Question

我正在尝试在java中创建一个小型绘图工具。我希望用户绘制的颜色在选择按钮时更改。我试图设置我的按钮来做到这一点。但是当我运行应用程序并选择一个按钮时，颜色不会改变。我该如何解决这个问题？

myJPanel.java

$rootScope.$on('$stateChangeStart', 
  function(event, toState, toParams, fromState, fromParams) {

    var alreadyGoingToLogin = toState.name === "login";
    if(alreadyGoingToLogin) {
      return
    }
    ...

Answer 1

使用不用于绘画的图形。

无论如何，不要这样绘制，覆盖paintComponent方法以使其绘制您喜欢的内容，并在需要绘制时调用repaint：

public class myJPanel extends JPanel implements MouseMotionListener, ActionListener
{
    JButton red, blue, yellow, eraser;
    JPanel p1;
    Color currentColor;
    int x, y;
    public myJPanel() {
        setBackground(Color.white);
        setLayout(new BorderLayout());
        p1 = new JPanel();
        p1.setLayout(new GridLayout(3,3));
        yellow = new JButton("Yellow");
        eraser = new JButton("Eraser");
        p1.add(yellow);
        p1.add(eraser);
        add(p1,"South");
        addMouseMotionListener(this);
    }

    public void paintComponent(Graphics g) { // draw something on request
        g.setColor(currentColor);
        g.fillRect(x, y, 5, 5);
    }
    public void mouseDragged(MouseEvent evt)
    {
        Point pt = evt.getPoint();
        x = pt.x;
        y = pt.y;
        repaint(); // a new point to draw, please call me back...
     }

    @Override
    public void actionPerformed(ActionEvent event) {
      Object obj = event.getSource();
      String choice = event.getActionCommand();

      if (obj == yellow) {
        currentColor = Color.yellow);
      }
      if (obj == eraser) {
        currentColor = Color.white);
      }
  }
}

Java代码：创建绘图应用程序

1 个答案: