TITLE:JPanelにマウスで自由曲線を描画

Posted by terai at 2005-12-19

JPanelにマウスで自由曲線を描画

マウスをドラッグしてパネル上に自由曲線を描画します。

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#screenshot

サンプルコード

class PaintPanel extends JPanel implements MouseMotionListener, MouseListener {
  private Point startPoint = new Point(-1,-1);
  private Point endPoint   = new Point(-1,-1);
  public PaintPanel() {
    super();
    addMouseMotionListener(this);
    addMouseListener(this);
  }
  public void paintComponent(Graphics g) {
    //super.paintComponent(g);
    Graphics2D g2d = (Graphics2D)g;
    g2d.setStroke(new BasicStroke(3.0F));
    g2d.setPaint(Color.BLACK);
    g2d.drawLine(startPoint.x, startPoint.y,
                 endPoint.x,   endPoint.y);
    startPoint = endPoint;
  }
  public void mouseDragged(MouseEvent e) {
    endPoint = e.getPoint();
    repaint();
  }
  public void mousePressed(MouseEvent e) {
    startPoint = e.getPoint();
  }
  public void mouseMoved(MouseEvent e) {}
  public void mouseExited(MouseEvent e) {}
  public void mouseEntered(MouseEvent e) {}
  public void mouseReleased(MouseEvent e) {}
  public void mouseClicked(MouseEvent e) {}
}

解説

上記のサンプルでは、パネル上でマウスがドラッグされている場合、その軌跡を短い直線でつなぎ合わせて描画することで、お絵かきしています。

  • マウスがクリックされた場所を始点にする
  • ドラッグされた時の位置を終点にしてパネルをrepaint
  • paintComponentをオーバーライドして、上記の始点、終点で直線を描画
  • 次の直線のための始点を現在の終点に変更

コメント

  • マウス右ボタンをドラッグで消しゴム…のテスト -- terai
    import java.awt.*;
    import java.awt.event.*;
    import java.awt.geom.*;
    import java.awt.image.*;
    import javax.swing.*;
    
    class PaintPanel2 extends JPanel implements MouseMotionListener, MouseListener {
      public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
          public void run() {
            createAndShowGUI();
          }
        });
      }
      public static void createAndShowGUI() {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.getContentPane().add(new PaintPanel2());
        frame.setSize(320, 240);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
      }
    
      private final Polygon polygon = new Polygon();
      private Point startPoint = new Point(-1,-1);
      private BufferedImage offImage = null;
      private BufferedImage backImage = null;
      private TexturePaint texture  = makeTexturePaint();
      private int[] pix = new int[320 * 240];
      public PaintPanel2() {
        super();
        addMouseMotionListener(this);
        addMouseListener(this);
        offImage = new BufferedImage(320, 240, BufferedImage.TYPE_4BYTE_ABGR);
        PixelGrabber pg = new PixelGrabber(offImage, 0, 0, 320, 240, pix, 0, 320);
        try {
          pg.grabPixels();
        } catch (Exception e) {
          e.printStackTrace();
        }
        backImage = new BufferedImage(320, 240, BufferedImage.TYPE_4BYTE_ABGR);
        Graphics2D g2 = backImage.createGraphics();
        g2.setPaint(texture);
        g2.fillRect(0,0,320,240);
        g2.dispose();
      }
    
      private static BufferedImage makeBGImage() {
        Color color = new Color(200,150,100,50);
        int cs = 6, sz = cs*cs;
        BufferedImage img = new BufferedImage(sz,sz,BufferedImage.TYPE_4BYTE_ABGR);
        Graphics2D g2 = img.createGraphics();
        g2.setPaint(color);
        g2.fillRect(0,0,sz,sz);
        for (int i=0; i*cs<sz; i++) {
          for (int j=0; j*cs<sz; j++) {
            if ((i+j)%2==0) g2.fillRect(i*cs, j*cs, cs, cs);
          }
        }
        g2.dispose();
        return img;
      }
      private static TexturePaint makeTexturePaint() {
        BufferedImage img = makeBGImage();
        int w = img.getWidth(), h = img.getHeight();
        Rectangle2D r2d = new Rectangle2D.Float(0,0,w,h);
        return new TexturePaint(img, r2d);
      }
      @Override
      public void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (backImage!=null) {
          ((Graphics2D)g).drawImage(backImage, 0, 0, this);
        }
        if (offImage!=null) {
          MemoryImageSource producer = new MemoryImageSource(320, 240, pix, 0, 320);
          g.drawImage(createImage(producer), 0, 0, null);
          g.dispose();
        }
      }
      int penc = 0x0;
      public void mouseDragged(MouseEvent e) {
        Point pt = e.getPoint();
        double xDelta = e.getX() - startPoint.getX();
        double yDelta = e.getY() - startPoint.getY();
        double delta = Math.max(Math.abs(xDelta), Math.abs(yDelta));
    
        double xIncrement = xDelta / delta;
        double yIncrement = yDelta / delta;
        double xStart = startPoint.x;
        double yStart = startPoint.y;
        for (int i=0; i<delta; i++) {
          Point p = new Point((int)xStart, (int)yStart);
          if (p.x<0 || p.y<0 || p.x>=320 || p.y>=240) break;
          pix[p.x + p.y * 320] = penc;
          for(int n=-1;n<=1;n++) {
            for(int m=-1;m<=1;m++) {
              int t = (p.x+n) + (p.y+m) * 320;
              if(t>=0 && t<320*240) {
                pix[t] = penc;
              }
            }
          }
          repaint(p.x-2, p.y-2, 4, 4);
          xStart += xIncrement;
          yStart += yIncrement;
        }
        startPoint = pt;
      }
      private Rectangle getRepaintRectangle(Point srcPoint, Point destPoint) {
        polygon.reset();
        polygon.addPoint(srcPoint.x,  srcPoint.y);
        polygon.addPoint(destPoint.x, srcPoint.y);
        polygon.addPoint(destPoint.x, destPoint.y);
        polygon.addPoint(srcPoint.x,  destPoint.y);
        return polygon.getBounds();
      }
      public void mousePressed(MouseEvent e) {
        startPoint = e.getPoint();
        penc = (e.getButton()==MouseEvent.BUTTON1)?0xff000000:0x0;
      }
      public void mouseMoved(MouseEvent e) {}
      public void mouseExited(MouseEvent e) {}
      public void mouseEntered(MouseEvent e) {}
      public void mouseReleased(MouseEvent e) {}
      public void mouseClicked(MouseEvent e) {}
    }
    
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