Pourquoi ce JPanel ne s'efface-t-il pas des graphiques?

Question

J'essaie d'afficher 100 chaînes avec le JTextField donné une fois que j'appuie sur le bouton dessiner, et puis être capable de les faire pivoter tous les 90 degrés lorsque j'appuie sur le bouton de rotation. Cependant, quand je tourne, certaines des chaînes de plus tôt apparaissent toujours. Mais alors tout le panneau s'efface une fois que les cordes pointent vers le bas. Pourquoi est-ce?

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

Eh bien, il a été plus difficile que prévu mais je pense que je l'ai eu à travailler :-)

Le premier problème est que vous effectuaient des opérations graphiques (dessin et transformation) en actionPerformed. Vous devez faire ces choses dans paintComponent parce que c'est la méthode qui est exécutée automatiquement par l'environnement graphique chaque fois qu'il doit peindre le composant.

Puis j'ai dû faire un petit tour avec les transformations. Je pense que le problème était que vous appeliez g2.setTransform (at) pour appliquer une nouvelle transformation de coordonnées. J'ai lu sur les docs que vous ne devriez pas: "La méthode setTransform est destinée uniquement à la restauration de la transformation Graphics2D originale après le rendu"

Voici ce que je suis sorti avec. J'espère que cela aide.

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(); 
    } 

}