使用捏合手势时，uiview 的边界是不是会发生变化？

Posted 2023-03-13

【中文标题】使用捏合手势时，uiview 的边界是不是会发生变化？

【英文标题】：Does the bounds of a uiview change when a pinch gesture is used on it?使用捏合手势时，uiview 的边界是否会发生变化？

【发布时间】：2011-08-30 11:30:13

【问题描述】：

我正在使用 UIPinchGestureRecognizer 来扩展/缩小 uiview。

UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scaleElement:)];
[pinchGesture setDelegate:self];
[element addGestureRecognizer:pinchGesture];
[pinchGesture release];

//缩放元素方法

- (void)scaleElement:(UIPinchGestureRecognizer *)gestureRecognizer 
    UIView *element = [gestureRecognizer view];
    [self adjustAnchorPointForGestureRecognizer:gestureRecognizer];
    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan)
        lastTouchPosition = [gestureRecognizer locationInView:element];
     
    else if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged)
            CGPoint currentTouchPosition = [gestureRecognizer locationInView:element];
            CGPoint deltaMove = [self calculatePointDistancewithPoint1:currentTouchPosition andPoint2:lastTouchPosition];
            float distance = sqrt(deltaMove.x*deltaMove.x + deltaMove.y*deltaMove.y);
            float hScale = 1 - deltaMove.x/distance * (1-gestureRecognizer.scale);
            float vScale = 1 - deltaMove.y/distance * (1-gestureRecognizer.scale);
            if (distance == 0) 
                hScale = 1;
                vScale = 1;
            
            element.transform = CGAffineTransformScale([element transform], hScale, vScale);
            CGAffineTransform transform = CGAffineTransformMakeScale(hScale, vScale);
            element.bounds = CGRectApplyAffineTransform(element.bounds, transform);
                [gestureRecognizer setScale:1];
                lastTouchPosition = currentTouchPosition;
            
            if ([gestureRecognizer state] == UIGestureRecognizerStateEnded) 
                NSLog(@"scaling over");
                NSLog(@"bounds = %@",NSStringFromCGRect(element.bounds));
                NSLog(@"frame = %@", NSStringFromCGRect(element.frame));
            
            NSLog(@"scalePiece exit");
    

//adjustAnchorPointForGestureRecognizer method

    - (void)adjustAnchorPointForGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer 
        if (gestureRecognizer.state == UIGestureRecognizerStateBegan) 
            UIView *elementToAdjust = gestureRecognizer.view;
            [self.view bringSubviewToFront:gestureRecognizer.view];
            CGPoint locationInView = [gestureRecognizer locationInView:elementToAdjust];
            CGPoint locationInSuperview = [gestureRecognizer locationInView:elementToAdjust.superview];
            elementToAdjust.layer.anchorPoint = CGPointMake(locationInView.x / elementToAdjust.bounds.size.width, locationInView.y / elementToAdjust.bounds.size.height);
            elementToAdjust.center = locationInSuperview;
        
    

控制台打印：

bounds = 0, 0, 178.405, 179.018
frame = 300.642, 566.184, 192.899, 194.227

为什么当框架改变时边界没有调整？ 由于我对此视图有子视图，因此它与自动调整蒙版大小有关吗？

【参考方案1】：

这与UIPinchGestureRecognizer 无关。这与您设置 transform 以执行缩放有关。更改 transform 不会更改 bounds。它只是改变了这个视图的坐标空间（bounds）如何映射到父视图的坐标空间（frame）。如果你需要bounds匹配frame，你必须直接更改其中一个，而不是使用transform。也就是说，您通常应该使用transform，因为它更快。

编辑

如果您不是要缩放，而是要调整视图大小，请致电setBounds:。您可以通过将转换应用于bounds 而不是元素来找到新的bounds。

CGPoint currentTouchPosition = [gestureRecognizer locationInView:element];
CGPoint deltaMove = [self calculatePointDistancewithPoint1:currentTouchPosition andPoint2:lastTouchPosition];
...

CGAffineTransform transform = CGAffineTransformMakeScale(hScale, vScale);
self.bounds = CGRectApplyAffineTransform(self.bounds, transform);

【讨论】：

那么你建议我如何改变视图的边界？

gestureRecognizer 没有属性转换。你的意思是 [gestureRecognizer view].transform 吗？

CGAffineTransformMakeScale()。固定。

抱歉回复晚了。这样做之后，框架和边界仍然不一样。我正在更新问题。请仔细查看。

您仍在设置element.transform。如果您还设置了bounds，则不应该这样做。