Java Swing 拖动鼠标时重绘

Question

Java Swing 拖动鼠标时重绘

3

我能够帮助您进行翻译，以下是内容：

我在拖动鼠标时无法使自定义面板重新绘制。

基本上，我正在一个自定义面板上绘制自由形式的线条，并在其上添加以下处理程序：

MouseInputAdapter mia = new MouseInputAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                if(_app_split_right_buttons_radioInkBtn.isSelected()) {
                    _app_split_right_journal.StartLine();
                    _app_split_right_journal.AddLineSegment(e.getX(), e.getY());
                }
                _app_split_right_journal.repaint();
            }
            @Override
            public void mouseReleased(MouseEvent e) {
                if(_app_split_right_buttons_radioInkBtn.isSelected()) {
                    _app_split_right_journal.AddLineSegment(e.getX(), e.getY());
                    _app_split_right_journal.EndLine();
                }
                _app_split_right_journal.repaint();
            }
            @Override
            public void mouseDragged(MouseEvent e) {
                if(_app_split_right_buttons_radioInkBtn.isSelected()) {
                    _app_split_right_journal.AddLineSegment(e.getX(), e.getY());
                }
                _app_split_right_journal.repaint();
            }
        };
        _app_split_right_journal.addMouseListener(mia);
        _app_split_right_journal.addMouseMotionListener(mia);

然而，我似乎无法在拖动鼠标时重绘它，只有在释放后（线条绘制正确）才能重绘。奇怪的是，在我的拖动过程中，如果我右键单击，线条将突然开始随着我的拖动而绘制。

任何帮助都将不胜感激。

编辑：为了清晰起见，StartLine() / AddLineSegment() / EndLine() 只是将点添加到Point对象的ArrayList中，并且repaint()函数已被覆盖以循环遍历这些点并在每个点之间绘制线段。以下是代码：

public void DrawShapes(Graphics g) {
        g.setColor(Color.black);
        for(Geometry.Shape shape : _shapeList) {
            if(shape instanceof Geometry.Line) {
                ArrayList<Point> points = ((Line) shape).GetPointList();
                Point p1 = points.get(0);
                for(int i=1; i<points.size(); i++) {
                    Point p = points.get(i);
                    g.drawLine(p1.x, p1.y, p.x, p.y);
                    p1 = p;
                }
            }
}

编辑：问题已解决。原因是我在遍历行列表时忘记了，直到释放鼠标并调用EndLine()之前，我不会将当前正在绘制的线添加到该列表中。我必须在repaint()方法中添加单独的代码来绘制我当前正在绘制的形状。代码已添加到repaint()中：

if(_currentShape instanceof Geometry.Line) {
            ArrayList<Point> points = ((Line)_currentShape).GetPointList();
            Point p1 = points.get(0);
            for(int i=1; i<points.size(); i++) {
                Point p = points.get(i);
                g.drawLine(p1.x, p1.y, p.x, p.y);
                p1 = p;
            }
        }

- sichinumi

尝试在父容器上/代替调用repaint。 - MadProgrammer

1个回答

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- MadProgrammer · Accepted Answer

这是我为另一个问题做的一个示例，但它使用鼠标拖动来绘制线条到组件上...

public class PaintingExample {

    private BufferedImage bImage;
    private ImageIcon image;
    private JLabel imageLabel;
    private int xClicked = 0;
    private int yClicked = 0;
    private int xDragged = 0;
    private int yDragged = 0;
    private MouseAdapter mouseListener =
        new MouseAdapter() {
            private boolean paint = false;
            @Override
            public void mousePressed(MouseEvent me) {

                xClicked = me.getX();
                yClicked = me.getY();
                xDragged = xClicked;
                yDragged = yClicked;

                paint = true;

            }

            @Override
            public void mouseReleased(MouseEvent e) {

                xClicked = -1;
                xClicked = -1;
                xDragged = -1;
                yDragged = -1;

                paint = false;

            }

            @Override
            public void mouseMoved(MouseEvent me) {
            }

            @Override
            public void mouseDragged(MouseEvent me) {

                if (paint) {

                    xClicked = xDragged;
                    yClicked = yDragged;

                    xDragged = me.getX();
                    yDragged = me.getY();

                    xDragged = me.getX();
                    yDragged = me.getY();

                    Graphics2D g2 = bImage.createGraphics();
                    g2.setColor(Color.WHITE);
                    g2.drawLine(xClicked, yClicked, xDragged, yDragged);
                    g2.dispose();
                    imageLabel.setIcon(new ImageIcon(bImage));

                    me.getComponent().repaint();

                }

            }
        };

    public PaintingExample() {
        try {
            bImage = ImageIO.read(new URL(
                            "http://gagandeepbali.uk.to/"
                            + "gaganisonline/images/planetbackground.jpg"));
            image = new ImageIcon(bImage);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void displayGUI() {
        JFrame frame = new JFrame("Painting on Image");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel contentPane = new JPanel();
        imageLabel = new JLabel(image);
        imageLabel.addMouseListener(mouseListener);
        imageLabel.addMouseMotionListener(mouseListener);

        contentPane.add(imageLabel);

        frame.setContentPane(contentPane);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String... args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new PaintingExample().displayGUI();
            }
        });
    }
}