flash as3 加载bmp格式图片

主时间轴：

import BMPDecoder;
loadBMPFile("1.bmp");
function loadBMPFile(url:String ):void {

 var loader:URLLoader = new URLLoader();

 //指定loader以二进制返回数据
 loader.dataFormat = URLLoaderDataFormat.BINARY;
 loader.addEventListener(Event.COMPLETE,loader_completeHandler);
 loader.load( new URLRequest(url));
}

function loader_completeHandler( e:Event ):void {

 var loader:URLLoader = e.target as URLLoader;
 var decoder:BMPDecoder = new BMPDecoder();

 //将二进制数据转换成BitmapData
 var bd:BitmapData = decoder.decode( loader.data );
 //用来显示效果的Bitmap获取位图数据，图片平滑
 var myBitmap:Bitmap = new Bitmap(bd,"auto",true);
 addChild(myBitmap);
}

 

 

BMPDecoder.as类：

package
{
import flash.display.BitmapData;
import flash.errors.IOError;
import flash.utils.ByteArray;
import flash.utils.Endian;
public class BMPDecoder {
private const BITMAP_HEADER_TYPE:String = "BM";
private const BITMAP_FILE_HEADER_SIZE:int = 14;
private const BITMAP_CORE_HEADER_SIZE:int = 12;
private const BITMAP_INFO_HEADER_SIZE:int = 40;
private const COMP_RGB      :int = 0;
private const COMP_RLE8     :int = 1;
private const COMP_RLE4     :int = 2;
private const COMP_BITFIELDS:int = 3;
private const BIT1 :int = 1;
private const BIT4 :int = 4;
private const BIT8 :int = 8;
private const BIT16:int = 16;
private const BIT24:int = 24;
private const BIT32:int = 32;
private var bytes:ByteArray;
private var palette:Array;
private var bd:BitmapData;
private var nFileSize:uint;
private var nReserved1:uint;
private var nReserved2:uint;
private var nOffbits:uint;
private var nInfoSize:uint;
private var nWidth:int;
private var nHeight:int;
private var nPlains:uint;
private var nBitsPerPixel:uint;
private var nCompression:uint;
private var nSizeImage:uint;
private var nXPixPerMeter:int;
private var nYPixPerMeter:int;
private var nColorUsed:uint;
private var nColorImportant:uint;
private var nRMask:uint;
private var nGMask:uint;
private var nBMask:uint;
private var nRPos:uint;
private var nGPos:uint;
private var nBPos:uint;
private var nRMax:uint;
private var nGMax:uint;
private var nBMax:uint;
public function BMPDecoder() {
nRPos = 0;
nGPos = 0;
nBPos = 0;
}
public function decode( data:ByteArray ):BitmapData {
bytes = data;
bytes.endian = Endian.LITTLE_ENDIAN;
bytes.position = 0;
readFileHeader();
nInfoSize = bytes.readUnsignedInt();
switch ( nInfoSize ) {
case BITMAP_CORE_HEADER_SIZE:
readCoreHeader();
break;
case BITMAP_INFO_HEADER_SIZE:
readInfoHeader();
break;
default:
readExtendedInfoHeader();
break;
}
bd = new BitmapData( nWidth, nHeight );
switch ( nBitsPerPixel ){
case BIT1:
readColorPalette();
decode1BitBMP();
break;
case BIT4:
readColorPalette();
if ( nCompression == COMP_RLE4 ){
decode4bitRLE();
} else {
decode4BitBMP();
}
break;
case BIT8:
readColorPalette();
if ( nCompression == COMP_RLE8 ){
decode8BitRLE();
} else {
decode8BitBMP();
}
break;
case BIT16:
readBitFields();
checkColorMask();
decode16BitBMP();
break;
case BIT24:
decode24BitBMP();
break;
case BIT32:
readBitFields();
checkColorMask();
decode32BitBMP();
break;
default:
