Java jFrame画布绘制点而不是线条

Question

我一直想为龙曲线设计一个生成器。

（如果你想要查看this的信息，但问题并不重要）

龙曲线是重复的数学结构。我已经为画布绘制的内容编写了一个生成器，它通过返回一个由'r'或'l'组成的char数组来工作，说明该行是否必须向左或向右转。在这里的代码中，它是方法input()。这部分很完美。

问题在于，每当我想在画布上绘制它时（使用drawLine），它只会将前两行绘制为实际线条，其余的只是点。

点位于正确的位置，如果你把东西变得很大，你就不能再说出差异，但是，那里应该有线条。

图片：

这是我使用的代码：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;




/**
  *
  * Description
  *
  * @version 1.0 from 4/20/2016
  * @author 
  */

public class CurveGen extends JFrame {
  // start attributes
  private Canvas display = new Canvas();
  private JButton startButton = new JButton();
  private JLabel jLabel1 = new JLabel();
  private JTextArea outText = new JTextArea("");
    private JScrollPane outTextScrollPane = new JScrollPane(outText);
  private JLabel jLabel2 = new JLabel();
  private JSlider xSlider = new JSlider();
  private JSlider ySlider = new JSlider();
  private JNumberField iterationsNF = new JNumberField();
  private JNumberField sizeNF = new JNumberField();
  // end attributes




  public CurveGen(String title) { 
    // Frame-Init
    super(title);
    setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
    int frameWidth = 1022; 
    int frameHeight = 731;
    setSize(frameWidth, frameHeight);
    Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
    int x = (d.width - getSize().width) / 2;
    int y = (d.height - getSize().height) / 2;
    setLocation(x, y);
    setResizable(false);
    Container cp = getContentPane();
    cp.setLayout(null);
    // start components

    display.setBounds(16, 64, 601, 601);
    cp.add(display);
    startButton.setBounds(736, 464, 241, 129);
    startButton.setText("START!");
    startButton.setMargin(new Insets(2, 2, 2, 2));
    startButton.addActionListener(new ActionListener() { 
      public void actionPerformed(ActionEvent evt) { 
        startButton_ActionPerformed(evt);
      }
    });
    startButton.setFont(new Font("Dialog", Font.BOLD, 36));
    cp.add(startButton);
    jLabel1.setBounds(760, 96, 75, 41);
    jLabel1.setText("Iterations:");
    cp.add(jLabel1);
    outTextScrollPane.setBounds(728, 392, 257, 57);
    cp.add(outTextScrollPane);
    jLabel2.setBounds(768, 144, 67, 41);
    jLabel2.setText("Size:");
    cp.add(jLabel2);
    xSlider.setBounds(0, 8, 633, 49);
    xSlider.setMinorTickSpacing(25);
    xSlider.setMajorTickSpacing(100);
    xSlider.setPaintTicks(true);
    xSlider.setPaintLabels(true);
    xSlider.setToolTipText("Starting point y-coordinate");
    xSlider.setMaximum(600);
    xSlider.setValue(300);
    cp.add(xSlider);
    ySlider.setBounds(624, 56, 65, 625);
    ySlider.setMinorTickSpacing(25);
    ySlider.setMajorTickSpacing(100);
    ySlider.setPaintTicks(true);
    ySlider.setPaintLabels(true);
    ySlider.setOrientation(SwingConstants.VERTICAL);
    ySlider.setMaximum(600);
    ySlider.setInverted(true);
    ySlider.setValue(300);
    ySlider.setToolTipText("Starting point x-coordinate");
    cp.add(ySlider);
    iterationsNF.setBounds(856, 96, 81, 41);
    iterationsNF.setText("");
    cp.add(iterationsNF);
    sizeNF.setBounds(856, 144, 81, 41);
    sizeNF.setText("");
    cp.add(sizeNF);
    // end components

    setVisible(true);
  } // end of public CurveGen

  // start methods

  public static void main(String[] args) {
    new CurveGen("CurveGen");



  } // end of main

  public char[] input(int iter) {         
    char oldOut[] = new char[0];            
    for (int i=1;i<=iter;i++) {
      char newOut[] = new char[((int)Math.pow(2, i))-1];
      for (int n=0;n<oldOut.length;n++) {
        newOut[n] = oldOut[n];
        if (oldOut[n]=='r') {
          newOut[newOut.length-n-1] = 'l';
        }
        if (oldOut[n]=='l') {
          newOut[newOut.length-n-1] = 'r';
        } // end of if
      } // end of for
      newOut[oldOut.length]='l';      
      oldOut = newOut; 
    } // end of for        
    return oldOut;
  }  



  public void startButton_ActionPerformed(ActionEvent evt) {


    int iterations = iterationsNF.getInt();
    int size = sizeNF.getInt();

    char com[] = input(iterations);
    outText.setText(String.valueOf(com));

    int dir = 0;
    int newDir = 0;
    int lastPos[] = {xSlider.getValue(),ySlider.getValue()-size};
    int newPos[] = {0,0};

    Graphics g = display.getGraphics();

    g.clearRect(0,0,601,601);
    g.drawLine(xSlider.getValue(),ySlider.getValue(),xSlider.getValue(),ySlider.getValue()-size);


    for (int i=0;i<=com.length-1;i++) {
      dir = newDir;
      if (dir==0) {
        if (com[i]=='l') {
          newPos[0] = lastPos[0]-size;
          newPos[1] = lastPos[1];
          newDir = 3;
        } 
        if (com[i]=='r') {
          newPos[0] = lastPos[0]+size;
          newPos[1] = lastPos[1];
          newDir = 1;
        }              
      } 
      if (dir==1) {
        if (com[i]=='l') {
          newPos[0] = lastPos[0];
          newPos[1] = lastPos[1]-size;
          newDir = 0;
        } 
        if (com[i]=='r') {
          newPos[0] = lastPos[0];
          newPos[1] = lastPos[1]+size;
          newDir = 2;
        }              
      } 
      if (dir==2) {
        if (com[i]=='l') {
          newPos[0] = lastPos[0]+size;
          newPos[1] = lastPos[1];
          newDir = 1;
        } 
        if (com[i]=='r') {
          newPos[0] = lastPos[0]-size;
          newPos[1] = lastPos[1];
          newDir = 3;
        }              
      } 
      if (dir==3) {                                
        if (com[i]=='l') {
          newPos[0] = lastPos[0];
          newPos[1] = lastPos[1]+size;
          newDir = 2;
        } 
        if (com[i]=='r') {
          newPos[0] = lastPos[0];
          newPos[1] = lastPos[1]-size;
          newDir = 0;
        }              
      } 

      g.drawLine(lastPos[0],lastPos[1],newPos[0],newPos[1]);

      lastPos=newPos;
    } // end of for




  } // end of startButton_ActionPerformed

  // end methods
} // end of class CurveGen

Answer 1

另一答案