82 lines
2.4 KiB
JavaScript
82 lines
2.4 KiB
JavaScript
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/**
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* @author shaozilee
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*
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* BMP format encoder,encode 24bit BMP
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* Not support quality compression
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*
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*/
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function BmpEncoder(imgData){
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this.buffer = imgData.data;
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this.width = imgData.width;
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this.height = imgData.height;
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this.extraBytes = this.width%4;
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this.rgbSize = this.height*(3*this.width+this.extraBytes);
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this.headerInfoSize = 40;
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this.data = [];
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/******************header***********************/
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this.flag = "BM";
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this.reserved = 0;
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this.offset = 54;
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this.fileSize = this.rgbSize+this.offset;
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this.planes = 1;
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this.bitPP = 24;
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this.compress = 0;
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this.hr = 0;
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this.vr = 0;
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this.colors = 0;
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this.importantColors = 0;
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}
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BmpEncoder.prototype.encode = function() {
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var tempBuffer = new Buffer(this.offset+this.rgbSize);
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this.pos = 0;
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tempBuffer.write(this.flag,this.pos,2);this.pos+=2;
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tempBuffer.writeUInt32LE(this.fileSize,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.reserved,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.offset,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.headerInfoSize,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.width,this.pos);this.pos+=4;
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tempBuffer.writeInt32LE(-this.height,this.pos);this.pos+=4;
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tempBuffer.writeUInt16LE(this.planes,this.pos);this.pos+=2;
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tempBuffer.writeUInt16LE(this.bitPP,this.pos);this.pos+=2;
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tempBuffer.writeUInt32LE(this.compress,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.rgbSize,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.hr,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.vr,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.colors,this.pos);this.pos+=4;
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tempBuffer.writeUInt32LE(this.importantColors,this.pos);this.pos+=4;
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var i=0;
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var rowBytes = 3*this.width+this.extraBytes;
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for (var y = 0; y <this.height; y++){
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for (var x = 0; x < this.width; x++){
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var p = this.pos+y*rowBytes+x*3;
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i++;//a
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tempBuffer[p]= this.buffer[i++];//b
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tempBuffer[p+1] = this.buffer[i++];//g
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tempBuffer[p+2] = this.buffer[i++];//r
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}
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if(this.extraBytes>0){
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var fillOffset = this.pos+y*rowBytes+this.width*3;
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tempBuffer.fill(0,fillOffset,fillOffset+this.extraBytes);
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}
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}
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return tempBuffer;
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};
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module.exports = function(imgData, quality) {
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if (typeof quality === 'undefined') quality = 100;
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var encoder = new BmpEncoder(imgData);
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var data = encoder.encode();
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return {
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data: data,
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width: imgData.width,
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height: imgData.height
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};
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};
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