throw new VerifyError("invalid bits per pixel : " + nBitsPerPixel );
}
return bd;
}
private function readFileHeader():void {
var fileHeader:ByteArray = new ByteArray();
fileHeader.endian = Endian.LITTLE_ENDIAN;
try {
bytes.readBytes( fileHeader, 0, BITMAP_FILE_HEADER_SIZE );
if ( fileHeader.readUTFBytes( 2 ) != BITMAP_HEADER_TYPE ){
throw new VerifyError("invalid bitmap header type");
}
nFileSize  = fileHeader.readUnsignedInt();
nReserved1 = fileHeader.readUnsignedShort();
nReserved2 = fileHeader.readUnsignedShort();
nOffbits   = fileHeader.readUnsignedInt();
} catch ( e:IOError ) {
throw new VerifyError("invalid file header");
}
}
private function readCoreHeader():void {
var coreHeader:ByteArray = new ByteArray();
coreHeader.endian = Endian.LITTLE_ENDIAN;
try {
bytes.readBytes( coreHeader, 0, BITMAP_CORE_HEADER_SIZE - 4 );
nWidth  = coreHeader.readShort();
nHeight = coreHeader.readShort();
nPlains = coreHeader.readUnsignedShort();
nBitsPerPixel = coreHeader.readUnsignedShort();
} catch ( e:IOError ) {
throw new VerifyError("invalid core header");
}
}
private function readInfoHeader():void {
var infoHeader:ByteArray = new ByteArray();
infoHeader.endian = Endian.LITTLE_ENDIAN;
try {
bytes.readBytes( infoHeader, 0, BITMAP_INFO_HEADER_SIZE - 4 );
nWidth  = infoHeader.readInt();
nHeight = infoHeader.readInt();
nPlains = infoHeader.readUnsignedShort();
nBitsPerPixel = infoHeader.readUnsignedShort();
nCompression = infoHeader.readUnsignedInt();
nSizeImage = infoHeader.readUnsignedInt();
nXPixPerMeter = infoHeader.readInt();
nYPixPerMeter = infoHeader.readInt();
nColorUsed = infoHeader.readUnsignedInt();
nColorImportant = infoHeader.readUnsignedInt();
} catch ( e:IOError ) {
throw new VerifyError("invalid info header");
}
}
private function readExtendedInfoHeader():void {
var infoHeader:ByteArray = new ByteArray();
infoHeader.endian = Endian.LITTLE_ENDIAN;
try {
bytes.readBytes( infoHeader, 0, nInfoSize - 4 );
nWidth  = infoHeader.readInt();
nHeight = infoHeader.readInt();
nPlains = infoHeader.readUnsignedShort();
nBitsPerPixel = infoHeader.readUnsignedShort();
nCompression = infoHeader.readUnsignedInt();
nSizeImage = infoHeader.readUnsignedInt();
nXPixPerMeter = infoHeader.readInt();
nYPixPerMeter = infoHeader.readInt();
nColorUsed = infoHeader.readUnsignedInt();
nColorImportant = infoHeader.readUnsignedInt();
if ( infoHeader.bytesAvailable >= 4 ) nRMask = infoHeader.readUnsignedInt();
if ( infoHeader.bytesAvailable >= 4 ) nGMask = infoHeader.readUnsignedInt();
if ( infoHeader.bytesAvailable >= 4 ) nBMask = infoHeader.readUnsignedInt();
} catch ( e:IOError ) {
throw new VerifyError("invalid info header");
}
}
private function readBitFields():void {
if ( nCompression == COMP_RGB ){
if ( nBitsPerPixel == BIT16 ){
// RGB555
nRMask = 0x00007c00;
nGMask = 0x000003e0;
nBMask = 0x0000001f;
} else {
//RGB888;
nRMask = 0x00ff0000;
nGMask = 0x0000ff00;
nBMask = 0x000000ff;
}
} else if ( ( nCompression == COMP_BITFIELDS ) && ( nInfoSize < 52 ) ){
try {
nRMask = bytes.readUnsignedInt();
nGMask = bytes.readUnsignedInt();
