JScrollPane包含更新的图像，大小错误

Question

我正在编写一个包含JScrollPane的GUI，该GUI显示一个更新的图像（可能会修改其尺寸）。该图像位于JLabel中的ImageIcon中。使用ImageIcon.getIconWith（）和getIconHeight（）检索图像大小。 JLabel首选尺寸会根据这些尺寸进行更新。

首次启动应用程序时，JScrollPane及其滚动条具有正确的尺寸以查看整个图像（可能使用滚动）。但是当图像更新时，JScrollPane和滚动条假设图像具有前一图像的尺寸。如何让JScrollPane正确更新？

这是我的GUI的策划版本。 Visualizer.java使用GUI VisualizerGUI.java。按下“运行”按钮时，将使用ImageDrawer.drawImage()随机生成新图像（模拟实际应用程序的行为），并使用函数VisualizerGUI.setTransitionsImage(String imgPath)更新JScrollPane的内容。

Visualizer.java：

import java.util.*;
import java.io.*;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class Visualizer implements ActionListener {

    private VisualizerGUI gui = null;

    public Visualizer() {
    gui =  VisualizerGUI.createAndStart(this);
    }

    public static void main(String[] args) {
    Visualizer viz = new Visualizer();
    }

    public void actionPerformed(ActionEvent e) {
    if (e.getActionCommand().equals("Run command")) {
        run();
    }
    }

    public void run() {
    updateGUIwithSolution();
    }

    public void updateGUIwithSolution() {
    gui.initGUIupdate();
    try {
        ImageDrawer.drawImage();
        gui.setTransitionsImage("image.png");
    } catch (Exception e) {
        System.out.println("Error while generating image");
        e.printStackTrace();
    }
    gui.finalizeGUIupdate();
    }
}

VisualizerGUI.java：

import java.util.*;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

import java.awt.*;
import java.awt.event.ActionListener;
import javax.swing.*;
import java.lang.reflect.InvocationTargetException;

public final class VisualizerGUI {

    private JFrame frame;
    private JButton runButton;
    private JButton nextButton;
    private JScrollPane transitionsDisplay;
    private JTabbedPane executionsDisplay;
    private JTabbedPane tracesDisplay;
    private JTextArea textInfoArea;

    public VisualizerGUI() {}

    private void initGUI(ActionListener actionsHandler) {
        //Create and set up the window.
        frame = new JFrame("Visualizer");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel controlPanel = new JPanel(new FlowLayout());
    runButton = new JButton("Run");
    runButton.addActionListener(actionsHandler);
    runButton.setActionCommand("Run command");
    controlPanel.add(runButton);
    nextButton = new JButton("Next");
    nextButton.addActionListener(actionsHandler);
    nextButton.setActionCommand("Find next solution");
    controlPanel.add(nextButton);

    transitionsDisplay = new JScrollPane();
    executionsDisplay = new JTabbedPane();
    tracesDisplay = new JTabbedPane();

    JSplitPane ETspliter = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, executionsDisplay, tracesDisplay);
    JSplitPane graphsSpliter = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, transitionsDisplay, ETspliter);

    textInfoArea = new JTextArea();
    textInfoArea.setLineWrap(true);
    textInfoArea.setWrapStyleWord(true);
    textInfoArea.setEditable(false);
    JScrollPane textInfoAreaSP = new JScrollPane(textInfoArea);

    JSplitPane topSpliter = new JSplitPane(JSplitPane.VERTICAL_SPLIT, graphsSpliter, textInfoAreaSP);

    transitionsDisplay.setPreferredSize(new Dimension(200,200));
    executionsDisplay.setPreferredSize(new Dimension(200,200));
    tracesDisplay.setPreferredSize(new Dimension(200,200));
    textInfoAreaSP.setPreferredSize(new Dimension(200,100));

    frame.getContentPane().setLayout(new BorderLayout());
        frame.getContentPane().add(controlPanel, BorderLayout.NORTH);
        frame.getContentPane().add(topSpliter, BorderLayout.CENTER);

