0

我知道 Java RepaintManager 将合并对 repaint() 的调用，这对于 99% 的渲染来说都很好。我有一个 JPanel，我想在计时器（100 毫秒）上更新图像，以提供像视频一样的平滑渲染。在实践中，除非鼠标被移动，否则 RepaintManager 似乎会窃取/忽略所有其他 repaint() 。我想知道我必须有哪些选项来解决这个问题。我还查看了paintImmediately()，但它导致与repaint() 相同的行为，因此不是很有用。提前感谢您的有用想法！

  1. 是否可以为特定的 JPanel 创建和使用自定义 RepaintManager，并为其他所有内容使用默认值？
  2. 有没有办法让默认的 RepaintManger 确定某个面板是“脏的”，这样它会被重新绘制而不是被忽略？

下面是一些用于说明实现的代码，您会注意到（至少在我的 Linux 测试中），这些数字几乎会跳过所有其他序列。

    public class PanelRepaintIssue
    {
        private static final int kWIDTH = 200;
        private static final int kHEIGHT = 100;
        private static final int kNUM_IMAGES = 10;
        private static final int kREPAINT_DELAY = 250;

        private final JPanel _ImagePanel;
        private final BufferedImage[] _Images;
        private final Timer _Timer;

        private TimerTask _TimerTask;
        private int _Index;

        public PanelRepaintIssue()
        {
            _Index = 0;

            _ImagePanel = new JPanel()
            {
                @Override
                protected void paintComponent(Graphics g)
                {
                    super.paintComponent(g);

                    if (_Index < kNUM_IMAGES)
                    {
                        g.drawImage(_Images[_Index], 0, 0, null);
                    }
                }
            };
            _ImagePanel.setSize(new Dimension(kWIDTH, kHEIGHT));
            _ImagePanel.setPreferredSize(new Dimension(kWIDTH, kHEIGHT));

            _Images = new BufferedImage[kNUM_IMAGES];

            for (int i = 0; i < _Images.length; ++i)
            {
                _Images[i] = new BufferedImage(kWIDTH, kHEIGHT, BufferedImage.TYPE_INT_ARGB);
                Graphics2D t2d = _Images[i].createGraphics();
                t2d.setColor(Color.BLACK);
                t2d.fillRect(0, 0, kWIDTH, kHEIGHT);
                t2d.setColor(Color.RED);
                t2d.drawString(Integer.toString(i), kWIDTH/2, kHEIGHT/2);
                t2d.dispose();
            }

            _Timer = new Timer(this.getClass().getName());
        }

        public JPanel getPanel()
        {
            return _ImagePanel;
        }

        public void start()
        {
            if (null != _TimerTask)
            {
                _TimerTask.cancel();
                _TimerTask = null;
            }

            _TimerTask = new TimerTask()
            {
                @Override
                public void run()
                {
                    ++_Index;

                    if (_Index >= kNUM_IMAGES)
                    {
                        _Index = 0;
                    }

                    _ImagePanel.repaint();
                    // Also tried _ImagePanel.paintImmediately(0, 0, kWIDTH, kHEIGHT);
                }
            };

            _Timer.scheduleAtFixedRate(_TimerTask, 1000, kREPAINT_DELAY);
        }

        public static void main(String[] args)
        {
            PanelRepaintIssue tPanel = new PanelRepaintIssue();
            tPanel.start();
            JFrame tFrame = new JFrame("PanelRepaintIssue");
            tFrame.add(tPanel.getPanel());
            tFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            tFrame.setResizable(false);
            tFrame.pack();
            tFrame.setVisible(true);
        }
    }
4

