CODEWITHSUNDEEP
ioscocoacore-animationtransformcalayer
Mazyod
Mazyod

Reputation: 22569

Animating CALayer anchorPoint

I have successfully animated my layers' position and transform (rotation).

Now, I needed to animate the anchorPoint, but failed at all attempts! Even when I do this:

2012... App[6437:403] layer: 1, KeyPath: anchorPoint, fromValue: NSPoint: {1.05, 0.5}, toValue: NSPoint: {1.05, 0.5}, Duration: 2.5

This is an NSLog stuck before animating the layer.. The result I get is the layer moving to the left in the X-Axis waaaay too far, then coming back .. and repeating (since autoreverse is ON).

Note about the layers hierarchy: SuperLayer has three sublayers that I am applying the animation on.

Why? How should the anchor point be animated?

My Code:

    NSArray* subKeyPath     = [keyPaths objectAtIndex:tag];
    NSArray* subToValue     = [toValues objectAtIndex:tag];
    NSArray* subDuration    = [durations objectAtIndex:tag];

    NSEnumerator* keyPathsEnum  = [subKeyPath objectEnumerator];
    NSEnumerator* toValuesEnum  = [subToValue objectEnumerator];
    NSEnumerator* durationsEnum = [subDuration objectEnumerator];

    NSString* keyPath;
    NSNumber* toValue;
    NSNumber* duration;

    while ((keyPath = [keyPathsEnum nextObject]) && (toValue = [toValuesEnum nextObject]) && (duration = [durationsEnum nextObject])) {
        CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:keyPath];

        id offsetToValue;
        if ([keyPath hasPrefix:@"position"]) {
        //I removed the position animation, since animating the anchorPoint should suffice
        } else if ([keyPath hasPrefix:@"anchorPoint"]) {
            //This was when I used anchorPoint.x float value         = [[subLayer valueForKeyPath:keyPath] floatValue] - ([toValue floatValue]/[[subLayer contents] size].width);
            offsetToValue       = [NSNumber valueWithPoint:CGPointMake(1.05, 0.5)];
            keyPath             = [keyPath substringToIndex:[keyPath length]-2];
        } else {
            offsetToValue       = toValue;
        }

...

        animation.toValue       = offsetToValue;
        animation.duration      = [duration floatValue];
        animation.fillMode      = kCAFillModeForwards;
        animation.repeatCount   = INFINITY;
        animation.autoreverses  = YES;
        animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

        [subLayer addAnimation:animation forKey:keyPath];

        //update the model

    }

I tried animating the "anchorPoint.x" keyPath, same result :(

Last note, I am writing a cocoa app, but animating the X value should be exactly the same on both cocoa and cocoa touch.

Upvotes: 1

Views: 1224

Answers (1)

Mazyod
Mazyod

Reputation: 22569

you are not gonna believe this (As if I am sitting with you from the beginning)..

Animating the position and the rotation was working properly without setting the fromValue. However, animating the anchor point required that I set the anchor point fromValue to the initial value!

animation.fromValue = [subLayer valueForKeyPath:keyPath];

Upvotes: 2

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