BitMiracle.LibJpeg.Classic.Internal.my_upsampler.my_upsampler C# (CSharp) Method

        public my_upsampler(jpeg_decompress_struct cinfo)
        {
            m_cinfo = cinfo;
            m_need_context_rows = false; /* until we find out differently */

            if (cinfo.m_CCIR601_sampling)    /* this isn't supported */
                cinfo.ERREXIT(J_MESSAGE_CODE.JERR_CCIR601_NOTIMPL);

            /* Verify we can handle the sampling factors, select per-component methods,
            * and create storage as needed.
            */
            for (int ci = 0; ci < cinfo.m_num_components; ci++)
            {
                jpeg_component_info componentInfo = cinfo.Comp_info[ci];

                /* Compute size of an "input group" after IDCT scaling.  This many samples
                * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
                */
                int h_in_group = (componentInfo.H_samp_factor * componentInfo.DCT_h_scaled_size) / cinfo.min_DCT_h_scaled_size;
                int v_in_group = (componentInfo.V_samp_factor * componentInfo.DCT_v_scaled_size) / cinfo.min_DCT_v_scaled_size;
                int h_out_group = cinfo.m_max_h_samp_factor;
                int v_out_group = cinfo.m_max_v_samp_factor;

                /* save for use later */
                m_rowgroup_height[ci] = v_in_group;

                if (!componentInfo.component_needed)
                {
                    /* Don't bother to upsample an uninteresting component. */
                    m_upsampleMethods[ci] = ComponentUpsampler.noop_upsampler;
                    continue;		/* don't need to allocate buffer */
                }

                if (h_in_group == h_out_group && v_in_group == v_out_group)
                {
                    /* Fullsize components can be processed without any work. */
                    m_upsampleMethods[ci] = ComponentUpsampler.fullsize_upsampler;
                    continue;		/* don't need to allocate buffer */
                }

                if (h_in_group * 2 == h_out_group && v_in_group == v_out_group)
                {
                    /* Special case for 2h1v upsampling */
                    m_upsampleMethods[ci] = ComponentUpsampler.h2v1_upsampler;
                }
                else if (h_in_group * 2 == h_out_group && v_in_group * 2 == v_out_group)
                {
                    /* Special case for 2h2v upsampling */
                    m_upsampleMethods[ci] = ComponentUpsampler.h2v2_upsampler;
                }
                else if ((h_out_group % h_in_group) == 0 && (v_out_group % v_in_group) == 0)
                {
                    /* Generic integral-factors upsampling method */
                    m_upsampleMethods[ci] = ComponentUpsampler.int_upsampler;
                    m_h_expand[ci] = (byte)(h_out_group / h_in_group);
                    m_v_expand[ci] = (byte)(v_out_group / v_in_group);
                }
                else
                {
                    cinfo.ERREXIT(J_MESSAGE_CODE.JERR_FRACT_SAMPLE_NOTIMPL);
                }

                ComponentBuffer cb = new ComponentBuffer();
                cb.SetBuffer(jpeg_common_struct.AllocJpegSamples(JpegUtils.jround_up(cinfo.m_output_width, 
                    cinfo.m_max_h_samp_factor), cinfo.m_max_v_samp_factor), null, 0);

                m_color_buf[ci] = cb;
            }
        }