compositor: Add a renderer function to read out pixels
diff --git a/src/compositor.h b/src/compositor.h
index e4ba19c..e2dbd0d 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -276,6 +276,10 @@
 };
 
 struct weston_renderer {
+	int (*read_pixels)(struct weston_output *output,
+			       pixman_format_code_t format, void *pixels,
+			       uint32_t x, uint32_t y,
+			       uint32_t width, uint32_t height);
 	void (*repaint_output)(struct weston_output *output,
 			       pixman_region32_t *output_damage);
 	void (*flush_damage)(struct weston_surface *surface);