Question

首先，我是Objective C的新手，非常感谢任何帮助。我试着写一个Gauge应用程序（最终会显示手机的角度）。我的问题是当我旋转Needle图像时，它旋转到正确的角度，但不是从Anchor点旋转 - 图像移动位置。即使我移动，从0渣到90，再回到0，图像也不会回到原来的位置！我正在使用的代码如下：。（PS我目前只在模拟器上运行应用程序）

*** Rotate Invoked by ....
// Rotate Image
[self rotateImage:_imgNeedle duration: vAnimationDuration curve: UIViewAnimationCurveLinear degrees:vValue];

-(void)rotateImage:(UIImageView *)image
       duration:(NSTimeInterval)duration
          curve:(int)curve
        degrees:(CGFloat)degrees
{
  // Setup the animation
  [self setAnchorPoint:CGPointMake(.44,.85) forView:image];
  // image.transform = CGAffineTransformMakeRotation(d2r(degrees));

  [UIView beginAnimations:nil context:NULL];
  [UIView setAnimationDuration:duration];
  [UIView setAnimationCurve:curve];
  [UIView setAnimationBeginsFromCurrentState:YES];

  // The transform matrix
  CGAffineTransform transform = CGAffineTransformMakeRotation(d2r(degrees));

  image.transform = transform;
  // Commit the changes
  [UIView commitAnimations];
}

// Set Anchor Point
-(void)setAnchorPoint:(CGPoint)anchorPoint forView:(UIView *)view
{
  CGPoint newPoint = CGPointMake(view.bounds.size.width * anchorPoint.x, view.bounds.size.height * anchorPoint.y);
  CGPoint oldPoint = CGPointMake(view.bounds.size.width * view.layer.anchorPoint.x, view.bounds.size.height * view.layer.anchorPoint.y);

  newPoint = CGPointApplyAffineTransform(newPoint, view.transform);
  oldPoint = CGPointApplyAffineTransform(oldPoint, view.transform);

  CGPoint position = view.layer.position;

  position.x -= oldPoint.x;
  position.x += newPoint.x;

  position.y -= oldPoint.y;
  position.y += newPoint.y;

  view.layer.position = position;
  view.layer.anchorPoint = anchorPoint;
}

Answer 1

我不确定图层位置，但是当我更改anchorPoint时，框架会发生变化，所以我会调整框架。

-(void)setAnchorPoint:(CGPoint)anchorPoint forView:(UIView *)view
{
  CGPoint newPoint = CGPointMake(view.bounds.size.width * anchorPoint.x, view.bounds.size.height * anchorPoint.y);
  CGPoint oldPoint = CGPointMake(view.bounds.size.width * view.layer.anchorPoint.x, view.bounds.size.height * view.layer.anchorPoint.y);

  newPoint = CGPointApplyAffineTransform(newPoint, view.transform);
  oldPoint = CGPointApplyAffineTransform(oldPoint, view.transform);
  /* 
  CGPoint position = view.layer.position;

  position.x -= oldPoint.x;
  position.x += newPoint.x;

  position.y -= oldPoint.y;
  position.y += newPoint.y;

  view.layer.position = position;
  */

  view.frame = CGRectOffset(view.frame, newPoint.x-oldPoint.x, newPoint.y-oldPoint.y);
  view.layer.anchorPoint = anchorPoint;
}

如果你想通过多次调用rotateImage回到原来的位置，我认为你应该只在此之前设置一次锚点。因为如果使用相同的rotateImage方法创建两个单独的动画，则将使用当前实现重新计算锚点。

-(void)rotateImage:(UIImageView *)image
       duration:(NSTimeInterval)duration
          curve:(int)curve
        degrees:(CGFloat)degrees
{
  // Setup the animation
  // [self setAnchorPoint:CGPointMake(.44,.85) forView:image];
  // image.transform = CGAffineTransformMakeRotation(d2r(degrees));

  [UIView beginAnimations:nil context:NULL];
  [UIView setAnimationDuration:duration];
  [UIView setAnimationCurve:curve];
  [UIView setAnimationBeginsFromCurrentState:YES];

  // The transform matrix
  CGAffineTransform transform = CGAffineTransformMakeRotation(d2r(degrees));

  image.transform = transform;
  // Commit the changes
  [UIView commitAnimations];
}

围绕固定点旋转图像

1 个答案: