TGA (AKA Truevision TGA, AKA TARGA) raster image file format: JavaScript parsing library

TGA (AKA Truevision TGA, AKA TARGA), is a raster image file format created by Truevision. It supports up to 32 bits per pixel (three 8-bit RGB channels + 8-bit alpha channel), color mapping and optional lossless RLE compression.

File extension

["tga", "icb", "vda", "vst"]

KS implementation details

License: CC0-1.0

References

This page hosts a formal specification of TGA (AKA Truevision TGA, AKA TARGA) raster image file format using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for JavaScript generated by Kaitai Struct depends on the JavaScript runtime library. You have to install it before you can parse data.

The JavaScript runtime library is available at npm:

npm install kaitai-struct

Code

See the usage examples in the JavaScript notes.

Parse structure from an ArrayBuffer:

var arrayBuffer = ...;
var data = new Tga(new KaitaiStream(arrayBuffer));

After that, one can get various attributes from the structure by accessing fields or properties like:

data.numColorMap // => Number of entries in a color map

JavaScript source code to parse TGA (AKA Truevision TGA, AKA TARGA) raster image file format

Tga.js

// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    define(['kaitai-struct/KaitaiStream'], factory);
  } else if (typeof module === 'object' && module.exports) {
    module.exports = factory(require('kaitai-struct/KaitaiStream'));
  } else {
    root.Tga = factory(root.KaitaiStream);
  }
}(this, function (KaitaiStream) {
/**
 * TGA (AKA Truevision TGA, AKA TARGA), is a raster image file format created by Truevision. It supports up to 32 bits per pixel (three 8-bit RGB channels + 8-bit alpha channel), color mapping and optional lossless RLE compression.
 * @see {@link http://www.dca.fee.unicamp.br/~martino/disciplinas/ea978/tgaffs.pdf|Source}
 */

var Tga = (function() {
  Tga.ColorMapEnum = Object.freeze({
    NO_COLOR_MAP: 0,
    HAS_COLOR_MAP: 1,

    0: "NO_COLOR_MAP",
    1: "HAS_COLOR_MAP",
  });

  Tga.ImageTypeEnum = Object.freeze({
    NO_IMAGE_DATA: 0,
    UNCOMP_COLOR_MAPPED: 1,
    UNCOMP_TRUE_COLOR: 2,
    UNCOMP_BW: 3,
    RLE_COLOR_MAPPED: 9,
    RLE_TRUE_COLOR: 10,
    RLE_BW: 11,

    0: "NO_IMAGE_DATA",
    1: "UNCOMP_COLOR_MAPPED",
    2: "UNCOMP_TRUE_COLOR",
    3: "UNCOMP_BW",
    9: "RLE_COLOR_MAPPED",
    10: "RLE_TRUE_COLOR",
    11: "RLE_BW",
  });

  function Tga(_io, _parent, _root) {
    this._io = _io;
    this._parent = _parent;
    this._root = _root || this;

    this._read();
  }
  Tga.prototype._read = function() {
    this.imageIdLen = this._io.readU1();
    this.colorMapType = this._io.readU1();
    this.imageType = this._io.readU1();
    this.colorMapOfs = this._io.readU2le();
    this.numColorMap = this._io.readU2le();
    this.colorMapDepth = this._io.readU1();
    this.xOffset = this._io.readU2le();
    this.yOffset = this._io.readU2le();
    this.width = this._io.readU2le();
    this.height = this._io.readU2le();
    this.imageDepth = this._io.readU1();
    this.imgDescriptor = this._io.readU1();
    this.imageId = this._io.readBytes(this.imageIdLen);
    if (this.colorMapType == Tga.ColorMapEnum.HAS_COLOR_MAP) {
      this.colorMap = new Array(this.numColorMap);
      for (var i = 0; i < this.numColorMap; i++) {
        this.colorMap[i] = this._io.readBytes(Math.floor((this.colorMapDepth + 7) / 8));
      }
    }
  }

