无法在Java中创建多个多边形-仅一个
给定以下代码:无法在Java中创建多个多边形-仅一个,java,swing,jframe,awt,Java,Swing,Jframe,Awt,给定以下代码: import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Point; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; import java.util.ArrayList; i
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import java.util.Iterator;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
*
* @author X2
*
*/
public class PolygonnerJframe
{
public static void main (String[] args)
{
JFrame frame = new JFrame("Draw polygons");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(new DrawingPanel());
frame.pack();
frame.setVisible(true);
}
}
/**
* Main class
* @author X2
*
*/
class DrawingPanel extends JPanel implements MouseListener, MouseMotionListener
{
/**
*
*/
private static final long serialVersionUID = 1L;
private static final Dimension MIN_DIM = new Dimension(300, 300);
private static final Dimension PREF_DIM = new Dimension(500, 500);
private boolean polygonDone = false;
private final Point trackPoint = new Point(); // The 'dummy' point tracking the mouse
private ArrayList<Point> points = new ArrayList<Point>(); // The list of points making up a polygon
private ArrayList<Point> helper = new ArrayList<Point>(); // The list of points making up a polygon
public ArrayList<Point> copyCreate(ArrayList<Point> input , ArrayList<Point> output)
{
int i = 0;
if (output == null)
output = new ArrayList<Point>();
while (i < input.size())
{
output.add(input.get(i));
i++;
}
return output;
}
/**
* Setting the dimensions of the windows
*/
public Dimension getMinimumSize() { return MIN_DIM; }
public Dimension getPreferredSize() { return PREF_DIM; }
/**
* The only constructor needed for this class
*/
DrawingPanel()
{
super();
addMouseListener(this);
addMouseMotionListener(this);
}
/**
* The drawing itself
*/
public void paintComponent(Graphics g)
{
super.paintComponent(g);
int numPoints = points.size();
if (numPoints == 0)
return; // nothing to draw
Point prevPoint = (Point) points.get(0);
// draw polygon
Iterator<Point> it = points.iterator();
while (it.hasNext())
{
Point curPoint = (Point) it.next();
draw(g, prevPoint, curPoint);
prevPoint = curPoint;
}
// now draw tracking line or complete the polygon
if (polygonDone == true)
{
draw(g, prevPoint, (Point) points.get(0));
}
else // polygonDone == false
draw(g, prevPoint, trackPoint);
}
/**
* MouseListener interface
*/
public void mouseClicked(MouseEvent evt)
{
int x = evt.getX();
int y = evt.getY();
switch (evt.getClickCount())
{
case 1: // single-click
if (polygonDone == true)
{
this.helper = this.copyCreate(this.points, this.helper); // copy the new coordinates into the helper
points.clear();
polygonDone = false;
}
points.add(new Point(x, y));
repaint();
break;
case 2: // double-click
polygonDone = true;
points.add(new Point(x, y));
// repaint();
break;
default: // ignore anything else
break;
}
}
/**
* MouseMotionListener interface
*/
public void mouseMoved(MouseEvent evt)
{
trackPoint.x = evt.getX();
trackPoint.y = evt.getY();
repaint();
}
/**
* draw points and lines
* @param g
* @param p1
* @param p2
*/
private void draw(Graphics g, Point p1, Point p2)
{
int x1 = p1.x;
int y1 = p1.y;
int x2 = p2.x;
int y2 = p2.y;
// draw the line first so that the points
// appear on top of the line ends, not below
g.setColor(Color.green.darker());
g.drawLine(x1 + 3, y1 + 3, x2 + 3, y2 + 3);
g.drawLine(x1 + 4, y1 + 4, x2 + 4, y2 + 4);
g.drawLine(x1 + 5, y1 + 5, x2 + 5, y2 + 5);
g.setColor(Color.green);
g.fillOval(x1, y1, 8, 8);
g.setColor(Color.black);
g.fillOval(x2, y2, 8, 8);
}
public void mouseDragged(MouseEvent evt) { /* EMPTY */ }
public void mousePressed(MouseEvent evt) { /* EMPTY */ }
public void mouseReleased(MouseEvent evt) { /* EMPTY */ }
public void mouseEntered(MouseEvent evt) { /* EMPTY */ }
public void mouseExited(MouseEvent evt) { /* EMPTY */ }
}
导入java.awt.Color;
导入java.awt.Dimension;
导入java.awt.Graphics;
导入java.awt.Point;
导入java.awt.event.MouseEvent;
导入java.awt.event.MouseListener;
导入java.awt.event.MouseMotionListener;
导入java.util.ArrayList;
导入java.util.Iterator;
导入javax.swing.JFrame;
导入javax.swing.JPanel;
/**
*
*@author X2
*
*/
公共级多连接框架
{
公共静态void main(字符串[]args)
{
JFrame=新JFrame(“绘制多边形”);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(新的DrawingPanel());
frame.pack();
frame.setVisible(true);
}
}
/**
*主类
*@author X2
*
*/
类DrawingPanel扩展JPanel实现MouseListener、MouseMotionListener
{
/**
*
*/
私有静态最终长serialVersionUID=1L;
专用静态最终尺寸最小值=新尺寸(300300);
专用静态最终尺寸PREF_DIM=新尺寸(500500);
私有布尔polygonDone=false;
private final Point trackPoint=new Point();//跟踪鼠标的“虚拟”点
private ArrayList points=new ArrayList();//组成多边形的点列表
private ArrayList helper=new ArrayList();//组成多边形的点列表
公共ArrayList copyCreate(ArrayList输入,ArrayList输出)
{
int i=0;
if(输出==null)
输出=新的ArrayList();
而(i
我每次只能画一个多边形,这意味着——当我尝试开始一个新多边形时
“旧”多边形消失了,但我不明白为什么
那么如何绘制多个多边形呢
是什么导致旧多边形消失?我想可能是因为repaint()
,但我尝试不使用它,但没有任何帮助
非常感谢您的帮助通过调用
points.clear()
,多边形确实被擦除了。为了解决这个问题,您可以在一个单独的列表中使用关于先前多边形的类来维护坐标信息,该列表可以与“进行中”多边形一起绘制。这在中进行了概述。调用points.clear()
确实可以擦除多边形。为了解决这个问题,您可以在一个单独的列表中使用关于先前多边形的类来维护坐标信息,该列表可以与“进行中”多边形一起绘制。这是在中概述的。它是否与行points.clear()有关代码>?很长时间没用画布了,但我没有