turtleverter.java

/**
 * Written by jmptable for 6.005 problem set 0 artwork problem
 * run in [processing](http://processing.org/)
*/

import java.awt.Color;
import java.util.*;
import javax.swing.*;
import java.io.File;

/**
 * Colors in the turtle's palette.
 * values gotten by dumping RGB values from Colors in PenColor.java.
 */
Color[] colors = new Color[] {
  new Color(0,0,0),
  new Color(0,0,255),
  new Color(0,255,255),
  new Color(128,128,128),
  new Color(0,255,0),
  new Color(255,0,255),
  new Color(255,200,0),
  new Color(255,175,175),
  new Color(255,0,0),
  new Color(228,228,0),
};

void setup() {
  PImage img = loadImage(choosefile());
  img.loadPixels();
  loadPixels();
  
  size(img.width, img.height);
  
  /**
   * Find colors in palette nearest to originals for each pixel.
  */
  
  int[] turtleColors = new int[img.width*img.height];
  for(int y=0; y < img.height; y++) {
    for(int x=0; x < img.width; x++) {
      int pixel = img.pixels[y*img.width+x];
      
      // calculate amount of difference from available colors
      // and find the index of the color with the smallest difference
      int smallest = -1;
      int smallestIndex = 0;
      for(int i=0; i < colors.length; i++) {
        int score = int(abs(red(pixel)-colors[i].getRed()) + abs(green(pixel)-colors[i].getGreen()) + abs(blue(pixel)-colors[i].getBlue()));
        
        if(score < smallest || smallest == -1) {
          smallest = score;
          smallestIndex = i;
        }
      }
      
      turtleColors[y*img.width+x] = smallestIndex;
    }
  }
  
  /**
   * Draw the converted image for inspection.
   */
   
  for(int i=0; i < turtleColors.length; i++) {
    Color c = colors[turtleColors[i]];
    img.pixels[i] = color(c.getRed(), c.getGreen(), c.getBlue());
  }
  img.loadPixels();
  image(img, 0, 0);
  
  /**
   * Write the compressed image to Java source code file.
   */
   
  printArray(runLengthCompression(turtleColors));
}

int[] runLengthCompression(int[] arr) {
  ArrayList<Integer> encoded = new ArrayList<Integer>();
  
  // compress by storing long sequences of the same value as
  // value, length
  int last = arr[0];
  int len = 1;
  for(int i=0; i < arr.length; i++) {
    int current = arr[i];
    
    if(current != last) {
      encoded.add(last); encoded.add(len);
      
      len = 1;
      last = current;
    } else {
      len++;
    }
  }
  
  encoded.add(last); encoded.add(len);
  
  // generate statically allocated array from compressed data
  int[] result = new int[encoded.size()];
  for(int i=0; i < result.length; i++) result[i] = encoded.get(i);
  
  return result;
}

/**
 * Write an integer array to a Java source file for embedding in a program
 */
void printArray(int[] arr) {
  final int lineWidth = 80;
  
  ArrayList<String> lines = new ArrayList<String>();
  int i = 0;
  int lineIndex = 0;
  
  lines.add("new int[] {");
  
  boolean done = false;
  while(!done) {
    String line = "";
    
    line += "\t";
    
    int col = 0;
    while(col < lineWidth-1 && !done) {
      line += arr[i++] + ", ";
      done = !(i < arr.length);
      col++;
    }
    
    if(!done) {
      line += arr[i++] + ",";
    }
    done = !(i < arr.length);
    
    lines.add(line);
    lineIndex++;
  }
  
  lines.add("};");
  
  saveStrings("picture.java", lines.toArray(new String[1]));
}

/**
 * Show a file-chooser dialog to the user to select the image for conversion.
 * modified from http://wiki.processing.org/w/Open_Files_through_a_GUI .
 */
String choosefile() {
  try {
    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
  } catch (Exception e) {
    e.printStackTrace();
  }
   
  // create a file chooser 
  final JFileChooser fc = new JFileChooser("C:\\Users\\owen\\Pictures"); 
   
  // in response to a button click: 
  int returnVal = fc.showOpenDialog(this); 
   
  if (returnVal == JFileChooser.APPROVE_OPTION) { 
    File file = fc.getSelectedFile(); 
    
    // see if it's an image 
    if (file.getName().endsWith("jpg") || file.getName().endsWith("png")) { 
      return file.getPath();
    } else {
      println("Unsupported filetype.");
      exit();
    } 
  } else { 
    println("Open command cancelled by user.");
    exit();
  }
  
  return null;
}