Question

我的JFrame窗口具有系统外观和感觉，当我添加JSlider并单击其行时，它向前或向后移动90步，具体取决于我的鼠标位置。我希望钻石在我的鼠标下面工作，好像我点击并拖动钻石一样。

这是一个最小的程序，但我认为这只发生在Windows中，因为在默认的外观和感觉上，它没有捕捉到第90个数字，但仅前进了一个数字。

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JSlider;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;


@SuppressWarnings("serial")
public class Test extends JFrame {

    int value = 300;
    JSlider slider;
    JLabel label;

    public Test() {
        setSize(300, 200);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        label = new JLabel(String.valueOf(value));
        slider = new JSlider();
        slider.setMinimum(100);
        slider.setMaximum(1000);
        slider.setValue(value);
        slider.setSnapToTicks(false);
        slider.addChangeListener(new ChangeListener() {
            public void stateChanged(ChangeEvent e) {
                label.setText(String.valueOf(slider.getValue()));
            }
        });
        add(label, BorderLayout.NORTH);
        add(slider);
        setVisible(true);
    }

    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, UnsupportedLookAndFeelException {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        new Test();
    }
}

Answer 1

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

public class SliderMousePressed extends JPanel
{
    public SliderMousePressed()
    {
        JSlider slider = new JSlider(0, 50, 20);
        slider.setMajorTickSpacing(10);
        slider.setMinorTickSpacing(5);
        slider.setPaintTicks(true);
        slider.setPaintLabels(true);
        add(slider);

        snapToMouseClick( slider );
    }

    public static void snapToMouseClick(final JSlider slider)
    {
        MouseListener[] ml = slider.getMouseListeners();

        for (MouseListener l : ml)
            slider.removeMouseListener(l);

        MouseMotionListener[] mml = slider.getMouseMotionListeners();

        for (MouseMotionListener l : mml)
            slider.removeMouseMotionListener(l);

        final BasicSliderUI ui = (BasicSliderUI)slider.getUI();

        BasicSliderUI.TrackListener tl = ui.new TrackListener()
        {
            //  Position slider at mouse
            @Override
            public void mouseClicked(MouseEvent e)
            {
                Point p = e.getPoint();
                int value = ui.valueForXPosition(p.x);
                slider.setValue(value);
            }

            // Prevent scrolling while mouse button is held down

            @Override
            public boolean shouldScroll(int dir)
            {
                return false;
            }
        };

        slider.addMouseListener(tl);
        slider.addMouseMotionListener(tl);
    }

    private static void createAndShowUI()
    {

        JFrame frame = new JFrame("SliderMousePressed");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add( new SliderMousePressed() );
        frame.setLocationByPlatform( true );
        frame.pack();
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

此示例基于此answer，稍加修改以删除/添加MouseMotionListener以及MouseListener，以使拇指滑块的绘制与默认行为更加一致。现在，当拖动拇指时，拇指将绘制在与鼠标相同的相对位置，而不是在左侧。

JSlider捕捉每90个数字

1 个答案: