标签：style blog color io ar for sp div c
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 =3; //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:2]; [ 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。
标签：style blog color io ar for sp div c
原文地址：http://www.cnblogs.com/likun123/p/4002388.html
