How would I use a UIPinchGestureRecognizer to scale a CALayer using a Transform (based off an existing transform, the current state of the layer)?
- (IBAction)gesturePinch:(UIPinchGestureRecognizer *)sender
{
float scale = sender.scale;
scale = scale - previousScale;
previousScale = scale;
layer.transform = CATransform3DScale(square.transform, scale, scale, scale);
}
Because the scale is incrementing it gets either huge or very small very quickly. Any suggestions?
It is better to handle the scale like this:
layer.transform = CATransform3DScale(square.transform, sender.scale, sender.scale, sender.scale);
sender.scale = 1.f;
This will reset it every time, making the need to calculate it go away. You will lose the velocity calculations, but I don't think you will be using them anyway.
Related
I am trying to perform an animation that does three things at once: translates, rotates and changes the size of an image.
I can do two at once, translate and size. However, when I add in rotation at the end of the following code, it is ignored. And if I place it at the beginning of the code, the size change is ignored. I've read that you can do a composite transition with view.transform, however, I have not been able to get that to work.
Here is my current code:
CGPoint destPoint = CGPointMake(-100,-50);
float radians =[self Degrees2Radians:-35];
[UIView animateWithDuration:2
animations:^{
//TRANSLATE
self.imageView.center = CGPointMake(self.imageView.center.x + destPoint.x, self.imageView.center.y + destPoint.y);
//ROTATE
self.imageView.transform = CGAffineTransformMakeRotation(radians);
//SCALE
self.imageView.transform = CGAffineTransformMakeScale(0.2, 0.2); // here the final size will be 20%
}
completion:nil
];
}
Can anyone recommend way to get all three things to occur simultaneously.
Here is some code for swift that uses the transform property of the view, but I have not been able to find the equivalent in Objective-C.
view.transform= CGAffineTransform(scaleX: 1.5, y: 1.5)
view.transform = view.transform.rotated(by angle: CGFloat(45 * M_PI / 180))
Thanks in advance for any suggestions.
You can use CGAffineTransformRotate function on the existing transform to apply a rotation. You can also use CGAffineTransformTranslate and CGAffineTransformScale to apply translation and scaling. Please note that, order of the operations matter.
For example if you have an existing transform myTransform you can rotate it like:
myTransform = CGAffineTransformRotate(myTransform, M_PI / 2);
The operation does not affect the input variable, instead, it returns a new transform so make sure you use the return value of the function. That's why I started the line with myTransform = ....
More information is available at https://developer.apple.com/documentation/coregraphics/cgaffinetransform-rb5?language=objc.
I have a UIView that I scale down when it is touched and scale back up when the touch is ended or cancelled.
I had been scaling the view like this
Scale down:
CGAffineTransform transform = CGAffineTransformMakeScale(0.95, 0.95);
self.transform = transform;
Scale up:
CGAffineTransform transform = CGAffineTransformMakeScale(1.0, 1.0);
self.transform = transform;
This doesn't preserve any other transform. I know I can use this to preserve the old transforms:
Scale down:
CGAffineTransform transform = CGAffineTransformScale(self.transform, 0.95, 0.95);
self.transform = transform;
Scale up:
CGAffineTransform transform = CGAffineTransformScale(self.transform, 1.0, 1.0);
self.transform = transform;
But of course here the scale up has no effect- plus there is potential to have cumulative scale down animations applied. Basically I want a way to apply the scale transform absolutely without affecting any other transform. Is there a way to do this? I don't think using 1.0/0.95 for the scale up factor, because it is possible the view could receive two touches before one is cancelled or ended.
I think I am asking the same thing as this question: Applying just the scale component of a CGAffineTransform to a UIView but I don't think the answers here will work for me.
I am targeting iOS 7 and above.
I am not sure if this is exactly what you are looking for but for me I need the scale to be absolutely consistent all the time so I modify the matrix directly.
CATransform3D transform = layer.transform;
if (makeSmaller)
{
// Scale to 0.9
transform.m11 = 0.9f;
transform.m22 = 0.9f;
}
// Cell needs to grow to normal size
else if (restoreToOriginal)
{
// Scale to 1.0 again
transform.m11 = 1.0f;
transform.m22 = 1.0f;
}
// Set the desired Y translation
transform.m42 = desiredffset;
layer.transform = transform;
I'm writing an app such that sprites (subclasses of UIImageView) can be rotated, resized, and panned across the screen using gestures. I also would like to be able to apply a 3D perspective transformation to the sprites.
I have the rotate/resize/pan functionality working correctly, as well as the perspective transform. However, they don't seem to work together correctly. If I rotate an unmodified sprite, then try to skew it, the sprite 'resets' it's rotation, then applies the perspective. The opposite works though; if I skew first, I can apply any 2D transformation after without it resetting.
Here is the code I'm using: (rotate, resize, and pan are done using UIGestureRecognizers, whereas the skew uses a UISlider).
