如何从拇指上取消 JSlider 进度指示器的链接？

Question

我使用 JSlider 来显示应用程序的进度，以便它随着特定进程的计算而更新。

我希望用户能够将拇指向后拖动到过去的刻度线，但是当发生这种情况时，我希望进度指示器保持在当前位置。

// A dismal attempt at drawing the situation
Progress: ---------
Thumb:            |

// User drags backwards.  What I have:
Progress: ---
Thumb:       |

// What I want instead:
Progress: ---------
Thumb:       |

任何人都可以提供有关如何最好地实现这一目标的任何指导吗？ 预先感谢所有帮助！

Answer 1

啊，我明白你的意思了。不幸的是，没有办法做到这一点。

“蓝色条”实际上并不是 JSlider 的一部分，它是 Metal LAF 的一部分。这只是 Metal LAF 选择绘制组件的方式。如果您尝试使用另一个 LAF，则根本看不到该条。

您需要将 JProgressBar 和 JSlider 结合起来才能获得您想要的效果，

您需要对其进行调整以使其看起来正确。

import java.awt.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.swing.event.ChangeListener;

public class ProgressSlider extends javax.swing.JPanel
{
    private JProgressBar progressBar;
    private JSlider slider;
    public ProgressSlider() {
        this(0, 100);
    }
    public ProgressSlider(int min, int max) {
        setLayout(new GridBagLayout());

        GridBagConstraints gbc;
        gbc = new GridBagConstraints();
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        slider = new JSlider(min, max, min);
        progressBar = new JProgressBar(min, max);
        add(slider, gbc);
        add(progressBar, gbc);
    }
    public void setValue(int n) {
        boolean adjSlider = slider.getValue() == progressBar.getValue();
        progressBar.setValue(n);
        if (adjSlider)
            slider.setValue(n);
    }
    public int getValue() {
        return progressBar.getValue();
    }
    public int getSliderValue() {
        return slider.getValue();
    }
    public void syncSlider() {
        slider.setValue(progressBar.getValue());
    }
    public void addChangeListener(ChangeListener l) {
        slider.addChangeListener(l);
    }
    public void removeChangeListener(ChangeListener l) {
        slider.removeChangeListener(l);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JFrame jf = new JFrame();
                jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                final ProgressSlider ps = new ProgressSlider();
                final JTextField tf = new JTextField(4);
                final JButton jb = new JButton(new AbstractAction("Set") {
                    public void actionPerformed(ActionEvent e) {
                        ps.setValue(Integer.parseInt(tf.getText()));
                    }});
                JPanel jp = new JPanel();
                jp.add(tf);
                jp.add(jb);
                jf.getContentPane().add(ps, BorderLayout.CENTER);
                jf.getContentPane().add(jp, BorderLayout.SOUTH);
                jf.pack();
                jf.setVisible(true);
            }
        });
    }
}

Answer 2

我想通了。我扩展了 JSlider 以单独跟踪当前拇指位置的进度，然后重写 MetalSliderUI 的 PaintTrack 方法以将轨道绘制到我想要的位置。

这是解决方案，去掉了重要部分。

新的进度条：

public class ProgressSlider extends JSlider {
    protected int progress;
    private static final String uiClassID = "ProgressSliderUI";

    public ProgressSlider() {
        progress = 0;
        putClientProperty("JSlider.isFilled", Boolean.TRUE);
        updateUI();
    }
    public void updateUI() {
        setUI(new ProgressSliderUI(this));
    }
    public String getUIClassID() {
        return uiClassID;
    }

    public int getProgress() {
        return this.progress;
    }

    public void setProgress(int value) {
        if (value < this.getMinimum()) {
            this.progress = this.getMinimum();
        }
        else if (value > this.getMaximum()) {
            this.progress = this.getMaximum();
        }
        else {
            this.progress = value;
        }
    }
}

新的用户界面：
请注意，仅在 UI 类中的 PaintTrack() 方法中添加了 2 行，紧跟在注释后面。

public class ProgressSliderUI extends MetalSliderUI {

    public ProgressSliderUI() {
        super();
    }

    public ProgressSliderUI(JSlider b) {
    }

    @Override
    public void paintTrack(Graphics g) {
        Color trackColor = !slider.isEnabled() ? MetalLookAndFeel
                .getControlShadow() : Color.blue;

        boolean leftToRight = true;

        g.translate(trackRect.x, trackRect.y);

        int trackLeft = 0;
        int trackTop = 0;
        int trackRight = 0;
        int trackBottom = 0;

        // Draw the track
        if (slider.getOrientation() == JSlider.HORIZONTAL) {
            trackBottom = (trackRect.height - 1) - getThumbOverhang();
            trackTop = trackBottom - (getTrackWidth() - 1);
            trackRight = trackRect.width - 1;
        }
        else {
            if (leftToRight) {
                trackLeft = (trackRect.width - getThumbOverhang())
                        - getTrackWidth();
                trackRight = (trackRect.width - getThumbOverhang()) - 1;
            }
            else {
                trackLeft = getThumbOverhang();
                trackRight = getThumbOverhang() + getTrackWidth() - 1;
            }
            trackBottom = trackRect.height - 1;
        }

        if (slider.isEnabled()) {
            g.setColor(MetalLookAndFeel.getControlDarkShadow());
            g.drawRect(trackLeft, trackTop, (trackRight - trackLeft) - 1, 
                                           (trackBottom - trackTop) - 1);

            g.setColor(MetalLookAndFeel.getControlHighlight());
            g.drawLine(trackLeft + 1, trackBottom, trackRight, trackBottom);
            g.drawLine(trackRight, trackTop + 1, trackRight, trackBottom);

            g.setColor(MetalLookAndFeel.getControlShadow());
            g.drawLine(trackLeft + 1, trackTop + 1, 
                                            trackRight - 2, trackTop + 1);
            g.drawLine(trackLeft + 1, trackTop + 1, trackLeft + 1, 
                                                          trackBottom - 2);
        }
        else {
            g.setColor(MetalLookAndFeel.getControlShadow());
            g.drawRect(trackLeft, trackTop, (trackRight - trackLeft) - 1, 
                                            (trackBottom - trackTop) - 1);
        }

