使用手势对UIImageView进行缩放、旋转和移动(转)

原文地址：http://blog.csdn.net/crazy_frog/article/details/8664108

// 添加所有的手势
- (void) addGestureRecognizerToView:(UIView *)view
{
    // 旋转手势
    UIRotationGestureRecognizer *rotationGestureRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotateView:)];
    [view addGestureRecognizer:rotationGestureRecognizer];
    
    // 缩放手势
    UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchView:)];
    [view addGestureRecognizer:pinchGestureRecognizer];
    
    // 移动手势
    UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panView:)];
    [view addGestureRecognizer:panGestureRecognizer];
}

// 处理旋转手势
- (void) rotateView:(UIRotationGestureRecognizer *)rotationGestureRecognizer
{
    UIView *view = rotationGestureRecognizer.view;
    if (rotationGestureRecognizer.state == UIGestureRecognizerStateBegan || rotationGestureRecognizer.state == UIGestureRecognizerStateChanged) {
        view.transform = CGAffineTransformRotate(view.transform, rotationGestureRecognizer.rotation);
        [rotationGestureRecognizer setRotation:0];
    }
}

// 处理缩放手势
- (void) pinchView:(UIPinchGestureRecognizer *)pinchGestureRecognizer
{
    UIView *view = pinchGestureRecognizer.view;
    if (pinchGestureRecognizer.state == UIGestureRecognizerStateBegan || pinchGestureRecognizer.state == UIGestureRecognizerStateChanged) {
        view.transform = CGAffineTransformScale(view.transform, pinchGestureRecognizer.scale, pinchGestureRecognizer.scale);
        pinchGestureRecognizer.scale = 1;
    }
}

// 处理拖拉手势
- (void) panView:(UIPanGestureRecognizer *)panGestureRecognizer
{
    UIView *view = panGestureRecognizer.view;
    if (panGestureRecognizer.state == UIGestureRecognizerStateBegan || panGestureRecognizer.state == UIGestureRecognizerStateChanged) {
        CGPoint translation = [panGestureRecognizer translationInView:view.superview];
        [view setCenter:(CGPoint){view.center.x + translation.x, view.center.y + translation.y}];
        [panGestureRecognizer setTranslation:CGPointZero inView:view.superview];
    }
}

这样只需要简单调用

[self addGestureRecognizerToView:view];  
 
//如果处理的是图片，别忘了
[imageView setUserInteractionEnabled:YES];  
[imageView setMultipleTouchEnabled:YES]; 

具体使用一下：

在.h文件里边定义变量

@interface YourViewController : UIViewController<UIGestureRecognizerDelegate>
{
    CGFloat lastScale;
    CGRect oldFrame;    //保存图片原来的大小
    CGRect largeFrame;  //确定图片放大最大的程度
}

然后在viewDidLoad里面加上

- (void)viewDidLoad
{
    [super viewDidLoad];

    showImgView = [[UIImageView alloc] initWithFrame:<span class="s1">CGRectMake</span>(<span class="s2">0</span>, <span class="s2">0</span>, 320, 480)];
    [showImgView setMultipleTouchEnabled:YES];
    [showImgView setUserInteractionEnabled:YES];
    [showImgView setImage:[UIImage imageNamed:@"1.jpg"]];
    
    oldFrame = showImgView.frame;
    largeFrame = CGRectMake(0 - screenSize.width, 0 - screenSize.height, 3 * oldFrame.size.width, 3 * oldFrame.size.height);
    
    [self addGestureRecognizerToView:showImgView];
    [self.view addSubview:showImgView];

这样就实现了

但是，这样是不够的。

因为里边的缩放和移动等没有做相应的判断。

因为代码很简洁，所以扩展也非常方便。

我修改了缩放的代码，增加了限制，其他的类似

// 处理缩放手势
- (void) pinchView:(UIPinchGestureRecognizer *)pinchGestureRecognizer
{
    UIView *view = pinchGestureRecognizer.view;
    if (pinchGestureRecognizer.state == UIGestureRecognizerStateBegan || pinchGestureRecognizer.state == UIGestureRecognizerStateChanged) {
        view.transform = CGAffineTransformScale(view.transform, pinchGestureRecognizer.scale, pinchGestureRecognizer.scale);
        if (showImgView.frame.size.width < oldFrame.size.width) {
            showImgView.frame = oldFrame;
            //让图片无法缩得比原图小
        }
        if (showImgView.frame.size.width > 3 * oldFrame.size.width) {
            showImgView.frame = largeFrame;
        }
        pinchGestureRecognizer.scale = 1;
    }
}

这样就保证了图片的最大和最小比例。