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iOS提供了拍击、旋转、滑动、挤捏等丰富的手势,因此对图像的操作就显得非常友好、简单。下面代码展示了使用UIGestureRecognizer对图像进行缩放 、移动、旋转操作使用方法。在使用代码之前,首先建立一个UIView,并在该视图中增加一个UIImageView视图,用于展示图像。那么该UIView就类似图 像画板一样,对图像的操作都基于此视图中进行。
- (void)viewDidLoad { [super viewDidLoad]; UIPinchGestureRecognizer *pinchRecognizer = [[[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scale:)] autorelease]; [pinchRecognizer setDelegate:self]; [self.view addGestureRecognizer:pinchRecognizer]; UIRotationGestureRecognizer *rotationRecognizer = [[[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotate:)] autorelease]; [rotationRecognizer setDelegate:self]; [self.view addGestureRecognizer:rotationRecognizer]; UIPanGestureRecognizer *panRecognizer = [[[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(move:)] autorelease]; [panRecognizer setMinimumNumberOftouches:1]; [panRecognizer setMaximumNumberOftouches:1]; [panRecognizer setDelegate:self]; [canvas addGestureRecognizer:panRecognizer]; UITapGestureRecognizer *tapProfileImageRecognizer = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapped:)] autorelease]; [tapProfileImageRecognizer setNumberOfTapsrequired:1]; [tapProfileImageRecognizer setDelegate:self]; [canvas addGestureRecognizer:tapProfileImageRecognizer]; }
// 缩放 -(void)scale:(id)sender { if([(UIPinchGestureRecognizer*)sender state] == UIGestureRecognizerStateBegan) { _lastScale = 1.0; } CGFloat scale = 1.0 - (_lastScale - [(UIPinchGestureRecognizer*)sender scale]); CGAffineTransform currentTransform = photoImage.transform; CGAffineTransform newTransform = CGAffineTransformScale(currentTransform,scale,scale); [photoImage setTransform:newTransform]; _lastScale = [(UIPinchGestureRecognizer*)sender scale]; [self showOverlayWithFrame:photoImage.frame]; } // 旋转 -(void)rotate:(id)sender { if([(UIRotationGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded) { _lastRotation = 0.0; return; } CGFloat rotation = 0.0 - (_lastRotation - [(UIRotationGestureRecognizer*)sender rotation]); CGAffineTransform currentTransform = photoImage.transform; CGAffineTransform newTransform = CGAffineTransformRotate(currentTransform,rotation); [photoImage setTransform:newTransform]; _lastRotation = [(UIRotationGestureRecognizer*)sender rotation]; [self showOverlayWithFrame:photoImage.frame]; } // 移动 -(void)move:(id)sender { CGPoint translatedPoint = [(UIPanGestureRecognizer*)sender translationInView:canvas]; if([(UIPanGestureRecognizer*)sender state] == UIGestureRecognizerStateBegan) { _firstX = [photoImage center].x; _firstY = [photoImage center].y; } translatedPoint = CGPointMake(_firstX+translatedPoint.x,_firstY+translatedPoint.y); [photoImage setCenter:translatedPoint]; [self showOverlayWithFrame:photoImage.frame]; }
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