// -*- mode:actionscript; encoding: utf-8 -*-
//
// Author: Daichi Shinozaki
// Date: 11/Mar/2008
//
package
{
import flash.display.BitmapData;
import flash.utils.ByteArray;
import flash.utils.Endian;

import mx.graphics.codec.IImageEncoder;

public class BMPEncoder implements IImageEncoder
{
//--------------------------------------------------------------------------
//
//	Class constants
//
//--------------------------------------------------------------------------
/**
*	@private
*	The MIME type for a BMP image.
*/
private static const CONTENT_TYPE:String = "image/bmp";

//--------------------------------------------------------------------------
//
//	Constructor
//
//--------------------------------------------------------------------------
public function BMPEncoder(){
super();
}

/**
*	The MIME type for the BMP encoded image.
*	The value is <code>"image/bmp"</code>.
*/
public function get contentType():String
{
return CONTENT_TYPE;
}

//--------------------------------------------------------------------------
//
//  Methods
//
//--------------------------------------------------------------------------

/**
*  Converts the pixels of a BitmapData object
*  to a BMP-encoded ByteArray object.
*
*  @param bitmapData The input BitmapData object.
*
*  @returns A ByteArray object containing BMP-encoded image data.
*/
public function encode(bitmapData:BitmapData):ByteArray
{
return internalEncode(bitmapData, bitmapData.width, bitmapData.height,
bitmapData.transparent);
}

/**
*	Converts a ByteArray object containing raw pixels
*	in 32-bit ARGB (Alpha, Red, Green, Blue) format
*	to a new BMP-encoded ByteArray object.
*	The original ByteArray is left unchanged.
*
*	@param byteArray The input ByteArray object containing raw pixels.
*	This ByteArray should contain
*	<code>4 * width * height</code> bytes.
*	Each pixel is represented by 4 bytes, in the order ARGB.
*	The first four bytes represent the top-left pixel of the image.
*	The next four bytes represent the pixel to its right, etc.
*	Each row follows the previous one without any padding.
*
*	@param width The width of the input image, in pixels.
*
*	@param height The height of the input image, in pixels.
*
*	@param transparent If <code>false</code>, alpha channel information
*	is ignored but you still must represent each pixel
*	as four bytes in ARGB format.
*
*	@returns A ByteArray object containing BMP-encoded image data.
*/
public function encodeByteArray(byteArray:ByteArray, width:int, height:int,
transparent:Boolean = true):ByteArray
{
return internalEncode(byteArray, width, height, transparent);
}

/**
*	@private
*/
private function internalEncode(source:Object, width:int, height:int,
transparent:Boolean = true):ByteArray
{
// The source is either a BitmapData or a ByteArray.
var sourceBitmapData:BitmapData = source as BitmapData;
var sourceByteArray:ByteArray = source as ByteArray;

if (sourceByteArray)
sourceByteArray.position = 0;

// Create output byte array
var bmp:ByteArray = new ByteArray();
bmp.endian = Endian.LITTLE_ENDIAN;

var size:uint = width * height * 4;
/*
typedef struct tagBITMAPFILEHEADER {
unsigned short bfType;
unsigned long  bfSize;
unsigned short bfReserved1;
unsigned short bfReserved2;
unsigned long  bfOffBits;
} BITMAPFILEHEADER
*/
// Write BMP signature
bmp.writeShort(0x4D42);

// Write size
bmp.writeUnsignedInt(size + 54);

bmp.writeUnsignedInt(0);	// reserved 1, 2
bmp.writeUnsignedInt(54);	// offbits

/*
typedef struct tagBITMAPINFOHEADER{
unsigned long  biSize;
long           biWidth;
long           biHeight;
unsigned short biPlanes;
unsigned short biBitCount;
unsigned long  biCompression;
unsigned long  biSizeImage;
long           biXPixPerMeter;
long           biYPixPerMeter;
unsigned long  biClrUsed;
unsigned long  biClrImporant;
} BITMAPINFOHEADER;
*/
bmp.writeUnsignedInt(40);
bmp.writeInt(width);
bmp.writeInt(-height);
bmp.writeShort(1); // planes
bmp.writeShort(32);// bit count
bmp.writeUnsignedInt(0); // compression(0 -> no compression)
bmp.writeUnsignedInt(size); //
bmp.writeInt(0); // x pixels per meter
bmp.writeInt(0); // y pixels per meter
bmp.writeUnsignedInt(0); // color used
bmp.writeUnsignedInt(0); // color important

var pixel:uint
var x:uint, y:uint;
for (y = 0; y < height; y++) {
for (x = 0; x < width; x++) {
if (sourceBitmapData) {
pixel = sourceBitmapData.getPixel32(x, y);
} else {
pixel = sourceByteArray.readUnsignedInt();
}
bmp.writeUnsignedInt(pixel);
}
}

return bmp;
}
}

}