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having trouble creating ken burns effect with CALayer for iphone

- (CALayer*)buildKenBurnsLayerWithImage:(UIImage *)image startPoint:(CGPoint)startPoint endPoint:(CGPoint)endPoint fromScale:(float)fromScale toScale:(float)toScale

{

    float calFromScale = fromScale + 1;

    float calToScale = toScale + 1;

    float fromX = startPoint.x * calFromScale;

    float fromY = (image.size.height * calFromScale) - (videoSize.height + (startPoint.y * calFromScale));

    float toX = endPoint.x * calToScale;

    float toY = (image.size.height * calToScale) - (videoSize.height + (endPoint.y * calToScale));

 

    CGPoint anchor = CGPointMake(0.0, 0.0);

 

    CALayer* imageLayer    = [CALayer layer];

    imageLayer.contents    = (id)image.CGImage;

    imageLayer.anchorPoint = anchor;

    imageLayer.bounds      = CGRectMake(0.0, 0.0, image.size.width, image.size.height);

    imageLayer.position    = CGPointMake(image.size.width * anchor.x, image.size.height * anchor.y);

    imageLayer.contentsGravity = kCAGravityResizeAspect;

 

    // create the panning animation.

    CABasicAnimation* panningAnimation = [CABasicAnimation animationWithKeyPath:@"position"];

    panningAnimation.fromValue = [NSValue valueWithCGPoint:CGPointMake(-fromX, -fromY)];

    panningAnimation.toValue   = [NSValue valueWithCGPoint:CGPointMake(-toX, -toY)];

    panningAnimation.additive = YES;

    panningAnimation.removedOnCompletion = NO;

 

    // create the scale animation.

    CABasicAnimation* scaleAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];

    scaleAnimation.fromValue = [NSNumber numberWithFloat:fromScale];

    scaleAnimation.toValue = [NSNumber numberWithFloat:toScale];

    scaleAnimation.additive = YES;

    scaleAnimation.removedOnCompletion = NO;

 

    CAAnimationGroup* animationGroup = [CAAnimationGroup animation];

    animationGroup.animations = [[NSMutableArray alloc] initWithObjects:panningAnimation,scaleAnimation, nil];

    animationGroup.beginTime = 1e-100;

    animationGroup.duration = 5.0;

    animationGroup.removedOnCompletion = NO;

    animationGroup.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];

 

    [imageLayer addAnimation:animationGroup forKey:nil];

 

    return imageLayer;

}

       

CALayer* animatedLayer = [self buildKenBurnsLayerWithImage:image startPoint:CGPointMake(100, 100) endPoint:CGPointMake(500, 500) fromScale:5.0 toScale:2.0];