#import "ViewController.h"
@interface ViewController ()
@property (nonatomic, assign) CGPoint startP;
@property (weak, nonatomic) IBOutlet UIImageView *imageV;
@property (nonatomic, weak) UIView *clipView;
@end
@implementation ViewController
- (UIView *)clipView{
if (_clipView == nil) {
UIView *view = [[UIView alloc] init];
_clipView = view;
view.backgroundColor = [UIColor blackColor];
view.alpha = 0.5;
[self.view addSubview:view];
}
return _clipView;
}
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
// 给控制器的view添加一个pan手势
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
[self.view addGestureRecognizer:pan];
}
- (void)pan:(UIPanGestureRecognizer *)pan
{
CGPoint endA = CGPointZero;
if (pan.state == UIGestureRecognizerStateBegan) {
// 一开始拖动的时候
// 获取一开始触摸点
_startP = [pan locationInView:self.view];
}else if(pan.state == UIGestureRecognizerStateChanged){
// 一直拖动
// 获取结束点
endA = [pan locationInView:self.view];
CGFloat w = endA.x - _startP.x;
CGFloat h = endA.y - _startP.y;
// 获取截取范围
CGRect clipRect = CGRectMake(_startP.x, _startP.y, w, h);
// 生成截屏的view
self.clipView.frame = clipRect;
}else if (pan.state == UIGestureRecognizerStateEnded){
// 图片裁剪，生成一张新的图片
// 开启上下文
// 如果不透明，默认超出裁剪区域会变成黑色，通常都是透明
UIGraphicsBeginImageContextWithOptions(_imageV.bounds.size, NO, 0);
// 设置裁剪区域
UIBezierPath *path = [UIBezierPath bezierPathWithRect:_clipView.frame];
[path addClip];
// 获取上下文
CGContextRef ctx = UIGraphicsGetCurrentContext();
// 把控件上的内容渲染到上下文
[_imageV.layer renderInContext:ctx];
// 生成一张新的图片
_imageV.image = UIGraphicsGetImageFromCurrentImageContext();
// 关闭上下文
UIGraphicsEndImageContext();
// 先移除
[_clipView removeFromSuperview];
// 截取的view设置为nil
_clipView = nil;
}