UIView的特定部分放大/缩小而不增加View Objective C iOS的高度/宽度

Question

我实现了这个。但问题是它通过缩放增加了视图的高度/宽度。如何在不增加高度/宽度的情况下进行缩放。我的UIView高度/宽度是固定的。我的基本目标是视图高度/宽度保持相同但缩放视图的内侧。

    UIPinchGestureRecognizer * pinGeture =  [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(twoFingerPinch:)];
    [radarViewHolder addGestureRecognizer:pinGeture];



- (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer
{
    NSLog(@"Pinch scale: %f", recognizer.scale);

    if([recognizer state] == UIGestureRecognizerStateBegan) {
        // Reset the last scale, necessary if there are multiple objects with different scales
        lastScale = [recognizer scale];
    }

    if ([recognizer state] == UIGestureRecognizerStateBegan ||
        [recognizer state] == UIGestureRecognizerStateChanged) {

        CGFloat currentScale = [[[recognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];

        // Constants to adjust the max/min values of zoom
        const CGFloat kMaxScale = 2.0;
        const CGFloat kMinScale = 1.0;

        CGFloat newScale = 1 -  (lastScale - [recognizer scale]);
        newScale = MIN(newScale, kMaxScale / currentScale);
        newScale = MAX(newScale, kMinScale / currentScale);
        CGAffineTransform transform = CGAffineTransformScale([[recognizer view] transform], newScale, newScale);
        [recognizer view].transform = transform;

        lastScale = [recognizer scale];  // Store the previous scale factor for the next pinch gesture call
    }
}

Answer 1

@ShahbazAkram声明一个浮点变量CGFloat lastScale;

将此方法替换为您的代码。

- (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer
{
    NSLog(@"Pinch scale: %f", recognizer.scale);

    if([recognizer state] == UIGestureRecognizerStateBegan) {
        // Reset the last scale, necessary if there are multiple objects with different scales
        lastScale = [recognizer scale];
    }

    if ([recognizer state] == UIGestureRecognizerStateBegan ||
        [recognizer state] == UIGestureRecognizerStateChanged) {

        CGFloat currentScale = [[[recognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];

        // Constants to adjust the max/min values of zoom
        const CGFloat kMaxScale = 2.0;
        const CGFloat kMinScale = 1.0;

        CGFloat newScale = 1 -  (lastScale - [recognizer scale]);
        newScale = MIN(newScale, kMaxScale / currentScale);
        newScale = MAX(newScale, kMinScale / currentScale);
        CGAffineTransform transform = CGAffineTransformScale([[recognizer view] transform], newScale, newScale);
        [recognizer view].transform = transform;

        lastScale = [recognizer scale];  // Store the previous scale factor for the next pinch gesture call
    }
}

Answer 2

将您的视图添加到yourScroll中作为subView。

[yourScroll addSubView:radarViewHolder];


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

    CGFloat size = scrollView.zoomScale;
    if (size > ZoomMaxValue)
    {
        yourScroll.zoomScale = maximumScale;
    }
    if (size > ZoomMinValue && size < ZoomValue && size < 1.01)
    {
        yourScroll.zoomScale = minimumScale;
    }
    ZoomValue = size;
}

Answer 3

在视图上使用变换时，其帧的getter将使其坐标与此变换相乘。因此内部框架没有真正更新。

这通常不是问题，但在某些情况下可能是。通常，要避免此类情况，您只需将视图添加到另一个视图，然后缩放超级视图。假设这样的代码：

let baseView = UIView(frame: CGRect(x: 0.0, y: 0.0, width: 50.0, height: 50.0))
baseView.backgroundColor = .red
let addedView = UIView(frame: CGRect(x: 0.0, y: 0.0, width: 50.0, height: 50.0))
addedView.backgroundColor = .green
baseView.addSubview(addedView)
baseView.transform = CGAffineTransform(scaleX: 3.0, y: 3.0)

（抱歉Swift但你的情况应该没有区别）

当打印这两个视图的帧时，结果是

baseView: (-50 -50; 150 150)
addedView: (0 0; 50 50)

但在视觉上这两个视图是相同的，并且添加的视图完全重叠基本视图。

在您的情况下，没有足够的代码来显示特定的修复，但如果您为当前拥有的视图创建基本视图并缩放基本视图，则应修复更改框架的问题。