From dac0b7d609740f0f330c59bd9696c55302ec434f Mon Sep 17 00:00:00 2001
From: Christian Hergert <christian@hergert.me>
Date: Sun, 27 Feb 2022 23:17:40 -0800
Subject: [PATCH] macos: use video mode for refresh rate and interval

Using the mode allows better detection of refresh rate and refresh
interval for the CVDisplayLink bridge to GdkFrameClock. Using it can help
ensure that our 144hz displays can actually reach that rather than falling
back to just 60hz.

This will also need future commits to rework the displaylink source to be
per-monitor.
---
 gdk/macos/gdkdisplaylinksource.c | 61 ++++++++++++++++++++++----------
 gdk/macos/gdkdisplaylinksource.h |  4 ++-
 2 files changed, 46 insertions(+), 19 deletions(-)

diff --git a/gdk/macos/gdkdisplaylinksource.c b/gdk/macos/gdkdisplaylinksource.c
index 8b2f1a013f..fe75eb3a55 100644
--- a/gdk/macos/gdkdisplaylinksource.c
+++ b/gdk/macos/gdkdisplaylinksource.c
@@ -65,7 +65,7 @@ gdk_display_link_source_dispatch (GSource     *source,
 
   impl->needs_dispatch = FALSE;
 
-  if (callback != NULL)
+  if (!impl->paused && callback != NULL)
     ret = callback (user_data);
 
   return ret;
@@ -76,7 +76,9 @@ gdk_display_link_source_finalize (GSource *source)
 {
   GdkDisplayLinkSource *impl = (GdkDisplayLinkSource *)source;
 
-  CVDisplayLinkStop (impl->display_link);
+  if (!impl->paused)
+    CVDisplayLinkStop (impl->display_link);
+
   CVDisplayLinkRelease (impl->display_link);
 }
 
@@ -90,12 +92,18 @@ static GSourceFuncs gdk_display_link_source_funcs = {
 void
 gdk_display_link_source_pause (GdkDisplayLinkSource *source)
 {
+  g_return_if_fail (source->paused == FALSE);
+
+  source->paused = TRUE;
   CVDisplayLinkStop (source->display_link);
 }
 
 void
 gdk_display_link_source_unpause (GdkDisplayLinkSource *source)
 {
+  g_return_if_fail (source->paused == TRUE);
+
+  source->paused = FALSE;
   CVDisplayLinkStart (source->display_link);
 }
 
@@ -160,16 +168,16 @@ gdk_display_link_source_frame_cb (CVDisplayLinkRef   display_link,
  * Returns: (transfer full): A newly created `GSource`
  */
 GSource *
-gdk_display_link_source_new (CGDirectDisplayID display_id)
+gdk_display_link_source_new (CGDirectDisplayID display_id,
+                             CGDisplayModeRef  mode)
 {
   GdkDisplayLinkSource *impl;
   GSource *source;
-  CVReturn ret;
-  double period;
 
   source = g_source_new (&gdk_display_link_source_funcs, sizeof *impl);
   impl = (GdkDisplayLinkSource *)source;
   impl->display_id = display_id;
+  impl->paused = TRUE;
 
   /* Create DisplayLink for timing information for the display in
    * question so that we can produce graphics for that display at whatever
@@ -178,21 +186,34 @@ gdk_display_link_source_new (CGDirectDisplayID display_id)
   if (CVDisplayLinkCreateWithCGDisplay (display_id, &impl->display_link) != kCVReturnSuccess)
     {
       g_warning ("Failed to initialize CVDisplayLink!");
-      return source;
+      goto failure;
     }
 
-  /*
-   * Determine our nominal period between frames.
-   */
-  period = CVDisplayLinkGetActualOutputVideoRefreshPeriod (impl->display_link);
-  if (period == 0.0)
-    period = 1.0 / 60.0;
-  impl->refresh_interval = period * 1000000L;
-  impl->refresh_rate = 1.0 / period * 1000L;
-
-  /*
-   * Wire up our callback to be executed within the high-priority thread.
-   */
+  impl->refresh_rate = CGDisplayModeGetRefreshRate (mode) * 1000.0;
+
+  if (impl->refresh_rate == 0)
+    {
+      const CVTime time = CVDisplayLinkGetNominalOutputVideoRefreshPeriod (impl->display_link);
+      if (!(time.flags & kCVTimeIsIndefinite))
+        impl->refresh_rate = (double)time.timeScale / (double)time.timeValue * 1000.0;
+    }
+
+  if (impl->refresh_rate != 0)
+    {
+      impl->refresh_interval = 1000000.0 / (double)impl->refresh_rate * 1000.0;
+    }
+  else
+    {
+      double period = CVDisplayLinkGetActualOutputVideoRefreshPeriod (impl->display_link);
+
+      if (period == 0.0)
+        period = 1.0 / 60.0;
+
+      impl->refresh_rate = 1.0 / period * 1000L;
+      impl->refresh_interval = period * 1000000L;
+    }
+
+  /* Wire up our callback to be executed within the high-priority thread. */
   CVDisplayLinkSetOutputCallback (impl->display_link,
                                   gdk_display_link_source_frame_cb,
                                   source);
@@ -200,6 +221,10 @@ gdk_display_link_source_new (CGDirectDisplayID display_id)
   g_source_set_static_name (source, "[gdk] quartz frame clock");
 
   return source;
+
+failure:
+  g_source_unref (source);
+  return NULL;
 }
 
 static gint64
diff --git a/gdk/macos/gdkdisplaylinksource.h b/gdk/macos/gdkdisplaylinksource.h
index bff1c91475..6f465907a2 100644
--- a/gdk/macos/gdkdisplaylinksource.h
+++ b/gdk/macos/gdkdisplaylinksource.h
@@ -36,12 +36,14 @@ typedef struct
   CVDisplayLinkRef  display_link;
   gint64            refresh_interval;
   guint             refresh_rate;
+  guint             paused : 1;
 
   volatile gint64   presentation_time;
   volatile guint    needs_dispatch;
 } GdkDisplayLinkSource;
 
-GSource *gdk_display_link_source_new     (CGDirectDisplayID     display_id);
+GSource *gdk_display_link_source_new     (CGDirectDisplayID     display_id,
+                                          CGDisplayModeRef      mode);
 void     gdk_display_link_source_pause   (GdkDisplayLinkSource *source);
 void     gdk_display_link_source_unpause (GdkDisplayLinkSource *source);
 
-- 
2.30.2