我不确定如何使用一个类型形状的arraylist存储多个不同的形状。这是主要的。
public class A1 {
public static boolean rDraw = false;
public static boolean eDraw = false;
public static boolean lDraw = false;
public static void main(String[] args) {
JFrame frame = new JFrame();
JButton rect = new JButton("Rectangle");
rect.addActionListener(new ActionListener (){
public void actionPerformed(ActionEvent e){
if(e.getSource()==rect){
rDraw = true;
eDraw = false;
lDraw = false;
}
}
});
JButton ellipse = new JButton("Ellipse");
ellipse.addActionListener(new ActionListener (){
public void actionPerformed(ActionEvent e){
if(e.getSource()==ellipse){
rDraw = false;
eDraw = true;
lDraw = false;
}
}
});
JButton edge = new JButton("Edge");
edge.addActionListener(new ActionListener (){
public void actionPerformed(ActionEvent e){
if(e.getSource() == edge){
rDraw = false;
eDraw = false;
lDraw = true;
}
}
});
JButton label = new JButton("Label");
JTextField labelField = new JTextField(20);
JPanel panel = new JPanel();
panel.add(rect);
panel.add(ellipse);
panel.add(edge);
panel.add(label);
panel.add(labelField);
frame.add(panel,BorderLayout.NORTH);
JComponent canvas = new Canvas();
frame.add(canvas,BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(600, 600);
frame.setTitle("Graph Draw");
frame.setVisible(true);
}
}
在我的画布中，我不确定如何使用drawShape？以及要在paintComponent中存储形状的内容。
public class Canvas extends JComponent {
private Point p,p2;
private Rectangle r;
private Ellipse2D ep;
private Line2D l;
ArrayList<Shape> shapes = new ArrayList<Shape>();
public Canvas(){
class MyMouseListener implements MouseListener{
@Override
public void mouseClicked(MouseEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void mouseEntered(MouseEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent e) {
if(A1.rDraw == true && A1.eDraw == false && A1.lDraw == false){
p = e.getPoint();
r = new Rectangle(p.x, p.y, p.x - p.x, p.y - p.y);
}
else if (A1.rDraw == false && A1.eDraw == true && A1.lDraw == false){
p = e.getPoint();
ep = new Ellipse2D.Double(p.x, p.y, p.x - p.x, p.y - p.y);
}
else if (A1.rDraw == false && A1.eDraw == false && A1.lDraw == true){
p = e.getPoint();
l = new Line2D.Double(p.x, p.y, p.x - p.x, p.y - p.y);
}
}
@Override
public void mouseReleased(MouseEvent e) {
if(A1.rDraw == true && A1.eDraw == false && A1.lDraw == false){
if (r.width != 0 || r.height != 0)
{
addRectangle(r);
}
r = null;
}
else if (A1.rDraw == false && A1.eDraw == true && A1.lDraw == false){
if (ep.getWidth() != 0 || ep.getHeight() != 0){
addEllipse(ep);
}
ep = null;
}
else if (A1.rDraw == false && A1.eDraw == false && A1.lDraw == true){
if (l.getP1() != null || l.getP2() != null){
addLine(l);
}
l = null;
}
}
}
class MyMouseMotionListener implements MouseMotionListener{
@Override
public void mouseDragged(MouseEvent e) {
if(A1.rDraw == true && A1.eDraw == false && A1.lDraw == false){
int x = Math.min(p.x, e.getX());
int y = Math.min(p.y, e.getY());
int width = Math.abs(p.x - e.getX());
int height = Math.abs(p.y - e.getY());
r.setBounds(x, y, width, height);
repaint();
}
else if (A1.rDraw == false && A1.eDraw == true && A1.lDraw == false){
int x = Math.min(p.x, e.getX());
int y = Math.min(p.y, e.getY());
int width = Math.abs(p.x - e.getX());
int height = Math.abs(p.y - e.getY());
ep.setFrame(x, y, width, height);
repaint();
}
else if (A1.rDraw == false && A1.eDraw == false && A1.lDraw == true){
p2 = e.getPoint();
l.setLine(p, p2);
repaint();
}
}
@Override
public void mouseMoved(MouseEvent arg0) {
// TODO Auto-generated method stub
}
}
MouseListener mListener = new MyMouseListener();
addMouseListener(mListener);
MouseMotionListener mmListener = new MyMouseMotionListener();
addMouseMotionListener(mmListener);
}
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (Shape shape:shapes){
}
if(A1.rDraw == true && A1.eDraw == false && A1.lDraw == false){
g2d.draw(r);
}
else if (A1.rDraw == false && A1.eDraw == true && A1.lDraw == false){
g2d.draw(ep);
}
else if (A1.rDraw == false && A1.eDraw == false && A1.lDraw == true){
g2d.draw(l);
}
}
public void addRectangle(Rectangle rect){
if(r != null){
Rectangle cR = new Rectangle(rect);
shapes.add(cR);
repaint();
}
}
public void addEllipse(Ellipse2D ellipse){
if (ep != null){
Ellipse2D cEp = new Ellipse2D.Double(ellipse.getX(),ellipse.getY(),ellipse.getWidth(),ellipse.getHeight());
shapes.add(cEp);
repaint();
}
}
public void addLine(Line2D line){
if(l != null){
Line2D cL = new Line2D.Double(line.getP1(), line.getP2());
shapes.add(cL);
repaint();
}
}
}
答案 0 :(得分：3)
你的paintComponent方法似乎做得太多而且太少：太少，因为它没有绘制Shapes，而且太多了，因为它试图用不应该的静态布尔字段做事。
“......以及要在paintComponent中存储形状的内容。”
这不应该是paintComponent方法的一部分。此方法用于在组件上绘制项目，仅此而已。它不应该用于程序逻辑。存储形状的代码应该在鼠标侦听器类型代码中，而不是在paintComponent中。
我认为paintComponent所需要的只是：
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (Shape shape : shapes) {
g2d.draw(shape); // !! added
}
}
作为几个旁注：
java.awt.Canvas创建潜在的名称冲突，并且如果您将此类移动到另一个包，可能会使其他人甚至编译器感到困惑在将来。