272 lines
7.4 KiB
JavaScript
272 lines
7.4 KiB
JavaScript
/**
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* @author shaozilee
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*
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* Bmp format decoder,support 1bit 4bit 8bit 24bit bmp
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*
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*/
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function BmpDecoder(buffer,is_with_alpha) {
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this.pos = 0;
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this.buffer = buffer;
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this.is_with_alpha = !!is_with_alpha;
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this.flag = this.buffer.toString("utf-8", 0, this.pos += 2);
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if (this.flag != "BM") throw new Error("Invalid BMP File");
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this.parseHeader();
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this.parseBGR();
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}
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BmpDecoder.prototype.parseHeader = function() {
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this.fileSize = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.reserved = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.offset = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.headerSize = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.width = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.height = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.planes = this.buffer.readUInt16LE(this.pos);
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this.pos += 2;
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this.bitPP = this.buffer.readUInt16LE(this.pos);
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this.pos += 2;
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this.compress = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.rawSize = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.hr = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.vr = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.colors = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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this.importantColors = this.buffer.readUInt32LE(this.pos);
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this.pos += 4;
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if(this.bitPP === 16 && this.is_with_alpha){
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this.bitPP = 15
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};
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if (this.bitPP < 15) {
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var len = this.colors === 0 ? 1 << this.bitPP : this.colors;
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this.palette = new Array(len);
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for (var i = 0; i < len; i++) {
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var blue = this.buffer.readUInt8(this.pos++);
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var green = this.buffer.readUInt8(this.pos++);
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var red = this.buffer.readUInt8(this.pos++);
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var quad = this.buffer.readUInt8(this.pos++);
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this.palette[i] = {
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red: red,
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green: green,
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blue: blue,
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quad: quad
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};
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}
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}
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}
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BmpDecoder.prototype.parseBGR = function() {
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this.pos = this.offset;
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try {
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var bitn = "bit" + this.bitPP;
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var len = this.width * this.height * 4;
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this.data = new Buffer(len);
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this[bitn]();
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} catch (e) {
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console.log("bit decode error:" + e);
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}
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};
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BmpDecoder.prototype.bit1 = function() {
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var xlen = Math.ceil(this.width / 8);
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var mode = xlen%4;
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for (var y = this.height - 1; y >= 0; y--) {
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for (var x = 0; x < xlen; x++) {
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var b = this.buffer.readUInt8(this.pos++);
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var location = y * this.width * 4 + x*8*4;
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for (var i = 0; i < 8; i++) {
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if(x*8+i<this.width){
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var rgb = this.palette[((b>>(7-i))&0x1)];
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this.data[location+i*4] = rgb.blue;
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this.data[location+i*4 + 1] = rgb.green;
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this.data[location+i*4 + 2] = rgb.red;
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this.data[location+i*4 + 3] = 0xFF;
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}else{
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break;
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}
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}
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}
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if (mode != 0){
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this.pos+=(4 - mode);
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}
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}
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};
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BmpDecoder.prototype.bit4 = function() {
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var xlen = Math.ceil(this.width/2);
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var mode = xlen%4;
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for (var y = this.height - 1; y >= 0; y--) {
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for (var x = 0; x < xlen; x++) {
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var b = this.buffer.readUInt8(this.pos++);
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var location = y * this.width * 4 + x*2*4;
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var before = b>>4;
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var after = b&0x0F;
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var rgb = this.palette[before];
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this.data[location] = rgb.blue;
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this.data[location + 1] = rgb.green;
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this.data[location + 2] = rgb.red;
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this.data[location + 3] = 0xFF;
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if(x*2+1>=this.width)break;
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rgb = this.palette[after];
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this.data[location+4] = rgb.blue;
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this.data[location+4 + 1] = rgb.green;
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this.data[location+4 + 2] = rgb.red;
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this.data[location+4 + 3] = 0xFF;
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}
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if (mode != 0){
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this.pos+=(4 - mode);
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}
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}
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};
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BmpDecoder.prototype.bit8 = function() {
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var mode = this.width%4;
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for (var y = this.height - 1; y >= 0; y--) {
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for (var x = 0; x < this.width; x++) {
