在保持旋转的情况下缩放UIScrollView内的UIImageView

Question

我在缩放放置在UIScrollView中的UIImageView方面遇到了问题。我已经在StackOverflow上搜索并查看了所有与我的问题相关的问题。我也尝试了在StackOverflow上发布的所有答案，但没有任何效果。

首先，我在nib文件中将UIImageView放置在UIScrollView中，并从相机胶卷中获取图像并填充图像视图。然后我使用UIRotationGestureRecognizer旋转图像。

以下是我尝试的代码。

- (void)viewDidLoad
{
 [super viewDidLoad];
 NSLog(@"%@",[[UIDevice currentDevice] model]);

// Do any additional setup after loading the view, typically from a nib.
 self.imagePicker = [[[UIImagePickerController alloc] init] autorelease];

 self.picChosenImageView.layer.shouldRasterize = YES;
 self.picChosenImageView.layer.rasterizationScale = [UIScreen mainScreen].scale;

 self.picChosenImageView.layer.contents = (id)[UIImage imageNamed:@"test"].CGImage;
 self.picChosenImageView.layer.shadowColor = [UIColor blackColor].CGColor;
 self.picChosenImageView.layer.shadowOpacity = 0.8f;
 self.picChosenImageView.layer.shadowRadius = 8;
 self.picChosenImageView.layer.shadowPath = [UIBezierPath bezierPathWithRect:self.picChosenImageView.bounds].CGPath;

 UIRotationGestureRecognizer *rotationRecognizer = [[[UIRotationGestureRecognizer alloc]initWithTarget:self
                                                                                               action:@selector(handleRotate:)] autorelease];
 rotationRecognizer.delegate = self;
 [self.picChosenImageView addGestureRecognizer:rotationRecognizer];

 self.containerView.delegate = self;
 self.containerView.contentSize = self.picChosenImageView.layer.frame.size;
 self.containerView.maximumZoomScale = 4.0f;
 self.containerView.minimumZoomScale = 1.0f;
 angle = 0.0f;
 useRotation = 0.0;
 isRotationStarted=FALSE;
 isZoomingStarted = FALSE; 
}

-(void)lockZoom
{
 maximumZoomScale = self.containerView.maximumZoomScale;
 minimumZoomScale = self.containerView.minimumZoomScale;

 self.containerView.maximumZoomScale = 1.0;
 self.containerView.minimumZoomScale = 1.0;
 self.containerView.clipsToBounds = false;
 self.containerView.scrollEnabled = false;
}

-(void)unlockZoom
{
    self.containerView.maximumZoomScale = maximumZoomScale;
    self.containerView.minimumZoomScale = minimumZoomScale;
    self.containerView.clipsToBounds = true;
    self.containerView.scrollEnabled = true;
}

#pragma mark - ScrollView delegate methods

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return  self.picChosenImageView;
}

- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{

    CGRect frame = self.picChosenImageView.frame;
    frame.origin = CGPointZero;
    self.picChosenImageView.frame = frame;
    //self.picChosenImageView.transform = prevTransform;

}

-(void) scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view
{
    if(!isZoomingStarted)
    {
        self.picChosenImageView.transform = CGAffineTransformRotate(self.picChosenImageView.transform, angle);
        NSLog(@"The zooming started");
        isZoomingStarted = TRUE;
        CGSize contentSize = self.containerView.bounds.size;
        CGRect contentFrame = self.containerView.bounds;
        NSLog(@"frame on start: %@", NSStringFromCGRect(contentFrame));
        NSLog(@"size on start: %@", NSStringFromCGSize(contentSize));
        //prevTransform = self.picChosenImageView.transform;
    }
}

-(void) scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{
    if(isZoomingStarted)
    {
        self.picChosenImageView.transform = CGAffineTransformRotate(self.picChosenImageView.transform, angle);
        isZoomingStarted = FALSE;
        CGSize contentSize = self.containerView.contentSize;
        CGRect contentFrame = self.containerView.bounds;
        NSLog(@"frame on end: %@", NSStringFromCGRect(contentFrame));
        NSLog(@"size on end: %@", NSStringFromCGSize(contentSize));
    }
}

