Question

我正在尝试将一个imgView集中在scrollView中，这样当我放大时，它将保持正确居中（就像照片应用程序一样）。

首次加载屏幕时，它会居中。当我捏合并开始变焦时，位置会自动调整，使图像不再居中。在捏/缩放照片之前和之后查看。红色是滚动视图的背景颜色。

Before Zoom

After Zoom

以下是我用于在滚动视图中创建imgView并将其置于中心的代码。（MonoTouch，但应该转换为Obj-C easy）

private void LoadPageContent（int page） { // TODO：用于加载要在此面板/页面上显示的图像或代码的代码

        //Each page will have it's own scrollview for scrolling and zooming that image on the page
        var panelScrollView = new UIScrollView();
        _panels.Add (panelScrollView);

        panelScrollView.CanCancelContentTouches=false;
        panelScrollView.ClipsToBounds = true; 

        panelScrollView.MinimumZoomScale = 1f;
        panelScrollView.MaximumZoomScale = 50.0f;
        panelScrollView.MultipleTouchEnabled = true;

        panelScrollView.ScrollEnabled = true;
        panelScrollView.UserInteractionEnabled=true;
        var ui = new UIImage (_assetImages[page], 1.0f, UIImageOrientation.Up);

        UIImageView imgView = new UIImageView(ui);


        panelScrollView.Frame = new RectangleF(scrollView.Frame.Width * (_numberOfPanels - 1),
                                               0,
                                               _pageWidthPortrait,
                                               scrollView.Frame.Height);


        panelScrollView.BackgroundColor = UIColor.Red;

        //scale down image to get proper fitted imgview dimensions
        float nPercentW = (panelScrollView.Frame.Width / (float)imgView.Image.Size.Width);
        float nPercentH = (panelScrollView.Frame.Height / (float)imgView.Image.Size.Height);
        float newPercent;
        if (nPercentH >= nPercentW)
        {
            //wider than it is tall
            newPercent = nPercentW;
        }
        else{
            //taller than it is wide..
            newPercent = nPercentH;
        }
        int newWidth1 = Convert.ToInt32(imgView.Image.Size.Width * newPercent);
        int newHeight = Convert.ToInt32(imgView.Image.Size.Height * newPercent);

        panelScrollView.ViewForZoomingInScrollView += (UIScrollView sv) => { 
            return imgView; 
        };

        imgView.Frame = new RectangleF(0,0,newWidth1, newHeight);
        imgView.Center = new PointF(panelScrollView.Frame.Width /2,
                                    (panelScrollView.Frame.Height/2));


  //ScaleToFill and ScaleAspect fit - i used scaleaspectfit and it had the same problem
  //I tried scaletofill but resizing the imgView to fit the proper view dimensions so it is like an aspect fit, but same problem
        imgView.ContentMode=UIViewContentMode.ScaleToFill;//ScaleAspectFit;
        imgView.UserInteractionEnabled=true;

        panelScrollView.ContentSize = imgView.Image.Size;


        panelScrollView.DidZoom += (object sender, EventArgs e) => {

    };

    panelScrollView.AddSubview(imgView);
    scrollView.AddSubview(panelScrollView);


    }

Answer 1

这对我来说很好

- (void)centerScrollViewContents {

CGSize boundsSize = ScrollView.bounds.size;
CGRect contentsFrame = ImageView.frame;

if (contentsFrame.size.width < boundsSize.width) {
    contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width) / 2.0f;
} else {
    contentsFrame.origin.x = 0.0f;
}

if (contentsFrame.size.height < boundsSize.height) {
    contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2.0f;
} else {
    contentsFrame.origin.y = 0.0f;
}

ImageView.frame = contentsFrame;

}

您必须在

中调用此方法

- (void)scrollViewDidZoom:(UIScrollView *)scrollView

缩放后图像不在ScrollView中居中

1 个答案: