I'm making a game in UIView. I'm trying to simulate the way the iOS Maps app works, when the compass auto-map-orientation is enabled.
I have a UIView, and I'm trying to change the map's X & Y co-ordinates, its angle, and its center point (origin).
But I'm having some trouble getting my head around how to do it.
Here's what I'm trying to use:
(this code is inside a game loop)
//move map
CGRect oldFrame = mapView.frame;
oldFrame.origin.y += 1;
mapView.frame = oldFrame;
//rotate map
mapView.transform = CGAffineTransformMakeRotation(mapAngle);
So, does anyone have any suggestions?
Thanks.
Related
I have a simple rotation gesture implemented in my code, but the problem is when I rotate the image it goes off the screen/out of the view always to the right.
The image view that is being rotated center X gets off or increases (hence it going right off the screen out of the view).
I would like it to rotate around the current center, but it's changing for some reason. Any ideas what is causing this?
Code Below:
- (void)viewDidLoad
{
[super viewDidLoad];
CALayer *l = [self.viewCase layer];
[l setMasksToBounds:YES];
[l setCornerRadius:30.0];
self.imgUserPhoto.userInteractionEnabled = YES;
[self.imgUserPhoto setClipsToBounds:NO];
UIRotationGestureRecognizer *rotationRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:#selector(rotationDetected:)];
[self.view addGestureRecognizer:rotationRecognizer];
rotationRecognizer.delegate = self;
}
- (void)rotationDetected:(UIRotationGestureRecognizer *)rotationRecognizer
{
CGFloat angle = rotationRecognizer.rotation;
self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, angle);
rotationRecognizer.rotation = 0.0;
}
You want to rotate the image around it's center, but that's not what it is actually happening. Rotation transforms take place around the origin. So what you have to do is to apply a translate transform first to map the origin to the center of the image, and then apply the rotation transform, like so:
self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, self.imageView.bounds.size.width/2, self.imageView.bounds.size.height/2);
Please note that after rotating you'll probably have to undo the translate transform in order to correctly draw the image.
Hope this helps
Edit:
To quickly answer your question, what you have to do to undo the Translate Transform is to subtract the same difference you add to it in the first place, for example:
// The next line will add a translate transform
self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, 10, 10);
self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, radians);
// The next line will undo the translate transform
self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, -10, -10);
However, after creating this quick project I realized that when you apply a rotation transform using UIKit (like the way you're apparently doing it) the rotation actually takes place around the center. It is only when using CoreGraphics that the rotation happens around the origin. So now I'm not sure why your image goes off the screen. Anyway, take a look at the project and see if any code there helps you.
Let me know if you have any more questions.
The 'Firefox' image is drawn using UIKit. The blue rect is drawn using CoreGraphics
You aren't rotating the image around its centre. You'll need correct this manually by translating it back to the correct position
I am rotating main view with 360 degrees, and I have subviews added inside main view, everything works correctly, but with one issue.
What I want to do is when I rotate main view, inner views should not lost their frames/position. Right now, when I rotate main view with infinte repeat count and dynamically if I add subview inside main view, it goes into proper position, but it does not retain its frame.
For example, I am implementing orbit, and for that, I have used entire transparent view as orbit and orbit is rotated from center point to 360 degree infinite times, and User can add many planets as he wants onto orbit, so when planets added on orbit, planets do not retain its frame. Can you suggest any idea?
Thanks in advance.
Well it sounds like you need to add a rotating animation for every subview that you add in your main view. If the main view rotates clockwise your subviews will need to rotate around their center in a counter-clockwise direction.
I guess you're trying to keep the subviews' orientations while rotating.
If I were you, I'd use CAAnimation instead of using a view to rotate.
You may add the animation to every subview, try this:
CAKeyframeAnimation* animation;
animation = [CAKeyframeAnimation animation];
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path, NULL,imgview.layer.position.x,imgview.layer.position.y);
int p = [self getblank:tag];
float f = 2.0*M_PI - 2.0*M_PI *p/PHOTONUM;
float h = f + 2.0*M_PI *num/PHOTONUM;
float centery = self.view.center.y;
float centerx = self.view.center.x;
float tmpy = centery + RADIUS*cos(h);
float tmpx = centerx - RADIUS*sin(h);
imgview.center = CGPointMake(tmpx,tmpy);
CGPathAddArc(path,nil,self.view.center.x, self.view.center.y,RADIUS,f+ M_PI/2,f+ M_PI/2 + 2.0*M_PI *num/PHOTONUM,0);
animation.path = path;
CGPathRelease(path);
animation.duration = TIME;
animation.repeatCount = 1;
animation.calculationMode = #"paced";
return animation;
I assume you have a stored variable that represents the rotation of the "world", correct? If not, you should.
