NSOpenGLView - View not refreshing until i move the window

Question

I'm really tearing my head out on this one!

I'm subclassing NSOpenGLView to do some animations on the view. When i say animations, i mean that am moving some images from left to right of the view and so on.

This is what i do

a) Initialise the OpenGL system Code:

- (id)initWithFrame:(NSRect)frame
{
    NSOpenGLPixelFormatAttribute attrs[] = {

    NSOpenGLPFANoRecovery, // Enable automatic use of OpenGL "share" contexts.
    NSOpenGLPFAColorSize, 24,
    NSOpenGLPFAAlphaSize, 8,
    NSOpenGLPFADepthSize, 16,
    NSOpenGLPFADoubleBuffer,
    NSOpenGLPFAAccelerated,
    0
};
// Create our pixel format.
NSOpenGLPixelFormat* pixelFormat = [[NSOpenGLPixelFormat alloc]        initWithAttributes:attrs];
self = [super initWithFrame:frame pixelFormat:pixelFormat];


return self;
}

// Synchronize buffer swaps with vertical refresh rate
- (void)prepareOpenGL
{
    GLint swapInt = 1;
   [[self openGLContext] setValues:&swapInt forParameter:NSOpenGLCPSwapInterval];
}

b) Setup the Timers on Start

   Code:
   // Put our timer in -awakeFromNib, so it can start up right from the beginning
  -(void)awakeFromNib
  {
   if( gameTimer != nil )
     [gameTimer invalidate];

   gameTimer = [NSTimer timerWithTimeInterval:0.02   //time interval
                                    target:self
                                  selector:@selector(timerFired:)
                                  userInfo:nil
                                   repeats:YES];

   [[NSRunLoop currentRunLoop] addTimer:gameTimer
                             forMode:NSDefaultRunLoopMode];
   [[NSRunLoop currentRunLoop] addTimer:gameTimer
                             forMode:NSEventTrackingRunLoopMode]; //Ensure timer fires   during resize*/
   }


   // Timer callback method
  - (void)timerFired:(id)sender
 {
    //The timer fires this method every second
    currentTime ++;

    // All we do here is tell the display it needs a refresh
   [self setNeedsDisplay:YES];
 }

c) Animate my stuff in drawRect

 Code:
 - (void)drawRect:(NSRect)rect
{
   [self animateFrame:rect];

  // the correct way to do double buffering is this:
  [[self openGLContext] flushBuffer];
}

d) The animateFrame method just draws images in various rectangle positions

 Code:
 [curImage drawInRect:targetRect
            fromRect:sourceRect
           operation:NSCompositeSourceOver
            fraction:1.0f];

---

So here is the problem

When i start the app - i can see that time timer is being fired, drawRect is being invoked and the images are being drawn.

However i can only see the animation of the images, when i drag the window and move the window.. When the window is still the images just stay frozen. When i move the window - i see the images are moving... Or even if i get the window out of focus and back in focus - i can see the image changes positions...

I feel that the OpenGLView is not painting itself when static... I dont know what else is to be done...

Do i have to invoke - [[self openGLContext] flushBuffer]; How do i ensure the View is getting painted always?

Can someone shed light on what is going on here or what have i missed?

Appreciate some help. Thanks in advance! KamyFC

Answer 1

Ok i started to see the animations - once i replaced NSOpenGLView by NSView.

Maybe drawing images is not an OpenGL task and can be accomplished by the simpler NSView.