如果用户移动了分隔线的位置，如何让 JSplitPane 保持相同的比例位置答案

【问题标题】：How do you get JSplitPane to keep the same proportional location if the user has moved the location of the divider如果用户移动了分隔线的位置，如何让 JSplitPane 保持相同的比例位置
【发布时间】：2016-07-04 05:20:27
【问题描述】：

我无法让 JSplitPane 在调整其容器大小时保持相同的相对位置。如果假设拆分窗格具有固定位置，则一切正常。我可以使用下面显示的代码使分隔线位置保持接近相同的相对位置，但是当 JFrame 调整大小时分隔线会向左移动。如果 JFrame 的大小调整缓慢，则偏移会更大。如果 JFrame 变小或变大，则向左移动。

如何让分隔线保持在完全相同的比例位置？

这是 GUI 最初的样子。

这是几次调整大小后的样子。

这就是代码的样子。此尝试基于此处提供的信息：

JSplitPane splitting 50% precisely

JSplitPane SetDividerLocation Problem

https://docs.oracle.com/javase/tutorial/uiswing/components/splitpane.html

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSplitPane;

public class Example {

    public static void main(String[] args) {
        new Example().showGui();
    }

    private void showGui() {
        // create the jframe
        JFrame jFrame = new JFrame();
        jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jFrame.setSize(400, 200);
        // create the left and right panels
        JPanel left = new JPanel();
        left.setBackground(Color.yellow);
        JPanel right = new JPanel();
        right.setBackground(Color.orange);
        ResizableSplitPane split = new ResizableSplitPane(JSplitPane.HORIZONTAL_SPLIT, left, right, jFrame);
        jFrame.getContentPane().add(split);
        // show the gui
        jFrame.setVisible(true);
    }

    public class ResizableSplitPane extends JSplitPane {

        //
        // instance variables
        //

        private boolean painted;

        private double defaultDividerLocation;

        private ResizableSplitPane resizableSplitPane = this;

        private double currentDividerLocation;

        private Component first;

        private Component second;

        private boolean dividerPositionCaptured = false;

        //
        // constructors
        //

        public ResizableSplitPane(int splitType, Component first, Component second, Component parent) {
            this(splitType, first, second, parent, 0.5);
        }

        public ResizableSplitPane(int splitType, Component first, Component second, Component parent, double defaultDividerLocation) {
            super(splitType, first, second);
            this.defaultDividerLocation = defaultDividerLocation;
            this.currentDividerLocation = defaultDividerLocation;
            this.setResizeWeight(defaultDividerLocation);
            this.first = first;
            this.second = second;
            parent.addComponentListener(new DividerLocator());
            first.addComponentListener(new DividerMovedByUserComponentAdapter());
        }

        //
        // trivial getters and setters
        //

        public double getDefaultDividerLocation() {
            return defaultDividerLocation;
        }

        public void setDefaultDividerLocation(double defaultDividerLocation) {
            this.defaultDividerLocation = defaultDividerLocation;
        }

        //
        // implementation
        //

        @Override
        public void paint(Graphics g) {
            super.paint(g);
            if (!painted) {
                painted = true;
                this.setDividerLocation(currentDividerLocation);
            }
            dividerPositionCaptured = false;
        }

        private class DividerLocator extends ComponentAdapter {
            @Override
            public void componentResized(ComponentEvent e) {
                setDividerLocation(currentDividerLocation);
            }
        }

        private class DividerMovedByUserComponentAdapter extends ComponentAdapter {
            @Override
            public void componentResized(ComponentEvent e) {
                if (dividerPositionCaptured == false) {
                    dividerPositionCaptured = true;
                    currentDividerLocation = (double) first.getWidth() / (double) (first.getWidth() + second.getWidth());
                    System.out.println(currentDividerLocation);
                }
            }
        }

    }

}

【问题讨论】：

我假设当您说“在完全相同的比例位置” 时，您的意思是如果拆分器位于中间，则在调整大小期间它会停留在中间？

标签： java swing jsplitpane

【解决方案1】：

这是我的尝试：
- 覆盖JSplitPane的父组件的doLayout方法，在JSplitPane大小调整完成后，调整分隔线的位置。

import java.awt.*;
import java.awt.event.*;
import java.math.BigDecimal;
import javax.swing.*;

public class Example2 {
  public static void main(String[] args) {
    EventQueue.invokeLater(() -> {
      JFrame f = new JFrame();
      f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
      f.getContentPane().add(new Example2().makeUI());
      f.setSize(400, 240);
      f.setLocationRelativeTo(null);
      f.setVisible(true);
    });
  }
  private JComponent makeUI() {
    JPanel p = new JPanel(new GridLayout(0, 1, 0, 0));

