ios - 从当前比例捏/缩放

Posted 2023-03-13

【中文标题】ios - 从当前比例捏/缩放

【英文标题】：ios - Pinch/zoom from current scale

【发布时间】：2012-05-28 06:02:22

【问题描述】：

以下代码正确地捏合/缩放容器视图，但仅在它跳转到 1.0 的比例之后。如何修改它以使容器视图从当前比例缩放？

UIPinchGestureRecognizer *twoFingerPinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingerPinch:)];
[self.container addGestureRecognizer:twoFingerPinch];

- (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer 

    _scale = recognizer.scale;
    CGAffineTransform tr = CGAffineTransformScale(self.view.transform, _scale, _scale);
    self.container.transform = tr;

【问题讨论】：

您的问题解决了吗？如果是，请分享代码。

【参考方案1】：

在.h文件中，添加：

CGFloat _lastScale;

在.m文件中，

- (id)init  
    ...
    _lastScale = 1.0f;
    ...


- (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer 

    if (recognizer.state == UIGestureRecognizerStateEnded)  
        _lastScale = 1.0f;
        return;
    

    CGFloat scale = 1.0f - (_lastScale - recognizer.scale);
    CGAffineTransform tr = CGAffineTransformScale(self.view.transform, scale, scale);
    self.container.transform = tr;

    _lastScale = recognizer.scale;

【讨论】：

_lastScale 和识别器.scale 总是几乎相同，所以比例总是非常接近 1.0，所以视图几乎不会放大或缩小。

【参考方案2】：

我是这样做的：

- (void)handlePinchGesture:(UIPinchGestureRecognizer *)recognizer 

    static float initialDifference = 0.0;
    static float oldScale = 1.0;

    if (recognizer.state == UIGestureRecognizerStateBegan)
        initialDifference = oldScale - recognizer.scale;
    

    CGFloat scale = oldScale - (oldScale - recognizer.scale) + initialDifference;

    myView.transform = CGAffineTransformScale(self.view.transform, scale, scale);

    oldScale = scale;    

【讨论】：

这需要更多编码才能缩小。