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如何在java swing中创建可调整大小的矩形？

分类: 技术问答 • 2022-06-10 16:31:34
问题描述：

我需要在一个项目中添加一个小功能，其中包含一些可拼写文本的矩形，矩形应该可以调整大小。

I need to add a small feature in a project where, rectangle with some trimable text in it, and the rectangle should be resizable.

我缺少时间所以没有尝试阅读和工作很多。
我需要知道如何去做。

I'm short of time so didnt try out reading and working on it much. I need some idea how to go for it.

提前致谢。

-Uday

答

我从网上得到了以下示例，我不是此代码示例的所有者。我忘了它在哪里得到这个。无论如何希望这会对你有所帮助：

I got the following example from online only, I am not the owner of this code sample. I forgot it where did I get this. Anyway hope this would help you:

Resizable.java 

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Cursor;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;

import javax.swing.JComponent;
import javax.swing.event.MouseInputAdapter;
import javax.swing.event.MouseInputListener;

// Resizable.java

public class Resizable extends JComponent {

  public Resizable(Component comp) {
    this(comp, new ResizableBorder(8));
  }

  public Resizable(Component comp, ResizableBorder border) {
    setLayout(new BorderLayout());
    add(comp);
    addMouseListener(resizeListener);
    addMouseMotionListener(resizeListener);
    setBorder(border);
  }

  private void resize() {
      if (getParent() != null) {
        ((JComponent)getParent()).revalidate();
      }
  }

  MouseInputListener resizeListener = new MouseInputAdapter() {
    public void mouseMoved(MouseEvent me) {
      if (hasFocus()) {
          ResizableBorder border = (ResizableBorder)getBorder();
          setCursor(Cursor.getPredefinedCursor(border.getCursor(me)));
      }
    }

    public void mouseExited(MouseEvent mouseEvent) {
       setCursor(Cursor.getDefaultCursor());
    }

    private int cursor;
    private Point startPos = null;

    public void mousePressed(MouseEvent me) {
      ResizableBorder border = (ResizableBorder)getBorder();
      cursor = border.getCursor(me);
      startPos = me.getPoint();
      requestFocus();
      repaint();
    }

    public void mouseDragged(MouseEvent me) {

      if (startPos != null) {

        int x = getX();
        int y = getY();
        int w = getWidth();
        int h = getHeight();

        int dx = me.getX() - startPos.x;
        int dy = me.getY() - startPos.y;

        switch (cursor) {
          case Cursor.N_RESIZE_CURSOR:
            if (!(h - dy < 50)) {
              setBounds(x, y + dy, w, h - dy);
              resize();
            }
            break;

          case Cursor.S_RESIZE_CURSOR:
            if (!(h + dy < 50)) {
              setBounds(x, y, w, h + dy);
              startPos = me.getPoint();
              resize();
            }
            break;

          case Cursor.W_RESIZE_CURSOR:
            if (!(w - dx < 50)) {
              setBounds(x + dx, y, w - dx, h);
              resize();
            }
            break;

          case Cursor.E_RESIZE_CURSOR:
            if (!(w + dx < 50)) {
              setBounds(x, y, w + dx, h);
              startPos = me.getPoint();
              resize();
            }
            break;

          case Cursor.NW_RESIZE_CURSOR:
            if (!(w - dx < 50) && !(h - dy < 50)) {
              setBounds(x + dx, y + dy, w - dx, h - dy);
              resize();
            }
            break;

          case Cursor.NE_RESIZE_CURSOR:
            if (!(w + dx < 50) && !(h - dy < 50)) {
              setBounds(x, y + dy, w + dx, h - dy);
              startPos = new Point(me.getX(), startPos.y);
              resize();
            }
            break;

          case Cursor.SW_RESIZE_CURSOR:
            if (!(w - dx < 50) && !(h + dy < 50)) {
              setBounds(x + dx, y, w - dx, h + dy);
              startPos = new Point(startPos.x, me.getY());
              resize();
            }
            break;

          case Cursor.SE_RESIZE_CURSOR:
            if (!(w + dx < 50) && !(h + dy < 50)) {
              setBounds(x, y, w + dx, h + dy);
              startPos = me.getPoint();
              resize();
            }
          break;

          case Cursor.MOVE_CURSOR:
            Rectangle bounds = getBounds();
            bounds.translate(dx, dy);
            setBounds(bounds);
            resize();
          }


          setCursor(Cursor.getPredefinedCursor(cursor));
        }
     }

   public void mouseReleased(MouseEvent mouseEvent) {
     startPos = null;
    }
  };
}

ResizableBorder.java 

import java.awt.Color;
import java.awt.Component;
import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;

import javax.swing.SwingConstants;
import javax.swing.border.Border;

