如何在iPhone WWDC 2010-104 PhotoScroller上通过双击进行照片缩放

Question

如何在iPhone WWDC 2010-104 PhotoScroller上通过双击进行照片缩放

iphoneuiscrollviewuitouchtouchesbeganwwdc

44

我正在研究iPhone WWDC 2010 - 104 PhotoScroller应用程序的示例代码。它与我的项目相关图像（PDF页面图像）很好地配合使用。

但是我正在努力在PhotoScroller App中检测触摸。使用多点触摸进行缩放由ScrollVoiew处理。现在我想双击放大/缩小照片。Touchesbegan方法在TilingView类中被调用。然后我使用[super touchesbegan：withevent：]，现在触摸事件在ImageScrollView类中。

如何在PhotoViewController中获取这些触摸事件？如何通过触摸实现缩放？

有人能帮忙吗？

- Roger_iPhone

你不应该已经接受一个回答吗？ - Radu Simionescu

14个回答

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- richy · Answer 1

在点击位置放大

CGFloat scale = 3.0;
CGFloat scale = ScaleToAspectFitRectAroundRect(frame, self.bounds) * 2.0;

CGRect zoomRect;
CGPoint point = [gestureRecognizer locationOfTouch:0 inView:[gestureRecognizer view]];

zoomRect.size.height = frame.size.height * scale;
zoomRect.size.width  = frame.size.width  * scale;

zoomRect.origin.x = CGRectGetMidX(frame) - (CGRectGetWidth(zoomRect)/2) + (scale * (CGRectGetWidth(frame)/2 - point.x)) - (CGRectGetWidth(frame)/2 - point.x);
zoomRect.origin.y = CGRectGetMidY(frame) - (CGRectGetHeight(zoomRect)/2) + (scale * (CGRectGetHeight(frame)/2 - point.y)) - (CGRectGetHeight(frame)/2 - point.y);

- Alex Terente · Answer 2

继承UIScrollView，然后在.m文件中添加

#pragma mark -
#pragma mark doubleTouch

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    NSUInteger tapCount = [touch tapCount];
    switch (tapCount) {
        case 2:
        {
            if(self.zoomScale <1.0){
                [self setZoomScale:1.0 animated:YES];
            }else{
                [self setZoomScale:0.1 animated:YES];
            }

            break;
        }
        default:
            break;
    }
}

- jjrscott · Answer 3

这似乎可以使用convertRect:fromView:和zoomToRect:animated:来实现：

-(void)tap:(UITapGestureRecognizer *)tapGestureRecognizer
{
    CGFloat zoomeScaleMultiplier = 0.5;
    UIScrollView *scrollView = (UIScrollView *) tapGestureRecognizer.view;
    UIView *zoomableView = [scrollView.delegate viewForZoomingInScrollView:scrollView];

    CGRect rect = scrollView.bounds;
    rect.origin = CGPointZero;

    CGAffineTransform transform = CGAffineTransformMakeScale(zoomeScaleMultiplier, zoomeScaleMultiplier);
    rect = CGRectApplyAffineTransform(rect, transform);

    rect.origin = [tapGestureRecognizer locationInView:scrollView];

    rect = CGRectOffset(rect, CGRectGetWidth(rect)/-2., CGRectGetHeight(rect)/-2.);

    rect = [zoomableView convertRect:rect fromView:scrollView];

    [scrollView zoomToRect:rect animated:YES];
}

- Ha cong Thuan · Answer 4

这里是我的代码，对我来说很简单：

// Listen for Double Tap Zoom
UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];

[doubleTap setNumberOfTapsRequired:2];

[self addGestureRecognizer:doubleTap];

你需要

BOOL checkZoomImage;

这里是tab方法

- (void)handleDoubleTap:(UIGestureRecognizer *)gestureRecognizer {

    if (self.zoomScale > self.minimumZoomScale && self.zoomScale == self.maximumZoomScale){
        checkZoomImage = YES;
    }
    if (self.zoomScale < self.maximumZoomScale && self.zoomScale == self.minimumZoomScale) {
        checkZoomImage = NO;
    }


    if (checkZoomImage) {
        [self setZoomScale:self.zoomScale *0.5 animated:YES];
    }else{
        [self setZoomScale:self.zoomScale *1.5 animated:YES];
    }

}