java - JScrollPane 不会更新 JSplitPane 上的 JScrollBar

Question

我想创建能够编辑图像的简单应用程序。应用程序的主视图包含 JSplitPane有两个JScrollPane 。每个JScrollPane包含JPanel 。右边JPanel有几个按钮等，左边JPanel是我的绘图区域。

这是我的问题...

当我第一次创建JPanelDrawingArea时我可以设置首选尺寸。如果尺寸大于 JScrollPane 的尺寸JScrollBars显示(默认情况下是相等的)。但是当我将图像加载到JPanelDrawingArea时滚动条不更新。尽管事实上我设置了新的首选大小 JPanelDrawingArea (大于 JScrollPane 的大小)滚动条不会更新，除非我手动更改 JSplitPanes分隔线位置。

这是我的JSplitPane自定义类:

public class DrawingPaneView extends JSplitPane{

private DrawingWorkMode drawingWorkMode;
private ImageWorkerView imageWorker;
JScrollPane workScrollPane;
JScrollPane pictureScrollPane;
private DrawingPaneController controller;

private Dimension minimumSize = new Dimension(100, 200);
private JPanel imagePanel;


public DrawingPaneView() {

    setPreferredSize(new Dimension(ConfigClass.APP_WIDTH,ConfigClass.DRAWING_PANE_HEIGHT));
    controller = new DrawingPaneController(this); 

    //Panel
    drawingWorkMode = new DrawingWorkMode();
    workScrollPane = new JScrollPane(drawingWorkMode);

    //Image
    imageWorker = new ImageWorkerView();
    pictureScrollPane = new JScrollPane(imageWorker);


    workScrollPane.setMinimumSize(minimumSize);
    pictureScrollPane.setMinimumSize(minimumSize);


    //addJPanels
    this.setOrientation(JSplitPane.HORIZONTAL_SPLIT);
    this.setRightComponent(workScrollPane);
    this.setLeftComponent(pictureScrollPane);

    //addLeftPanelWithJButtonOnly
    imagePanel = new ImagePanelView();
    pictureScrollPane.setRowHeaderView(imagePanel);

    this.setDividerLocation(ConfigClass.DRAWING_PANE_WIDTH);
    this.setOneTouchExpandable(true);

}

//Change mode
public void changeMode(String mode){
    drawingWorkMode.changeMode(mode);
}      
}

这是我的自定义JPanel执行绘图:

public class ImageWorkerView extends JPanel {

private BufferedImage img;
private ImageWorkerController controller;
private int defaultBounds = 50;
private double scale=1.0;
int imgW;
int imgH;

public ImageWorkerView() {
    //setLayout(new BorderLayout(0, 0));
    controller = new ImageWorkerController(this);
}


public void setScale(double scale) {
    this.scale = scale;
}

public void setImage(File image) {
    try {
        img = ImageIO.read(image);
        if (img.getType() != BufferedImage.TYPE_INT_RGB) {
            BufferedImage img2 =
                new BufferedImage(img.getWidth(null), img.getHeight(null), BufferedImage.TYPE_INT_RGB);
            Graphics big = img2.getGraphics();
            big.drawImage(img, 0, 0, null);
            img = img2;
        }
    } catch (IOException e) {
        System.out.println("Image could not be read");
    }
}

private void adjustPreferredSize(Boolean defaultSize){

    if(defaultSize){
        //Calculate the proper size of drawing area
        imgW = ConfigClass.DRAWING_PANE_WIDTH - ImagePanelView.PREFERRED_WIDTH-10;
        imgH = ConfigClass.DRAWING_PANE_HEIGHT-50;
        setPreferredSize(new Dimension(imgW,imgH));
        controller.setWindowHeight(imgH);
    }
    else{
        imgW = (int)(img.getWidth() * scale + (defaultBounds*2));
        imgH = (int)(img.getHeight() * scale + (defaultBounds*2));
        setPreferredSize(new Dimension(imgW,imgH));
        controller.setWindowHeight(imgH);
    }   
}

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;

    if(img!=null){
        if(scale!=1.0){
            AffineTransform at = AffineTransform.getScaleInstance(scale, scale);
            AffineTransformOp aop =
                new AffineTransformOp(at, AffineTransformOp.TYPE_BICUBIC);
            g2.drawImage(img, aop, defaultBounds, defaultBounds);
        }
        else
            g2.drawImage(img, defaultBounds, defaultBounds, null);
        adjustPreferredSize(false);
    }
    else{
        adjustPreferredSize(true);
    }



}
}

以及我如何加载图像:

public class ImageWorkerController {
ImageWorkerView view;
ImageModel model;


public ImageWorkerController(ImageWorkerView workerView) {
    this.view = workerView;
    this.model = ApplicationContext.getObject(ImageModel.class);

    //Load image
    ApplicationContext.getObject(Context.class).addPropertyChangeListener(new PropertyChangeListener() {
        public void propertyChange(PropertyChangeEvent evt) {
            if(Context.IMAGE_LOADED.equals(evt.getPropertyName())){
                view.setImage((File) evt.getNewValue());
                view.repaint();
            }
        }
    });

public void setWindowHeight(int h){
    model.setDrawingWindowHeight(h);
}

}

如您所见，有 adjustPreferredSize()方法，当第一次调用它时，它设置 preferredSize大于JScrollPane , JScrollBars出现。但当再次调用它时，它什么也不做。

有趣的是，当我手动更改分隔符的位置时JScrollBars出现，在下面的屏幕上有一个示例:

http://s17.postimage.org/e1nkja3zx/liliebead.jpg

所以有某种事件，使得JScrollPane更新？我尝试了几种方法:updateUI() , repaint() , revalidate() 。它们都不起作用。

知道我做错了什么吗？

Answer 1

简而言之，您需要revalidate()您的ImageWorkerView(就在您调用repaint()的地方)。这将要求组件及其父组件“重新布局”，进而触发滚动条的必要调整。