Warum löscht sich dieses JPanel nicht von irgendwelchen Grafiken?

Question

Ich versuche, 100 Strings mit dem angegebenen JTextField anzuzeigen, sobald ich die Draw-Taste drücke, und kann dann alle 90 Grad drehen, wenn ich den Drehknopf drücke. Wenn ich rotiere, erscheinen jedoch einige der Saiten von früher. Aber dann wird das ganze Panel gelöscht, sobald die Saiten nach unten zeigen. Warum ist das?

import java.awt.Color; 
import java.awt.Component; 
import java.awt.FlowLayout; 
import java.awt.Font; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.GridLayout; 
import java.awt.RenderingHints; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.geom.AffineTransform; 
import java.util.ArrayList; 

import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JTextField; 
import javax.swing.SwingConstants; 
public class RotateAndDraw extends JFrame implements ActionListener{ 
    // Declare all member variables 
    private JFrame window; 
    private JButton drawButton; 
    private JButton rotateButton; 
    JTextField userInput = new JTextField("Enter text here"); 
    private static JPanel p3 = new JPanel(); // Drawing surface 
    private static Graphics g = p3.getGraphics(); // Graphics context 

    private static int[] xArray = new int[100]; 
    private static int[] yArray = new int[100]; 
    private static int[] fontArray = new int[100]; 
    private static float[] colorArray = new float[100]; 

    private static int rotateCount = 0; 
    private static int theta; 
    public RotateAndDraw(){ 
     // Declare all components 
     window = new JFrame("Rotate and Draw"); 
     drawButton = new JButton("Draw"); 
     rotateButton = new JButton("Rotate"); 
     drawButton.addActionListener(this); 
     rotateButton.addActionListener(this); 
     JPanel drawingSurface = new JPanel(); 
     JLabel userInputLabel = new JLabel("Text:   "); 

     // Create some containers 
     JPanel content = new JPanel(); 
     content.setLayout(new GridLayout(3, 1)); 

     JPanel p1 = new JPanel(); 
     p1.setLayout(new GridLayout(1, 2)); 
     p1.add(drawButton); 
     p1.add(rotateButton); 

     JPanel p2 = new JPanel(); 
     p2.setLayout(new GridLayout(1, 3)); 
     userInputLabel.setHorizontalAlignment(SwingConstants.RIGHT); 
     p2.add(userInputLabel); 
     p2.add(userInput); 
     JLabel nullLabel = new JLabel(""); 
     p2.add(nullLabel); 

     p3.setBackground(Color.BLACK); 

     content.add(p1); 
     content.add(p2); 
     content.add(p3); 

     window.add(content); 
    } 

    public void run(){ 
     window.setLocation(100, 100); 
     window.setSize(10000, 10000); 
     window.setDefaultCloseOperation(EXIT_ON_CLOSE); 
     window.setVisible(true); 
    } 

    private void paintComponent(Graphics g){ 
     // TODO Auto-generated method stub 
     super.paintComponents(g); 

    } 

    @Override 
    public void actionPerformed(ActionEvent e) { 
     // TODO Auto-generated method stub 
     super.paintComponents(g); 
     Graphics2D g2 = (Graphics2D)g; 

     String message = userInput.getText(); 

     Font font1, font2, font3, font4, font5; // The five fonts. 
     font1 = new Font("Serif", Font.BOLD, 14); 
     font2 = new Font("SansSerif", Font.BOLD + Font.ITALIC, 24); 
     font3 = new Font("Monospaced", Font.PLAIN, 30); 
     font4 = new Font("Dialog", Font.PLAIN, 36); 
     font5 = new Font("Serif", Font.ITALIC, 48); 

     if(e.getSource() == drawButton){ 
      g = p3.getGraphics(); 
      g.setColor(Color.BLACK); 
      g.fillRect(0, 0, p3.getWidth(), p3.getHeight()); 

      rotateCount = 0; 

      int width = p3.getWidth(); 
      int height = p3.getHeight(); 

