Add GdkFrameClock

Add an object GdkFrameClock that we associate with a GdkWindow.
This tracks when the window needs to be repainted, and will also
be used for other operations in the future like relayout and
updating animations.

Based on a patch from Havoc Pennington:

 https://mail.gnome.org/archives/gtk-devel-list/2010-October/msg00004.html

https://bugzilla.gnome.org/show_bug.cgi?id=685460

1 files changed, 182 insertions, 0 deletions

diff --git a/gdk/gdkframeclockidle.c b/gdk/gdkframeclockidle.c
new file mode 100644
index 0000000000..ff20632e70
--- /dev/null
+++ b/gdk/gdkframeclockidle.c
@@ -0,0 +1,182 @@
+/* GDK - The GIMP Drawing Kit
+ * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/*
+ * Modified by the GTK+ Team and others 1997-2010.  See the AUTHORS
+ * file for a list of people on the GTK+ Team.  See the ChangeLog
+ * files for a list of changes.  These files are distributed with
+ * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
+ */
+
+#include "config.h"
+
+#include "gdkframeclockidle.h"
+#include "gdk.h"
+
+struct _GdkFrameClockIdlePrivate
+{
+  GTimer *timer;
+  /* timer_base is used to avoid ever going backward */
+  guint64 timer_base;
+  guint64 frame_time;
+
+  guint idle_id;
+
+  unsigned int in_paint : 1;
+};
+
+static void gdk_frame_clock_idle_finalize             (GObject                *object);
+static void gdk_frame_clock_idle_interface_init       (GdkFrameClockInterface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (GdkFrameClockIdle, gdk_frame_clock_idle, G_TYPE_OBJECT,
+			 G_IMPLEMENT_INTERFACE (GDK_TYPE_FRAME_CLOCK,
+						gdk_frame_clock_idle_interface_init))
+
+static void
+gdk_frame_clock_idle_class_init (GdkFrameClockIdleClass *klass)
+{
+  GObjectClass *gobject_class = (GObjectClass*) klass;
+
+  gobject_class->finalize     = gdk_frame_clock_idle_finalize;
+
+  g_type_class_add_private (klass, sizeof (GdkFrameClockIdlePrivate));
+}
+
+static void
+gdk_frame_clock_idle_init (GdkFrameClockIdle *frame_clock_idle)
+{
+  GdkFrameClockIdlePrivate *priv;
+
+  frame_clock_idle->priv = G_TYPE_INSTANCE_GET_PRIVATE (frame_clock_idle,
+                                                        GDK_TYPE_FRAME_CLOCK_IDLE,
+                                                        GdkFrameClockIdlePrivate);
+  priv = frame_clock_idle->priv;
+
+  priv->timer = g_timer_new ();
+}
+
+static void
+gdk_frame_clock_idle_finalize (GObject *object)
+{
+  GdkFrameClockIdlePrivate *priv = GDK_FRAME_CLOCK_IDLE (object)->priv;
+
+  g_timer_destroy (priv->timer);
+
+  G_OBJECT_CLASS (gdk_frame_clock_idle_parent_class)->finalize (object);
+}
+
+static guint64
+compute_frame_time (GdkFrameClockIdle *idle)
+{
+  GdkFrameClockIdlePrivate *priv = idle->priv;
+  guint64 computed_frame_time;
+  guint64 elapsed;
+
+  elapsed = ((guint64) (g_timer_elapsed (priv->timer, NULL) * 1000)) + priv->timer_base;
+  if (elapsed < priv->frame_time)
+    {
+      /* clock went backward. adapt to that by forevermore increasing
+       * timer_base.  For now, assume we've gone forward in time 1ms.
+       */
+      /* hmm. just fix GTimer? */
+      computed_frame_time = priv->frame_time + 1;
+      priv->timer_base += (priv->frame_time - elapsed) + 1;
+    }
+  else
+    {
+      computed_frame_time = elapsed;
+    }
+
+  return computed_frame_time;
+}
+
+static guint64
+gdk_frame_clock_idle_get_frame_time (GdkFrameClock *clock)
+{
+  GdkFrameClockIdlePrivate *priv = GDK_FRAME_CLOCK_IDLE (clock)->priv;
+  guint64 computed_frame_time;
+
+  /* can't change frame time during a paint */
+  if (priv->in_paint)
+    return priv->frame_time;
+
+  /* Outside a paint, pick something close to "now" */
+  computed_frame_time = compute_frame_time (GDK_FRAME_CLOCK_IDLE (clock));
+
+  /* 16ms is 60fps. We only update frame time that often because we'd
+   * like to try to keep animations on the same start times.
+   * get_frame_time() would normally be used outside of a paint to
+   * record an animation start time for example.
+   */
+  if ((computed_frame_time - priv->frame_time) > 16)
+    priv->frame_time = computed_frame_time;
+
+  return priv->frame_time;
+}
+
+static gboolean
+gdk_frame_clock_paint_idle (void *data)
+{
+  GdkFrameClock *clock = GDK_FRAME_CLOCK (data);
+  GdkFrameClockIdle *clock_idle = GDK_FRAME_CLOCK_IDLE (clock);
+  GdkFrameClockIdlePrivate *priv = clock_idle->priv;
+
+  priv->idle_id = 0;
+
+  priv->in_paint = TRUE;
+  priv->frame_time = compute_frame_time (clock_idle);
+
+  gdk_frame_clock_paint (clock);
+
+  priv->in_paint = FALSE;
+
+  return FALSE;
+}
+
+static void
+gdk_frame_clock_idle_request_frame (GdkFrameClock *clock)
+{
+  GdkFrameClockIdlePrivate *priv = GDK_FRAME_CLOCK_IDLE (clock)->priv;
+
+  if (priv->idle_id == 0)
+    {
+      priv->idle_id = gdk_threads_add_idle_full (GDK_PRIORITY_REDRAW,
+                                                 gdk_frame_clock_paint_idle,
+                                                 g_object_ref (clock),
+                                                 (GDestroyNotify) g_object_unref);
+
+      gdk_frame_clock_frame_requested (clock);
+    }
+}
+
+static gboolean
+gdk_frame_clock_idle_get_frame_requested (GdkFrameClock *clock)
+{
+  GdkFrameClockIdlePrivate *priv = GDK_FRAME_CLOCK_IDLE (clock)->priv;
+
+  return priv->idle_id != 0;
+}
+
+static void
+gdk_frame_clock_idle_interface_init (GdkFrameClockInterface *iface)
+{
+  iface->get_frame_time = gdk_frame_clock_idle_get_frame_time;
+  iface->request_frame = gdk_frame_clock_idle_request_frame;
+  iface->get_frame_requested = gdk_frame_clock_idle_get_frame_requested;
+}