Java JApplet呈現問題

Question

我對JApplet有問題。代碼工作得很好，但是當我將它從JFrame轉換爲JApplet時，渲染部分停止正常工作。基本上我試圖做的是簡單的繪製應用程序。啓動applet時，一半時間repaint（）不起作用（沒有灰色背景;必須將鼠標放在按鈕上才能更新其顏色等），而且像素渲染部分根本沒有顯示出來。下面的代碼：

Frame類（JApplet的）

package painter; 

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.Toolkit; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.MouseAdapter; 
import java.awt.event.MouseEvent; 
import java.util.ArrayList; 
import javax.swing.JApplet; 
import javax.swing.JButton; 
import javax.swing.JColorChooser; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.Timer; 

public class Frame extends JApplet { 

public JPanel panel; 
private JButton plus, minus, buttonColor; 
private int scaleSize; 
private JLabel labelScale; 
private final Timer updateTimer; 
private static boolean painting = false; 
public static Color currentColor; 
public static int mode = 0; 
// 0 = draw; 1 = setcolor; 2 = erase 

private ArrayList<Pixel> pixelArray; 

public Frame() { 

    pixelArray = new ArrayList<>(); 
    for (int i = 1; i <= 8; i++) { 
     for (int j = 1; j <= 8; j++) { 
      pixelArray.add(new Pixel(i, j)); 
     } 
    } 

    setLayout(new BorderLayout()); 
    panel = new JPanel() { 

     @Override 
     public void paintComponent(Graphics g) { 
      super.paintComponent(g); 
      //g.fillRect(10, 10, 100, 100); <- test if fillRect works at all. Yus it does. 
      for (int i = 0; i < pixelArray.size(); i++) { 
       pixelArray.get(i).render(g); 
      } 
      Toolkit.getDefaultToolkit().sync(); 
      g.dispose(); 
     } 

    }; 

    //panel.setBounds(0, 0, 800, 800); 
    //add(panel); 
    getContentPane().add(panel); 
    //panel.setLayout(null); 
    //panel.setOpaque(true); 

    //panel.setDoubleBuffered(true); 
    currentColor = Color.yellow; 

    buttonColor = new JButton("Choose color"); 
    buttonColor.setBounds(10, 10, 128, 64); 
    buttonColor.setBackground(currentColor); 
    buttonColor.addActionListener(new ActionListener() { 

     @Override 
     public void actionPerformed(ActionEvent e) { 
      currentColor = JColorChooser.showDialog(null, "JColorChooser Sample", Color.gray); 
     } 

    }); 

    updateTimer = new Timer(20, new ActionListener() { 

     @Override 
     public void actionPerformed(ActionEvent e) { 
      buttonColor.setBackground(currentColor); 
      repaint(); 
     } 

    }); 
    updateTimer.start(); 
    addMouseListener(new MouseAdapter() { 
     @Override 
     public void mousePressed(MouseEvent e) { 
      painting = true; 
     } 
    }); 
    addMouseListener(new MouseAdapter() { 
     @Override 
     public void mouseReleased(MouseEvent e) { 
      painting = false; 
     } 
    }); 

    panel.add(buttonColor); 

    repaint(); 
} 

public static boolean getPaint() { 
    return painting; 
} 

public static void main(String[] args) { 
    new Frame(); 
} 
} 

這裏是像素級：

package painter; 

import java.awt.Color; 
import java.awt.Graphics; 
import java.awt.MouseInfo; 
import java.awt.Point; 

public class Pixel { 

private Color color; 
private int size; 
private int x, y, relativex, relativey; 

public Pixel(int relx, int rely) { 
    color = new Color(0x999999, false); 
    size = 32; 
    x = relx * size + 64; 
    y = rely * size + 64; 

} 

public boolean mouseOver() { 
    Point pos, mousepos; 
    pos = new Point(x, y); 
    mousepos = MouseInfo.getPointerInfo().getLocation(); 
    if ((mousepos.x > pos.x) 
      && (mousepos.x < pos.x + size) 
      && (mousepos.y > pos.y) 
      && (mousepos.y < pos.y + size)) { 
     return true; 
    } else { 
     return false; 
    } 
} 

public void render(Graphics g) { 
    g.setColor(color); 
    if (mouseOver() && Frame.getPaint()) { 

     if (Frame.mode == 0) { 
      color = Frame.currentColor; 
     } 
     if (Frame.mode == 1) { 
      Frame.currentColor = color; 
     } 
     if (Frame.mode == 2) { 
      color = new Color(0xffffffff, true); 
     } 
    } 

    g.fillRect(x, y, size, size); 
    if (mouseOver()) { 
     g.setColor(Color.black); 
     g.drawRect(x, y, size - 1, size - 1); 
     g.setColor(Color.yellow); 
     g.drawRect(x + 1, y + 1, size - 3, size - 3); 
    } 
    //g.fillRect(10, 10, 250, 250); 
} 

} 

Answer 1

如在黑暗中刺，不叫Graphics#dipose上Graphics環境下，你沒有創建自己明確

除了事實的Graphics上下文是一個共享的資源，所有的組件使用可能需要在給定的油漆週期內進行噴漆，也可以防止在某些平臺上顯示的油漆

在15年的專業發展中，我從來沒有理由致電Toolkit.getDefaultToolkit().sync();。我懷疑它會做出多大區別，我只是說

Answer 2

Java小程序爲我們提供了這些方法

[這裏] http://docs.oracle.com/javase/tutorial/deployment/applet/appletMethods.html

該方法

public void paint(Graphics g){} 

被用作

public void paintComponent(Graphics g){} 

擺動的

替代。

Answer 3

退房http://docs.oracle.com/javase/tutorial/uiswing/painting/index.html用於執行Swing組件的風俗畫的推薦方式