deyou
124 lines
3.1 KiB
Java
124 lines
3.1 KiB
Java
package mouse;
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import java.awt.*;
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import java.awt.event.*;
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import java.awt.geom.*;
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import java.util.*;
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import javax.swing.*;
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/**
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* A component with mouse operations for adding and removing squares.
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*/
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public class MouseComponent extends JComponent
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{
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private static final int DEFAULT_WIDTH = 300;
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private static final int DEFAULT_HEIGHT = 200;
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private static final int SIDELENGTH = 10;
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private ArrayList<Rectangle2D> squares;
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private Rectangle2D current; // the square containing the mouse cursor
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public MouseComponent()
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{
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squares = new ArrayList<>();
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current = null;
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addMouseListener(new MouseHandler());
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addMouseMotionListener(new MouseMotionHandler());
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}
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public Dimension getPreferredSize() { return new Dimension(DEFAULT_WIDTH, DEFAULT_HEIGHT); }
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public void paintComponent(Graphics g)
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{
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Graphics2D g2 = (Graphics2D) g;
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// draw all squares
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for (Rectangle2D r : squares)
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g2.draw(r);
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}
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/**
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* Finds the first square containing a point.
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* @param p a point
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* @return the first square that contains p
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*/
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public Rectangle2D find(Point2D p)
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{
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for (Rectangle2D r : squares)
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{
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if (r.contains(p)) return r;
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}
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return null;
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}
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/**
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* Adds a square to the collection.
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* @param p the center of the square
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*/
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public void add(Point2D p)
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{
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double x = p.getX();
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double y = p.getY();
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current = new Rectangle2D.Double(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH,
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SIDELENGTH);
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squares.add(current);
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repaint();
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}
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/**
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* Removes a square from the collection.
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* @param s the square to remove
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*/
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public void remove(Rectangle2D s)
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{
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if (s == null) return;
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if (s == current) current = null;
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squares.remove(s);
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repaint();
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}
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private class MouseHandler extends MouseAdapter
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{
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public void mousePressed(MouseEvent event)
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{
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// add a new square if the cursor isn't inside a square
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current = find(event.getPoint());
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if (current == null) add(event.getPoint());
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}
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public void mouseClicked(MouseEvent event)
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{
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// remove the current square if double clicked
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current = find(event.getPoint());
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if (current != null && event.getClickCount() >= 2) remove(current);
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}
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}
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private class MouseMotionHandler implements MouseMotionListener
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{
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public void mouseMoved(MouseEvent event)
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{
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// set the mouse cursor to cross hairs if it is inside
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// a rectangle
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if (find(event.getPoint()) == null) setCursor(Cursor.getDefaultCursor());
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else setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
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}
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public void mouseDragged(MouseEvent event)
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{
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if (current != null)
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{
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int x = event.getX();
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int y = event.getY();
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// drag the current rectangle to center it at (x, y)
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current.setFrame(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH, SIDELENGTH);
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repaint();
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}
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}
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}
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}
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