2 回答 2

0

我仍然不确定绘画问题是什么。

我对您的代码进行了一些更改。

  1. 我使用该SwingUtilities invokeLater方法将 Swing 组件的创建和执行放在事件调度线程(EDT) 上。

  2. 我从paintComponent方法中删除了除绘画代码之外的所有内容。paintComponent除了绘画之外，该方法不应该发生任何其他事情。

这是我运行的代码。

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Timer;
import java.util.TimerTask;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class PanelRepaintIssue {
    private static final int kWIDTH = 200;
    private static final int kHEIGHT = 100;
    private static final int kNUM_IMAGES = 10;
    private static final int kREPAINT_DELAY = 250;

    private final JPanel _ImagePanel;
    private final BufferedImage[] _Images;
    private final Timer _Timer;

    private TimerTask _TimerTask;
    private int _Index;
    private int _TimerCnt;
    private int _PaintCnt;

    public PanelRepaintIssue() {
        _Index = 0;
        _TimerCnt = 0;
        _PaintCnt = 0;

        _ImagePanel = new JPanel() {

            private static final long serialVersionUID = 1L;

            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);

//              if (_Index < kNUM_IMAGES) {
                    g.drawImage(_Images[_Index], 0, 0, null);
                    ++_PaintCnt;
//                  System.out.println("Timer: " + _TimerCnt + 
//                          " Paint: " + _PaintCnt);
//              }
            }
        };
        _ImagePanel.setSize(new Dimension(kWIDTH, kHEIGHT));
        _ImagePanel.setPreferredSize(
                new Dimension(kWIDTH, kHEIGHT));

        _Images = new BufferedImage[kNUM_IMAGES];

        for (int i = 0; i < _Images.length; ++i) {
            _Images[i] = new BufferedImage(kWIDTH, kHEIGHT, 
                    BufferedImage.TYPE_INT_ARGB);
            Color color = new Color(128, 128, 20 * i);
            Graphics g = _Images[i].getGraphics();
            g.setColor(color);
            g.fillRect(0, 0, kWIDTH, kHEIGHT);
            g.dispose();
        }

        _Timer = new Timer(this.getClass().getName());
    }

    public JPanel getPanel() {
        return _ImagePanel;
    }

    public void start() {
        if (null != _TimerTask) {
            _TimerTask.cancel();
            _TimerTask = null;
        }

        _TimerTask = new TimerTask() {
            @Override
            public void run() {
                ++_TimerCnt;
                ++_Index;

                if (_Index >= kNUM_IMAGES) {
                    _Index = 0;
                }

                _ImagePanel.repaint();

                System.out.println("Timer: " + _TimerCnt + 
                        " Paint: " + _PaintCnt);
                // Also tried _ImagePanel.paintImmediately
                //    (0, 0, kWIDTH, kHEIGHT);
            }
        };

        _Timer.scheduleAtFixedRate(_TimerTask, 1000, 
                kREPAINT_DELAY);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                PanelRepaintIssue tPanel = 
                        new PanelRepaintIssue();
                tPanel.start();
                JFrame tFrame = new JFrame("PanelRepaintIssue");
                tFrame.add(tPanel.getPanel());
                tFrame.setDefaultCloseOperation(
                        JFrame.EXIT_ON_CLOSE);
                tFrame.setResizable(false);
                tFrame.pack();
                tFrame.setVisible(true);
            }   
        });
    }
}

编辑：根据评论中提供的新信息而不是原始问题，我重新编写了代码。

我没看出问题。这是printlnfromTimer方法的最后 4 行。

Timer: 200 Paint: 201
Timer: 201 Paint: 202
Timer: 202 Paint: 203
Timer: 203 Paint: 205

如您所见，数字是同步的，除了最后一行。差异可能是由于我通过 Eclipse 取消程序造成的。

这是修改后的代码。我仍然没有看到这个问题。

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Timer;
import java.util.TimerTask;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class PanelRepaintIssue {
    private static final int kWIDTH = 300;
    private static final int kHEIGHT = 200;
    private static final int kNUM_IMAGES = 10;
    private static final int kREPAINT_DELAY = 250;

    private final JPanel _ImagePanel;
    private final BufferedImage[] _Images;
    private final Timer _Timer;

    private TimerTask _TimerTask;
    private int _Index;
    private int _TimerCnt;
    private int _PaintCnt;

    public PanelRepaintIssue() {
        _Index = 0;
        _TimerCnt = 0;
        _PaintCnt = 0;