nBMask = bytes.readUnsignedInt();
} catch ( e:IOError ) {
throw new VerifyError("invalid bit fields");
}
}
}
private function readColorPalette():void {
var i:int;
var len:int = ( nColorUsed > 0 ) ? nColorUsed : Math.pow( 2, nBitsPerPixel );
palette = new Array( len );
for ( i = 0; i < len; ++i ){
palette[ i ] = bytes.readUnsignedInt();
}
}
private function decode1BitBMP():void {
var x:int;
var y:int;
var i:int;
var col:int;
var buf:ByteArray = new ByteArray();
var line:int = nWidth / 8;
if ( line % 4 > 0 ){
line = ( ( line / 4 | 0 ) + 1 ) * 4;
}
try {
for ( y = nHeight - 1; y >= 0; --y ){
buf.length = 0;
bytes.readBytes( buf, 0, line );
for ( x = 0; x < nWidth; x += 8 ){
col = buf.readUnsignedByte();
for ( i = 0; i < 8; ++i ){
bd.setPixel( x + i, y, palette[ col >> ( 7 - i ) & 0x01 ] );
}
}
}
} catch ( e:IOError ) {
throw new VerifyError("invalid image data");
}
}
private function decode4bitRLE():void {
var x:int;
var y:int;
var i:int;
var n:int;
var col:int;
var data:uint;
var buf:ByteArray = new ByteArray();
try {
for ( y = nHeight - 1; y >= 0; --y ){
buf.length = 0;
while ( bytes.bytesAvailable > 0 ){
n = bytes.readUnsignedByte();
if ( n > 0 ){
data = bytes.readUnsignedByte();
for ( i = 0; i < n/2; ++i ){
buf.writeByte( data );
}
} else {
n = bytes.readUnsignedByte();
if ( n > 0 ){
bytes.readBytes( buf, buf.length, n/2 );
buf.position += n/2;
if ( n/2 + 1 >> 1 << 1 != n/2 ){
bytes.readUnsignedByte();
}
} else {
// EOL
break;
}
}
}
buf.position = 0;
for ( x = 0; x < nWidth; x += 2 ){
col = buf.readUnsignedByte();
bd.setPixel( x, y, palette[ col >> 4 ] );
bd.setPixel( x + 1, y, palette[ col & 0x0f ] );
}
}
} catch ( e:IOError ) {
throw new VerifyError("invalid image data");
}
}
private function decode4BitBMP():void {
var x:int;
var y:int;
var i:int;
var col:int;
var buf:ByteArray = new ByteArray();
var line:int = nWidth / 2;
if ( line % 4 > 0 ){
line = ( ( line / 4 | 0 ) + 1 ) * 4;
}
try {
for ( y = nHeight - 1; y >= 0; --y ){
buf.length = 0;
bytes.readBytes( buf, 0, line );
for ( x = 0; x < nWidth; x += 2 ){
col = buf.readUnsignedByte();
bd.setPixel( x, y, palette[ col >> 4 ] );
bd.setPixel( x + 1, y, palette[ col & 0x0f ] );
}
}
} catch ( e:IOError ) {
throw new VerifyError("invalid image data");
}
}
private function decode8BitRLE():void {
var x:int;
var y:int;
var i:int;
var n:int;
var col:int;
var data:uint;
var buf:ByteArray = new ByteArray();
try {
for ( y = nHeight - 1; y >= 0; --y ){
buf.length = 0;
while ( bytes.bytesAvailable > 0 ){
n = bytes.readUnsignedByte();
if ( n > 0 ){
data = bytes.readUnsignedByte();
for ( i = 0; i < n; ++i ){
buf.writeByte( data );
}
} else {
n = bytes.readUnsignedByte();
if ( n > 0 ){
bytes.readBytes( buf, buf.length, n );
buf.position += n;
if ( n + 1 >> 1 << 1 != n ){
bytes.readUnsignedByte();
}
} else {
// EOL
break;
}
}
}
buf.position = 0;
for ( x = 0; x < nWidth; ++x ){
bd.setPixel( x, y, palette[ buf.readUnsignedByte() ] );
}
}
} catch ( e:IOError ) {
throw new VerifyError("invalid image data");
}
}
private function decode8BitBMP():void {
