From d67e8667886329ad4717178e8e09ceef1a42af34 Mon Sep 17 00:00:00 2001
From: Rhody Lugo <rhodylugo@gmail.com>
Date: Tue, 10 Feb 2015 15:24:22 -0430
Subject: [PATCH] add support for CADisplayLink

---
 platform/iphone/gl_view.h  |  8 ++++++++
 platform/iphone/gl_view.mm | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/platform/iphone/gl_view.h b/platform/iphone/gl_view.h
index 8ae7c2f87db..a5b1b8731f1 100755
--- a/platform/iphone/gl_view.h
+++ b/platform/iphone/gl_view.h
@@ -34,6 +34,8 @@
 #import <MediaPlayer/MediaPlayer.h>
 #import <AVFoundation/AVFoundation.h>
 
+#define USE_CADISPLAYLINK      1   //iOS version 3.1+ is required
+
 @protocol GLViewDelegate;
 
 @interface GLView : UIView<UIKeyInput>
@@ -51,8 +53,14 @@
 	// OpenGL name for the depth buffer that is attached to viewFramebuffer, if it exists (0 if it does not exist)
 	GLuint depthRenderbuffer;
 	
+#if USE_CADISPLAYLINK
+	// CADisplayLink available on 3.1+ synchronizes the animation timer & drawing with the refresh rate of the display, only supports animation intervals of 1/60 1/30 & 1/15
+	CADisplayLink *displayLink;
+#else
 	// An animation timer that, when animation is started, will periodically call -drawView at the given rate.
 	NSTimer *animationTimer;
+#endif
+	
 	NSTimeInterval animationInterval;
 	
 	// Delegate to do our drawing, called by -drawView, which can be called manually or via the animation timer.
diff --git a/platform/iphone/gl_view.mm b/platform/iphone/gl_view.mm
index bee01d3c723..0625361b968 100755
--- a/platform/iphone/gl_view.mm
+++ b/platform/iphone/gl_view.mm
@@ -413,7 +413,19 @@ static void clear_touches() {
 		return;
 	active = TRUE;
 	printf("start animation!\n");
+#if USE_CADISPLAYLINK
+	// Approximate frame rate
+	// assumes device refreshes at 60 fps
+	int frameInterval = (int) floor(animationInterval * 60.0f);
+
+	displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(drawView)];
+	[displayLink setFrameInterval:frameInterval];
+
+	// Setup DisplayLink in main thread
+	[displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
+#else
 	animationTimer = [NSTimer scheduledTimerWithTimeInterval:animationInterval target:self selector:@selector(drawView) userInfo:nil repeats:YES];
+#endif
 
 	if (video_playing)
 	{
@@ -427,8 +439,13 @@ static void clear_touches() {
 		return;
 	active = FALSE;
 	printf("******** stop animation!\n");
+#if USE_CADISPLAYLINK
+	[displayLink invalidate];
+	displayLink = nil;
+#else
 	[animationTimer invalidate];
 	animationTimer = nil;
+#endif
 	clear_touches();
 
 	if (video_playing)
@@ -441,7 +458,11 @@ static void clear_touches() {
 {
 	animationInterval = interval;
 	
+#if USE_CADISPLAYLINK
+	if(displayLink)
+#else
 	if(animationTimer)
+#endif
 	{
 		[self stopAnimation];
 		[self startAnimation];
@@ -451,6 +472,17 @@ static void clear_touches() {
 // Updates the OpenGL view when the timer fires
 - (void)drawView
 {
+#if USE_CADISPLAYLINK
+	// Pause the CADisplayLink to avoid recursion
+	[displayLink setPaused: YES];
+
+	// Process all input events
+	while(CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0, TRUE) == kCFRunLoopRunHandledSource);
+
+	// We are good to go, resume the CADisplayLink
+	[displayLink setPaused: NO];
+#endif
+
 	if (!active) {
 		printf("draw view not active!\n");
 		return;