UIGestureRecognizer对图像进行缩放、移动、旋转操作

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。

[代码] 在视图中创建手势识别器UIGestureRecognizers

01 - (void)viewDidLoad {

02 [super viewDidLoad];

03

04 UIPinchGestureRecognizer *pinchRecognizer = [[[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scale:)] autorelease];

05 [pinchRecognizer setDelegate:self];

06 [self.view addGestureRecognizer:pinchRecognizer];

07

08 UIRotationGestureRecognizer *rotationRecognizer = [[[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotate:)] autorelease];

09 [rotationRecognizer setDelegate:self];

10 [self.view addGestureRecognizer:rotationRecognizer];

11

12 UIPanGestureRecognizer *panRecognizer = [[[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(move:)] autorelease];

13 [panRecognizer setMinimumNumberOfTouches:1];

14 [panRecognizer setMaximumNumberOfTouches:1];

15 [panRecognizer setDelegate:self];

16 [canvas addGestureRecognizer:panRecognizer];

17

18 UITapGestureRecognizer *tapProfileImageRecognizer = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapped:)] autorelease];

19 [tapProfileImageRecognizer setNumberOfTapsRequired:1];

20 [tapProfileImageRecognizer setDelegate:self];

21 [canvas addGestureRecognizer:tapProfileImageRecognizer];

22 }

[代码] 下面是响应各手势消息的方法：

01 // 缩放

02 -(void)scale:(id)sender {

03

04 if([(UIPinchGestureRecognizer*)sender state] == UIGestureRecognizerStateBegan) {

05 _lastScale = 1.0;

06 }

07

08 CGFloat scale = 1.0 - (_lastScale - [(UIPinchGestureRecognizer*)sender scale]);

09

10 CGAffineTransform currentTransform = photoImage.transform;

11 CGAffineTransform newTransform = CGAffineTransformScale(currentTransform, scale, scale);

12

13 [photoImage setTransform:newTransform];

14

15 _lastScale = [(UIPinchGestureRecognizer*)sender scale];

16 [self showOverlayWithFrame:photoImage.frame];

17 }

18

19 // 旋转

20 -(void)rotate:(id)sender {

21

22 if([(UIRotationGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded) {

23

24 _lastRotation = 0.0;

25 return;

26 }

27

28 CGFloat rotation = 0.0 - (_lastRotation - [(UIRotationGestureRecognizer*)sender rotation]);

29

30 CGAffineTransform currentTransform = photoImage.transform;

31 CGAffineTransform newTransform = CGAffineTransformRotate(currentTransform,rotation);

32

33 [photoImage setTransform:newTransform];

34

35 _lastRotation = [(UIRotationGestureRecognizer*)sender rotation];

36 [self showOverlayWithFrame:photoImage.frame];

37 }

38

39 // 移动

40 -(void)move:(id)sender {

41

42 CGPoint translatedPoint = [(UIPanGestureRecognizer*)sender translationInView:canvas];

43

44 if([(UIPanGestureRecognizer*)sender state] == UIGestureRecognizerStateBegan) {

45 _firstX = [photoImage center].x;

46 _firstY = [photoImage center].y;

47 }

48

49 translatedPoint = CGPointMake(_firstX+translatedPoint.x, _firstY+translatedPoint.y);

50

51 [photoImage setCenter:translatedPoint];

52 [self showOverlayWithFrame:photoImage.frame];

53 }