From 169ee4cbd1bcd7388ed0074e12cdea7db03665eb Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Thu, 15 Nov 2007 13:26:31 +0000
Subject: [PATCH] more tweaks to avoid editor flicker under Mac OS X

svn: r7737
---
 src/mred/mredmac.cxx       | 32 ++++++++++++++++++++++++++++++--
 src/mred/wxme/wx_medad.cxx | 12 ++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/src/mred/mredmac.cxx b/src/mred/mredmac.cxx
index 879af98778..3173ed6d2e 100644
--- a/src/mred/mredmac.cxx
+++ b/src/mred/mredmac.cxx
@@ -533,17 +533,25 @@ void WakeUpMrEd()
    nothing and return 0. */
 
 static unsigned long lastTime;
+
+static int wne_delay_on;
+static unsigned long wne_delay_until;
  
 static int TransferQueue(int all)
 {
   EventRecord e;
+  unsigned long tc;
   int sleep_time = 0;
   int delay_time = 0;
   
   /* Don't call WaitNextEvent() too often. */
-  if (TickCount() <= lastTime + delay_time)
+  tc = TickCount();
+  if (tc <= lastTime + delay_time)
     return 0;
-  
+  if (wne_delay_on && (tc < wne_delay_until))
+    return 0;
+  wne_delay_on = 0;
+
   while (WNE(&e, dispatched ? ((double)sleep_time/60.0) : 0)) {
     QueueTransferredEvent(&e);
   }
@@ -553,6 +561,26 @@ static int TransferQueue(int all)
   return 1;
 }
 
+void wxStartRefreshSequence(void)
+{
+  /* Editors are not buffered offscreen under Mac OS X, instead
+     relying on the OS's buffering of all windows, which are updated
+     on WNE boundaries. To avoid flicker, avoid calling WNE in the
+     middle of an editor refresh.  The refresh might get stuck,
+     though, so we only wait a little while. */
+
+  if (!wne_delay_on) {
+    wne_delay_until = TickCount() + 10;
+  }
+  wne_delay_on++;
+}
+
+void wxEndRefreshSequence(void)
+{
+  if (wne_delay_on)
+    --wne_delay_on;
+}
+
 static void MrDequeue(MrQueueElem *q)
 {
   if (q->prev)
diff --git a/src/mred/wxme/wx_medad.cxx b/src/mred/wxme/wx_medad.cxx
index 20ab0723d4..8d9dc3d37c 100644
--- a/src/mred/wxme/wx_medad.cxx
+++ b/src/mred/wxme/wx_medad.cxx
@@ -27,6 +27,14 @@
 
 static wxMemoryDC *wx_canvasless_offscreen;
 
+#ifdef wx_mac
+extern void wxStartRefreshSequence(void);
+extern void wxEndRefreshSequence(void);
+#else
+# define wxStartRefreshSequence() /* empty */
+# define wxEndRefreshSequence() /* empty */
+#endif
+
 extern void *MrEdGetWindowContext(wxWindow *w);
 
 class SimpleScroll
@@ -812,6 +820,8 @@ void wxMediaCanvas::Redraw(double localx, double localy, double fw, double fh)
   if (!media || media->printing)
     return;
 
+  wxStartRefreshSequence();
+
   GetView(&x, &y, &w, &h);
 
   right = x + w;
@@ -851,6 +861,8 @@ void wxMediaCanvas::Redraw(double localx, double localy, double fw, double fh)
       media->SetAdmin(oldadmin);
     }
   }
+
+  wxEndRefreshSequence();
 }
 
 Bool wxMediaCanvas::ScrollTo(double localx, double localy, double fw, double fh,