From e2a0bf60412ede6c4d449939e8c414f7104b0cd7 Mon Sep 17 00:00:00 2001
From: Matej Jan <zxretro@gmail.com>
Date: Tue, 9 Oct 2012 15:26:47 +0000
Subject: [PATCH] CADisplayLink support for running the game loop

git-svn-id: http://xni.googlecode.com/svn/XNI@118 ac433895-eea3-a490-d80a-17149a75e588
---
 Classes/Retronator/Xni/Framework/Game.h     |  7 ++++++
 Classes/Retronator/Xni/Framework/Game.m     | 24 +++++++++++++++++----
 Classes/Retronator/Xni/Framework/GameHost.m | 20 ++++++++---------
 3 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/Classes/Retronator/Xni/Framework/Game.h b/Classes/Retronator/Xni/Framework/Game.h
index dafe858..237eb3a 100644
--- a/Classes/Retronator/Xni/Framework/Game.h
+++ b/Classes/Retronator/Xni/Framework/Game.h
@@ -37,6 +37,10 @@
     GameTime *gameTime;
     NSDate *currentFrameTime;
     NSDate *lastFrameTime;
+    
+    BOOL usesDisplayLink;
+    int displayLinkFrameInterval;
+    CADisplayLink *displayLink;
 	
 	// Content manager
 	ContentManager *content;
@@ -63,6 +67,9 @@
 @property (nonatomic) NSTimeInterval targetElapsedTime;
 @property (nonatomic) NSTimeInterval inactiveSleepTime;
 
+@property (nonatomic) BOOL usesDisplayLink;
+@property (nonatomic) int displayLinkFrameInterval;
+
 @property (nonatomic, retain) ContentManager *content;
 @property (nonatomic, readonly) GameComponentCollection *components;
 @property (nonatomic, readonly) GameServiceContainer *services;
diff --git a/Classes/Retronator/Xni/Framework/Game.m b/Classes/Retronator/Xni/Framework/Game.m
index 2de124d..f4e9990 100644
--- a/Classes/Retronator/Xni/Framework/Game.m
+++ b/Classes/Retronator/Xni/Framework/Game.m
@@ -108,6 +108,13 @@ static NSArray *drawOrderSort;
 @synthesize targetElapsedTime;
 @synthesize inactiveSleepTime;
 
+@synthesize usesDisplayLink, displayLinkFrameInterval;
+
+- (void)setDisplayLinkFrameInterval:(int)value {
+    displayLinkFrameInterval = value;
+    [displayLink setFrameInterval:displayLinkFrameInterval];
+}
+
 @synthesize content;
 @synthesize components;
 @synthesize services;
@@ -143,8 +150,14 @@ static NSArray *drawOrderSort;
     // Force redraw.
     [self.window.gameViewController.gameView layoutSubviews];
     
-    // Run the game host with a delay event, so we don't block this method.
-    [gameHost performSelector:@selector(run) withObject:nil afterDelay:0];
+    if (usesDisplayLink) {
+        displayLink = [[CADisplayLink displayLinkWithTarget:self selector:@selector(tick)] retain];
+        [displayLink setFrameInterval:displayLinkFrameInterval];
+        [displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
+    } else {
+        // Run the game host with a delay event, so we don't block this method.
+        [gameHost performSelector:@selector(run) withObject:nil afterDelay:0];
+    }
 }
 
 - (void) tick {
@@ -154,7 +167,9 @@ static NSArray *drawOrderSort;
     
     // Sleep if inactive.
     if (!isActive) {
-        CFRunLoopRunInMode(kCFRunLoopDefaultMode, inactiveSleepTime, NO);
+        if (!usesDisplayLink) {
+            CFRunLoopRunInMode(kCFRunLoopDefaultMode, inactiveSleepTime, NO);
+        }
 		return;
     }
     
@@ -163,7 +178,7 @@ static NSArray *drawOrderSort;
     NSTimeInterval elapsedRealTime = [currentFrameTime timeIntervalSinceDate:lastFrameTime];
     
     // Sleep if we're ahead of the target elapsed time.
-	if (isFixedTimeStep) {
+	if (isFixedTimeStep && !usesDisplayLink) {
 		if (elapsedRealTime < targetElapsedTime) {
 			NSTimeInterval sleepTime = targetElapsedTime - elapsedRealTime;
 			CFRunLoopRunInMode(kCFRunLoopDefaultMode, sleepTime, NO);
@@ -420,6 +435,7 @@ static NSArray *drawOrderSort;
 	
 	[self unloadContent];
     [gameTime release];
+    [displayLink release];
     
 	[componentsList release];	
 	[enabledComponents release];
diff --git a/Classes/Retronator/Xni/Framework/GameHost.m b/Classes/Retronator/Xni/Framework/GameHost.m
index 2c06c37..31d1ba5 100644
--- a/Classes/Retronator/Xni/Framework/GameHost.m
+++ b/Classes/Retronator/Xni/Framework/GameHost.m
@@ -26,11 +26,15 @@
 @synthesize window;
 
 - (void) run {    	
-    // Hijack the run loop.
-    NSLog(@"Starting the game loop.");
     
     game = [self delegate];
-    	
+    
+    // If game uses display link we don't need to run our own game loop.
+    if (game.usesDisplayLink) return;
+	
+    // Hijack the run loop.
+    NSLog(@"Starting the game loop.");
+        
     SInt32 runResult;
     
 	isExiting = NO;
@@ -48,16 +52,12 @@
         
         // We release memory every frame.
         [pool release];
-    }
-	
-	/*
-	CADisplayLink *aDisplayLink = [CADisplayLink displayLinkWithTarget:game selector:@selector(tick)];
-	[aDisplayLink setFrameInterval:1];
-	[aDisplayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
-	 */
+    }    
 }
 
 - (void) exit {
+    if (game.usesDisplayLink) return;
+
     NSLog(@"Exiting the game loop.");
     isExiting = YES;
 }