// ResizableBorder.java

public class ResizableBorder implements Border {
  private int dist = 8;

  int locations[] =
  {
    SwingConstants.NORTH, SwingConstants.SOUTH, SwingConstants.WEST,
    SwingConstants.EAST, SwingConstants.NORTH_WEST,
    SwingConstants.NORTH_EAST, SwingConstants.SOUTH_WEST,
    SwingConstants.SOUTH_EAST
  };

  int cursors[] =
  {
    Cursor.N_RESIZE_CURSOR, Cursor.S_RESIZE_CURSOR, Cursor.W_RESIZE_CURSOR,
    Cursor.E_RESIZE_CURSOR, Cursor.NW_RESIZE_CURSOR, Cursor.NE_RESIZE_CURSOR,
    Cursor.SW_RESIZE_CURSOR, Cursor.SE_RESIZE_CURSOR
  };

  public ResizableBorder(int dist) {
    this.dist = dist;
  }

  public Insets getBorderInsets(Component component) {
      return new Insets(dist, dist, dist, dist);
  }

  public boolean isBorderOpaque() {
      return false;
  }

  public void paintBorder(Component component, Graphics g, int x, int y,
                          int w, int h) {
      g.setColor(Color.black);
      g.drawRect(x + dist / 2, y + dist / 2, w - dist, h - dist);

      if (component.hasFocus()) {


        for (int i = 0; i < locations.length; i++) {
          Rectangle rect = getRectangle(x, y, w, h, locations[i]);
          g.setColor(Color.WHITE);
          g.fillRect(rect.x, rect.y, rect.width - 1, rect.height - 1);
          g.setColor(Color.BLACK);
          g.drawRect(rect.x, rect.y, rect.width - 1, rect.height - 1);
        }
      }
  }

  private Rectangle getRectangle(int x, int y, int w, int h, int location) {
      switch (location) {
      case SwingConstants.NORTH:
          return new Rectangle(x + w / 2 - dist / 2, y, dist, dist);
      case SwingConstants.SOUTH:
          return new Rectangle(x + w / 2 - dist / 2, y + h - dist, dist,
                               dist);
      case SwingConstants.WEST:
          return new Rectangle(x, y + h / 2 - dist / 2, dist, dist);
      case SwingConstants.EAST:
          return new Rectangle(x + w - dist, y + h / 2 - dist / 2, dist,
                               dist);
      case SwingConstants.NORTH_WEST:
          return new Rectangle(x, y, dist, dist);
      case SwingConstants.NORTH_EAST:
          return new Rectangle(x + w - dist, y, dist, dist);
      case SwingConstants.SOUTH_WEST:
          return new Rectangle(x, y + h - dist, dist, dist);
      case SwingConstants.SOUTH_EAST:
          return new Rectangle(x + w - dist, y + h - dist, dist, dist);
      }
      return null;
  }

  public int getCursor(MouseEvent me) {
      Component c = me.getComponent();
      int w = c.getWidth();
      int h = c.getHeight();

      for (int i = 0; i < locations.length; i++) {
          Rectangle rect = getRectangle(0, 0, w, h, locations[i]);
          if (rect.contains(me.getPoint()))
              return cursors[i];
      }

      return Cursor.MOVE_CURSOR;
  }
}

示例实施： ResizableComponent.java 

    import java.awt.Color;
    import java.awt.Dimension;
    import java.awt.event.MouseAdapter;
    import java.awt.event.MouseEvent;

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


    /* ResizableComponent.java */



 public class ResizableComponent extends JFrame {

      private JPanel panel = new JPanel(null);
      private Resizable resizer;


      public ResizableComponent() {

          add(panel);

          JPanel area = new JPanel();
          area.setBackground(Color.white);
          resizer = new Resizable(area);
          resizer.setBounds(50, 50, 200, 150);
          panel.add(resizer);


          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          setSize(new Dimension(350, 300));
          setTitle("Resizable Component");
          setLocationRelativeTo(null);

          addMouseListener(new MouseAdapter() {
            public void mousePressed(MouseEvent me) {

              requestFocus();
              resizer.repaint();
            }
          });
      }

      public static void main(String[] args) {
          ResizableComponent rc = new ResizableComponent();
          rc.setVisible(true);
      }
    }

更新：ResizeRectangle.java 

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Rectangle2D;

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

public class ResizeRectangle extends JPanel {

    private int SIZE = 8;
    private Rectangle2D[] points = {new Rectangle2D.Double(50, 50, SIZE, SIZE), new Rectangle2D.Double(150, 100, SIZE, SIZE)};
    Rectangle2D s = new Rectangle2D.Double();
    ShapeResizeHandler ada = new ShapeResizeHandler();

    public ResizeRectangle() {
        addMouseListener(ada);
        addMouseMotionListener(ada);
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        Graphics2D g2 = (Graphics2D) g;

        for (int i = 0; i < points.length; i++) {
            g2.fill(points[i]);
        }
        s.setRect(points[0].getCenterX(), points[0].getCenterY(),
                Math.abs(points[1].getCenterX() - points[0].getCenterX()),
                Math.abs(points[1].getCenterY() - points[0].getCenterY()));

        g2.draw(s);
    }

    class ShapeResizeHandler extends MouseAdapter {

        Rectangle2D r = new Rectangle2D.Double(0, 0, SIZE, SIZE);
        private int pos = -1;

        public void mousePressed(MouseEvent event) {
            Point p = event.getPoint();

            for (int i = 0; i < points.length; i++) {
                if (points[i].contains(p)) {
                    pos = i;
                    return;
                }
            }
        }

        public void mouseReleased(MouseEvent event) {
            pos = -1;
        }

        public void mouseDragged(MouseEvent event) {
            if (pos == -1) {
                return;
            }

            points[pos].setRect(event.getPoint().x, event.getPoint().y, points[pos].getWidth(),
                    points[pos].getHeight());
            repaint();
        }
    }

    public static void main(String[] args) {

        JFrame frame = new JFrame("Resize Rectangle");

        frame.add(new ResizeRectangle());
        frame.setSize(300, 300);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

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