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//
// ViewController.m
// ScrollView
//
// Created by ad on 03/07/2017.
//
// 详细博文：https://github.com/pro648/tips/wiki/UIScrollView%E7%9A%84%E7%94%A8%E6%B3%95
#import "ViewController.h"
@interface ViewController () <UIScrollViewDelegate>
@property (strong, nonatomic) UIScrollView *scrollView;
@property (strong, nonatomic) UIImageView *imageView;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self.view addSubview:self.scrollView];
[self.scrollView addSubview:self.imageView];
// 设定最小缩放比
[self setZoomScale];
// 添加双击手势
UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
doubleTap.numberOfTapsRequired = 2;
[self.scrollView addGestureRecognizer:doubleTap];
}
- (void)viewWillLayoutSubviews {
[super viewWillLayoutSubviews];
// 1.移除子视图
for (UIView *view in self.scrollView.subviews) {
[view removeFromSuperview];
}
// 2.初始化imageView 将其添加到scrollView 设置contentSize
self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"image"]];
[self.scrollView addSubview:self.imageView];
self.scrollView.contentSize = self.imageView.frame.size;
// 3.重设minimumZoomScale
[self setZoomScale];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Properties
- (UIImageView *)imageView {
if (!_imageView) {
UIImage *image = [UIImage imageNamed:@"image"];
// 1.初始化imageView
_imageView = [[UIImageView alloc] initWithImage:image];
}
return _imageView;
}
- (UIScrollView *)scrollView {
if (!_scrollView) {
// 2.初始化、配置scrollView
_scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
_scrollView.backgroundColor = [UIColor blackColor];
_scrollView.contentSize = self.imageView.frame.size;
_scrollView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
_scrollView.contentOffset = CGPointMake(1000, 450);
_scrollView.delegate = self;
// _scrollView.minimumZoomScale = 0.1;
// _scrollView.maximumZoomScale = 4.0;
// _scrollView.zoomScale = 1.0;
}
return _scrollView;
}
#pragma mark - UIScrollViewDelegate
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return self.imageView;
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
// 计算imageView缩小到最小时 imageView与屏幕边缘距离
CGFloat horizontalPadding = CGRectGetWidth(self.imageView.frame) < CGRectGetWidth(scrollView.frame) ? (CGRectGetWidth(scrollView.frame) - CGRectGetWidth(self.imageView.frame)) / 2 : 0 ;
CGFloat verticalPadding = CGRectGetHeight(self.imageView.frame) < CGRectGetHeight(scrollView.frame) ? (CGRectGetHeight(scrollView.frame) - CGRectGetHeight(self.imageView.frame)) / 2 : 0 ;
scrollView.contentInset = UIEdgeInsetsMake(verticalPadding, horizontalPadding, verticalPadding, horizontalPadding);
}
#pragma mark - Help Method
- (void)setZoomScale {
CGFloat widthScale = CGRectGetWidth(self.scrollView.frame) / CGRectGetWidth(self.imageView.frame);
CGFloat heightScale = CGRectGetHeight(self.scrollView.frame) / CGRectGetHeight(self.imageView.frame);
self.scrollView.minimumZoomScale = MIN(widthScale, heightScale);
}
- (void)handleDoubleTap:(UITapGestureRecognizer *)doubleTap {
if (self.scrollView.zoomScale > self.scrollView.minimumZoomScale) {
// 视图大于最小视图时 双击将视图缩小至最小
[self.scrollView setZoomScale:self.scrollView.minimumZoomScale animated:YES];
}
else
{
/*
// 视图为最小时 双击将视图放大至最大
[self.scrollView setZoomScale:self.scrollView.maximumZoomScale animated:YES];
*/
// 1.获取点击位置
CGPoint touchPoint = [doubleTap locationInView:self.imageView];
// 2.获取要显示的imageView区域
CGRect zoomRect = [self zoomRectForScrollView:self.scrollView withScale:self.scrollView.maximumZoomScale withCenter:touchPoint];
// 5.将要显示的imageView区域显示到scrollView
[self.scrollView zoomToRect:zoomRect animated:YES];
}
}
- (CGRect)zoomRectForScrollView:(UIScrollView *)scrollView withScale:(CGFloat)scale withCenter:(CGPoint)center {
// 3.声明一个区域 滚动视图的宽除以放大倍数可以得到要显示imageView宽度
CGRect zoomRect;
zoomRect.size.width = CGRectGetWidth(scrollView.frame) / scale;
zoomRect.size.height = CGRectGetHeight(scrollView.frame) / scale;
// 4.点击位置x坐标减去1/2图像宽度，可以得到要显示imageView的原点x坐标 y坐标类似
zoomRect.origin.x = center.x - zoomRect.size.width / 2;
zoomRect.origin.y = center.y - zoomRect.size.height / 2;
return zoomRect;
}
@end