    JPanel left1 = new JPanel();
    left1.setBackground(Color.YELLOW);
    JPanel right1 = new JPanel();
    right1.setBackground(Color.ORANGE);
    JSplitPane split1 = new ResizableSplitPane(
        JSplitPane.HORIZONTAL_SPLIT, left1, right1, p);
    p.add(split1);

    JPanel left2 = new JPanel();
    left2.setBackground(Color.YELLOW);
    JPanel right2 = new JPanel();
    right2.setBackground(Color.ORANGE);
    JSplitPane split2 = new JSplitPane(
        JSplitPane.HORIZONTAL_SPLIT, left2, right2);
    p.add(new SplitPaneWrapper(split2));

    return p;
  }
}

class ResizableSplitPane extends JSplitPane {
  //
  // instance variables
  //

  private boolean painted;

  private double defaultDividerLocation;

  private ResizableSplitPane resizableSplitPane = this;

  private double currentDividerLocation;

  private Component first;

  private Component second;

  private boolean dividerPositionCaptured = false;

  //
  // constructors
  //

  public ResizableSplitPane(int splitType, Component first, Component second, Component parent) {
    this(splitType, first, second, parent, 0.5);
  }

  public ResizableSplitPane(int splitType, Component first, Component second, Component parent, double defaultDividerLocation) {
    super(splitType, first, second);
    this.defaultDividerLocation = defaultDividerLocation;
    this.currentDividerLocation = defaultDividerLocation;
    this.setResizeWeight(defaultDividerLocation);
    this.first = first;
    this.second = second;
    parent.addComponentListener(new DividerLocator());
    first.addComponentListener(new DividerMovedByUserComponentAdapter());
  }

  //
  // trivial getters and setters
  //

  public double getDefaultDividerLocation() {
    return defaultDividerLocation;
  }

  public void setDefaultDividerLocation(double defaultDividerLocation) {
    this.defaultDividerLocation = defaultDividerLocation;
  }

  //
  // implementation
  //

  @Override
  public void paint(Graphics g) {
    super.paint(g);
    if (!painted) {
      painted = true;
      this.setDividerLocation(currentDividerLocation);
    }
    dividerPositionCaptured = false;
  }

  private class DividerLocator extends ComponentAdapter {
    @Override
    public void componentResized(ComponentEvent e) {
      setDividerLocation(currentDividerLocation);
    }
  }

  private class DividerMovedByUserComponentAdapter extends ComponentAdapter {
    @Override
    public void componentResized(ComponentEvent e) {
      if (dividerPositionCaptured == false) {
        dividerPositionCaptured = true;
        currentDividerLocation = (double) first.getWidth() / (double)(first.getWidth() + second.getWidth());
        System.out.println(currentDividerLocation);
      }
    }
  }

}

class SplitPaneWrapper extends JPanel {
  private final JSplitPane splitPane;
  protected SplitPaneWrapper(JSplitPane splitPane) {
    super(new BorderLayout());
    this.splitPane = splitPane;
    splitPane.setResizeWeight(.5);
    add(splitPane);
  }
  private static int getOrientedSize(JSplitPane sp) {
    return sp.getOrientation() == JSplitPane.VERTICAL_SPLIT
           ? sp.getHeight() - sp.getDividerSize()
           : sp.getWidth()  - sp.getDividerSize();
  }
  @Override public void doLayout() {
    int size = getOrientedSize(splitPane);
    double d = splitPane.getDividerLocation() / (double) size;
    BigDecimal bd = new BigDecimal(d).setScale(2, BigDecimal.ROUND_HALF_UP);
    super.doLayout();
    if (splitPane.isShowing()) {
      EventQueue.invokeLater(() -> {
        int s = getOrientedSize(splitPane);
        int iv = (int)(.5 + s * bd.doubleValue());
        splitPane.setDividerLocation(iv);
      });
    }
  }
}

