我使用NetBeans(JDK 1.7)在Windows 8.1中運行該應用程序:風俗畫的JPanel抵消繪圖
- 採用
Graphics
對象draw a frog在400x400的JPanel
的paintComponent()
; - 將面板添加到
JFrame
用於顯示目的;
這當然應該是一個非常簡單的任務,但我無法理解此應用程序中的特定行爲。
下面是問題:第一次顯示窗口時,面板顯示在一個偏移量(下圖),當它不應該。我試圖理解爲什麼會發生,以及如何解決它:
的一個箭頭鍵之後按下鍵盤上的圖紙被移位5個像素左/右/上/下。但是,當發生這種情況時,整個JPanel
似乎被移動到窗口的(0,0)座標處(這是我從一開始就預期的),因此移動繪圖比它應該多得多:
我在面板的邊緣畫了一個黑色的邊框,使問題更加明顯。
這裏是Short, Self Contained, Correct (Compilable), Example:
KAfrog.java:
import javax.swing.SwingUtilities;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class KAfrog
{
public static void main(String args[])
{
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
} // end of anonymous innerclass
); // end of invokeLater
}
private static void createAndShowGUI()
{
System.out.println("Created GUI on EDT? " + SwingUtilities.isEventDispatchThread());
Window janela = new Window("Khan Academy Frog");
janela.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
} // end of anonymous innerclass
); // end of addWindowListener
}
}
Window.java:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;
class DrawingPanel extends JPanel
{
private int x = 50, y = 50;
public DrawingPanel() {
super();
setBorder(new LineBorder(Color.BLACK));
}
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
public void setX(int x) {
if (x < 0 || x >= 400)
return;
this.x = x;
repaint();
}
public void setY(int y) {
if (y < 0 || y >= 400)
return;
this.y = y;
repaint();
}
public int getX() { return this.x; }
public int getY() { return this.y; }
public void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("DrawingPanel::paintComponent: drawing at x:" + x + " y:" + y);
System.out.println("DrawingPanel::paintComponent: panel size " + getWidth() + "x" + getHeight());
// face
Color green = new Color(30, 204, 91);
g.setColor(green);
g.fillOval(x, y, 200, 100);
// mouth
g.setColor(Color.BLACK); // g.setColor(new Color(0, 0, 0));
g.fillOval(x+25, y+25, 150, 50);
// left eye
g.setColor(green);
g.fillOval(x+30, y-30, 45, 45); // background
g.setColor(Color.WHITE);
g.fillOval(x+35, y-25, 35, 35); // white eye sockets
g.setColor(Color.BLACK);
g.fillOval(x+48, y-15, 10, 10); // black eyes pretos
// right eye
g.setColor(green);
g.fillOval(x+110, y-30, 45, 45); // background
g.setColor(Color.WHITE);
g.fillOval(x+115, y-25, 35, 35); // white eye sockets
g.setColor(Color.BLACK);
g.fillOval(x+128, y-15, 10, 10); // black eyes
}
}
public class Window extends JFrame
{
DrawingPanel frog_panel;
public Window(String title)
{
super(title);
frog_panel = new DrawingPanel();
addKeyListener(new KeyListener() {
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_LEFT)
frog_panel.setX(frog_panel.getX()-5);
if (e.getKeyCode() == KeyEvent.VK_RIGHT)
frog_panel.setX(frog_panel.getX()+5);
if (e.getKeyCode() == KeyEvent.VK_UP)
frog_panel.setY(frog_panel.getY()-5);
if (e.getKeyCode() == KeyEvent.VK_DOWN)
frog_panel.setY(frog_panel.getY()+5);
}
public void keyReleased(KeyEvent e) { }
public void keyTyped(KeyEvent e) { }
}
);
add(frog_panel);
pack();
setVisible(true);
System.out.println("Window::Window: size is " + getWidth() + "x" + getHeight());
}
}
有誰知道爲什麼會這樣,以及如何解決它?
+1非常感謝! – karlphillip 2014-09-28 20:25:30