Rotate:
- (void)didRotateSprite:(UIRotationGestureRecognizer *)rotate
{
CGFloat angle = rotate.rotation;
CATransform3D transform = CATransform3DIdentity;
transform = CATransform3DRotate(spriteView.layer.transform, angle, 0, 0, 1);
spriteView.layer.transform = transform;
rotate.rotation = 0.0;
}
Resize:
- (void)didPinchSprite:(UIPinchGestureRecognizer *)pinch
{
CGFloat scale = pinch.scale;
CATransform3D transform = CATransform3DIdentity;
transform = CATransform3DScale(spriteView.layer.transform, scale, scale, 1);
view.layer.transform = transform;
pinch.scale = 1.0;
}
Perspective:
- (IBAction)perspectiveChanged:(UISlider *)slider
{
CATransform3D transform = CATransform3DIdentity;
transform.m34 = 1.0 / -100;
transform = CATransform3DRotate(transform, (1 - (slider.value * 2)) * M_PI_2, 1, 0, 0);
spriteView.layer.transform = transform;
}
Thank you!
Found the answer with a lot of debugging and the help of this question. The trick was to transform the view's perspective using:
spriteView.superview.layer.sublayerTransform = transform;
This recursively applies the transformation to the view's superview and any subviews contained in it. For more information about this, check out the documentation and Apple's Layer Style Properties guide too.
I've been working on a maps replacement for quite a while now. The whole thing works with a UIScrollView backed by a CATiledLayer.
To rotate my map, i rotate the layer itself. (Using CATransform3DMakeRotation) Works pretty well so far =)
But if I ever call setZoomScale method the CATransform3D that is going to be submitted to my layer is resetting the rotation to 0.
My question is, is there any way to set the zoomscale of my scrollView without loosing the applied rotation?
The same problem exists for the pinch gestures.
//Additional Infos
To rotate around the current Position, i have to edit the anchor point. Maybe this is a problem for the scaling, too.
- (void)correctLayerPosition {
CGPoint position = rootView.layer.position;
CGPoint anchorPoint = rootView.layer.anchorPoint;
CGRect bounds = rootView.bounds;
// 0.5, 0.5 is the default anchorPoint; calculate the difference
// and multiply by the bounds of the view
position.x = (0.5 * bounds.size.width) + (anchorPoint.x - 0.5) * bounds.size.width;
position.y = (0.5 * bounds.size.height) + (anchorPoint.y - 0.5) * bounds.size.height;
rootView.layer.position = position;
}
- (void)onFinishedUpdateLocation:(CLLocation *)newLocation {
if (stayOnCurrentLocation) {
[self scrollToCurrentPosition];
}
if (rotationEnabled) {
CGPoint anchorPoint = [currentConfig layerPointForLocation:newLocation];
anchorPoint.x = anchorPoint.x / rootView.bounds.size.width;
anchorPoint.y = anchorPoint.y / rootView.bounds.size.height;
rootView.layer.anchorPoint = anchorPoint;
[self correctLayerPosition];
}
}
You can implement scrollViewDidZoom: delegate method and concatenate the two transforms to achieve desired effect:
- (void) scrollViewDidZoom:(UIScrollView *) scrollView
{
CATransform3D scale = contentView.layer.transform;
CATransform3D rotation = CATransform3DMakeRotation(M_PI_4, 0, 0, 1);
contentView.layer.transform = CATransform3DConcat(rotation, scale);
}
EDIT
I've got simpler idea! How about adding another view to the hierarchy with the rotation transform attached? Here's the proposed hierarchy:
ScrollView
ContentView - the one returned by viewForZoomingInScrollView:
RotationView - the one with rotation transform
MapView - the one with all the tiles
I don't think that performance should be any concern here and it's worth trying.
I have an imageview that I am scaling and rotating via UISliders. Here is how I do so:
- (IBAction)sizeSlider:(UISlider *)sender
{
int SCALE_MAX = 200;
int SCALE_MIN = 10;
CGAffineTransform transform = image.transform;
float scale = sqrt(transform.a*transform.a + transform.c*transform.c);
if (scale > SCALE_MAX)
image.transform = CGAffineTransformScale(transform, SCALE_MAX/scale*sender.value, SCALE_MAX/scale*sender.value);
else if (scale < SCALE_MIN)
image.transform = CGAffineTransformScale(transform, SCALE_MIN/scale*sender.value, SCALE_MIN/scale*sender.value);
}
- (IBAction)angleSlider:(UISlider *)sender
{
CGAffineTransform t = CGAffineTransformMakeRotation(sender.value);
image.transform = t;
}
This works, however if the imageview has been scaled from its original size then rotating the image resets it to its original size. How can I prevent this?
Use the similar approach of your scale in your rotation. Meaning, use:
CGAffineTransformRotate(image.transform, theAngle);
CGAffineTransformMakeRotation
creates a new transform based on identity. Scaling is part of a transform--you want to use
CGAffineTransformRotate
instead which adds rotation to the existing, scaled transform.