ios - 为什么平移让用户将缩放 View 移到 super View 之外？

Question

我正在研究 pdf 页面上的收缩和收缩功能。我的捏合和平移(移动)工作正常，但是当用户连续移动缩放 View 时，缩放 View 超出了 super View 边界。是这样的:

我如何限制平移移动，以便用户无法将缩放 View /pdf 移动到 super View 之外。
我使用的相关代码是:

// This method will handle the PINCH / ZOOM gesture 

- (void)pinchZoom:(UIPinchGestureRecognizer *)gestureRecognizer{

    if([gestureRecognizer state] == UIGestureRecognizerStateBegan) {
        // Reset the last scale, necessary if there are multiple objects with different scales
        lastScale = [gestureRecognizer scale];
    }
if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {

    if (!zoomActive) {
        zoomActive = YES;
        panActive = YES;
        UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panMove:)];
        [panGesture setMaximumNumberOfTouches:2];
        [panGesture setDelegate:self];
        [self addGestureRecognizer:panGesture];
        [panGesture release];

    }

            CGFloat currentScale = [[[gestureRecognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];

            // Constants to adjust the max/min values of zoom
            const CGFloat kMaxScale = 2.0;
            const CGFloat kMinScale = 1.0;

            CGFloat newScale = 1 -  (lastScale - [gestureRecognizer scale]); 
            newScale = MIN(newScale, kMaxScale / currentScale);   
            newScale = MAX(newScale, kMinScale / currentScale);
            CGAffineTransform transform = CGAffineTransformScale([[gestureRecognizer view] transform], newScale, newScale);
            [gestureRecognizer view].transform = transform;

            lastScale = [gestureRecognizer scale];  // Store the previous scale factor for the next pinch gesture call 



    [delegate leavesView:self zoomingCurrentView:[gestureRecognizer scale]];            




}

我处理平移移动的方法:

// This method will handle the PAN / MOVE gesture 
- (void)panMove:(UIPanGestureRecognizer *)gestureRecognizer  
{  
    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged)   {  
        CGPoint translation = [gestureRecognizer translationInView:[[gestureRecognizer view] superview]];  
        [[gestureRecognizer view] setCenter:CGPointMake([[gestureRecognizer view] center].x + translation.x, [[gestureRecognizer view] center].y + translation.y)];  

        [gestureRecognizer setTranslation:CGPointZero inView:[[gestureRecognizer view] superview]];  
    }  
}  

请建议如何在其父 View 范围内处理平移/移动限制平移。

Answer 1

在你的 panMove 方法中尝试这段代码。它在我的情况下工作正常。

        static CGPoint initialCenter;

        if (recognizer.state == UIGestureRecognizerStateBegan)
        {
            initialCenter = recognizer.view.center;
        }

        CGPoint translation = [recognizer translationInView:recognizer.view];
        CGPoint newCenter = CGPointMake(initialCenter.x + translation.x,
                                       initialCenter.y + translation.y);
        CGRect newFrame = recognizer.view.frame;
        CGRect superViewBounds = recognizer.view.superview.bounds;
        CGPoint superViewOrigin = recognizer.view.superview.frame.origin;

        if(newCenter.x-(newFrame.size.width/2) >= (superViewBounds.size.width+superViewOrigin.x)-200 /*right*/
           ||
           newCenter.x+(newFrame.size.width/2) <= (superViewOrigin.x+200) /*left*/
           ||
           newCenter.y-(newFrame.size.height/2) >= (superViewBounds.size.height+superViewOrigin.y)-200 /*bottom*/
            ||
            newCenter.y+(newFrame.size.height/2) <= (superViewOrigin.y+100)) /*top*/
        {
            return;
        }else{
            recognizer.view.center = newCenter;
        }