Question

我正在尝试设置一个与iPhone上的照片应用非常相似的应用。我遇到的问题是，我无法找到一种设置最小缩放比例的好方法，如果当前小于最小值，则将当前缩放比例强制回到最小值。

以下是我目前正在设置我的滚动视图...

- (void)viewDidLoad{

NSData * imageData = [[[NSData alloc] autorelease] initWithContentsOfURL: [NSURL URLWithString: imageURL]];
UIImage *babe = [UIImage imageWithData:imageData];
babeView = [[UIImageView alloc]
            initWithImage:babe];
[self.view addSubview:babeView];
UIBabeScrollView* myScrollview = (UIBabeScrollView*)self.view;
myScrollview.frame = [UIScreen mainScreen].applicationFrame;
[myScrollview setContentSize:[babe size]];
[myScrollview setMaximumZoomScale:2.0];
// Work out a nice minimum zoom for the image - if it's smaller than the ScrollView then 1.0x zoom otherwise a scaled down zoom so it fits in the ScrollView entirely when zoomed out
CGSize imageSize = babeView.image.size;
CGSize scrollSize = myScrollview.frame.size;
CGFloat widthRatio = scrollSize.width / imageSize.width;
CGFloat heightRatio = scrollSize.height / imageSize.height;
CGFloat minimumZoom = MIN(1.0, (widthRatio > heightRatio) ? heightRatio : widthRatio);

[myScrollview setMinimumZoomScale:minimumZoom];
[myScrollview setZoomScale:minimumZoom];

我的UIBabeScrollView被子类化为重载它的layoutSubviews，如此......

- (void)layoutSubviews {
[super layoutSubviews];

// center the image as it becomes smaller than the size of the screen
CGSize boundsSize = self.bounds.size;
CGRect frameToCenter = ((UIImageView*)[self.subviews objectAtIndex:0]).frame;

// center horizontally
if (frameToCenter.size.width < boundsSize.width)
    frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2;
else
    frameToCenter.origin.x = 0;

// center vertically
if (frameToCenter.size.height < boundsSize.height)
    frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2;
else
    frameToCenter.origin.y = 0;

((UIImageView*)[self.subviews objectAtIndex:0]).frame = frameToCenter;

}

我想要的效果是图像始终居中，并且无法缩小图像的宽度或高度。

现在这在纵向模式下工作正常，但当切换到横向时，缩放比例不正确。

任何帮助都会受到赞赏，因为我还是一个初出茅庐的iphone应用开发者。

Answer 1

在视图控制器中，实施-willRotateToInterfaceOrientation:duration:

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
  if (toInterfaceOrientation == UIDeviceOrientationLandscapeLeft ||
      toInterfaceOrientation == UIDeviceOrientationLandscapeRight) {    
    [myScrollview setMinimumZoomScale:yourLandscapeMinimumZoomValue];
    [myScrollview setZoomScale:yourLandscapeMinimumZoomValue];
  } else {
    [myScrollview setMinimumZoomScale:yourPortraitMinimumZoomValue];
    [myScrollview setZoomScale:yourPortraitMinimumZoomValue];
  }
}

Answer 2

另一点，仅供参考。我正在尝试[scrollview setZoomScale :: animated]方法。在方向更改时，它不会缩放到所需的值。

导致动画未完成。

如何更改方向更改时的最小缩放比例？

2 个答案: