package control;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import javax.swing.JButton;
import elements.Circle;
import elements.Elements;
import elements.Line;
import elements.Rectangle;
public class Control implements ActionListener, MouseListener, MouseMotionListener {
Graphics g;
public String doit = "";
public int x1, y1, x2, y2; //鼠标的按下和释放时的坐标
// private Color curColor;//当前画笔颜色
ArrayList <Elements> drawX = new ArrayList <Elements>();
public ArrayList<Elements> getDrawX() {
return drawX;
}
public void setDrawX(ArrayList<Elements> drawX) {
this.drawX = drawX;
}
public void setG(Graphics g)
{
this.g= g;
}//传递画笔
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource().equals(""))
{
Color newcolor = new Color((int) e.getSource());
g.setColor(newcolor);
}
else
{
doit = e.getActionCommand();
JButton buttonblack = new JButton();
buttonblack.setBackground(java.awt.Color.black);
Color coloruse = buttonblack.getBackground();
g.setColor(coloruse);
}
}
@Override
public void mouseMoved(MouseEvent e) {
}
@Override
public void mouseClicked(MouseEvent e) {
}
@Override
public void mousePressed(MouseEvent e) {
System.out.println("2");// 鼠标点下 点x1,y1
x1 = e.getX();
y1 = e.getY();
}
@Override
public void mouseReleased(MouseEvent e) {
x2=e.getX();
y2=e.getY();
}
@Override
public void mouseEntered(MouseEvent e) {
}
@Override
public void mouseExited(MouseEvent e) {
}
@Override
public void mouseDragged(MouseEvent e) {
System.out.println("3");
if ( doit.equals("circle"))
{
drawX.add(new Circle(x1, y1, x2, y2));
}
if ( doit.equals("rectangle"))
{
drawX.add(new Rectangle(x1, y1, x2, y2));
}
if ( doit.equals("line"))
{
drawX.add(new Line(x1, y1, x2, y2));
}
}
}
=============================
package view;
import java.awt.*;
import javax.swing.*;
import control.Control;
import java.awt.event.*;
public class Gui extends JFrame {
public Control drawit;
private static final long serialVersionUID = 1L;
public Gui()
{
JFrame frame = new JFrame("miniCAD");
JPanel panelBig = new JPanel();//画板
JPanel panelSmall = new JPanel();//图形和颜色板
JSplitPane pane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, panelBig, panelSmall);
panelBig.setBackground(Color.white);
panelSmall.setBackground(Color.white);
pane.setRightComponent(panelSmall);
pane.setLeftComponent(panelBig);
pane.setContinuousLayout(true);
pane.setOneTouchExpandable(true);
// Container C = frame.getContentPane();
// C.add(pane);
frame.add(pane);
//添加图形
JButton buttoncircle = new JButton("circle");
JButton buttonline = new JButton("line");
JButton buttonrectangle = new JButton("rectangle");
JButton buttontext = new JButton("text");
JButton buttontriangle = new JButton("triangle");
frame.setVisible(true);
panelSmall.setLayout(new GridLayout(6,1,0,0));
panelSmall.add(buttoncircle);
panelSmall.add(buttonline);
panelSmall.add(buttonrectangle);
panelSmall.add(buttontext);
panelSmall.add(buttontriangle);
//监听使用哪个图形
control.Control monitor = new control.Control();
buttoncircle.addActionListener(monitor);
buttonline.addActionListener(monitor);
buttonrectangle.addActionListener(monitor);
buttontext.addActionListener(monitor);
buttontriangle.addActionListener(monitor);
//添加颜色板
JPanel colorpane = new JPanel();
panelSmall.add(colorpane);
colorpane.setLayout(new GridLayout(3,3));
JButton buttonred = new JButton();
buttonred.setBackground(Color.red);
colorpane.add(buttonred);
JButton buttonblack = new JButton();
buttonblack.setBackground(Color.black);
colorpane.add(buttonblack);
JButton buttonblue = new JButton();
buttonblue.setBackground(Color.blue);
buttonblue.setContentAreaFilled(false);
colorpane.add(buttonblue);
JButton buttongreen = new JButton();
buttongreen.setBackground(Color.green);
colorpane.add(buttongreen);
JButton buttongray = new JButton();
buttongray.setBackground(Color.gray);
colorpane.add(buttongray);
JButton buttonwhite = new JButton();
buttonwhite.setBackground(Color.white);
colorpane.add(buttonwhite);
JButton buttonyellow = new JButton();
buttonyellow.setBackground(Color.yellow);
colorpane.add(buttonyellow);
JButton buttonpink = new JButton();
buttonpink.setBackground(Color.pink);
colorpane.add(buttonpink);
JButton buttonorange = new JButton();
buttonorange.setBackground(Color.orange);
colorpane.add(buttonorange);
frame.setVisible(true);
//添加颜色监听器
control.Control color = new control.Control();
buttonred.addActionListener(color);
buttonblack.addActionListener(color);
buttonblue.addActionListener(color);
buttongreen.addActionListener(color);
buttongray.addActionListener(color);
buttonwhite.addActionListener(color);
buttonyellow.addActionListener(color);
buttonpink.addActionListener(color);
buttonorange.addActionListener(color);
control.Control drawit = new control.Control();
panelBig.addMouseListener(drawit);
panelBig.addMouseMotionListener(drawit);
drawit.setG(panelBig.getGraphics());
}
public static void main(String[] args)
{
Gui pic = new Gui();
}
}
在control类里
g.setColor(coloruse);这句报错，查了下资料，我想可能是Graphics g问题或者是JPanel问题，不知道怎么改
每次点击按钮，报错空指针异常
