UIImageView Rotation and zooming in iPhone Sdk

Question

i'm implementing zooming and rotation using UIImageview in my project, i'm facing problem in zoom in and zoom out after rotating the image,

Here is my code follows:

in .h file

@interface ViewController : UIViewController{
 float degrees;
 float height;
 float width;

float moveLeft;
float moveRight;
}

@property(nonatomic,retain)UIImageView *imageView;

-(IBAction)rotationLeft:(id)sender;
-(IBAction)rotationRight:(id)sender;
-(IBAction)zoomIn:(id)sender;
-(IBAction)zoomOut:(id)sender;

-(IBAction)moveLeft:(id)sender;
-(IBAction)moveRight:(id)sender;

in .m file

- (void)viewDidLoad
{
[super viewDidLoad];



height=50;
width=50;
degrees=20;
moveLeft=20;
moveRight=20;
imageView=[[UIImageView alloc]initWithImage:[UIImage imageNamed:@"1.png"]];
imageView.frame=CGRectMake(100, 100,width, height);
[self.view addSubview:imageView];



// Do any additional setup after loading the view, typically from a nib.
}
-(IBAction)rotationLeft:(id)sender{
//the value in degrees
imageView.transform = CGAffineTransformMakeRotation(degrees*M_PI/180);
degrees=degrees+25;
}

-(IBAction)rotationRight:(id)sender{
//the value in degrees
degrees=degrees-25;
imageView.transform = CGAffineTransformMakeRotation(degrees*M_PI/180);

}
-(IBAction)zoomIn:(id)sender{
height=height-15;
width=width-15;
imageView.frame=CGRectMake(100, 100,width, height);
}
-(IBAction)zoomOut:(id)sender{
height=height+15;
width=width+15;
imageView.frame=CGRectMake(100, 100,width, height);
}

Please find the attached image for your reference. enter image description here

its zooming but image is stretching like given reference image. — VSN, Jul 19 '12 at 11:01

score 1 · Answer 1 · answered Jul 19 '12 at 11:05

1

you should use CGAffineTransformMakeScale for zooming purposes, instead of forcing the frame.

define somewhere a global foal x = 1; then:

-(IBAction)zoomIn:(id)sender{
   x += 0.3;
   imageView.transform = CGAffineTransformMakeScale(x, x);
}

-(IBAction)zoomOut:(id)sender{
   x -= 0.3;
   imageView.transform = CGAffineTransformMakeScale(x, x);
}

answered Jul 19 '12 at 11:05

John Smith

2,012
1
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33

And play a little with that "0.3" value to gain the desired zooming factor. – John Smith Jul 19 '12 at 11:09
Teodor, it should be work zooming while rotating the image also... Here is the scenario... if i click zoomin and zoomout methods its working fine... after some time when i call rotation function, the image position is coming to normal instead of rotation position. – VSN Jul 19 '12 at 11:34
Perhaps you reset somewhere the "degrees" value. Make sure it is not reset, and also, make sure to keep it always between zero and 360 ( like if degree is more than 360 then degree = zero , and viceversa if it is less than zero, then degree = 360) – John Smith Jul 19 '12 at 12:45

score 1 · Answer 2 · answered Jul 19 '12 at 11:06

1

I would recommend scaling the image using a very similar method to the rotation code that you have:

CGAffineTransformMakeScale(CGFloat sx, CGFloat sy);

Just send it more than 1.0 to scale up and less than 1.0 to scale down;

answered Jul 19 '12 at 11:06

Mazyod

22,319
10
92
157

score 1 · Accepted Answer · answered Jul 20 '12 at 06:17

Below code worked for me perfect!!!

-(IBAction)rotationLeft:(id)sender{
//the value in degrees
    degrees=degrees+25;
    CGAffineTransform t;
    t=CGAffineTransformMakeScale(x, x);
    // imageView.transform = CGAffineTransformMakeRotation(degrees*M_PI/180,x,x);
    imageView.transform=CGAffineTransformRotate(t, degrees*M_PI/180);
}

-(IBAction)rotationRight:(id)sender{
    degrees=degrees-25;
    CGAffineTransform t;
    t=CGAffineTransformMakeScale(x, x);
    imageView.transform=CGAffineTransformRotate(t, degrees*M_PI/180);

 }
 -(IBAction)zoomIn:(id)sender{
    x += 0.3;
    CGAffineTransform t;
    t=CGAffineTransformMakeRotation(degrees*M_PI/180);
    imageView.transform=CGAffineTransformScale(t, x, x);
 }

 -(IBAction)zoomOut:(id)sender{
     x -= 0.3;
    CGAffineTransform t;
    t=CGAffineTransformMakeRotation(degrees*M_PI/180);
    imageView.transform=CGAffineTransformScale(t, x, x);
 }

UIImageView Rotation and zooming in iPhone Sdk

3 Answers3