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.
Related
Changing the anchor point of a CALayer after a CATransform3dRotate gives weird results. I think the problem is, anchorPoint property is set on the previous state (no transform) of layer not the current state (after transform) of the layer.
Is there a way to change the anchorPoint of a CALayer's current state??
Code for Transform:
CATransform3D transform = CATransform3DIdentity;
transform.m34 = -(1.0/800.0);
videoPlayerView.layer.zPosition = 100;
videoPlayerView.layer.transform = CATransform3DRotate(transform, (30*M_PI)/180, 1.0f, 0.0f, 0.0f);
Code to change the anchor Point
if(videoPlayerView.layer.anchorPoint.x != 0.0)
{
videoPlayerView.layer.anchorPoint = CGPointMake(0.0, 0.5);
videoPlayerView.layer.position = CGPointMake(videoPlayerView.layer.frame.origin.x - videoPlayerView.layer.frame.size.width/2,videoPlayerView.layer.position.y);
}
Basically, I have to rotate the Layer like a book flip. I have already done this without using the 30 degree transofrm, but I want it to look more 3D so applied the 30 degree transform along the x axis. So that it looks like the book is placed on a table.
And in order to rotate, setting the anchor point is necessary. If not, please advice otherwise...
instead of changing anchorPoint use
CATransform3DTranslate(transform, 50.0000f, 0.0000f, 0.0000f);
Translate along X by 50.00 points
Apply 0.40 percent of perspective or you can use the same code you are using right now
rotate the CAlayer using Y .
CATransform3D transform = CATransform3DIdentity;
CATransform3D tmp = CATransform3DIdentity;
transform = CATransform3DRotate(transform, 0.0146f, 0, 1, 0);
transform = CATransform3DTranslate(transform, 50.0000f, 0.0000f, 0.0000f);
tmp = CATransform3DIdentity;
tmp.m34 = 0.0040f;
transform = CATransform3DConcat(transform, tmp);
check the link for more reference.
let me know if it works.
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.
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.
I am trying to rotate an image using slider..its working well but when i zoom in or zoom out that imageView using Pinch gesture and then try to rotate it using Slider then it resizes the imageView's frame to its original frame and then rotate it..i Want it to rotate the new imageview after performing zoom operation...heres my code.
//for rotation
- (IBAction)sliderChanged:(id)sender
{
imageView.transform = CGAffineTransformMakeRotation(Slider.value * 2*M_PI / Slider.maximumValue);
}
//for zoom in zoom out
- (IBAction)handlePinch:(UIPinchGestureRecognizer *)recognizer
{
recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
recognizer.scale = 1;
}
In handlePinch you correctly modify existing transform, but in sliderChanged you create new transform, losing scaling.
You are not maintaining the scale. an example of something that works:
-(IBAction)zoomIn:(id)sender{
x += 0.3;
CGAffineTransform t;
t=CGAffineTransformMakeRotation(degrees*M_PI/180);
imageView.transform=CGAffineTransformScale(t, x, x);
}
you are using the recognizer.view.transform in the CGAffineTransformScale. Try using the imageView.transform