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我有一个图像视图，想添加一些自定义捏合手势识别器。我可以缩放我的图像视图，但问题是，它不是从两个手指的中心放大。

如何从两个手指的中心进行缩放？这就是我目前正在做的（在viewDidLoad）

UIPinchGestureRecognizer* pinchRecognizer = 
    [[UIPinchGestureRecognizer alloc] initWithTarget:self
                                              action:@selector(handlePinch:)];    
 [imageView addGestureRecognizer:pinchRecognizer];

这是捏法的代码

- (IBAction)handlePinch:(UIPinchGestureRecognizer *)recognizer
{  

    recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
    recognizer.scale = 1;

}

感谢代表们...现在我在这里更新我的问题..我想在按钮单击时缩放图像..我正在做的是

-(IBAction)Zoom_image:(id)sender {

 CGFloat scaleValue = 2;

 CGAffineTransform transform = GAffineTransformMakeScale(scaleValue,scaleValue);

 self.backgroundImgView.transform = transform;

}

4

2 回答 2

5

这也将起作用。只需将图像移动到捏合的中心，对其进行缩放，然后在一次变换中返回其位置。

- (void) pinch:(UIPinchGestureRecognizer *) recognizer {

    CGPoint anchor = [recognizer locationInView:imageToScale];
    anchor = CGPointMake(anchor.x - imageToScale.bounds.size.width/2, anchor.y-imageToScale.bounds.size.height/2);

    CGAffineTransform affineMatrix = imageToScale.transform;
    affineMatrix = CGAffineTransformTranslate(affineMatrix, anchor.x, anchor.y);
    affineMatrix = CGAffineTransformScale(affineMatrix, [recognizer scale], [recognizer scale]);
    affineMatrix = CGAffineTransformTranslate(affineMatrix, -anchor.x, -anchor.y);
    imageToScale.transform = affineMatrix;

    [recognizer setScale:1];
}
于 2013-04-23T15:18:35.287 回答
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问题是您所做的只是缩放视图。

您不会尝试将缩放转换为以两个手指点的中心为中心。

所以抓住两个手指点。制定他们的中心并添加翻译。

请注意，下面的代码原则上将显示您需要做什么，我可以保证它需要修复，因为在实践中仿射变换并非微不足道，而且我不是您的错误修复程序。

- (IBAction)handlePinch:(UIPinchGestureRecognizer *)recognizer
{
    UIView *view = recognizer.view;

    CGRect frame = view.bounds;

    //you may wish to get more accurate by querying and calculating against the touches via 
    //- (NSUInteger)numberOfTouches;
    //- (CGPoint)locationOfTouch:(NSUInteger)touchIndex inView:(UIView*)view;
    CGPoint nominalCenter = [recognizer locationInView:view];

    CGFloat deltaFromCenterX = CGRectGetMidX(frame) - nominalCenter.x;

    CGFloat deltaFromCenterY = CGRectGetMidY(frame) - nominalCenter.y;

    currentScale = currentScale * recognizer.scale;

    CGAffineTransform scale = CGAffineTransformMakeScale(currentScale, currentScale);

    CGAffineTransform translate = CGAffineTransformMakeTranslation(deltaFromCenterX, deltaFromCenterY);

    //possibly its going to be scale then translate instead
    CGAffineTransform final = CGAffineTransformConcat(translate, scale);

    recognizer.view.transform = final;
    recognizer.scale = 1;
}
于 2013-04-23T14:52:57.053 回答