Function gifImage

src/qrcode.js:1774–1971

(width, height)

  // ---------------------------------------------------------------------

  var gifImage = function (width, height) {
    var _width = width
    var _height = height
    var _data = new Array(width * height)

    var _this = {}

    _this.setPixel = function (x, y, pixel) {
      _data[y * _width + x] = pixel
    }

    _this.write = function (out) {
      // ---------------------------------
      // GIF Signature

      out.writeString('GIF87a')

      // ---------------------------------
      // Screen Descriptor

      out.writeShort(_width)
      out.writeShort(_height)

      out.writeByte(0x80) // 2bit
      out.writeByte(0)
      out.writeByte(0)

      // ---------------------------------
      // Global Color Map

      // black
      out.writeByte(0x00)
      out.writeByte(0x00)
      out.writeByte(0x00)

      // white
      out.writeByte(0xff)
      out.writeByte(0xff)
      out.writeByte(0xff)

      // ---------------------------------
      // Image Descriptor

      out.writeString(',')
      out.writeShort(0)
      out.writeShort(0)
      out.writeShort(_width)
      out.writeShort(_height)
      out.writeByte(0)

      // ---------------------------------
      // Local Color Map

      // ---------------------------------
      // Raster Data

      var lzwMinCodeSize = 2
      var raster = getLZWRaster(lzwMinCodeSize)