BitMiracle.LibJpeg.Classic.Internal.my_1pass_cquantizer.create_colorindex C# (CSharp) Method

        private void create_colorindex()
        {
            /* For ordered dither, we pad the color index tables by MAXJSAMPLE in
             * each direction (input index values can be -MAXJSAMPLE .. 2*MAXJSAMPLE).
             * This is not necessary in the other dithering modes.  However, we
             * flag whether it was done in case user changes dithering mode.
             */
            int pad;
            if (m_cinfo.m_dither_mode == J_DITHER_MODE.JDITHER_ORDERED)
            {
                pad = JpegConstants.MAXJSAMPLE * 2;
                m_is_padded = true;
            }
            else
            {
                pad = 0;
                m_is_padded = false;
            }

            m_colorindex = jpeg_common_struct.AllocJpegSamples(JpegConstants.MAXJSAMPLE + 1 + pad, m_cinfo.m_out_color_components);
            m_colorindexOffset = new int[m_cinfo.m_out_color_components];

            /* blksize is number of adjacent repeated entries for a component */
            int blksize = m_sv_actual;
            for (int i = 0; i < m_cinfo.m_out_color_components; i++)
            {
                /* fill in colorindex entries for i'th color component */
                int nci = m_Ncolors[i]; /* # of distinct values for this color */
                blksize = blksize / nci;

                /* adjust colorindex pointers to provide padding at negative indexes. */
                if (pad != 0)
                    m_colorindexOffset[i] += JpegConstants.MAXJSAMPLE;

                /* in loop, val = index of current output value, */
                /* and k = largest j that maps to current val */
                int val = 0;
                int k = largest_input_value(0, nci - 1);
                for (int j = 0; j <= JpegConstants.MAXJSAMPLE; j++)
                {
                    while (j > k)
                    {
                        /* advance val if past boundary */
                        k = largest_input_value(++val, nci - 1);
                    }

                    /* premultiply so that no multiplication needed in main processing */
                    m_colorindex[i][m_colorindexOffset[i] + j] = (byte)(val * blksize);
                }

                /* Pad at both ends if necessary */
                if (pad != 0)
                {
                    for (int j = 1; j <= JpegConstants.MAXJSAMPLE; j++)
                    {
                        m_colorindex[i][m_colorindexOffset[i] + -j] = m_colorindex[i][m_colorindexOffset[i]];
                        m_colorindex[i][m_colorindexOffset[i] + JpegConstants.MAXJSAMPLE + j] = m_colorindex[i][m_colorindexOffset[i] + JpegConstants.MAXJSAMPLE];
                    }
                }
            }
        }