var x:int;
var y:int;
var i:int;
var col:int;
var buf:ByteArray = new ByteArray();
var line:int = nWidth;
if ( line % 4 > 0 ){
line = ( ( line / 4 | 0 ) + 1 ) * 4;
}
try {
for ( y = nHeight - 1; y >= 0; --y ){
buf.length = 0;
bytes.readBytes( buf, 0, line );
for ( x = 0; x < nWidth; ++x ){
bd.setPixel( x, y, palette[ buf.readUnsignedByte() ] );
}
}
} catch ( e:IOError ) {
throw new VerifyError("invalid image data");
}
}
private function decode16BitBMP():void {
var x:int;
var y:int;
var col:int;
try {
for ( y = nHeight - 1; y >= 0; --y ){
for ( x = 0; x < nWidth; ++x ){
col = bytes.readUnsignedShort();
bd.setPixel( x, y, ( ( ( col & nRMask ) >> nRPos )*0xff/nRMax << 16 ) + ( ( ( col & nGMask ) >> nGPos )*0xff/nGMax << 8 ) + ( ( ( col & nBMask ) >> nBPos )*0xff/nBMax << 0 ) );
}
}
} catch ( e:IOError ) {
throw new VerifyError("invalid image data");
}
}
private function decode24BitBMP():void {
var x:int;
var y:int;
var col:int;
var buf:ByteArray = new ByteArray();
var line:int = nWidth * 3;
if ( line % 4 > 0 ){
line = ( ( line / 4 | 0 ) + 1 ) * 4;
}
try {
for ( y = nHeight - 1; y >= 0; --y ){
buf.length = 0;
bytes.readBytes( buf, 0, line );
for ( x = 0; x < nWidth; ++x ){
bd.setPixel( x, y, buf.readUnsignedByte() + ( buf.readUnsignedByte() << 8 ) + ( buf.readUnsignedByte() << 16 ) );
}
}
} catch ( e:IOError ) {
throw new VerifyError("invalid image data");
}
}
private function decode32BitBMP():void {
var x:int;
var y:int;
var col:int;
try {
for ( y = nHeight - 1; y >= 0; --y ){
for ( x = 0; x < nWidth; ++x ){
col = bytes.readUnsignedInt();
bd.setPixel( x, y, ( ( ( col & nRMask ) >> nRPos )*0xff/nRMax << 16 ) + ( ( ( col & nGMask ) >> nGPos )*0xff/nGMax << 8 ) + ( ( ( col & nBMask ) >> nBPos )*0xff/nBMax << 0 ) );
}
}
} catch ( e:IOError ) {
throw new VerifyError("invalid image data");
}
}
private function checkColorMask():void {
if ( ( nRMask & nGMask ) | ( nGMask & nBMask ) | ( nBMask & nRMask ) ){
throw new VerifyError("invalid bit fields");
}
while ( ( nRMask >> nRPos ) & 0x00000001 == 0 ){
nRPos++;
}
while ( ( nGMask >> nGPos ) & 0x00000001 == 0 ){
nGPos++;
}
while ( ( nBMask >> nBPos ) & 0x00000001 == 0 ){
nBPos++;
}
nRMax = nRMask >> nRPos;
nGMax = nGMask >> nGPos;
nBMax = nBMask >> nBPos;
}
public function traceInfo():void {
trace("---- FILE HEADER ----");
trace("nFileSize: " + nFileSize );
trace("nReserved1: " + nReserved1 );
trace("nReserved2: " + nReserved2 );
trace("nOffbits: " + nOffbits );
trace("---- INFO HEADER ----");
trace("nWidth: " + nWidth );
trace("nHeight: " + nHeight );
trace("nPlains: " + nPlains );
trace("nBitsPerPixel: " + nBitsPerPixel );
if ( nInfoSize >= 40 ){
trace("nCompression: " + nCompression );
trace("nSizeImage: " + nSizeImage );
trace("nXPixPerMeter: " + nXPixPerMeter );
trace("nYPixPerMeter: " + nYPixPerMeter );
trace("nColorUsed: " + nColorUsed );
trace("nColorUsed: " + nColorImportant );
}
if ( nInfoSize >= 52 ){
trace("nRMask: " + nRMask.toString( 2 ) );
trace("nGMask: " + nGMask.toString( 2 ) );
trace("nBMask: " + nBMask.toString( 2 ) );
}
}
}
}