        _ImagePanel = new JPanel() {

            private static final long serialVersionUID = 1L;

            @Override
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.drawImage(_Images[_Index], 0, 0, null);
                ++_PaintCnt;
            }
        };
        _ImagePanel.setSize(new Dimension(kWIDTH, kHEIGHT));
        _ImagePanel.setPreferredSize(
                new Dimension(kWIDTH, kHEIGHT));

        _Images = new BufferedImage[kNUM_IMAGES];

        int x = kWIDTH / 2;
        int y = kHEIGHT / 2;

        for (int i = 0; i < _Images.length; ++i) {
            _Images[i] = new BufferedImage(kWIDTH, kHEIGHT, 
                    BufferedImage.TYPE_INT_ARGB);
            String text = Integer.toString(i + 1);
            Graphics g = _Images[i].getGraphics();
            g.setFont(g.getFont().deriveFont(80f));
            g.setColor(Color.BLACK);
            g.drawString(text, x, y);
            g.dispose();
        }

        _Timer = new Timer(this.getClass().getName());
    }

    public JPanel getPanel() {
        return _ImagePanel;
    }

    public void start() {
        if (null != _TimerTask) {
            _TimerTask.cancel();
            _TimerTask = null;
        }

        _TimerTask = new TimerTask() {
            @Override
            public void run() {
                ++_TimerCnt;
                ++_Index;

                if (_Index >= kNUM_IMAGES) {
                    _Index = 0;
                }

                updateImagePanel();

                System.out.println("Timer: " + _TimerCnt + 
                        " Paint: " + _PaintCnt);
            }
        };

        _Timer.scheduleAtFixedRate(_TimerTask, 1000, 
                kREPAINT_DELAY);
    }

    private void updateImagePanel() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                _ImagePanel.repaint();
            }
        });
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                PanelRepaintIssue tPanel = 
                        new PanelRepaintIssue();
                tPanel.start();
                JFrame tFrame = new JFrame("PanelRepaintIssue");
                tFrame.add(tPanel.getPanel());
                tFrame.setDefaultCloseOperation(
                        JFrame.EXIT_ON_CLOSE);
                tFrame.setResizable(false);
                tFrame.pack();
                tFrame.setVisible(true);
            }   
        });
    }
}

再次编辑：我在准备午餐时运行了您的代码。这是println输出的最后几行。

Timer: 4037 Paint: 4038
Timer: 4038 Paint: 4040
Timer: 4039 Paint: 4040
Timer: 4040 Paint: 4041
Timer: 4041 Paint: 4042
Timer: 4042 Paint: 4043

如您所见，没有一帧动画被丢弃。在每帧 250 毫秒的情况下，Swing 重绘管理器可以毫无问题地绘制图像。

只是为了好玩，我将kREPAINT_DELAY每帧减少到 10 毫秒。那是100帧/秒。

这是该测试中的 println 行。

Timer: 1104 Paint: 1105
Timer: 1105 Paint: 1106
Timer: 1106 Paint: 1107
Timer: 1107 Paint: 1108
Timer: 1108 Paint: 1109
Timer: 1109 Paint: 1110

同样，没有丢失一帧。

问题可能出在您的代码中，而不是 Swing 重绘管理器中。

于 2020-05-06T21:13:33.467 回答
0

该问题最终成为特定于 Linux 的平台，可能还有其他问题，但仅测试了 Linux。通过使用以下方法更正或避免了该问题：

_ImagePanel.repaint();
Toolkit.getDefaultToolkit().sync();

Toolkit.getDefaultToolkit().sync() 的添加确保 repaint() 实际上更新了屏幕上的图像。

于 2020-05-19T21:28:07.073 回答