minimalistic OpenGL window in Objective-C

gistfile1.m

#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>
#import <CoreVideo/CVDisplayLink.h>

@interface SxgeView : NSOpenGLView <NSWindowDelegate>

-(void)registerDisplayLink;
-(void)renderForTime:(CVTimeStamp)time;

-(void)windowWillClose:(NSNotification*)note;
@end

CVReturn displayCallback(CVDisplayLinkRef displayLink,
	const CVTimeStamp *inNow, const CVTimeStamp *inOutputTime,
	CVOptionFlags flagsIn, CVOptionFlags *flagsOut,
	void *displayLinkContext)
{
	SxgeView *view = (SxgeView*)displayLinkContext;
	[view renderForTime: *inOutputTime];
	return kCVReturnSuccess;
}

@implementation SxgeView
{
	CVDisplayLinkRef displayLink;
}

-(id)initWithFrame:(NSRect)frameRect pixelFormat:(NSOpenGLPixelFormat*)format
{
	self = [super initWithFrame:frameRect pixelFormat:format];
	[self registerDisplayLink];
	return self;
}

-(void)registerDisplayLink
{
	CGDirectDisplayID displayID = CGMainDisplayID();
	CVReturn error = CVDisplayLinkCreateWithCGDisplay(displayID, &displayLink);
	NSAssert((kCVReturnSuccess == error),
		@"Creating Display Link error %d", error); 

	error = CVDisplayLinkSetOutputCallback(displayLink, displayCallback, self);
	NSAssert((kCVReturnSuccess == error),
		@"Setting Display Link callback error %d", error);
	CVDisplayLinkStart(displayLink);
}

-(void)renderForTime:(CVTimeStamp)time
{
	NSLog(@"Render");
	//CGLContextObj contextObj = [[self openGLContext] CGLContextObj];
	//CGLLockContext(contextObj);
	//[self lockFocus];
	if ([self lockFocusIfCanDraw] == NO) {
		return;
	}
	[[self openGLContext] makeCurrentContext];
	static int i = 0;
	double s = sin((i++ % 628) / 100.0);
	glClearColor(0.0, 0.0, s >= 0 ? s : -s, 1.0);
	glClear(GL_COLOR_BUFFER_BIT);
	[[self openGLContext] flushBuffer];
	[self unlockFocus];
	//CGLUnlockContext(contextObj);
}

-(void)dealloc
{
	[super dealloc];
}

-(void)windowWillClose:(NSNotification *)note {
	CVDisplayLinkRelease(displayLink);
	[[NSApplication sharedApplication] terminate:self];
}
@end

@interface GLController : NSWindow
-(void)createGLView;

@property(nonatomic, readwrite, retain) SxgeView *glView;
@end

@implementation GLController
-(id)init
{
	self = [super initWithContentRect: NSMakeRect(0, 0, 640, 480)
		styleMask: NSTitledWindowMask|NSResizableWindowMask|
			NSClosableWindowMask|NSMiniaturizableWindowMask
		backing: NSBackingStoreBuffered
		defer: false];

	[self setTitle: @"Opengl Test"];
	[self center];
	[self createGLView];
	[self setDelegate:[self glView]];
	[self makeKeyAndOrderFront:nil];
	[self display];

	return self;
}

-(void)createGLView
{
	NSOpenGLPixelFormatAttribute attribs[] = {
		NSOpenGLPFAOpenGLProfile, NSOpenGLProfileVersion3_2Core,
		NSOpenGLPFAColorSize, 24,
		NSOpenGLPFAAlphaSize, 8,
		NSOpenGLPFADoubleBuffer,
		NSOpenGLPFAAccelerated,
		NSOpenGLPFANoRecovery,
		NSOpenGLPFAClosestPolicy,
		0,
	};

	NSOpenGLPixelFormat *pixelFormat =
	[
		[[NSOpenGLPixelFormat alloc]
			initWithAttributes:attribs]
	autorelease];

	[self setGlView:
		[
			[[SxgeView alloc]
				initWithFrame: [[self contentView] bounds]
				pixelFormat:pixelFormat]
		autorelease]
	];
	[self setContentView:[self glView]];
}

-(void)dealloc
{
	[[self glView] release];
	[super dealloc];
}
@end

int main(int argc, char** argv) {
	NSAutoreleasePool *pool = [NSAutoreleasePool new];
	NSApplication *app = [NSApplication sharedApplication];
	GLController *controller = [[GLController alloc] init];
	[app run];
	[pool release];
	return 0;
}