iOS 使用手勢UIGestureRecognizer對圖像進行縮放、移動、旋轉操作

iOS提供了拍擊、旋轉、滑動、擠捏等豐富的手勢，因此對圖像的操作就顯得非常友好、簡單。

下面代碼展示了使用UIGestureRecognizer對圖像進行縮放、移動、旋轉操作使用方法。

 

在使用代碼之前，首先建立一個UIView，並在該視圖中增加一個UIImageView視圖，用於展示圖像。那么該UIView就類似圖像畫板一樣，對圖像的操作都基於此視圖中進行。

在視圖中創建手勢識別器UIGestureRecognizers

- (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]; }

 

下面是響應各手勢消息的方法：

 

// 縮放
-(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];
}

// 旋轉
-(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];
}

// 移動
-(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];
}