单击激活pen java paint

Question

所以我用java做了一个绘图应用程序。然而，不是单击并按住，然后拖动来绘制一些东西。相反，我想单击以激活画笔/笔，它将绘制到我使用鼠标的任何位置，然后再次单击以停用画笔/笔。

public class DrawArea extends JComponent {

private Image image;
private Graphics2D g2;

// Mouse coordinates
private int currentX, currentY, oldX, oldY;    


public DrawArea() {

addMouseListener(new MouseAdapter() {
    public void mousePressed(MouseEvent e) {
        // save coord x,y when mouse is pressed
        oldX = e.getX();
        oldY = e.getY();
    }
});

addMouseMotionListener(new MouseMotionAdapter() {
    public void mouseDragged(MouseEvent e) {
        // coord x,y when drag mouse
        currentX = e.getX();
        currentY = e.getY();

        if (g2 != null) {
        // draw oval if g2 context not null
        g2.drawOval(oldX, oldY, 20, 20);
        g2.fillOval(oldX, oldY, 20, 20);

        // refresh draw area to repaint
        repaint();
        // store current coords x,y as olds x,y
        oldX = currentX;
        oldY = currentY;
        }
    }
});

Answer 1

创建一个在单击时激活、运行到再次单击的变量，将该变量设置为false。这就是我要做的。