我目前在其中一项任务中遇到了很多困难。这项任务的任务是使用java的GUI功能创建一个航空雷达VOR。当用户按下键盘上的左/右箭头时，圆形雷达应该旋转，雷达中间的针应该向左/向右移动。 我很接近完成，但我被困在一个部分。我画了雷达的图像，我试图在它上面划一条线。但是，当我能够使所有JPanel透明时，我才成功。这会导致问题，因为很难看到我在它上面绘制的内容。 所以，我的问题是，如何在不使一切透明的情况下在雷达图像上绘制它？以下是我的代码
public class finalVORGUI extends JPanel{
private JPanel rotationPanel;
private JPanel needle;
private JPanel attributes;
private int degrees;
private String CurrentRadial;
private int x;
private int y1;
private int y2;
final int WIDTH = 600;
final int HEIGHT = 600;
private ImageIcon radar = new ImageIcon("image/vor1.png");
/**
* The constructor for the class
* It's going to set the dimension of the program to 600x600, the
* background is going to be white (in order to blend in with the
* vor image), and it is going to add in the VOR radar and a radial
* indicator that will let the user know which radial he/she is on
*/
public finalVORGUI(){
JLayeredPane lp = new JLayeredPane();
lp.setPreferredSize(new Dimension(WIDTH, HEIGHT));
setBackground(Color.white);
lp.setLayout(null);
lp.setFocusable(true);
lp.addKeyListener(new KeyboardListener());
rotationPanel = new JPanel();
rotationPanel = new TurningCanvas();
needle = new JPanel();
needle = new DrawNeedle();
attributes = new JPanel();
attributes = new DrawAttributes();
lp.add(rotationPanel, Integer.valueOf(1));
lp.add(needle, Integer.valueOf(2));
lp.add(attributes, Integer.valueOf(3));
needle.setBounds(100,0, needle.getPreferredSize().width, needle.getPreferredSize().height);
rotationPanel.setBounds(100, 100, rotationPanel.getPreferredSize().width, rotationPanel.getPreferredSize().height);
attributes.setBounds(100, 100, rotationPanel.getPreferredSize().width, rotationPanel.getPreferredSize().height);
add(lp);
degrees = 360; //to edit: this is going to be the radial the radar is currently facing
x = 172; //x is the location of the needle
y1 = 155;
y2 = 330;
CurrentRadial = "Radial: " + degrees; //A string that is always going to be above the radar. it's going to let the user know the current radial
}
public void paintComponent(Graphics g){
super.paintComponent(g);
g.drawString(CurrentRadial, 250, 100);
}
public class DrawAttributes extends JPanel{
public DrawAttributes(){
setOpaque(false);
add(new Attributes());
}
public class Attributes extends JPanel{
int w = 500;
int h = 400;
public Attributes(){
setPreferredSize(new Dimension(w,h));
setBackground(Color.white);
}
public void paintComponent(Graphics g){
Graphics2D g2 = (Graphics2D) g;
g2.drawString("To",300,400);
g2.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, 0.3f));
g2.setStroke(new BasicStroke(3));
super.paintComponent (g);
g2.dispose();
}
}
}
public class DrawNeedle extends JPanel{ //todo: make sure this works and adds correctly to the LayeredPane
public DrawNeedle(){
setOpaque(false);
add(new Needle());
}
public class Needle extends JPanel{
int w = 500;
int h = 400;
public Needle(){
setPreferredSize(new Dimension(w,h));
setBackground(Color.white);
}
private void doDrawing(Graphics g){
Graphics2D g4 = (Graphics2D) g;
g4.drawString("TO", 190, 200);
g4.drawString("FROM",190, 300);
}
public void paintComponent(Graphics g){
Graphics2D g2 = (Graphics2D) g;
RenderingHints hints = new RenderingHints(null);
hints.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
hints.put(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2.setRenderingHints(hints);
g2.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, 0.3f));
g2.setStroke(new BasicStroke(3));
doDrawing(g);
g2.drawLine(x,y1,x,y2);
super.paintComponent (g);
g2.dispose();
}
}
}
public class TurningCanvas extends JPanel{
public TurningCanvas(){
setOpaque(false);
add(new TurningImage());
}
public class TurningImage extends JPanel{
int w = radar.getIconWidth()- 20;
int h = radar.getIconHeight() -20;
public TurningImage(){
setPreferredSize(new Dimension(w,h));
setBackground(Color.white);
}
public void paintComponent(Graphics g){
super.paintComponent (g);
Graphics2D g2 = (Graphics2D) g;
RenderingHints hints = new RenderingHints(null);
hints.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
hints.put(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2.setRenderingHints(hints);
g2.rotate (Math.toRadians(degrees),w/2, h/2);
g2.drawImage(radar.getImage(), 0, 0, this);
//g2.drawLine(171,0,x,300);
g2.dispose();
}
}
}
/**
* This is the keyboard listener that this program will be using
* Depending on what the user wishes, or what type of keyboard they have,
* they will be able to find their desired radial by using the arrow keys
* or the "a" and "d" buttons. Left arrow to minus radial, right arrow to plus radial, etc etc...
*
*/
public class KeyboardListener implements KeyListener{
public void keyPressed (KeyEvent event) {
if(event.getKeyCode() == KeyEvent.VK_LEFT){
degrees--;
x--;
if(degrees <= 0){
degrees = 360;
}
if(x <= 89){
x = 89;
}
CurrentRadial = "Radial: " + degrees;
repaint();
}
if(event.getKeyCode() == KeyEvent.VK_RIGHT){
degrees++;
x++;
if(degrees >= 360){
degrees = 1;
}
if(x >= 250){
x = 250;
}
CurrentRadial = "Radial: " + degrees;
repaint();
}
}
public void keyTyped (KeyEvent event) {}
public void keyReleased (KeyEvent event) {}
}
/**
* The main method of this class
* This is going to make a new JFrame, which will hold the new
* VOR radar
* @param args
*/
public static void main(String[] args){
finalVORGUI test = new finalVORGUI();
JFrame frame = new JFrame("VOR Radar");
frame.setContentPane(test);
frame.pack();
frame.setVisible(true);
}
}