// Copyright 2000, CERN, Geneva, Switzerland and University of Santa Cruz, California, U.S.A.
package org.freehep.graphicsio.ps;

import java.awt.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;

import org.freehep.graphicsio.ImageEncoder;

/**
 *
 * @author Charles Loomis
 * @version $Id: EPSIEncoder.java,v 1.2 2003/04/30 00:24:08 duns Exp $
 */
public class EPSIEncoder extends ImageEncoder {

    // Number of bits per byte.
    final static int maxBitsPerByte = 8;

    // Number of bytes per scan line (maximum here is 254).
    final static int maxBytesPerScan = 128;

    // The number of bits to use to represent the grayscale.
    private int grayscaleBits;

    // Boolean which gives the orientation of the image.
    private boolean portrait;

    // The width and height of the image.
    int width, height;

    // The array to hold the pixels.
    byte[][] grayPixels;

    // An array which hold enough bytes for one scan line.
    Scanline scanline;

    // Private conversion of bytes to hex digits.
    private static char[] hexDigit
    = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};

    // Masks to strip off last n bits.
    final private static byte[] lowBitMask
    = {(byte) 0, (byte) 1, (byte) 3,
       (byte) 7, (byte) 15, (byte) 31,
       (byte) 63, (byte) 127, (byte) 255};

    /**
     * Constructor from Image with number of grayscale bits to use.
     * @param img The image to encode.
     * @param out The stream to write the GIF to.
     * @param grayscaleBits Number of grayscale bits to use.
     * @param portrait Flag indicating a portrait orientation. */
    public EPSIEncoder(Image img, OutputStream out,
               int grayscaleBits, boolean portrait )
            throws IOException {

        super( img, new DataOutputStream(out) );
        this.grayscaleBits = grayscaleBits;
        this.portrait = portrait;
    }

    /**
     * Constructor from ImageProducer with number of grayscale bits to use.
     * @param prod The ImageProducer to encode.
     * @param out The stream to write the GIF to.
     * @param grayscaleBits Number of grayscale bits to use.
     * @param portrait Flag indicating a portrait orientation. */
    public EPSIEncoder( ImageProducer prod, OutputStream out,
            int grayscaleBits, boolean portrait )
                throws IOException {

        super( prod, new DataOutputStream(out) );
        this.grayscaleBits = grayscaleBits;
        this.portrait = portrait;
    }

    protected void encodeStart( int width, int height )
            throws IOException {

        this.width = width;
        this.height = height;
        grayPixels = new byte[height][width];

        // Use the appropriate width and height depending on the orientation.
        int w, h;
        if (portrait) {
            w = width;
            h = height;
        } else {
            w = height;
            h = width;
        }

        // Calculate the number of lines in the image.
        int bitsPerScan = w*grayscaleBits;
        int bytesPerScan = (bitsPerScan/maxBitsPerByte) +
            ((bitsPerScan%maxBitsPerByte==0) ? 0 : 1 );
        int linesPerScan = (bytesPerScan/maxBytesPerScan) +
            ((bytesPerScan%maxBytesPerScan==0) ? 0 : 1 );
        int lines = linesPerScan*h;

        // Make a byte array which holds the information for one scan line.
        scanline = new Scanline(bytesPerScan, grayscaleBits);

        // Write out the header.
        putString("%%BeginPreview "+width+" "+height+" "+
              grayscaleBits+" "+lines+"\n");
    }

    protected void encodePixels(int x, int y, int w, int h, int[] rgbPixels, int off, int scansize )
        throws IOException {

        // Save the pixels as a grayscale value.
        for ( int row = 0; row < h; ++row )
            {
            for (int column=0; column<w; column++)
                {
                grayPixels[y+row][column] =
                    toGrayscale(rgbPixels[row*scansize+off+column]);
                }
            }
        }

        // Convert a value given as AARRGGBB to a single grayscale value.
        private byte toGrayscale(int argb) {
        int mask = 0xFF;
        double blue  = ((double) ((argb>> 0) & mask))/255.;
        double green = ((double) ((argb>> 8) & mask))/255.;
        double red   = ((double) ((argb>>16) & mask))/255.;

        return (byte) (255.*Math.max(0.,(1.-(0.3*red+0.59*green+0.11*blue))));
    }

    protected void encodeDone() throws IOException {

        if (portrait) {
            for (int row=height-1; row>=0 ; row--) {
            scanline.reset();
            for (int col=0; col<width; col++) {
                byte gray = grayPixels[row][col];
                scanline.add(gray);
            }
            scanline.put();
            }
        } else {
            for (int col=width-1; col>=0; col--) {
            scanline.reset();
            for (int row=height-1; row>=0 ; row--) {
                byte gray = grayPixels[row][col];
                scanline.add(gray);
            }
            scanline.put();
            }
        }

        // Write out the trailer.
        putString("%%EndPreview\n");
    }

    // Write a string to the file.
    void putString(String s)
            throws IOException {

        out.write(s.getBytes());
    }

    // Write out a character to the file.
    void putChar(char c)
            throws IOException {

        out.write(c);
    }

    // Write out a byte to the GIF file
    void putByte( byte b)
            throws IOException {

        int highNibble = (b>>4) & 0xF;
        int lowNibble = b & 0xF;

        out.write(hexDigit[highNibble]);
        out.write(hexDigit[lowNibble]);
    }

    // This class handles packing the scan data into a hexadecimal byte array.
    // This only works if the number of bits is 1, 2, 4, or 8.
    private class Scanline {

    private byte[] line;
    private int nbits;
    private int currentByte;
    private int currentOffset;

    public Scanline(int size, int nbits) {
        line = new byte[size];
        this.nbits = nbits;
        reset();
    }

    // Reset the scan line.  Always zero the last byte in case the
    // scan line isn't fully used by the image.
    public void reset() {
        currentByte = 0;
        currentOffset = 0;
        for (int i=0; i<line.length; i++) {
        line[i] = 0;
        }
    }

    public void add(byte b) {

        // Put the most significant bits in the lowest bits.
        b >>= (maxBitsPerByte-nbits);
        b &= lowBitMask[nbits];

        // OR in the information.
        line[currentByte] |= b;

        // Update the offsets.
        if (maxBitsPerByte-nbits-currentOffset == 0) {

        // We're reached the end of a byte, just reset the counters.
        currentOffset = 0;
        currentByte++;
        } else {

        // Increment the offset and shift the word for the next
        // bits of information.
        currentOffset += nbits;
        line[currentByte] <<= nbits;
        }
    }

    public void put()
        throws IOException {

        // Check the last byte.  If currentOffset isn't zero then
        // the last byte hasn't been fully shifted into place.
        // Do it now!
        while (maxBitsPerByte-nbits-currentOffset > 0) {
        line[line.length-1] <<= nbits;
        currentOffset += nbits;
        }

        for (int i=0; i<line.length; i++) {
        if (i%maxBytesPerScan==0) {
            if (i!=0) putChar('\n');
            putChar('%');
        }
        putByte(line[i]);
        }
        putChar('\n');
    }
    }

}