I have an UIImageView that is being pinched, zoomed, rotated, etc. When the user ends transforming the image he presses the DONE button and I have to figure out how much the object was scaled and rotated.
All I know is the angle and scale of the object before the user started modifying it. Now I need the new angle and scale.
How to do that? If you can point to a code, it will help.
thanks
I suggest to keep a track of all changes made.
If the user pinches zooms,etc, it means that the app will calculate the rotation and zooming for every touch the user does right?
So, Why don't use the last touch to know the rotation and zoom?
You could update your zoom and rotation variable every time the user does a touch.
Regards
Ignacio
Related
I am trying to create a menu for my app with a few icons in a circle. User should be able to spin this menu, making the icons change their positions around this circle path, but not rotating themselves. I read this earlier http://www.raywenderlich.com/9864/how-to-create-a-rotating-wheel-control-with-uikit so I can see how to follow the finger movement, but I need this menu to have inertial spin after the touch ends. I have 2 questions about how to do this.
First one, what's the best way to make animation with icons moving around in a circle? It should be slowing down until it stops and, if user moves his finger fast enough, should be able to do more than one full circle.
Second, how do I measure speed of finger movement at the end of it? I tried to use locationInView and previousLocationInView and just spin it by difference of angles between them multiplied by some constant. Problem is, when I keep my finger in one place for a while and take it up, I still get inertial movement of the circle and in this case I don't want it to move at all.
You want to use a scroll view. Specifically you want a hidden scroll view where you attach the pan gesture recogniser from the scroll view to your custom menu view. Then you implement the delegate methods of the scroll view to redraw your menu. This WWDC video has a good overview of the process. The benefit of this approach is that you get true iOS style acceleration and deceleration for free. You don't need to worry about finger position or speed, only the content offset of the scroll view.
Unless you want to spin your finger round in a circle with the menu items. That's a different ball game...
In theory, the same approach as above can be used for spinning your finger in a circle. You would need to ensure that directionalLockEnabled was set to NO on the scroll view. The problem is that the calculations to determine the rotation of your menu view are a lot more complex. Probably you would want to be modal and check if the scroll view is dragging in the callbacks. If it is dragging you would use the touches on the pan gesture to find the exact finger location to set the rotation. You'd also want to maintain data on the instantaneous direction of finger movement so that when the touch is released... If it isn't dragging then you use the scroll view content offset to apply the deceleration effect on the rotation (using the scroll direction just before the touch was released to know how to use the content offset changes).
I'm trying to have a sort of gesture that will seamlessly switch between a group of images this part I have sorted. The part that is catching me up is the gesture to do so and how I might introduce acceleration.
Basically the user would swipe as normal and after the swipe is registered it would change the image displayed and the faster once swiped the faster the image would change ideally it would then keep that speed until the users finger was lifted leaving the possibility to just scroll repeatedly through the images.
Any direction someone could give me would be great.
Thanks.
Assuming you would be using a UIScrollView for this, setting the scrollView.decelerationRate property would allow you to manipulate the deceleration rate/scroll speed. To calculate the "swipe speed", take a look here: Detecting Special touch on the iphone for some pointers.
Been having real trouble with this one and wondered if someone may have found a solution to this issue.
I would like to be able to rotate a UIImageView using a touch gesture
-> So when the user places two fingers on the touch area and rotates their fingers the UIImageView will rotate with them (Rotating in whatever direction the user moves their fingers)
I can do this but with one issue.... as the UIImageView rotates it does not keep its shape. It seems to skew?? It is really strange and i can not understand why it is happening.
So if i start with an equal sided square... as i rotate it does not remain as an equal sided square the sides seem to skew and not remain equal.
SOOOO i was wondering if anyone has come across this issue, or if anyone has successfully rotated a UIImageView with a touch gesture without it skewing.
Any help regarding this issue is highly appreciated.
Cheers
Tom
Can you give us some more information, like the rotation code?
Hopefully you're doing something like the following:
[imageView setTransform: CGAffineTransformMakeRotation(M_PI/2)];
I'm making an app where one of the objects needs to appear not to move or rotate during AutoRotation, but everything else needs to rotate and be repositioned. The way I did this is by manually rotating the object, and moving it into the same position, relative to the device, that it had prior to rotation. The problem is that it looks funny, appearing to rotate into the same position it had before.