  var TgaFooter = Tga.TgaFooter = (function() {
    function TgaFooter(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    TgaFooter.prototype._read = function() {
      this.extAreaOfs = this._io.readU4le();
      this.devDirOfs = this._io.readU4le();
      this.versionMagic = this._io.readBytes(18);
    }
    Object.defineProperty(TgaFooter.prototype, 'isValid', {
      get: function() {
        if (this._m_isValid !== undefined)
          return this._m_isValid;
        this._m_isValid = (KaitaiStream.byteArrayCompare(this.versionMagic, [84, 82, 85, 69, 86, 73, 83, 73, 79, 78, 45, 88, 70, 73, 76, 69, 46, 0]) == 0);
        return this._m_isValid;
      }
    });
    Object.defineProperty(TgaFooter.prototype, 'extArea', {
      get: function() {
        if (this._m_extArea !== undefined)
          return this._m_extArea;
        if (this.isValid) {
          var _pos = this._io.pos;
          this._io.seek(this.extAreaOfs);
          this._m_extArea = new TgaExtArea(this._io, this, this._root);
          this._io.seek(_pos);
        }
        return this._m_extArea;
      }
    });

    /**
     * Offset to extension area
     */

    /**
     * Offset to developer directory
     */

    return TgaFooter;
  })();

  var TgaExtArea = Tga.TgaExtArea = (function() {
    function TgaExtArea(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    TgaExtArea.prototype._read = function() {
      this.extAreaSize = this._io.readU2le();
      this.authorName = KaitaiStream.bytesToStr(this._io.readBytes(41), "ASCII");
      this.comments = new Array(4);
      for (var i = 0; i < 4; i++) {
        this.comments[i] = KaitaiStream.bytesToStr(this._io.readBytes(81), "ASCII");
      }
      this.timestamp = this._io.readBytes(12);
      this.jobId = KaitaiStream.bytesToStr(this._io.readBytes(41), "ASCII");
      this.jobTime = KaitaiStream.bytesToStr(this._io.readBytes(6), "ASCII");
      this.softwareId = KaitaiStream.bytesToStr(this._io.readBytes(41), "ASCII");
      this.softwareVersion = this._io.readBytes(3);
      this.keyColor = this._io.readU4le();
      this.pixelAspectRatio = this._io.readU4le();
      this.gammaValue = this._io.readU4le();
      this.colorCorrOfs = this._io.readU4le();
      this.postageStampOfs = this._io.readU4le();
      this.scanLineOfs = this._io.readU4le();
      this.attributes = this._io.readU1();
    }

    /**
     * Extension area size in bytes (always 495)
     */

    /**
     * Comments, organized as four lines, each consisting of 80 characters plus a NULL
     */

    /**
     * Image creation date / time
     */

    /**
     * Internal job ID, to be used in image workflow systems
     */

    /**
     * Hours, minutes and seconds spent creating the file (for billing, etc.)
     */

    /**
     * The application that created the file.
     */

    /**
     * Number of bytes from the beginning of the file to the color correction table if present
     */

    /**
     * Number of bytes from the beginning of the file to the postage stamp image if present
     */

    /**
     * Number of bytes from the beginning of the file to the scan lines table if present
     */

    /**
     * Specifies the alpha channel
     */

    return TgaExtArea;
  })();
  Object.defineProperty(Tga.prototype, 'footer', {
    get: function() {
      if (this._m_footer !== undefined)
        return this._m_footer;
      var _pos = this._io.pos;
      this._io.seek((this._io.size - 26));
      this._m_footer = new TgaFooter(this._io, this, this._root);
      this._io.seek(_pos);
      return this._m_footer;
    }
  });

  /**
   * Number of entries in a color map
   */

  /**
   * Number of bits in a each color maps entry
   */

  /**
   * Width of the image, in pixels
   */

  /**
   * Height of the image, in pixels
   */

  /**
   * Arbitrary application-specific information that is used to
   * identify image. May contain text or some binary data.
   */

  /**
   * Color map
   */

  return Tga;
})();
return Tga;
}));