iOS - Quartz 2D 手势截屏绘制

1、绘制手势截屏

• 具体实现代码见 GitHub 源码 QExtension

• QTouchClipView.h

  	@interface QTouchClipView : UIView
  
  	/**
  	 *  创建手势截屏视图控件，获取截屏结果
  	 *
  	 *  @param view     截取图片的视图控件
  	 *  @param result   手势截屏结果
  	 *
  	 *  @return 手势截屏视图控件
  	 */
  	+ (instancetype)q_touchClipViewWithView:(UIView *)view
  	                             clipResult:(void (^)(UIImage * _Nullable image))result;
  
  	@end
  

• QTouchClipView.m

  	@interface QTouchClipView ()
  
  	/// 截取图片的视图控件
  	@property (nonatomic, strong) UIView *baseView;
  
  	/// 滑动手势结果
  	@property (nonatomic, copy) void (^resultBlock)(UIImage * _Nullable);
  
  	/// 触摸开始结束点
  	@property (nonatomic, assign) CGPoint startP;
  	@property (nonatomic, assign) CGPoint endP;
  
  	@end
  
  	@implementation QTouchClipView
  
  	/// 创建手势截屏视图控件，获取截屏结果
  	+ (instancetype)q_touchClipViewWithView:(UIView *)baseView
  	                             clipResult:(void (^)(UIImage * _Nullable image))result {
  
  	    QTouchClipView *clipView = [[self alloc] initWithFrame:baseView.frame];
  
  	    clipView.baseView = baseView;
  	    clipView.resultBlock = result;
  
  	    return clipView;
  	}
  
  	/// 初始化
  	- (instancetype)initWithFrame:(CGRect)frame {
  
  	    if (self = [super initWithFrame:frame]) {
  	        self.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5];
  	    }
  	    return self;
  	}
  
  	/// 触摸开始
  	- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
  
  	    // 获取触摸起始点位置
  	    CGPoint startPoint = [touches.anyObject locationInView:self];
  	    self.startP = startPoint;
  	}
  
  	/// 触摸移动
  	- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
  
  	    // 获取触摸点位置
  	    CGPoint touchPoint = [touches.anyObject locationInView:self];
  	    self.endP = touchPoint;
  
  	    // 刷新视图
  	    [self setNeedsDisplay];
  	}
  
  	/// 触摸结束
  	- (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event {
  
  	    // 截取屏幕图片
  	    UIGraphicsBeginImageContextWithOptions(self.baseView.bounds.size, NO, 0);
  
  	    CGContextRef ctx = UIGraphicsGetCurrentContext();
  	    [self.baseView.layer renderInContext:ctx];
  
  	    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  
  	    UIGraphicsEndImageContext();
  
  	    // 切割图片
  	    CGFloat x = self.startP.x;
  	    CGFloat y = self.startP.y;
  	    CGFloat w = self.endP.x - x;
  	    CGFloat h = self.endP.y - y;
  
  	    CGRect cutRect = CGRectMake(x * 2, y * 2, w * 2, h * 2);
  
  	    CGImageRef cgImage = CGImageCreateWithImageInRect(image.CGImage, cutRect);
  	    UIImage *newImage = [[UIImage alloc] initWithCGImage:cgImage];
  	    CGImageRelease(cgImage);
  
  	    // 返回截取结果
  	    if (self.resultBlock) {
  	        self.resultBlock(newImage);
  	    }
  
  	    // 移除截取视图控件
  	    [self removeFromSuperview];
  	    self.startP = CGPointZero;
  	    self.endP = CGPointZero;
  
  	    // 刷新视图
  	    [self setNeedsDisplay];
  	}
  
  	/// 触摸取消
  	- (void)touchesCancelled:(NSSet *)touches withEvent:(nullable UIEvent *)event {
  	    [self touchesEnded:touches withEvent:event];
  	}
  
  	/// 绘制触摸区域
  	- (void)drawRect:(CGRect)rect {
  
  	    CGFloat x = self.startP.x;
  	    CGFloat y = self.startP.y;
  	    CGFloat w = self.endP.x - x;
  	    CGFloat h = self.endP.y - y;
  
  	    CGRect clipRect = CGRectMake(x, y, w, h);
  
  	    UIBezierPath *path = [UIBezierPath bezierPathWithRect:clipRect];
  	    [[[UIColor whiteColor] colorWithAlphaComponent:0.2] setFill];
  	    [path fill];
  	}
  
  	@end
  

• ViewController.m

  	// 创建手势截屏视图
  	QTouchClipView *touchClipView = [QTouchClipView q_touchClipViewWithView:self.imageView
  	                                                             clipResult:^(UIImage * _Nullable image) {
  
  	    // 获取处理截屏结果
  	    if (image) {
  	        UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
  	    }
  	}];
  
  	// 添加手势截屏视图
  	[self.view addSubview:touchClipView];
  

• 效果