      for (int i = 0; i < 100; i++) { 
       int fontNum = (int)(5*Math.random()) + 1; 
       fontArray[i] = fontNum; 
       switch (fontNum) { 
       case 1: 
        g.setFont(font1); 
        break; 
       case 2: 
        g.setFont(font2); 
        break; 
       case 3: 
        g.setFont(font3); 
        break; 
       case 4: 
        g.setFont(font4); 
        break; 
       case 5: 
        g.setFont(font5); 
        break; 
       } // end switch 


       float hue = (float)Math.random(); 
       colorArray[i] = hue; 
       g.setColor(Color.getHSBColor(hue, 1.0F, 1.0F)); 


       int x,y; 
       x = (int)(Math.random()*(width)); 
       y = (int)(Math.random()*(height)); 
       xArray[i] = x; 
       yArray[i] = y; 

       // Draw the message. 
       g.drawString(message,x,y); 
      } // end for 
     }// end if 
     if(e.getSource() == rotateButton){ 
      super.paintComponents(g2); 
      g2.setColor(Color.BLACK); 
      g2.fillRect(0, 0, p3.getWidth(), p3.getHeight()); 

      rotateCount++; 
      if(rotateCount == 4){ 
       rotateCount = 0; 
      } 

      switch(rotateCount){ 
      case 0: 
       theta = 0; 
       break; 
      case 1: 
       theta = 90; 
       break; 
      case 2: 
       theta = 180; 
       break; 
      case 3: 
       theta = 270; 
       break; 
      } 

      for(int i = 0; i < 100; i++){ 
       switch(fontArray[i]){ 
       case 1: 
        g2.setFont(font1); 
        break; 
       case 2: 
        g2.setFont(font2); 
        break; 
       case 3: 
        g2.setFont(font3); 
        break; 
       case 4: 
        g2.setFont(font4); 
        break; 
       case 5: 
        g2.setFont(font5); 
        break; 
       } // end switch 

      g2.setColor(Color.getHSBColor(colorArray[i], 1.0F, 1.0F)); 

      AffineTransform at = new AffineTransform(); 
      at.rotate(Math.toRadians(theta), xArray[i], yArray[i]); 
      g2.setTransform(at); 
      g2.drawString(message, xArray[i], yArray[i]); 
      g2.transform(new AffineTransform()); 
      }// end for 
     } 
    } 
} 

Answer 1

Nun, es ist schon schwieriger, als ich erwartet hatte, aber ich glaube, ich habe es :-)

Das erste Problem zu arbeiten, wurde die grafische Darstellung Operationen durchführten (Zeichnung und Transformation) in actionPerformed. Sie müssen diese Dinge in paintComponent tun, da dies die Methode ist, die automatisch von der Grafikumgebung ausgeführt wird, wenn die Komponente gezeichnet werden muss.

Dann musste ich ein wenig mit Transformationen herumspielen. Ich denke, das Problem war, dass Sie g2.setTransform (at) aufgerufen haben, um eine neue Koordinatentransformation anzuwenden. Ich lese auf die Dokumente, die Sie nicht sollten: "setTransform-Methode ist nur für die Wiederherstellung der ursprünglichen Graphics2D-Transformation nach dem Rendern"

Hier ist, was ich herauskam mit. Ich hoffe es hilft.

import java.awt.Color; 
import java.awt.Font; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.GridLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.geom.AffineTransform; 

import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JTextField; 
import javax.swing.SwingConstants; 

class Tag { 

    private int  x; 
    private int  y; 
    private int  font; 
    private float color; 
    private String message; 

    public Tag(String message, int x, int y, int font, float color) { 
     this.message = message; 
     this.x = x; 
     this.y = y; 
     this.font = font; 
     this.color = color; 
    } 

    public String getMessage() { 
     return message; 
    } 

    public int getX() { 
     return x; 
    } 

    public int getY() { 
     return y; 
    } 

    public int getFont() { 
     return font; 
    } 

    public float getColor() { 
     return color; 
    } 
} 

class Board extends JPanel { 

    private Font[] font = new Font[5]; 
    private Tag[] tags; 
    private int  theta; 

    public Board() { 
     font[0] = new Font("Serif", Font.BOLD, 14); 
     font[1] = new Font("SansSerif", Font.BOLD + Font.ITALIC, 24); 
     font[2] = new Font("Monospaced", Font.PLAIN, 30); 
     font[3] = new Font("Dialog", Font.PLAIN, 36); 
     font[4] = new Font("Serif", Font.ITALIC, 48); 
    } 