If I suppress the animation effects during rotation, it would appear that the object never moved, and everything else just snapped into place, which is what I want. I haven't been able to find anything in the documentation that tells me how to do this though. How do I do this?
When it comes to UIViewController rotation there are two ways you can set up so you get a chance to rotate and move your own views.
In the one-step process, in your UIViewController-derived class provide an implementation of willAnimateRotationToInterfaceOrientation. It gets called and you can kick off your object rotation so while the system is rotating everything else your object is getting counter-rotated so it looks like it's staying put. You'll want to calculate how much to counter-rotate and in which direction based on current interface orientation vs. new orientation.
The other way is to get notified to do custom rotation in two steps. For example, in the first half you can shrink the object down, move it, and rotate it part way then in the second half finish the rotation as you scale back up to normal size. It's a pretty clever way to make the rotation animation look smoother to the eye.
For the two-step process, you need to define two methods. willAnimateFirstHalfOfRotationToInterfaceOrientation gets called for the first half of the rotation (i.e. up to 45 degrees for a 90 degree rotation and at 90 degrees for an upside down flip). Once past that point the second half is called via willAnimateSecondHalfOfRotationFromInterfaceOrientation.
If your object has a 1:1 aspect ratio (i.e square or round) and in the middle of the view then the one-step process will probably work fine. But if it's a non-square object and has to move position (for example if it's at position 40, 60 in portrait but moves to 20, 100 in landscape) and maybe even needs a bit of scaling to look better then you may want to try the two-step process and see if it looks smoother.
If your object is inside its own individual UIView then it's pretty easy to schedule the rotations through UIView animations. Just create a transform through CGAffineTransformMakeRotation, then inside a pair of UIView beginAnimations/commitAnimations blocks set the transform property of the view to this value. You can tweak the timing through setAnimationDuration.
EDIT: Based on the comments, I'm adding some code to show how you could attach the view to the top-level window instead of to the view controller. Your object would then reside in this view instead of the one managed by controller (which is getting rotated). You still need to over-ride the UIViewController rotate methods, but instead of rotating an object under control of the view controller you would trigger a counter-rotation in the object on the top-level.
To add a view to the top-level window:
YourAppDelegate* windowDelegate = ((YourAppDelegate*) [UIApplication sharedApplication].delegate);
[windowDelegate.window addSubview:yourView];
Keep a reference to yourView somewhere you can get to, then in the UIViewController's willAnimateRotationToInterfaceOrientation counter-rotate yourView, i.e. calculate how much to rotate the view in reverse to where you're going--if the phone is turning 90-degrees clockwise, you'll want to rotate the view back 90 degrees counter-clockwise, etc. Then use UIView animations on yourView.
If you don't want rotation animations, overload -shouldAutorotateToInterfaceOrientation: in your UIViewController and return NO. You can then observe UIDeviceOrientationDidChangeNotification to receive manual orientation change notifications.
This may work:
Listen for willRotateToInterfaceOrientation
[UIView setAnimationsEnabled:NO];
Listen for UIDeviceOrientationDidChangeNotification
[UIView setAnimationsEnabled:YES];
Untested, but I know that does work for some cases.
I am working on a project where i need to rotate an image by touching it.
It can be rotate faster or slower depending on how the user touches it.
Can you show me some tutorials or how this can be done?
Place your image within a UIImageView, then either subclass that view and replace touchesBegan:withEvent: or set a delegate for it and implement the same method as a delegate method. This will give you the ability to respond to touch events (the beginning of a touch, in this case, although you can do the same for ending a touch or moving of the finger).
Within this touch handling method, you can implement something similar to what I describe here in order to perform a Core-Animation-enabled rotation of your UIImageView at a given speed. To alter the speed, change the duration property on the animation I provide. As I suggest there, you may want to look into a CAKeyframeAnimation to do a smoother animation with acceleration and deceleration at the beginning and end.
An easier way is to set up an NStimer and rotate the transform everytime it fires.
I've some sample code here that coincidentally does something similar:
http://github.com/kailoa/touchsamplecode/tree/master
Using Cocos2d, you can't have 'touch enabled' sprites, 'isTouchEnabled' is at the Layer level. You'll have to receive the touch at the layer level, then check the location of the touch against the location of the touchable sprite. The CGRect* functions include a 'rect contains point' which you can pass the touch location to, with the sprite's rect to see if it was 'touched', and which point you could then say [sprite runAction:[Rotate ....]]