当在 uiview 上使用捏合手势时，它的边界会改变吗？

Question

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}}

为什么框架改变时边界没有调整？ 它与自动调整蒙版大小有什么关系，因为我有此视图的子视图？

Answer 1

这与UIPinchGestureRecognizer无关。这与您设置 transform 以执行缩放有关。更改变换不会更改边界。它只是更改此视图的坐标空间 (bounds) 映射到父视图的坐标空间 (frame) 的方式。如果您需要bounds来匹配frame，则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 因为它要快得多。

编辑

如果您不想缩放，而是想调整视图大小，请调用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);