mutex_t                 draw_callbacks_mutex;

libobs/obs.h

@@ -619,6 +619,9 @@ EXPORT void obs_display_remove_draw_callback(obs_display_t *display,
 		void (*draw)(void *param, uint32_t cx, uint32_t cy),
 		void *param);
 
+EXPORT void obs_display_set_enabled(obs_display_t *display, bool enable);
+EXPORT bool obs_display_enabled(obs_display_t *display);
+
 
 /* ------------------------------------------------------------------------- */
 /* Sources */