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var b = this.buffer.readUInt8(this.pos++);
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var location = y * this.width * 4 + x*4;
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if(b < this.palette.length) {
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var rgb = this.palette[b];
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this.data[location] = rgb.blue;
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this.data[location + 1] = rgb.green;
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this.data[location + 2] = rgb.red;
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this.data[location + 3] = 0xFF;
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} else {
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this.data[location] = 0xFF;
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this.data[location + 1] = 0xFF;
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this.data[location + 2] = 0xFF;
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this.data[location + 3] = 0xFF;
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}
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}
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if (mode != 0){
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this.pos+=(4 - mode);
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}
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}
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};
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BmpDecoder.prototype.bit15 = function() {
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var dif_w =this.width % 3;
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var _11111 = parseInt("11111", 2),_1_5 = _11111;
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for (var y = this.height - 1; y >= 0; y--) {
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for (var x = 0; x < this.width; x++) {
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var B = this.buffer.readUInt16LE(this.pos);
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this.pos+=2;
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var blue = (B & _1_5) / _1_5 * 255 | 0;
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var green = (B >> 5 & _1_5 ) / _1_5 * 255 | 0;
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var red = (B >> 10 & _1_5) / _1_5 * 255 | 0;
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var alpha = (B>>15)?0xFF:0x00;
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var location = y * this.width * 4 + x * 4;
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this.data[location] = red;
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this.data[location + 1] = green;
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this.data[location + 2] = blue;
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this.data[location + 3] = alpha;
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}
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//skip extra bytes
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this.pos += dif_w;
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}
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};
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BmpDecoder.prototype.bit16 = function() {
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var dif_w =this.width % 3;
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var _11111 = parseInt("11111", 2),_1_5 = _11111;
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var _111111 = parseInt("111111", 2),_1_6 = _111111;
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for (var y = this.height - 1; y >= 0; y--) {
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for (var x = 0; x < this.width; x++) {
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var B = this.buffer.readUInt16LE(this.pos);
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this.pos+=2;
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var alpha = 0xFF;
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var blue = (B & _1_5) / _1_5 * 255 | 0;
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var green = (B >> 5 & _1_6 ) / _1_6 * 255 | 0;
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var red = (B >> 11) / _1_5 * 255 | 0;
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var location = y * this.width * 4 + x * 4;
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this.data[location] = red;
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this.data[location + 1] = green;
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this.data[location + 2] = blue;
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this.data[location + 3] = alpha;
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}
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//skip extra bytes
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this.pos += dif_w;
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}
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};
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BmpDecoder.prototype.bit24 = function() {
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//when height > 0
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for (var y = this.height - 1; y >= 0; y--) {
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for (var x = 0; x < this.width; x++) {
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var blue = this.buffer.readUInt8(this.pos++);
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var green = this.buffer.readUInt8(this.pos++);
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var red = this.buffer.readUInt8(this.pos++);
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var location = y * this.width * 4 + x * 4;
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this.data[location] = red;
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this.data[location + 1] = green;
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this.data[location + 2] = blue;
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this.data[location + 3] = 0xFF;
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}
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//skip extra bytes
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this.pos += (this.width % 4);
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}
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};
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/**
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* add 32bit decode func
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* @author soubok
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*/
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BmpDecoder.prototype.bit32 = function() {
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//when height > 0
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for (var y = this.height - 1; y >= 0; y--) {
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for (var x = 0; x < this.width; x++) {
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var blue = this.buffer.readUInt8(this.pos++);
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var green = this.buffer.readUInt8(this.pos++);
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var red = this.buffer.readUInt8(this.pos++);
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var alpha = this.buffer.readUInt8(this.pos++);
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var location = y * this.width * 4 + x * 4;
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this.data[location] = red;
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this.data[location + 1] = green;
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this.data[location + 2] = blue;
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this.data[location + 3] = alpha;
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}
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//skip extra bytes
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this.pos += (this.width % 4);
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}
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};
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BmpDecoder.prototype.getData = function() {
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return this.data;
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};
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module.exports = function(bmpData) {
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var decoder = new BmpDecoder(bmpData);
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return {
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data: decoder.getData(),
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width: decoder.width,
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height: decoder.height
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};
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};
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