I am building a custom UIView that you can rotate and resize. I can resize the UIView by dragging the corners of the UIView. I calculate how much I have dragged then change the frame of the UIView accordingly.
However, I am running into problems once I added a rotation gesture recognizer to the view. If I rotate or apply a transform to the view, I no longer know how to calculate drag distance and change the frame of the view. How could I calculate the width and height change between my new view and the original view when things are put at an added angle or if they have some other transform, like a translation transform?
I thought of possibilities to set the view's transform back to .identity, change the size of the view, then re-apply its transform, but I'm not sure how to actually go about implementing this.
After applying transform you can not use frame
You have two options
1) First Calculate everything using center of your view
2) As you know apply identity and change frame
for point 2 I have added example that might helpful to you
let transform = imageView.transform
imageView.transform = CGAffineTransform.identity
var rect: CGRect = imageView.frame
rect = // Change Rect here
imageView.frame = rect // Assign it
imageView.transform = transform // Apply Transform
Related
recently I have been working with CGAffineTransform and CATransform3D on views and layers. When I apply transformation at layer level and especially on view level, shouldn't autolayout updates the frames of related views. For example, consider following layout |H:[ViewA]-[ViewB]|. If I apply transformation on just ViewA.
//We can either
ViewA.transform = CGAffineTransformMakeScale(1.5, 1.5)
ViewA.layer.transform = CATransform3DMakeScale(1.5, 1.5, 1.0)
shouldn't ViewB auto adjust it rect since ViewA height, width or position has changed after transformation. I also tried calling
self.view.layoutIfNeeded()
Transformations don't affect the Frame or Bounds of a view or the frame will be in an undefined state. To illustrate that: image you have a rectangular view with a frame of X:10, Y:10, W:100, H:100 and you rotate that by 45 degrees...what should the frame be?
From Apple's docs about the transformation:
If this property is not the identity transform, the value of the frame
property is undefined and therefore should be ignored.
This explains why AutoLayout does not perform any updates.
According to the Apple documentation available here the bounds property of a UIView can be animated.
In order to programmatically rotate one of my views (in this case from portrait to landscape), I implemented the following code:
float w = controlsView.bounds.size.width;
float h = controlsView.bounds.size.height;
CGAffineTransform T = CGAffineTransformMakeRotation(M_PI/2);
UIViewContentMode oldContentMode = controlsView.contentMode;
controlsView.contentMode = UIViewContentModeRedraw;
[UIView animateWithDuration:1.0 animations:^{
controlsView.bounds = CGRectMake(0, 0, h, w);
controlsView.transform = T;
}];
controlsView.contentMode = oldContentMode;
I added the two instructions for contentMode because I have read somewhere on StackOverflow that contentMode must be set to that value in order for a UIView to redraw the content while the bounds property is modified (however, in this case it does not affect the behaviour in any way).
The problem of that code is that UIView is not resized with an animation but all at once.
Executing that code, the UIView is first resized (without animation) then rotated with an animation.
How can I animate the resizing?
-- UPDATE --
I tried to combine a scaling and rotating transformation. The UIView rotates and scales in an animation, but at the end its bounds property does not change: even if it has been rotated to a landscape orientation (which should be 568x320 on my iPhone), its width and height stay at the portrait values (320x568). Indeed, the UI controls on the controlsView are deformed (wrong aspect ratio) and appears stretched.
This worked for me using UIViewAnimationOptions.LayoutSubviews (Swift):
UIView.animateWithDuration(1.0,delay:0.0,
options:UIViewAnimationOptions.LayoutSubviews,
animations:{ () -> Void in
myView.transform = myRotationTransform
myView.bounds = myBounds
}, completion: nil)
(no explicit scaling nor changing contentMode)
The problem is that when you set a transform property, all other transforms (bounds) are overwritten. To fix it you have to create one transform that combines scaling and rotating.
Example:
CGAffineTransform scaleTransform = CGAffineTransformMakeScale(0.5, 0.5);
[UIView animateWithDuration:1.0 animations:^
{
controlsView.transform = CGAffineTransformRotate(scaleTransform, M_PI/2);
}];
You will need to calculate the scaling X and Y values based on the size you want to have at the end of the animations. You might also want to change the anchorPoint property to set a center point used for scaling (controlsView.layer.anchorPoint).
Animating your bounds doesn't change its value. It reverts to its original value once the animation ends.
Change the value of the bounds to the final value once the animation is over. I'll solve the trouble.
I'm developing an animated column bar chart and i having some trouble.
The bars show up with an scale animation. At the beginning all columns have 1 point size and will scale till a predefined height.
The point is: I want to draw a gradient into the columns (They are subclasses of UIView) and want the scale animation to recalculate the gradient.
Until now, i have drawn the gradient, but when the column scale, the gradient does not scale with it.
As the view have 1 point height, the gradient is show as 1 color only.
Can someone give me a north to solve this issue?
Solved the problem!
i was using scale instead of changing the view's bounds..
Was
view.transform = CGAffineTransformMakeScale(1.0, scaleY.floatValue);
Must be
view.bounds = CGRectMake(view.bounds.origin.x, view.bounds.origin.y * scaleY.floatValue, view.bounds.size.width, view.bounds.size.height * scaleY.floatValue);
Where scaleY was calculated before and is a NSNumber that contains the Y scale factor.
It's not necessary to set
view.contentMode = UIViewContentModeRedraw;
Thank you DarkDusk for the help.
Try setting the contentMode:
myView.contentMode = UIViewContentModeRedraw;
This will force a redraw on every size change.
I have a round image that I want to "squish" vertically so that it looks more like a horizontal line, then expand it back to the original shape. I thought this would work by setting the layer's anchor point to the center and then animating the frame via UIViewAnimation with the height of the frame = 1.
[self.imageToSquish.layer setAnchorPoint:CGPointMake(0.5, 0.5)];
CGRect newFrame = CGRectMake(self.imageToSquish.frame.origin.x, self.imageToSquish.frame.origin.y, self.imageToSquish.frame.size.width, 1 );
[UIView animateWithDuration:3
animations:^{self.imageToSquish.frame = newFrame;}
completion:nil];
But the image shrinks toward the top instead of around the center.
You’re giving it a frame that has its origin—at the top left—in the same position as it started. You probably want to do something more like this, adding half the image’s height:
CGRect newFrame = CGRectMake(self.imageToSquish.frame.origin.x, self.imageToSquish.frame.origin.y + self.imageToSquish.frame.size.height / 2, self.imageToSquish.frame.size.width, 1);
Alternatively—and more efficiently—you could set the image view’s transform property to, say, CGAffineTransformMakeScale(1, 0.01) instead of messing with its frame. That’ll be centered on the middle of the image, and you can easily undo it by setting the transform to CGAffineTransformIdentity.
I have a UIImageView add to a UIView as a subview. When I apply a transformation on the UIView's layer the UIImageView gets blurry. Why is that? How can this problem be resolved?
view.layer.position = newPosition;
I apply only this transformation.
Edit:
I've tested it and if I apply other transformations like these:
view.layer.transform = newTransform;
view.layer.zPosition = newZPosition;
then the blurry doesn't appear, only if I change the layer position.
Use
blurryDialog.frame = CGRectIntegral(blurryDialog.frame);
To set the frame coordinates to integer values
I found the answer. When you set the position of a layer or a view then the origin of it can be float values and this causes the blurry thing.
So the solution is to set also the frame's origin after you set the position. You just have to set the frame's position to integer values. On the UI this change won't be seen, but the image will not be blurry.