    public void setTags(Tag[] tags) { 
     this.tags = tags; 
    } 

    public void updateBoard(int theta) { 
     this.theta = theta; 
    } 

    @Override 
    public void paintComponent(Graphics g) { 
     super.paintComponent(g); 
     Graphics2D g2 = (Graphics2D) g; 
     g2.setColor(Color.BLACK); 
     g2.fillRect(0, 0, getWidth(), getHeight()); 
     if (tags != null) { 
      AffineTransform at = new AffineTransform(); 
      for (Tag tag : tags) { 
       g2.setFont(font[tag.getFont()]); 

       g2.setColor(Color.getHSBColor(tag.getColor(), 1.0F, 1.0F)); 

       at = new AffineTransform(); 
       at.translate(tag.getX(), tag.getY()); 
       g2.transform(at); 

       at = new AffineTransform(); 
       at.rotate(Math.toRadians(theta)); 
       g2.transform(at); 

       g2.drawString(tag.getMessage(), 0, 0); 

       at = new AffineTransform(); 
       at.rotate(-Math.toRadians(theta)); 
       g2.transform(at); 

       at = new AffineTransform(); 
       at.translate(-tag.getX(), -tag.getY()); 
       g2.transform(at); 
      }// end for 
     } 
    } 

} 

public class RotateAndDraw extends JFrame implements ActionListener { 

    // Declare all member variables 
    private JFrame window; 
    private JButton drawButton; 
    private JButton rotateButton; 
    JTextField  userInput = new JTextField("Enter text here"); 
    private Board board  = new Board(); // Drawing surface 

    private int  rotateCount = 0; 

    public RotateAndDraw() { 
     // Declare all components 
     window = new JFrame("Rotate and Draw"); 
     drawButton = new JButton("Draw"); 
     rotateButton = new JButton("Rotate"); 
     drawButton.addActionListener(this); 
     rotateButton.addActionListener(this); 
     JLabel userInputLabel = new JLabel("Text:   "); 

     // Create some containers 
     JPanel content = new JPanel(); 
     content.setLayout(new GridLayout(3, 1)); 

     JPanel p1 = new JPanel(); 
     p1.setLayout(new GridLayout(1, 2)); 
     p1.add(drawButton); 
     p1.add(rotateButton); 

     JPanel p2 = new JPanel(); 
     p2.setLayout(new GridLayout(1, 3)); 
     userInputLabel.setHorizontalAlignment(SwingConstants.RIGHT); 
     p2.add(userInputLabel); 
     p2.add(userInput); 
     JLabel nullLabel = new JLabel(""); 
     p2.add(nullLabel); 

     board.setBackground(Color.BLACK); 

     content.add(p1); 
     content.add(p2); 
     content.add(board); 

     window.add(content); 
    } 

    public void run() { 
     window.setLocation(100, 100); 
     window.setSize(400, 400); 
     window.setDefaultCloseOperation(EXIT_ON_CLOSE); 
     window.setVisible(true); 
    } 

    @Override 
    public void actionPerformed(ActionEvent e) { 
     String message = userInput.getText(); 

     if (e.getSource() == drawButton) { 
      rotateCount = 0; 
      int width = board.getWidth(); 
      int height = board.getHeight(); 

      Tag[] tags = new Tag[100]; 

      for (int i = 0; i < tags.length; i++) { 
       int fontNum = (int) (5 * Math.random()); 
       float hue = (float) Math.random(); 
       int x = (int) (Math.random() * width); 
       int y = (int) (Math.random() * height); 

       tags[i] = new Tag(message, x, y, fontNum, hue); 
      } // end for 
      board.setTags(tags); 
     }// end if 
     if (e.getSource() == rotateButton) { 
      rotateCount = (rotateCount + 1) % 4; 
     } 
     board.updateBoard(90 * rotateCount); 
     board.repaint(); 
    } 

    public static void main(String[] args) { 
     RotateAndDraw rad = new RotateAndDraw(); 
     rad.run(); 
    } 

}