ios - 使用UIPinchGestureRecognizer可以在收缩的方向上缩放 View

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我需要一个可以在x或y或两个方向缩放的Pinch识别器，具体取决于收缩的方向。我在这里浏览了许多其他问题，而这些问题只包含部分答案。这是我使用自定义UIPinchGestureRecognizer的完整解决方案。

最佳答案

我创建了UIPinchGestureRecognizer的自定义版本。它使用两个手指之间的线的斜率来确定刻度的方向。它有3种类型:垂直；水平；和组合(对角线)。请在底部查看我的笔记。

-(void) scaleTheView:(UIPinchGestureRecognizer *)pinchRecognizer
{
if ([pinchRecognizer state] == UIGestureRecognizerStateBegan || [pinchRecognizer state] == UIGestureRecognizerStateChanged) {

if ([pinchRecognizer numberOfTouches] > 1) {

    UIView *theView = [pinchRecognizer view];

    CGPoint locationOne = [pinchRecognizer locationOfTouch:0 inView:theView];
    CGPoint locationTwo = [pinchRecognizer locationOfTouch:1 inView:theView];
        NSLog(@"touch ONE  = %f, %f", locationOne.x, locationOne.y);
        NSLog(@"touch TWO  = %f, %f", locationTwo.x, locationTwo.y);
    [scalableView setBackgroundColor:[UIColor redColor]];

    if (locationOne.x == locationTwo.x) {
            // perfect vertical line
            // not likely, but to avoid dividing by 0 in the slope equation
        theSlope = 1000.0;
    }else if (locationOne.y == locationTwo.y) {
            // perfect horz line
            // not likely, but to avoid any problems in the slope equation
        theSlope = 0.0;
    }else {
        theSlope = (locationTwo.y - locationOne.y)/(locationTwo.x - locationOne.x);
    }

    double abSlope = ABS(theSlope);

    if (abSlope < 0.5) {
                //  Horizontal pinch - scale in the X
        [arrows setImage:[UIImage imageNamed:@"HorzArrows.png"]];
        arrows.hidden = FALSE;
                // tranform.a  = X-axis
            NSLog(@"transform.A = %f", scalableView.transform.a);
                // tranform.d  = Y-axis
            NSLog(@"transform.D = %f", scalableView.transform.d);

                //  if hit scale limit along X-axis then stop scale and show Blocked image
        if (((pinchRecognizer.scale > 1.0) && (scalableView.transform.a >= 2.0)) || ((pinchRecognizer.scale < 1.0) && (scalableView.transform.a <= 0.1))) {
            blocked.hidden = FALSE;
            arrows.hidden = TRUE;
        } else {
                    // scale along X-axis
            scalableView.transform = CGAffineTransformScale(scalableView.transform, pinchRecognizer.scale, 1.0);
            pinchRecognizer.scale = 1.0;
            blocked.hidden = TRUE;
            arrows.hidden = FALSE;
        }
    }else if (abSlope > 1.7) {
                // Vertical pinch - scale in the Y
        [arrows setImage:[UIImage imageNamed:@"VerticalArrows.png"]];
        arrows.hidden = FALSE;
            NSLog(@"transform.A = %f", scalableView.transform.a);
            NSLog(@"transform.D = %f", scalableView.transform.d);

                //  if hit scale limit along Y-axis then don't scale and show Blocked image
        if (((pinchRecognizer.scale > 1.0) && (scalableView.transform.d >= 2.0)) || ((pinchRecognizer.scale < 1.0) && (scalableView.transform.d <= 0.1))) {
            blocked.hidden = FALSE;
            arrows.hidden = TRUE;
        } else {
                    // scale along Y-axis
            scalableView.transform = CGAffineTransformScale(scalableView.transform, 1.0, pinchRecognizer.scale);
            pinchRecognizer.scale = 1.0;
            blocked.hidden = TRUE;
            arrows.hidden = FALSE;
        }
    } else {
                // Diagonal pinch - scale in both directions
        [arrows setImage:[UIImage imageNamed:@"CrossArrows.png"]];
        blocked.hidden = TRUE;
        arrows.hidden = FALSE;