【讨论】：

我的项目仅限于 Java 1.7，因此无法为我编译 lambda 表达式。
@John 用匿名内部类替换它们。了解更多 here 和 here。

【解决方案2】：

这就是我最终使用的。它似乎完全按照我的计划做：创建一个按比例调整大小的拆分窗格，包括在移动分隔线后按比例调整大小。

这是示例 gui 在调整大小之前和之后的样子：

这就是代码的样子。这是一个完整的示例，包括按比例调整水平和垂直拆分窗格的拆分窗格大小以及用户移动分隔线的情况。

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSplitPane;

public class Example {

    public static void main(String[] args) {
        new Example().showGui();
    }

    private void showGui() {
        // create the jframe
        JFrame jFrame = new JFrame();
        jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jFrame.setSize(400, 200);
        // create the left panel
        JPanel left = new JPanel();
        left.setBackground(Color.yellow);
        // create the right panel
        JPanel right = new JPanel();
        right.setBackground(Color.orange);
        // create the bottom panel
        JPanel bottom = new JPanel();
        bottom.setBackground(Color.green);
        // create the split panes
        ResizableSplitPane horizontalSplit = new ResizableSplitPane(JSplitPane.HORIZONTAL_SPLIT, left, right, jFrame);
        ResizableSplitPane verticalSplit = new ResizableSplitPane(JSplitPane.VERTICAL_SPLIT, horizontalSplit, bottom, jFrame);
        jFrame.getContentPane().add(verticalSplit);
        // show the gui
        jFrame.setVisible(true);
    }

    public class ResizableSplitPane extends JSplitPane {

        //
        // instance variables
        //

        private boolean painted;

        private double defaultDividerLocation;

        private double dividerProportionalLocation;

        private int currentDividerLocation;

        private Component first;

        private Component second;

        private boolean dividerPositionCaptured = false;

        //
        // constructors
        //

        public ResizableSplitPane(int splitType, Component first, Component second, Component parent) {
            this(splitType, first, second, parent, 0.5);
        }

        public ResizableSplitPane(int splitType, Component first, Component second, Component parent, double defaultDividerLocation) {
            super(splitType, first, second);
            this.defaultDividerLocation = defaultDividerLocation;
            this.dividerProportionalLocation = defaultDividerLocation;
            this.setResizeWeight(defaultDividerLocation);
            this.first = first;
            this.second = second;
            parent.addComponentListener(new DividerLocator());
            second.addComponentListener(new DividerMovedByUserComponentAdapter());
        }

        //
        // trivial getters and setters
        //

        public double getDefaultDividerLocation() {
            return defaultDividerLocation;
        }

        public void setDefaultDividerLocation(double defaultDividerLocation) {
            this.defaultDividerLocation = defaultDividerLocation;
        }

        //
        // implementation
        //

        @Override
        public void paint(Graphics g) {
            super.paint(g);
            if (painted == false) {
                painted = true;
                this.setDividerLocation(dividerProportionalLocation);
                this.currentDividerLocation = this.getDividerLocation();
            }
        }

        private class DividerLocator extends ComponentAdapter {
            @Override
            public void componentResized(ComponentEvent e) {
                setDividerLocation(dividerProportionalLocation);
                currentDividerLocation = getDividerLocation();
            }
        }

        private class DividerMovedByUserComponentAdapter extends ComponentAdapter {
            @Override
            public void componentResized(ComponentEvent e) {
                System.out.println("RESIZED: " + dividerPositionCaptured);
                int newDividerLocation = getDividerLocation();
                boolean dividerWasMovedByUser = newDividerLocation != currentDividerLocation;
                System.out.println(currentDividerLocation + "\t" + newDividerLocation + "\t" + dividerProportionalLocation);
                if (dividerPositionCaptured == false || dividerWasMovedByUser == true) {
                    dividerPositionCaptured = true;
                    painted = false;
                    if(getOrientation() == JSplitPane.HORIZONTAL_SPLIT) {
                        dividerProportionalLocation = (double) first.getWidth() / (double) (first.getWidth() + second.getWidth());
                    } else {
                        dividerProportionalLocation = (double) first.getHeight() / (double) (first.getHeight() + second.getHeight());

                    }
                    System.out.println(dividerProportionalLocation);
                }
            }
        }

    }

}

【讨论】：