        frame.pack();
        frame.setVisible(true);
    }

    public static VisualizerGUI createAndStart(ActionListener actionsHandler) {
    VisualizerGUI gui = new VisualizerGUI();
    final Runnable guiRunner =
        new Runnable() {
        public void run() {
            gui.initGUI(actionsHandler);
            // gui.pack();
        }
        };
    try {
        javax.swing.SwingUtilities.invokeAndWait(guiRunner);
    } catch (InterruptedException e) {
        System.out.println(">>> WARNING <<< InterruptedException while creating the GUI");
    } catch (InvocationTargetException e) {
        System.out.println(">>> WARNING <<< InvocationTargetException while creating the GUI");
    }
    return gui;
    }

    public void clear() {
    initGUIupdate();
    finalizeGUIupdate();
    }

    public void initGUIupdate() {
    // frame.setVisible(false);
    transitionsDisplay.setViewportView(null);
    executionsDisplay.removeAll();
    tracesDisplay.removeAll();
    textInfoArea.setText(null);
    }

    public void pack() {
    frame.pack();
    }

    public void finalizeGUIupdate() {
    // frame.validate();
    // frame.repaint();
    // frame.setVisible(true);
    }

    public void setTransitionsImage(String imgPath) {
    ImageIcon icon = new ImageIcon(imgPath);
    icon.getImage().flush();
    int width = icon.getIconWidth();
    int height = icon.getIconHeight();
    JLabel label = new JLabel();
    label.setVerticalAlignment(SwingConstants.CENTER);
    label.setHorizontalAlignment(SwingConstants.CENTER);
    label.setIcon(icon);
    label.setPreferredSize(new Dimension(width,height));
    //label.setPreferredSize(null);
    transitionsDisplay.setViewportView(label);
    label.revalidate();
    label.repaint();
    transitionsDisplay.getViewport().revalidate();
    transitionsDisplay.getViewport().repaint();
    transitionsDisplay.revalidate();
    // transitionsDisplay.validate();
    transitionsDisplay.repaint();
    frame.revalidate();
    // frame.validate();
    frame.repaint();
    }

    public void setTransitionsImageInED(String imgPath) {
    final Runnable guiRunner =
        new Runnable() {
        public void run() { setTransitionsImage(imgPath); }
        };
    // javax.swing.SwingUtilities.invokeLater(guiRunner);
    try {
        javax.swing.SwingUtilities.invokeAndWait(guiRunner);
    } catch (InterruptedException e) {
        System.out.println(">>> WARNING <<< InterruptedException while creating the GUI");
    } catch (InvocationTargetException e) {
        System.out.println(">>> WARNING <<< InvocationTargetException while creating the GUI");
    }
    }
}

ImageDrawer.java：

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class ImageDrawer {

    public static void drawImage() throws Exception {
    try {
        int width = 20 + (int)(Math.random() * 1000);
        int height = 20 + (int)(Math.random() * 1000);

        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
        Graphics2D ig2 = bi.createGraphics();
        ig2.setPaint(Color.blue);
        ig2.fillRect(0, 0, width, height);
        ig2.setPaint(Color.red);
        ig2.fillRect(5, 5, width - 10, height - 10);
        ig2.setPaint(Color.blue);
        ig2.drawLine(0, 0, width, height);
        ig2.drawLine(0, height, width, 0);

        ImageIO.write(bi, "PNG", new File("image.png"));

    } catch (IOException ie) {
        ie.printStackTrace();
    }   
    }
}

有人可以解释为什么我有这个问题吗？谢谢！

Answer 1

transitionsDisplay.setPreferredSize(new Dimension(200,200));
executionsDisplay.setPreferredSize(new Dimension(200,200));
tracesDisplay.setPreferredSize(new Dimension(200,200));
textInfoAreaSP.setPreferredSize(new Dimension(200,100));

不要使用setPreferredSize（...）。每个Swing组件都负责确定自己的大小。

  

使用ImageIcon.getIconWith（）和getIconHeight（）检索图像大小。 JLabel首选尺寸会根据这些尺寸进行更新。

没必要。 JLabel将再次根据Icon的大小确定自己的大小。这是在图像/图标改变时动态完成的。

当标签的首选大小大于滚动窗格的大小时，将显示滚动窗格的滚动条。让布局经理完成他们的工作。