            NSLog(@"transform.A = %f", scalableView.transform.a);
            NSLog(@"transform.D = %f", scalableView.transform.d);

                // if we have hit any limit don't allow scaling
        if ((((pinchRecognizer.scale > 1.0) && (scalableView.transform.a >= 2.0)) || ((pinchRecognizer.scale < 1.0) && (scalableView.transform.a <= 0.1))) || (((pinchRecognizer.scale > 1.0) && (scalableView.transform.d >= 2.0)) || ((pinchRecognizer.scale < 1.0) && (scalableView.transform.d <= 0.1)))) {
            blocked.hidden = FALSE;
            arrows.hidden = TRUE;
        } else {
                    // scale in both directions
            scalableView.transform = CGAffineTransformScale(scalableView.transform, pinchRecognizer.scale, pinchRecognizer.scale);
            pinchRecognizer.scale = 1.0;
            blocked.hidden = TRUE;
            arrows.hidden = FALSE;
        }
    }  // else for diagonal pinch
}  // if numberOfTouches
}  // StateBegan if

if ([pinchRecognizer state] == UIGestureRecognizerStateEnded || [pinchRecognizer state] == UIGestureRecognizerStateCancelled) {
NSLog(@"StateEnded StateCancelled");
[scalableView setBackgroundColor:[UIColor whiteColor]];
arrows.hidden = TRUE;
blocked.hidden = TRUE;
}
}

记住将协议添加到视图控制器头文件中:

@interface WhiteViewController : UIViewController <UIGestureRecognizerDelegate>
{
IBOutlet UIView *scalableView;
IBOutlet UIView *mainView;
IBOutlet UIImageView *arrows;
IBOutlet UIImageView *blocked;
}
@property (strong, nonatomic) IBOutlet UIView *scalableView;
@property (strong, nonatomic) IBOutlet UIView *mainView;
@property (strong, nonatomic)IBOutlet UIImageView *arrows;
@property (strong, nonatomic)IBOutlet UIImageView *blocked;

-(void) scaleTheView:(UIPinchGestureRecognizer *)pinchRecognizer;
@end

并在viewDidLoad中添加识别器:

- (void)viewDidLoad
{
UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scaleTheView:)];
[pinchGesture setDelegate:self];
[mainView addGestureRecognizer:pinchGesture];
arrows.hidden = TRUE;
blocked.hidden = TRUE;
[scalableView setBackgroundColor:[UIColor whiteColor]];
}

设置为使用主视图来捕获夹点；并操纵第二个视图。这样，您仍然可以在视图变小时对其进行缩放。您可以更改它以直接对可伸缩视图做出反应。

限制:我任意选择了视图的起始大小，因此2.0的比例限制将等于全屏显示。我的小数位数设置为0.1。

用户交互:我搞砸了很多用户交互操作，例如更改视图的背景颜色以及在视图上添加/更改箭头以显示方向。在缩放过程中给他们反馈很重要，尤其是在更改此代码允许的方向时。

BUG:苹果的UIPinchGestureRecognizer中有一个错误。如您所料，它会用两根手指注册UIGestureRecognizerStateBegan。但是一旦它处于StateBegan或StateChanged中，您就可以举起一根手指而状态保持不变。在两个手指都松开之前，它不会移到StateEnded或StateCancelled。这在我的代码中创建了一个错误，并且令人头疼! if numberOfTouches> 1可以解决此问题。

future :您可以更改坡度设置以仅在一个方向或2个方向上缩放。如果添加箭头图像，则可以看到它们随着旋转手指而发生变化。

关于ios - 使用UIPinchGestureRecognizer可以在收缩的方向上缩放 View ，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/18048581/