Disabling implicit animations in -[CALayer setNeedsDisplayInRect:]

Ben_Gottlieb_6694 0
Viewed 51900

I've got a layer with some complex drawing code in its -drawInContext: method. I'm trying to minimize the amount of drawing I need to do, so I'm using -setNeedsDisplayInRect: to update just the changed parts. This is working splendidly. However, when the graphics system updates my layer, it's transitioning from the old to the new image using a cross-fade. I'd like it to switch over instantly.

I've tried using CATransaction to turn off actions and set the duration to zero, and neither work. Here's the code I'm using:

[CATransaction begin];
[CATransaction setDisableActions: YES];
[self setNeedsDisplayInRect: rect];
[CATransaction commit];

Is there a different method on CATransaction I should use instead (I also tried -setValue:forKey: with kCATransactionDisableActions, same result).

calayer core-animation iphone ios
15 Answers

You can do this by setting the actions dictionary on the layer to return [NSNull null] as an animation for the appropriate key. For example, I use

NSDictionary *newActions = @{
    @"onOrderIn": [NSNull null],
    @"onOrderOut": [NSNull null],
    @"sublayers": [NSNull null],
    @"contents": [NSNull null],
    @"bounds": [NSNull null]
};

layer.actions = newActions;

to disable fade in / out animations on insertion or change of sublayers within one of my layers, as well as changes in the size and contents of the layer. I believe the contents key is the one you're looking for in order to prevent the crossfade on updated drawing.

Swift version:

let newActions = [
        "onOrderIn": NSNull(),
        "onOrderOut": NSNull(),
        "sublayers": NSNull(),
        "contents": NSNull(),
        "bounds": NSNull(),
    ]
user_196790

Based on Sam's answer, and Simon's difficulties... add the delegate reference after creating the CSShapeLayer:

CAShapeLayer *myLayer = [CAShapeLayer layer];
myLayer.delegate = self; // <- set delegate here, it's magic.

... elsewhere in the "m" file...

Essentially the same as Sam's without the ability to toggle via the custom "disableImplicitAnimations" variable arrangement. More of a "hard-wire" approach.

- (id<CAAction>)actionForLayer:(CALayer *)layer forKey:(NSString *)event {

    // disable all implicit animations
    return (id)[NSNull null];

    // allow implicit animations
    // return nil;

    // you can also test specific key names; for example, to disable bounds animation:
    // if ([event isEqualToString:@"bounds"]) return (id)[NSNull null];

}
user_10888660

Updated for swift and disabling only one implicit property animation in iOS not MacOS

// Disable the implicit animation for changes to position
override open class func defaultAction(forKey event: String) -> CAAction? {
    if event == #keyPath(position) {
        return NSNull()
    }
    return super.defaultAction(forKey: event)
}

Another example, in this case eliminating two implicit animations.

class RepairedGradientLayer: CAGradientLayer {

    // Totally ELIMINATE idiotic implicit animations, in this example when
    // we hide or move the gradient layer

    override open class func defaultAction(forKey event: String) -> CAAction? {
        if event == #keyPath(position) {
            return NSNull()
        }
        if event == #keyPath(isHidden) {
            return NSNull()
        }
        return super.defaultAction(forKey: event)
    }
}
user_23402640
Related