Swing/PaintPanel のバックアップ(No.8)

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

マウス右ボタンをドラッグで消しゴム…のテスト -- terai 2010-01-12 (火) 16:16:59

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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JPanelにマウスで自由曲線を描画

サンプルコード

解説

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