基于Quartz 2D实现截图功能

对于手机上的截屏功能,使用Quartz 2D绘制可以完成该功能,下面奉上小Demo仅供参考:

@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"1.png"]];}- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{    // 1.记录当前手指的位置    UITouch *touch = [touches anyObject];    _beginPoint = [touch locationInView:self.view];    // 2.创建可一个可视的遮罩视图    if (_maskView == nil) {        _maskView = [[UIView alloc] initWithFrame:CGRectZero];        _maskView.backgroundColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:.3];        // 设置描边        _maskView.layer.borderWidth = 1;        _maskView.layer.borderColor = [UIColor blackColor].CGColor;    }    // 3.设置位置    _maskView.frame = CGRectMake(_beginPoint.x, _beginPoint.y, 1, 1);    // 添加到当前视图上    [self.view addSubview:_maskView];}- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{    // 1.获取手指当前的位置计算出视图显示的大小    // 1.1 获取当前手指的位置    UITouch *_moveTouch = [touches anyObject];    CGPoint _movePoint = [_moveTouch locationInView:self.view];    // 1.2 当前遮罩视图的大小    float width = _movePoint.x - _beginPoint.x;    float height = _movePoint.y - _beginPoint.y;    // 1.3 设置给遮罩视图    _maskView.frame = CGRectMake(_beginPoint.x, _beginPoint.y, width, height);    }- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{    // 1.获取当前视图的frame    // 2.移除当前遮罩视图    [_maskView removeFromSuperview];    // 3.获取指定区域内容内容    // 设置lay的锚点位置    self.view.frame = CGRectMake(-_maskView.frame.origin.x, -_maskView.frame.origin.y, self.view.frame.size.width, self.view.frame.size.height);    // 3.1 开始绘制图片画布    UIGraphicsBeginImageContextWithOptions(_maskView.frame.size, YES, 0);    [self.view.window.layer renderInContext:UIGraphicsGetCurrentContext()];    // 3.2 获取整张图片大小    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();    // 3.3 结束图片绘制    UIGraphicsEndImageContext();        self.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);    // 保存到本地相册    UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);}// 相册保存完成调用的方法- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo{    if (error == nil) {        NSLog(@"截图图片成功");    } else {        NSLog(@"保存失败");    }}- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event{    // 1.移除当前遮罩视图}/** * 截取部分图像 * **/- (UIImage*)getSubImage:(UIImage *)image mCGRect:(CGRect)mCGRect centerBool:(BOOL)centerBool{        /*如若centerBool为Yes则是由中心点取mCGRect范围的图片*/            float imgwidth = image.size.width;    float imgheight = image.size.height;    float viewwidth = mCGRect.size.width;    float viewheight = mCGRect.size.height;    CGRect rect;    if(centerBool)        rect = CGRectMake((imgwidth-viewwidth)/2, (imgheight-viewheight)/2, viewwidth, viewheight);    else{        if (viewheight < viewwidth) {            if (imgwidth <= imgheight) {                rect = CGRectMake(0, 0, imgwidth, imgwidth*viewheight/viewwidth);            }else {                float width = viewwidth*imgheight/viewheight;                float x = (imgwidth - width)/2 ;                if (x > 0) {                    rect = CGRectMake(x, 0, width, imgheight);                }else {                    rect = CGRectMake(0, 0, imgwidth, imgwidth*viewheight/viewwidth);                }            }        }else {            if (imgwidth <= imgheight) {                float height = viewheight*imgwidth/viewwidth;                if (height < imgheight) {                    rect = CGRectMake(0, 0, imgwidth, height);                }else {                    rect = CGRectMake(0, 0, viewwidth*imgheight/viewheight, imgheight);                }            }else {                float width = viewwidth*imgheight/viewheight;                if (width < imgwidth) {                    float x = (imgwidth - width)/2 ;                    rect = CGRectMake(x, 0, width, imgheight);                }else {                    rect = CGRectMake(0, 0, imgwidth, imgheight);                }            }        }    }        CGImageRef subImageRef = CGImageCreateWithImageInRect(image.CGImage, rect);    CGRect smallBounds = CGRectMake(0, 0, CGImageGetWidth(subImageRef), CGImageGetHeight(subImageRef));        UIGraphicsBeginImageContext(smallBounds.size);    CGContextRef context = UIGraphicsGetCurrentContext();    CGContextDrawImage(context, smallBounds, subImageRef);    UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];    UIGraphicsEndImageContext();        return smallImage;}@end