ScrollView双击图片定点放大

直接先说原理吧--原理：利用了scrollview的回调函数（如下）以及scrollview自己内部的一些缩放规则（其实我也还没弄清楚具体scrollview干了什么事），只是知道了它可以怎么做-_-#

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView

{

    returnself.zoomImageView;

}

其实今天的缩放部分我还加上了常见的双击图片的缩小与放大，先上代码：

- (id)initWithFrame:(CGRect)frame

{

    self = [super initWithFrame:frame];

    if (self) {

       //自身属性的一些设置

        NSLog(@"%@",NSStringFromCGRect(frame));

        self.delegate =self;

        self.showsVerticalScrollIndicator =NO;

        self.showsHorizontalScrollIndicator =NO;

        self.maximumZoomScale =;

        //承载当前图片的imageview

        self.zoomImageView = [[[UIImageViewalloc] init] autorelease];

        self.zoomImageView.userInteractionEnabled =YES;

        self.zoomImageView.frame =CGRectMake(0.0f, 0.0f, frame.size.width  , frame.size.height);

        self.zoomImageView.image = [UIImageimageNamed:@"lichengwu.jpeg"];

        [self addSubview:self.zoomImageView];

        // Add gesture,double tap zoom imageView.

        UITapGestureRecognizer *doubleTapGesture = [[UITapGestureRecognizeralloc] initWithTarget:self

                                                                                          action:@selector(handleDoubleTap:)];

        [doubleTapGesture setNumberOfTapsRequired:];

        [ self.zoomImageViewaddGestureRecognizer:doubleTapGesture];

        [doubleTapGesture release];

        //  initialize tapclicks

        tapClicks = NO;

    }

    return self;

}

#pragma mark - Zoom methods

- (void)handleDoubleTap:(UIGestureRecognizer *)gesture

{

    float newScale;

    if (!tapClicks) {

        newScale = self.zoomScale *2.0;

    }

    else{

        newScale = self.zoomScale *0.0;

    }

    CGRect zoomRect = [selfzoomRectForScale:newScale withCenter:[gesturelocationInView:gesture.view]];

    [self zoomToRect:zoomRectanimated:YES];

    tapClicks = !tapClicks;

}

这一部分也是相当的一目了然，就是处理双击事件函数，是缩小还是放大，正正的处理图片的函数如下：

#pragma mark - CommonMethods

- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center

{

    CGRect zoomRect;

    zoomRect.size.height =self.frame.size.height / scale;

    zoomRect.size.width  =self.frame.size.width  / scale;

    zoomRect.origin.x = center.x - (zoomRect.size.width  /2.0);

    zoomRect.origin.y = center.y - (zoomRect.size.height /2.0);

    return zoomRect;

}

看见原理了没，其实就是获得当前点击处的中心X与原来图片尺寸的差值，然后传递给Scrollview进行缩放，至于scrollview具体干了什么事情，这就要让喜欢刨根问底的童鞋用一些力气了，然后@给我哦。

巴特西

ScrollView双击图片定点放大

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