clutter: Add a max render time debug HUD

Not sure how to update the damage or redraw clip or something; at least
this works properly when under a constantly-redrawing window, which is
ok for debugging purposes.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1762>

clutter/clutter/clutter-frame-clock.c

@@ -678,6 +678,51 @@ clutter_frame_clock_record_flip_time (ClutterFrameClock *frame_clock,
   frame_clock->last_flip_time_us = flip_time_us;
 }
 
+GString *
+clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clock)
+{
+  int64_t max_dispatch_to_swap_us = 0;
+  int64_t max_swap_to_rendering_done_us = 0;
+  int64_t max_swap_to_flip_us = 0;
+  int i;
+  GString *string;
+
+  string = g_string_new (NULL);
+  g_string_append_printf (string, "Max render time: %ld µs",
+                          clutter_frame_clock_compute_max_render_time_us (frame_clock));
+
+  if (frame_clock->got_measurements_last_frame)
+    g_string_append_printf (string, " =");
+  else
+    g_string_append_printf (string, " (no measurements last frame)");
+
+  for (i = 0; i < ESTIMATE_QUEUE_LENGTH; ++i)
+    {
+      max_dispatch_to_swap_us =
+        MAX (max_dispatch_to_swap_us,
+             frame_clock->dispatch_to_swap_us.values[i]);
+      max_swap_to_rendering_done_us =
+        MAX (max_swap_to_rendering_done_us,
+             frame_clock->swap_to_rendering_done_us.values[i]);
+      max_swap_to_flip_us =
+        MAX (max_swap_to_flip_us,
+             frame_clock->swap_to_flip_us.values[i]);
+    }
+
+  g_string_append_printf (string, "\nVblank duration: %ld µs +",
+                          frame_clock->vblank_duration_us);
+  g_string_append_printf (string, "\nDispatch to swap: %ld µs +",
+                          max_dispatch_to_swap_us);
+  g_string_append_printf (string, "\nmax(Swap to rendering done: %ld µs,",
+                          max_swap_to_rendering_done_us);
+  g_string_append_printf (string, "\nSwap to flip: %ld µs) +",
+                          max_swap_to_flip_us);
+  g_string_append_printf (string, "\nConstant: %d µs",
+                          clutter_max_render_time_constant_us);
+
+  return string;
+}
+
 static GSourceFuncs frame_clock_source_funcs = {
   NULL,
   NULL,

clutter/clutter/clutter-frame-clock.h

@@ -94,4 +94,6 @@ float clutter_frame_clock_get_refresh_rate (ClutterFrameClock *frame_clock);
 void clutter_frame_clock_record_flip_time (ClutterFrameClock *frame_clock,
                                            int64_t            flip_time_us);
 
+GString * clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clock);
+
 #endif /* CLUTTER_FRAME_CLOCK_H */

clutter/clutter/clutter-main.c

@@ -136,6 +136,7 @@ static const GDebugKey clutter_paint_debug_keys[] = {
   { "paint-deform-tiles", CLUTTER_DEBUG_PAINT_DEFORM_TILES },
   { "damage-region", CLUTTER_DEBUG_PAINT_DAMAGE_REGION },
   { "disable-dynamic-max-render-time", CLUTTER_DEBUG_DISABLE_DYNAMIC_MAX_RENDER_TIME },
+  { "max-render-time", CLUTTER_DEBUG_PAINT_MAX_RENDER_TIME },
 };
 
 gboolean

clutter/clutter/clutter-main.h

@@ -73,6 +73,7 @@ typedef enum
   CLUTTER_DEBUG_PAINT_DEFORM_TILES              = 1 << 7,
   CLUTTER_DEBUG_PAINT_DAMAGE_REGION             = 1 << 8,
   CLUTTER_DEBUG_DISABLE_DYNAMIC_MAX_RENDER_TIME = 1 << 9,
+  CLUTTER_DEBUG_PAINT_MAX_RENDER_TIME           = 1 << 10,
 } ClutterDrawDebugFlag;
 
 /**

clutter/clutter/clutter-stage.c

@@ -1312,6 +1312,51 @@ clutter_stage_real_paint_view (ClutterStage         *stage,
   clutter_stage_do_paint_view (stage, view, redraw_clip);
 }
 
+static void
+clutter_stage_paint (ClutterActor        *actor,
+                     ClutterPaintContext *paint_context)
+{
+  ClutterStageView *view;
+
+  CLUTTER_ACTOR_CLASS (clutter_stage_parent_class)->paint (actor, paint_context);
+
+  view = clutter_paint_context_get_stage_view (paint_context);
+  if (view &&
+      G_UNLIKELY (clutter_paint_debug_flags & CLUTTER_DEBUG_PAINT_MAX_RENDER_TIME))
+    {
+      cairo_rectangle_int_t view_layout;
+      ClutterFrameClock *frame_clock;
+      g_autoptr (GString) string = NULL;
+      PangoLayout *layout;
+      PangoRectangle logical;
+      ClutterColor color;
+      g_autoptr (ClutterPaintNode) node = NULL;
+      ClutterActorBox box;
+
+      clutter_stage_view_get_layout (view, &view_layout);
+      frame_clock = clutter_stage_view_get_frame_clock (view);
+
+      string = clutter_frame_clock_get_max_render_time_debug_info (frame_clock);
+
+      layout = clutter_actor_create_pango_layout (actor, string->str);
+      pango_layout_set_alignment (layout, PANGO_ALIGN_RIGHT);
+      pango_layout_get_pixel_extents (layout, NULL, &logical);
+
+      clutter_color_init (&color, 255, 255, 255, 255);
+      node = clutter_text_node_new (layout, &color);
+
+      box.x1 = view_layout.x;
+      box.y1 = view_layout.y + 30;
+      box.x2 = box.x1 + logical.width;
+      box.y2 = box.y1 + logical.height;
+      clutter_paint_node_add_rectangle (node, &box);
+
+      clutter_paint_node_paint (node, paint_context);
+
+      g_object_unref (layout);
+    }
+}
+
 static void
 clutter_stage_class_init (ClutterStageClass *klass)
 {
@@ -1335,6 +1380,7 @@ clutter_stage_class_init (ClutterStageClass *klass)
   actor_class->hide_all = clutter_stage_hide_all;
   actor_class->queue_relayout = clutter_stage_real_queue_relayout;
   actor_class->apply_transform = clutter_stage_real_apply_transform;
+  actor_class->paint = clutter_stage_paint;
 
   klass->paint_view = clutter_stage_real_paint_view;