Then, for each image you add, also store a variable with it that represents its rotation to the world.
For example, if your world is rotated 180°, and you added a cup (which you want to appear right-side up when the world is upside-down) the cup's "offset" to the world rotation would be -180°.
Then, if the world is at 180° and you rotate your world by adding 90°, then the cup's new rotation value would be cup_rotate_offset + world_rotation, or 180°+270°, which is the same as saying 90°, and the top of the world would be facing left and the cup's top would be facing right.
You have to independently track the offset values for each added object.
Me again. I have a simple question. I have an UIImageView like the one shown below.
alt text http://img683.imageshack.us/img683/1999/volumen.png
That UIimageView is supposed to be the knob to control the volume of my iphone project. My question is, how to know the positions of bar on the UIImageView when it is rotated? Because the volume needs to be 0.5 when the little bar on the cercle is vertical.
I got a piece of code which is (in the touchMoved method):
float dx = locationT.x - imgVVolume.center.x;
float dy = locationT.y - imgVVolume.center.y;
CGFloat angleDif = 0.0f;
movedRotationAngle = atan2(dy,dx);
if (beganRotationAngle == 0.0) {
beganRotationAngle = movedRotationAngle;
initialTransform = imgVVolume.transform;
}
else {
angleDif = beganRotationAngle - movedRotationAngle;
CGAffineTransform newTrans = CGAffineTransformRotate(initialTransform, -angleDif);
imgVVolume.transform = newTrans;
}
Help please.
It depends on what input mechanism you want to use to control the rotation.
If the knob is to rotate based on a single finger touch dragging from side to side then you can create a UIPanGestureRecognizer and attach it to the knob UIImageView. The translationInView: method returns a CGPoint which is the amount of X and Y movement from the touch-down point. You can feed that into a formula like the one you post to get an angle of rotation. You'll want to keep track of delta from last position and also check for stop limits (like 0..360) to prevent over-rotation.
OTOH, if you're going to use two finger rotation then you'll want to use a UIRotationGestureRecognizer and look for the rotation value. Just feed that into a CGAffineTransformRotate and set it to the UIImageView transform. That takes care of all of the above for you. Again, you'll want to check for stop limits.
I am programming a gauge display for an iphone application: a centered needle UIImageView against a fixed background UIImageView. I am new to iPhone programming, and don't know much about CoreAnimation, but with looking through examples and fiddling with my anchorPoint setting and the position of the needle image against the background in InterfaceBuilder, my needle is coming up with my desired rotation point properly centered against the background:
self.needleIV.layer.anchorPoint = CGPointMake( 0.5, 0.68 );
My test animations work perfectly (the needle remains properly centered in the gauge, and rotates around my desired rotation point, the anchor point), using this code:
CABasicAnimation *rotateAnimation = [CABasicAnimation animation];
rotateAnimation.keyPath = #"transform.rotation.z";
rotateAnimation.fromValue = [NSNumber numberWithFloat:DegreesToRadians( (rand() % 270 - 135) )];
rotateAnimation.toValue = [NSNumber numberWithFloat:DegreesToRadians( (rand() % 270 - 135) )];
rotateAnimation.duration = 4.0;
rotateAnimation.removedOnCompletion = NO;
// leaves presentation layer in final state; preventing snap-back to original state
rotateAnimation.fillMode = kCAFillModeBoth;
rotateAnimation.repeatCount = 0;
rotateAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
// Add the animation to the selection layer. This causes it to begin animating.
[self.needleIV.layer addAnimation:rotateAnimation forKey:#"rotateAnimation"];
The problem is that at application launch the needle comes up initially pointing straight up (which is how the needle looks in the image file), and I can't figure out how to give it an initial rotation value which doesn't mess up the animation code. (By "mess up" I mean the needle doesn't rotate on the correct axis, and becomes uncentered in the gauge).
