How to resize the UIView when CGAffineTransformIdentity

Question

I am doing an app which has a feature to rotate and re size a view. i have implemented this feature but i do face an issue.

My problem

The View wil be resized when dragging its four corners, after resizing it i can rotate the view in both directions.

Once the rotation is done, if i try again to resize the view by dragging its corner, the view's size gone to unpredictable value and its moving all around the screen.

I googled lot finally i got the following solution

The frame property is undefined when transform != CGAffineTransformIdentity, as per the docs on UIView

I saw one app which has implemented the feature exactly what i wish to implement.

How can i resize the UIView after rotation of UIView

My code for resize the view

Touches Began

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{

   UITouch *touch = [[event allTouches] anyObject];

   NSLog(@"[touch view]:::%@",[touch view]);

   touchStart = [[touches anyObject] locationInView:testVw];
   isResizingLR = (testVw.bounds.size.width - touchStart.x < kResizeThumbSize &&     testVw.bounds.size.height - touchStart.y < kResizeThumbSize);
   isResizingUL = (touchStart.x <kResizeThumbSize && touchStart.y <kResizeThumbSize);
   isResizingUR = (testVw.bounds.size.width-touchStart.x < kResizeThumbSize &&      touchStart.y<kResizeThumbSize);
   isResizingLL = (touchStart.x <kResizeThumbSize && testVw.bounds.size.height -touchStart.y <kResizeThumbSize);    
}

Touches Moved

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
CGPoint touchPoint = [[touches anyObject] locationInView:testVw];
CGPoint previous=[[touches anyObject]previousLocationInView:testVw];

float  deltaWidth = touchPoint.x-previous.x;
float  deltaHeight = touchPoint.y-previous.y;

NSLog(@"CVTM:%@",NSStringFromCGRect(testVw.frame));


if (isResizingLR) {
 testVw.frame = CGRectMake(testVw.frame.origin.x, testVw.frame.origin.y,touchPoint.x +   deltaWidth, touchPoint.y + deltaWidth);
 }  
if (isResizingUL) {
 testVw.frame = CGRectMake(testVw.frame.origin.x + deltaWidth, testVw.frame.origin.y +  deltaHeight, testVw.frame.size.width - deltaWidth, testVw.frame.size.height - deltaHeight);
 } 
if (isResizingUR) {
  testVw.frame = CGRectMake(testVw.frame.origin.x ,testVw.frame.origin.y + deltaHeight,  testVw.frame.size.width + deltaWidth, testVw.frame.size.height - deltaHeight);      
 } 
if (isResizingLL) {
 testVw.frame = CGRectMake(testVw.frame.origin.x + deltaWidth ,testVw.frame.origin.y ,  testVw.frame.size.width - deltaWidth, testVw.frame.size.height + deltaHeight);   
}

if (!isResizingUL && !isResizingLR && !isResizingUR && !isResizingLL) {
testVw.center = CGPointMake(testVw.center.x + touchPoint.x - touchStart.x,testVw.center.y + touchPoint.y - touchStart.y);
 }

 }

I have exact same problem and I am wondering if there is any solution to this. If so, please post. — Vad

Matic Oblak Matic Oblak · Accepted Answer · 2012-10-01T11:49:15

Since you don't use UIView animations you can save current view's transform, set view's transform to identity, resize the view and reapply saved transform:

UIView *v;
CGAffineTransform t = v.transform;
v.transform = CGAffineTransformIdentity;
CGFloat scale = 2.0f;
v.frame = CGRectMake(v.frame.origin.x, v.frame.origin.y, v.frame.size.width*scale , v.frame.size.height*scale);
v.transform = t;

(EDIT)About your resizing:

If you define your rectangle with 4 vectors (points) A,B,C,D where (A+C)*.5 = (B+D)*.5 = rectangle_center Then for moving point C to position C' would also move B and D to B' and D':

A' = A
C' = C' //touch input
B' = A + (normalized(B-A) * dotProduct((C'-A), normalized(B-A)))
D' = A + (normalized(D-A) * dotProduct((C'-A), normalized(D-A)))

After that:

transform your view to identity
set frame to (.0f, .0f, length(A-D), length(A-C))
set center to (A+D)*.5f
get rotation to create view's transform through atanf(height/width) and few "if's" OR fill/create transform with base vectors that are normalized(D-A) and normalized(B-A)

You can do that for any point in a rectangle.

How to resize the UIView when CGAffineTransformIdentity

1 Answers