在父UIView中移动UIView(UIPanGestureRecognizer)

Question

我使用以下代码移动UIView内部存在的UIImageView.

- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer {

CGPoint translation = [recognizer translationInView:self.view];
recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
                                     recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];

}

我想这样做,以便UIView不会移动到父视图之外.在那一刻,图像视图能够在整个屏幕上移动.

Answer 1

首先获取你的新框架UIImageView并检查它是否完全在其superView使用CGRectContainsRect()方法中.如果是,则将UImageView's帧设置为新帧.

- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer {

    CGPoint translation = [recognizer translationInView:self.view];
    CGRect recognizerFrame = recognizer.view.frame;
    recognizerFrame.origin.x += translation.x;
    recognizerFrame.origin.y += translation.y; 

    // Check if UIImageView is completely inside its superView
    if (CGRectContainsRect(self.view.bounds, recognizerFrame)) {
        recognizer.view.frame = recognizerFrame;
    }
    // Else check if UIImageView is vertically and/or horizontally outside of its
    // superView. If yes, then set UImageView's frame accordingly.
    // This is required so that when user pans rapidly then it provides smooth translation.
    else {
        // Check vertically
        if (recognizerFrame.origin.y < self.view.bounds.origin.y) {
            recognizerFrame.origin.y = 0;
        }        
        else if (recognizerFrame.origin.y + recognizerFrame.size.height > self.view.bounds.size.height) {
            recognizerFrame.origin.y = self.view.bounds.size.height - recognizerFrame.size.height;
        }

        // Check horizantally
        if (recognizerFrame.origin.x < self.view.bounds.origin.x) {
            recognizerFrame.origin.x = 0;
        }
        else if (recognizerFrame.origin.x + recognizerFrame.size.width > self.view.bounds.size.width) {
            recognizerFrame.origin.x = self.view.bounds.size.width - recognizerFrame.size.width;
        }
    }

    // Reset translation so that on next pan recognition
    // we get correct translation value
    [recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}

请确保你通过bounds上海华和frame中UIImageView,使两者CGRects在同一坐标系.

Answer 2

试试:

- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer 
{
    if (gesture.state==UIGestureRecognizerStateChanged || gesture.state == UIGestureRecognizerStateEnded){
        UIView *superview = recognizer.view.superview;
        CGSize superviewSize = superview.bounds.size;
        CGSize thisSize = recognizer.view.size;
        CGPoint translation = [recognizer translationInView:self.view];
        CGPoint center = CGPointMake(recognizer.view.center.x + translation.x,
                                 recognizer.view.center.y + translation.y);

        CGPoint resetTranslation = CGPointMake(translation.x, translation.y);

        if(center.x - thisSize.width/2 < 0)
            center.x = thisSize.width/2;
        else if (center.x + thisSize.width/2 > superviewSize.width)
            center.x = superviewSize.width-thisSize.width/2;
        else
            resetTranslation.x = 0; //Only reset the horizontal translation if the view *did* translate horizontally

        if(center.y - thisSize.height/2 < 0)
            center.y = thisSize.height/2;
        else if(center.y + thisSize.height/2 > superviewSize.height)
            center.y = superviewSize.height-thisSize.height/2;
        else
            resetTranslation.y = 0; //Only reset the vertical translation if the view *did* translate vertically

        recognizer.view.center = center;
        [recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
    }
}

这样它就不会移动到父视图边界之外,如果你试图将它移出边界,它就会"粘住"到边缘!

Answer 3

快速版 micantox 答案

let gesture = UIPanGestureRecognizer(target: self, action: #selector(self.wasDragged(gestureRecognizer:)))
imageView.addGestureRecognizer(gesture)
imageView.isUserInteractionEnabled = true

@objc func wasDragged(gestureRecognizer: UIPanGestureRecognizer) {
if gestureRecognizer.state == UIGestureRecognizerState.changed || gestureRecognizer.state == UIGestureRecognizerState.ended {
   let superview = gestureRecognizer.view?.superview
   let superviewSize = superview?.bounds.size
   let thisSize = gestureRecognizer.view?.frame.size
   let translation = gestureRecognizer.translation(in: self.view)
   var center = CGPoint(x: gestureRecognizer.view!.center.x + translation.x, y: gestureRecognizer.view!.center.y + translation.y)
   var resetTranslation = CGPoint(x: translation.x, y: translation.y)

   if center.x - (thisSize?.width)!/2 < 0 {
       center.x = (thisSize?.width)!/2
       } else if center.x + (thisSize?.width)!/2 > (superviewSize?.width)! {
       center.x = (superviewSize?.width)!-(thisSize?.width)!/2
       } else {
         resetTranslation.x = 0 //Only reset the horizontal translation if the view *did* translate horizontally
       }

   if center.y - (thisSize?.height)!/2 < 0 {
       center.y = (thisSize?.height)!/2
      } else if center.y + (thisSize?.height)!/2 > (superviewSize?.height)! {
       center.y = (superviewSize?.height)!-(thisSize?.height)!/2
      } else {
        resetTranslation.y = 0 //Only reset the vertical translation if the view *did* translate vertically
      }

      gestureRecognizer.view?.center = center
      gestureRecognizer.setTranslation(CGPoint(x: 0, y: 0), in: self.view)
    } 
}