        // Draw the fill
        if (filledSlider) {
            int middleOfThumb = 0;
            int fillTop = 0;
            int fillLeft = 0;
            int fillBottom = 0;
            int fillRight = 0;

            if (slider.getOrientation() == JSlider.HORIZONTAL) {
                middleOfThumb = thumbRect.x + (thumbRect.width / 2);
                middleOfThumb -= trackRect.x; // To compensate for the
                // g.translate()
                fillTop = !slider.isEnabled() ? trackTop : trackTop + 1;
                fillBottom = !slider.isEnabled() ? trackBottom - 1
                        : trackBottom - 2;

                if (!drawInverted()) {
                    fillLeft = !slider.isEnabled() ? trackLeft : trackLeft + 1;

                    // THIS IS THE CHANGE OF NOTE:
                    // Fills the progress with the value from the custom slider
                    fillRight = xPositionForValue(((ProgressSlider) slider)
                            .getProgress());
                    fillRight -= trackRect.x;
                }
                else {
                    fillLeft = middleOfThumb;
                    fillRight = !slider.isEnabled() ? trackRight - 1
                            : trackRight - 2;
                }
            }
            else {
                middleOfThumb = thumbRect.y + (thumbRect.height / 2);
                middleOfThumb -= trackRect.y; // To compensate for the
                // g.translate()
                fillLeft = !slider.isEnabled() ? trackLeft : trackLeft + 1;
                fillRight = !slider.isEnabled() ? trackRight - 1
                        : trackRight - 2;

                if (!drawInverted()) {
                    fillTop = middleOfThumb;
                    fillBottom = !slider.isEnabled() ? trackBottom - 1
                            : trackBottom - 2;
                }
                else {
                    fillTop = !slider.isEnabled() ? trackTop : trackTop + 1;
                    fillBottom = middleOfThumb;
                }
            }

            if (slider.isEnabled()) {
                g.setColor(slider.getBackground());
                g.drawLine(fillLeft, fillTop, fillRight, fillTop);
                g.drawLine(fillLeft, fillTop, fillLeft, fillBottom);

                g.setColor(trackColor);
                g.fillRect(fillLeft + 1, fillTop + 1, fillRight
                                - fillLeft, fillBottom - fillTop);
            }
            else {
                g.setColor(MetalLookAndFeel.getControlShadow());
                g.fillRect(fillLeft, fillTop, fillRight - fillLeft, 
                                      trackBottom - trackTop);
            }
        }

        g.translate(-trackRect.x, -trackRect.y);
    }

}

并让驱动程序对其进行测试：

public class ProgressExample extends JFrame
{
    public ProgressExample()
    {
        super("Progress Example");

        ProgressSlider mSlider = new ProgressSlider();
        mSlider.setMinimum(0);
        mSlider.setMaximum(100);
        mSlider.setValue(20);
        mSlider.setProgress(50);

        getContentPane().setLayout(new FlowLayout());
        getContentPane().add(slider);
        getContentPane().add(mSlider);
    }
    public static void main(String args[])
    {
        ProgressExample f = new ProgressExample();
        f.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e)
            {
                System.exit(0);
            }
        });
        f.setSize(300, 80);
        f.show();
    }
}

Answer 3

好吧，我不明白这怎么可能。您将需要自定义滑块 UI 并更改模型，因为您不需要存储两条模型信息：“跟踪值”和“拇指值”。

如果你想要一个大技巧，那么你可以在另一个之上绘制两个滑块。底部滑块用于轨道值，顶部滑块用于拇指值。

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.plaf.metal.*;

public class SliderTest extends JFrame
{
    public SliderTest()
    {
        JSlider bottom = createSlider();
        bottom.setUI( new MySliderUI1() );

        JSlider top = createSlider();
        top.setUI( new MySliderUI2() );
        top.setOpaque(false);

        JPanel panel = new JPanel();
        panel.setLayout( new OverlapLayout() );
        panel.add( bottom );
        panel.add( top );

        getContentPane().add( panel );
    }

    private JSlider createSlider()
    {
        JSlider slider = new JSlider(2, 50);
        slider.createStandardLabels(10, 5);
        slider.setMajorTickSpacing(10);
        slider.setPaintTicks(true);
        slider.setPaintLabels(true);
        slider.setValue(20);

        return slider;
    }

    class MySliderUI1 extends MetalSliderUI
    {
        public void paintThumb(Graphics g) {}
    }

    class MySliderUI2 extends MetalSliderUI
    {
        public void paintTrack(Graphics g) {}
    }

    public static void main(String[] args)
    {
        JFrame frame = new SliderTest();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
        frame.pack();
        frame.setLocationRelativeTo( null );
        frame.setVisible( true );
     }
}

您还需要重叠布局。如何使它们保持同步取决于您。该解决方案有很多缺陷，但它可能会给您一些想法。