java中的简单十字线
我必须画一个简单的十字线。我看到的只是一块空白的面板java中的简单十字线,java,swing,graphics,Java,Swing,Graphics,我必须画一个简单的十字线。我看到的只是一块空白的面板 class ChartPanel extends JPanel implements MouseMotionListener{ Graphics2D g; Dimension dimFrame; ChartPanel() { addMouseMotionListener(this); } public void mouseMoved(MouseEvent e) { dra
class ChartPanel extends JPanel implements MouseMotionListener{
Graphics2D g;
Dimension dimFrame;
ChartPanel() {
addMouseMotionListener(this);
}
public void mouseMoved(MouseEvent e) {
drawCrosshair(e.getX(),e.getY());
}
public void mouseDragged(MouseEvent e) {}
protected void paintComponent(Graphics g2) {
g = (Graphics2D)g2;
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
dimFrame = getSize();
setBackground(Color.WHITE);
}
public Dimension getPreferredSize() {
return new Dimension(700, 500);
}
void drawCrosshair(double x, double y) {
double maxx = dimFrame.getWidth();
double maxy = dimFrame.getHeight();
g.setPaint(Color.BLACK);
g.draw(new Line2D.Double(0, y, maxx, y));
g.draw(new Line2D.Double(x, 0, x, maxy));
}
}
public class pra {
public static void main(String[] args) {
JFrame jFrame = new JFrame();
ChartPanel chartPanel = new ChartPanel();
jFrame.add(chartPanel);
jFrame.pack();
jFrame.setVisible(true);
jFrame.setExtendedState(Frame.MAXIMIZED_BOTH);
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
它将以正确的值进入drawCrosshair()方法。我不知道我做错了什么 您只需处理
drawCrosshair()
,然后在paint
方法中绘制十字线,这将取代paintComponent
方法(实际上我认为您不应该重写paintComponent
):
这应该可以做到(事实上,我已经测试过了;)小提示:与其覆盖
getPreferredSize
,不如使用所需的维度调用setPreferredSize
。它工作了吗?@byxor:。另请参见。不要将图形上下文g
保存为实例变量。如果这不是重复的问题,请编辑您的问题以包括一个显示您修改过的方法的问题。“Swing程序应该覆盖paintComponent()
,而不是覆盖paint()
”。另见。为我工作。但我不明白我的代码出了什么问题?
Graphics2D g;
Dimension dimFrame;
int x, y;
ChartPanel() {
addMouseMotionListener(this);
setPreferredSize(new Dimension(700, 500));
}
public void mouseMoved(MouseEvent e) {
x = e.getX();
y = e.getY();
repaint();
}
public void mouseDragged(MouseEvent e) {
}
public void paint(Graphics g2) {
super.paint(g2);
g = (Graphics2D) g2;
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
dimFrame = getSize();
g.clearRect(0, 0, dimFrame.width, dimFrame.height);//clears previous drawings
g.setColor(Color.BLACK);
g.drawLine(x - 10, y, x + 10, y);
g.drawLine(x, y - 10, x, y + 10);
}