#pragma mark - GestureRecognizer methods

- (void) handleRotate:(UIRotationGestureRecognizer *)recognizer
{
    if(isZoomingStarted == FALSE)
    {
        if([recognizer state] == UIGestureRecognizerStateBegan)
        {
            angle = 0.0f;
            [self lockZoom];
        }

        useRotation+= recognizer.rotation;

        while( useRotation < -M_PI )
        {
            useRotation += M_PI*2;
        }
        while( useRotation > M_PI )
        {
            useRotation -= M_PI*2;
        }
        NSLog(@"The rotated value is %f",RADIANS_TO_DEGREES(useRotation));
        self.picChosenImageView.transform = CGAffineTransformRotate([self.picChosenImageView transform],
                                                                    recognizer.rotation);
        [recognizer setRotation:0];

        if([recognizer state] == UIGestureRecognizerStateEnded)
        {
            angle = useRotation;
            useRotation = 0.0f;
            isRotationStarted = FALSE;
            self.containerView.hidden = NO;
            //prevTransform = self.picChosenImageView.transform;
            [self unlockZoom];
        }
    }
}

我的问题是，我能成功地进行缩放和放大操作。我也能够按照我的意愿旋转uiimageview。但是，在将uiimageview旋转到某个角度后，当我尝试放大时，图像视图会回到原始位置（将自己旋转回零度），然后才会进行缩放。我希望保留旋转并且能够放大。我曾尝试在scrollDidzoom和scrollDidBegin委托方法中保存前一个变换，并将其分配回去。但均未奏效。请帮我找出我正在忽略的错误。

- jeevangs

---

在scrollViewWillBeginZooming和endZooming中添加以下代码行，可以使图像视图恢复到原始旋转状态 self.picChosenImageView.transform = CGAffineTransformRotate(self.picChosenImageView.transform, angle); - jeevangs

但是我无法保持图像视图的旋转，同时发生缩放，也就是说，在scrollviewdidZoom时。 - jeevangs

我也遇到了同样的问题。问题出在setZoomScale方法上，它会覆盖应用的旋转。请参考https://dev59.com/K2fWa4cB1Zd3GeqPgmQu。 - user289841

Answer 1

我曾经遇到过同样的问题。UIScrollView控制了UIImageView并使用了变换而没有旋转。

因此，我不将图像引用给滚动视图，并添加了UIPinchGestureRecognizer进行缩放。

func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
  return nil
}

拖拽仍在工作中 :)

// viewDidLoad
var pinchGestureRecognizer = UIPinchGestureRecognizer(target: self, action: #selector(pinchRecogniezed))
scrollView.addGestureRecognizer(pinchGestureRecognizer)


func pinchRecogniezed(sender: UIPinchGestureRecognizer) {
    if sender.state == .Began || sender.state == .Changed {
        let scale = sender.scale
        imageView.transform = CGAffineTransformScale(imageView.transform, scale, scale)
        sender.scale = 1
    }
}

- Konrad Nowicki

Answer 2

尝试使用CGAffineTransformScale而不仅仅是调整框架大小来进行缩放：

anImage.transform = CGAffineTransformScale(anImage.transform, 2.0, 2.0);

改变缩放的转化可能会解决你的旋转问题。

希望这可以帮到你。

- KDaker

---

我尝试过了。滚动视图中的图像按比例因子2进行缩放，但我无法滚动到图像的其他部分。只有在滚动视图中看到的图像被缩放。而且我假设你的代码放在scrollViewDidZoom中。 - jeevangs

好的，不要在上面的代码中使用2.0，您应该使用比例因子... 但是，无论如何，再次查看您的代码后，我认为那不是问题所在...似乎与scrollViewWillBeginZooming:有关。为什么在那个方法中要使用 self.picChosenImageView.transform = CGAffineTransformRotate(self.picChosenImageView.transform, angle);？每个缩放周期后角度不会被重置吗？ - KDaker

如果我从scrollViewWillBeginZooming中删除那行代码，我会遇到同样的问题。我可以看到问题出在scrollViewDidZoom中，我在那里重置了imageview的框架。如果我删除它，imageview中的图像将变得不可见，我的意思是内容偏移。希望我能清楚地向您解释。 - jeevangs