I've tried setting layer.transform to a 3d rotation matrix rotated around the z axis, but this moves the needle off center. I've tried this code as well:
[self.needleIV.layer setValue:[NSNumber numberWithFloat:DegreesToRadians(-135.0)] forKeyPath:#"transform.rotation.z"];
which didn't work either (needle moved off anchorPoint center), and I had high hopes since it's apparently using the same transform to the working animation code.
I also tried just putting the working animation snippet in my view controller's viewDidLoad function to "animate" the needle to it's start location, but it doesn't do anything at all -- apparently the animation doesn't run until the image is actually up and on the screen, and I've confirmed in the debugger that the screen is still black in viewDidLoad.
At this point I'm about to try just hacking in a timer to run an initial animation "long enough" after the app starts to set an animation that rotates the needle properly, but I'd really like to understand what's going wrong here, and why the animation is apparently rotating around a different axis than is my other attempts at pre-rotation/pre-animation.
The anchorPoint is relative to the bounds of the parent. Is it possible the bounds of the parent layer/view change after viewDidLoad?
You should be able to do all this using the UIView center and transform properties, which are 2D so implicitly rotate about the z axis.
On iPhone, how to implement rotating image around the center point using finger touch ?
Just like wheel, if you put finger on the iPhone screen , then move suddenly, then the image becoming rotating around center point just like the wheel, after a while, it becomes more and more slow , finally stop.
Who can help to give some pieces of codes (Object-C) or some suggest ?
I was working with a "spin the bottle"-app yesterday. On the window I have a ImageView with an bottle that's suppose to response to touches and rotate the way the user swipes his finger. I struggled to get my ImageView to rotate during the touch-events (TouchesBegan, Touchesoved, TouchesEnd). I used this code in TouchesMoved to find out the angle in witch to rotate the image.
public override void TouchesMoved (NSSet touches, UIEvent evt)
{
PointF pt = (touches.AnyObject as UITouch).LocationInView(this);
float x = pt.X - this.Center.X;
float y = pt.Y - this.Center.Y;
double ang = Math.Atan2(x,y);
// yada yada, rotate image using this.Transform
}
THIS IS IMPORTANT! When the ImageView rotates, even the x & y-coordinates changes. So touching the same area all the time would give me different values in the pt and prePt-points. After some thinking, googeling and reading I came up with an simple solution to the problem. The "SuperView"-property of the ImageView.
PointF pt = (touches.AnyObject as UITouch).LocationInView(this.SuperView);
Having that small change in place made it alot easier, no i can use the UITouch-metohs LocationInView and PreviousLocationInView and get the right x & y coordinates. Her is parts of my code.
float deltaAngle;
public override void TouchesMoved (NSSet touches, UIEvent evt)
{
PointF pt = (touches.AnyObject as UITouch).LocationInView(this.Superview);
float x = pt.X - this.Center.X;
float y = pt.Y - this.Center.Y;
float ang = float.Parse(Math.Atan2(dx,dy).ToString());
//do the rotation
if (deltaAngle == 0.0) {
deltaAngle = ang;
}
else
{
float angleDif = deltaAngle - ang;
this.Transform = CGAffineTransform.MakeRotation(angleDif);
}
}
Hope that helped someone from spending hours on how to figure out how to freaking rotate a bottle! :)
I would use the affine transformations - yuou can assign a transformation to any layer or UI element using the transform property.
You can create a rotation transform using CGAffineTransform CGAffineTransformMakeRotation( CGFloat angle) which will return a transformation that rotates an element. The default rotation should be around the centerpoint.
Be aware, the rotation is limited to 360 degrees, so if you want to rotate something more than that (say through 720 degrees) - you have to break the rotation into several sequences.
You may find this SO article useful as well.
The transform property of a view or layer can be used to rotate the image displayed within. As far as the spinning part goes, you just track the location and movement of touches in your view with touchesBegan, touchesMoved, and touchesEnded.
Use the distance and time between the touches updates to calculate a speed, and use that to set a rotational velocity. Once you start the image spinning, update the position periodically (with an NSTimer, maybe), and reduce the rotational velocity by some constant.