操作步骤
效果图
图片的剪切区域
)在pan手势结束时,通过alertView提示“是否将图片保存至相册?”
通过storyboard在控制器的view上添加一个imageView(设置图片
),并在控制器的.m文件中拥有该属性
@PRoperty (weak, nonatomic) IBOutlet UIImageView *imageView;
设置通过手势绘制的图片的剪切区域
@property (nonatomic, weak) UIView *clipView;
- (UIView *)clipView{ //如果clipView为被创建,就创建 if (_clipView == nil) { UIView *view = [[UIView alloc] init]; _clipView = view; //设置clipView的背景色和透明度 view.backgroundColor = [UIColor blackColor]; view.alpha = 0.5; //将clipView添加到控制器的view上,此时的clipView不会显示(未设置其frame) [self.view addSubview:_clipView]; } return _clipView;}
给控制器的view添加pan手势,跟踪pan手势,绘制图片剪切区域
/**创建手势**/UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)]; /** *每当pan手势的位置发生变化,就会调用pan:方法,并将手势作为参数传递 *//**添加手势**/[self.view addGestureRecognizer:pan];
@property (nonatomic, assign) CGPoint startPoint;
- (void)pan:(UIPanGestureRecognizer *)pan{ CGPoint endPoint = CGPointZero; if (pan.state == UIGestureRecognizerStateBegan) { /**开始点击时,记录手势的起点**/ self.startPoint = [pan locationInView:self.view]; } else if(pan.state == UIGestureRecognizerStateChanged) { /**当手势移动时,动态改变终点的值,并计算起点与终点之间的矩形区域**/ endPoint = [pan locationInView:self.view]; //计算矩形区域的宽高 CGFloat w = endPoint.x - self.startPoint.x; CGFloat h = endPoint.y - self.startPoint.y; //计算矩形区域的frame CGRect clipRect = CGRectMake(self.startPoint.x, self.startPoint.y, w, h); //设置剪切区域的frame self.clipView.frame = clipRect; } else if(pan.state == UIGestureRecognizerStateEnded) { /**若手势停止,将剪切区域的图片内容绘制到图形上下文中**/ //开启位图上下文 UIGraphicsBeginImageContextWithOptions(self.imageView.bounds.size, NO, 0); //创建大小等于剪切区域大小的封闭路径 UIBezierPath *path = [UIBezierPath bezierPathWithRect:self.clipView.frame]; //设置超出的内容不显示, [path addClip]; //获取绘图上下文 CGContextRef context = UIGraphicsGetCurrentContext(); //将图片渲染的上下文中 [self.imageView.layer renderInContext:context]; //获取上下文中的图片 UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); //关闭位图上下文 UIGraphicsEndImageContext(); //移除剪切区域视图控件,并清空 [self.clipView removeFromSuperview]; self.clipView = nil; //将图片显示到imageView上 self.imageView.image = image; //通过alertView提示用户,是否将图片保存至相册 UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"保存图片" message:@"是否将图片保存至相册?" delegate:self cancelButtonTitle:@"否" otherButtonTitles:@"是", nil]; [alertView show];}}
设置alertView的代理方法,确定是否保存图片
- (void)alertView:(nonnull UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{ //若点击了“是”,则保存图片 if (buttonIndex == 1) { UIImageWriteToSavedPhotosAlbum(self.imageView.image, nil, nil, nil); /** * 该方法可以设置保存完毕调用的方法,此处未进行设置 */ }}
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