iOS 捏合比例和两个手指同时旋转

问题描述

这是我的代码:

viewDidLoad:

viewDidLoad:

UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinch:)];
[self.canvas addGestureRecognizer:pinch];
pinch.delegate = self;

UIRotationGestureRecognizer *twoFingersRotate = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(pinchRotate:)];
[[self canvas] addGestureRecognizer:twoFingersRotate];

twoFingersRotate.delegate = self;

收缩和旋转代码:

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

-(void)pinchRotate:(UIRotationGestureRecognizer*)rotate
{
    SMImage *selectedImage = [DataCenter sharedDataCenter].selectedImage;

    switch (rotate.state)
    {
        case UIGestureRecognizerStateBegan:
        {
            selectedImage.referenceTransform = selectedImage.transform;
            break;
        }
        case UIGestureRecognizerStateChanged:
        {
            selectedImage.transform = CGAffineTransformRotate(selectedImage.referenceTransform, ([rotate rotation] * 55) * M_PI/180);
            break;
        }

        default:
            break;
    }
}

-(void)pinch:(UIPinchGestureRecognizer*)pinch
{
    SMImage *selectedImage = [DataCenter sharedDataCenter].selectedImage;
    [self itemSelected];

    switch (pinch.state)
    {
        case UIGestureRecognizerStateBegan:
        {
            selectedImage.referenceTransform = selectedImage.transform;
            break;
        }
        case UIGestureRecognizerStateChanged:
        {
            CGAffineTransform transform = CGAffineTransformScale(selectedImage.referenceTransform, pinch.scale, pinch.scale);
            selectedImage.transform = transform;
            break;
        }

        default:
            break;
    }
}

我的轮换单独工作很好，我的秤单独工作也很好，但它们不能一起工作.一个总是有效或另一个无效.当我实现 shouldRecognizeSimultaneouslyWithGestureRecognizer 时，这两个手势似乎相互对抗并产生不良结果.我错过了什么?(是的，我已经实现了 )

My rotation works great on its own and my scale works great on its own, but they wont work together. One always works or the other doesn't. When I implement shouldRecognizeSimultaneouslyWithGestureRecognizer the two gestures seem to fight against each other and produce poor results. What am I missing? (Yes I have implemented <UIGestureRecognizerDelegate>)

推荐答案

每次调用 pinch: 时，您只需根据捏合识别器的比例来计算变换.每次调用 pinchRotate: 时，您只需根据旋转识别器的旋转计算变换.您永远不会将缩放和旋转合并为一个变换.

Every time pinch: is called, you just compute the transform based on the pinch recognizer's scale. Every time pinchRotate: is called, you just compute the transform based on the rotation recognizer's rotation. You never combine the scale and the rotation into one transform.

这是一种方法.给自己一个新的实例变量，_activeRecognizers:

Here's an approach. Give yourself one new instance variable, _activeRecognizers:

NSMutableSet *_activeRecognizers;

在viewDidLoad中初始化:

_activeRecognizers = [NSMutableSet set];

使用一种方法作为两个识别器的动作:

Use one method as the action for both recognizers:

- (IBAction)handleGesture:(UIGestureRecognizer *)recognizer
{
    SMImage *selectedImage = [DataCenter sharedDataCenter].selectedImage;

    switch (recognizer.state) {
        case UIGestureRecognizerStateBegan:
            if (_activeRecognizers.count == 0)
                selectedImage.referenceTransform = selectedImage.transform;
            [_activeRecognizers addObject:recognizer];
            break;

        case UIGestureRecognizerStateEnded:
            selectedImage.referenceTransform = [self applyRecognizer:recognizer toTransform:selectedImage.referenceTransform];
            [_activeRecognizers removeObject:recognizer];
            break;

        case UIGestureRecognizerStateChanged: {
            CGAffineTransform transform = selectedImage.referenceTransform;
            for (UIGestureRecognizer *recognizer in _activeRecognizers)
                transform = [self applyRecognizer:recognizer toTransform:transform];
            selectedImage.transform = transform;
            break;
        }

        default:
            break;
    }
}

你需要这个辅助方法:

- (CGAffineTransform)applyRecognizer:(UIGestureRecognizer *)recognizer toTransform:(CGAffineTransform)transform
{
    if ([recognizer respondsToSelector:@selector(rotation)])
        return CGAffineTransformRotate(transform, [(UIRotationGestureRecognizer *)recognizer rotation]);
    else if ([recognizer respondsToSelector:@selector(scale)]) {
        CGFloat scale = [(UIPinchGestureRecognizer *)recognizer scale];
        return CGAffineTransformScale(transform, scale, scale);
    }
    else
        return transform;
}

如果您只允许旋转和缩放，这会起作用.(我什至测试过！)

This works if you're just allowing rotating and scaling. (I even tested it!)

如果要添加平移，请使用单独的操作方法，只需调整 selectedImage.center.尝试使用 selectedImage.transform 进行旋转和缩放平移要复杂得多.

If you want to add panning, use a separate action method and just adjust selectedImage.center. Trying to do panning with rotation and scaling using selectedImage.transform is much more complicated.

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