Rotating an UIImageView around an arbitrary point?

[Norbert]

Hi,

is there a function which lets an UIImageView rotate around a given point which is not the center of the UIImageView?
If not, do you know any method how I can accomplish this?

Thanks!

[spuy767]

It would be a complex mathematical translation, Give me a few minutes, and I'll work it out for you,

[CaptainRedmuff]

You could simply set the center point of the UIImageView before you rotate it?

//create rect
UIImageView *myImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"my_image.png"]];

//set point of rotation
myImageView.center = CGPointMake(100.0, 100.0);

//rotate rect
myImageView.transform = CGAffineTransformMakeRotation(3.14159265); //rotation in radians

Give that a bash, hope it helps

[Norbert]

Originally Posted by CaptainRedmuff

You could simply set the center point of the UIImageView before you rotate it?

Thanks, but this will let my image rotate around itself, right? I'm looking for a function or a method which lets my image rotate around a point that is not within the image. Like this:

[skinnytron]

I looked for a similar solution but couldn't find one. What I did was wrap my UIImageView in an empty UIView (ie no background or anything so that when you load the application its not visible) Then just make the UIView larger than the UIImageView and rotate the UIView.

Example: If you have a square that is 20,20 and you want to rotate at a point that was -10,-10 (ie diagonal to the top left corner). You would then make your UIView 60,60 and place the UIImageView at 40,40. If you then rotated the UIView it would appear that you were rotating it about that -10,-10 location when you would actually be rotating it about the center of the UIView (which is 30, 30).

Make sense?

[spuy767]

What I was talking about earlier, you can use CGPoints to to rotate. It would be something that you would probably want to write your own class for. Expouding on what the guy said above, I would acctually recommend, if this is not something that you're going to be doing on a regular basis, make a UIView the exact width of your image, and twich the width of the orbital radius that you want the object to have. You can rotate the entire UIView, and as long as your image is a subView of the UIView, it will rotate the image.

[Norbert]

Ok, thank you both for your help, I will try that.

[Norbert]

So:

I added my image to a new UIImageView. Then with

myImageView.transform = CGAffineTransformMakeRotation(pi/4);

I was able to to the desired rotation.

But how do I get my image back into my background view so that it keeps its properties such as position, rotation, etc.? I can't figure it out.

[Saurman]

actually, its a lot easier. U have to work with view's layer and it has so called anchorPoint and 3d rotation. Problem is - this is a part of quartz.

[Norbert]

Originally Posted by Saurman

actually, its a lot easier. U have to work with view's layer and it has so called anchorPoint and 3d rotation. Problem is - this is a part of quartz.

Oh, well, this sounds fine. What is the problem with it? Do you have any further information about layers and commands? I'm not sitting at my Mac right now so I cannot look in the XCode iPhone API.
Thanks!

[Saurman]

Originally Posted by Norbert

Oh, well, this sounds fine. What is the problem with it? Do you have any further information about layers and commands? I'm not sitting at my Mac right now so I cannot look in the XCode iPhone API.
Thanks!

https://developer.apple.com/iphone/l...es/Layers.html

[Norbert]

Hm, can someone post a quick code snippet how to add an image and then rotate/translate it?
Thanks!

[Saurman]

i will be doing app soon which will rotate image in the way it is in google maps, ill share my code when it will be working

[Norbert]

Originally Posted by Saurman

i will be doing app soon which will rotate image in the way it is in google maps, ill share my code when it will be working

That would be great, thanks!

[3DTOPO]

Originally Posted by Saurman

i will be doing app soon which will rotate image in the way it is in google maps, ill share my code when it will be working

Did you ever get it working? I would love to see your code....

[iphone66]

hi....


i have two images......how can i perform animation in them so that the first image rotates and the secomd image appears and vice versa

[ZunePod]

I have a related question:

How about making something that looks as if it's spinning (like a vinyl on a record player)

I tried using UIView commitAnimations, but it didn't work.

[chaseacton]

Is there a way to do it in degrees rather than in radians?

[markkram]

Here is a great little macro for converting degrees to radians:

#define degreesToRadians(x) (M_PI * (x) / 180.0)

which you can use like :

myView.transform = CGAffineTransformMakeRotation(degreesToRadians(90) );

[sahil4u91]

Originally Posted by markkram

Here is a great little macro for converting degrees to radians:

#define degreesToRadians(x) (M_PI * (x) / 180.0)

which you can use like :

myView.transform = CGAffineTransformMakeRotation(degreesToRadians(90) );

I've got an image (a straight line) and am trying to rotate it in some angle from a specific point. What happens is that the image is rotated from the center point of itself. I wan't a way through which the base of the image remains the same and it rotates in the angle I want to, just as in case of a clock.

[dany_dev]

Originally Posted by sahil4u91

I've got an image (a straight line) and am trying to rotate it in some angle from a specific point. What happens is that the image is rotated from the center point of itself. I wan't a way through which the base of the image remains the same and it rotates in the angle I want to, just as in case of a clock.

look at

imageView.layer.anchorPoint = CGPointMake(x,y);

[sahil4u91]

Originally Posted by dany88

look at

imageView.layer.anchorPoint = CGPointMake(x,y);

Thanks dany88. It worked.

[RLScott]

Originally Posted by markkram

Here is a great little macro for converting degrees to radians:

#define degreesToRadians(x) (M_PI * (x) / 180.0)

which you can use like :

myView.transform = CGAffineTransformMakeRotation(degreesToRadians(90) );

#define degreesToRadians(x) ((x) * (M_PI / 180.0))

is twice as efficient because the compiler will figure the division at compile time.

[mikelowe]

	
angle = angle+.11;
ball.center = CGPointMake(ball.center.x + cos(angle) * 7 , ball.center.y + sin (angle) * 7);

This got a UIImageView moving in a circle for me.