/**
 *
 *
 *  @(#)GIFEncoder.java    0.90 4/21/96 Adam Doppelt
 *
 * GIFEncoder is based upon gifsave.c, which was written and released
 * by:
 * 
 *                                  Sverre H. Huseby
 *                                   Bjoelsengt. 17
 *                                     N-0468 Oslo
 *                                       Norway
 *
 *                                 Phone: +47 2 230539
 *                                 sverrehu [at] ifi.uio.no
 */

/** ******************************************************
 *
 * GIFEncoder
 *
 */
public GIFEncoder(Image image) throws AWTException {

	width_ = (short)image.getWidth(null);
	height_ = (short)image.getHeight(null);

	int values[] = new int[width_ * height_];
	

	/** "Attach" pixelgrabber to the image */
	PixelGrabber grabber = new PixelGrabber(
	    image, 0, 0, width_, height_, values, 0, width_);
	
	
 
	
	
	/** Retrieve int values for the pixels of the image */
 	try {
	    if(grabber.grabPixels() != true)
		throw new AWTException("Grabber returned false: " +
				       grabber.status());
	}
	catch (InterruptedException e) {}
	
	
 
	

	/** Need 3 2-d Arrays to store RGB byte value for each pixel */
	/** NOTE: Each array is the size of the original image */
	byte r[][] = new byte[width_][height_];
	byte g[][] = new byte[width_][height_];
	byte b[][] = new byte[width_][height_];

	int index = 0;

	/** Bit shift the integer values to get the RGB values */
	for (int y = 0; y < height_; ++y) {
	    for (int x = 0; x < width_; ++x) {
			r[x][y] = (byte)((values[index] >> 16) & 0xFF);
			g[x][y] = (byte)((values[index] >> 8) & 0xFF);
			b[x][y] = (byte)((values[index]) & 0xFF);  
			++index;
	    }
	}

	/** Generate 256 color LUT for GIF */
	ToIndexedColor(r, g, b);
}



/** ******************************************************
 *
 * ToIndexedColor 
 *
 */
void ToIndexedColor(byte r[][], byte g[][],
			byte b[][]) throws AWTException {
	pixels_ = new byte[width_ * height_];

	
 
	

	/** Array for 256 color RGB byte values */
	colors_ = new byte[256 * 3];
	
	int colornum = 0;

	/** Iterate over 3 2-D RGB byte arrays */
	for (int x = 0; x < width_; ++x) {
	    for (int y = 0; y < height_; ++y) {
		int search;
		for (search = 0; search < colornum; ++search)
		    if (colors_[search * 3]     == r[x][y] &&
			colors_[search * 3 + 1] == g[x][y] &&
			colors_[search * 3 + 2] == b[x][y])
			break;
		
		if (search > 255)
		    throw new AWTException("Too many colors.");

		pixels_[y * width_ + x] = (byte)search;
		
		if (search == colornum) {
		    colors_[search * 3]     = r[x][y];
		    colors_[search * 3 + 1] = g[x][y];
		    colors_[search * 3 + 2] = b[x][y];
		    ++colornum;
		}
	    }
	}


	/** BitsNeeded is the number of bits required to specify 
	a unique index in the LUT.  Eg: If the LUT has 4 colors this 
	value is 2 */
	numColors_ = 1 << BitUtils.BitsNeeded(colornum);


	byte copy[] = new byte[numColors_ * 3];
	System.arraycopy(colors_, 0, copy, 0, numColors_ * 3);
	colors_ = copy;
}