write_file_header() public method

Write datastream header. This consists of an SOI and optional APPn markers. We recommend use of the JFIF marker, but not the Adobe marker, when using YCbCr or grayscale data. The JFIF marker is also used for other standard JPEG colorspaces. The Adobe marker is helpful to distinguish RGB, CMYK, and YCCK colorspaces. Note that an application can write additional header markers after jpeg_start_compress returns.
public write_file_header ( ) : void
return void
        /// <summary>
        /// Master selection of compression modules for transcoding.
        /// </summary>
        private void transencode_master_selection(jvirt_array<JBLOCK>[] coef_arrays)
        {
            /* Although we don't actually use input_components for transcoding, 
             * jcmaster.c's initial_setup will complain if input_components is 0.
             */
            m_input_components = 1;

            /* Initialize master control (includes parameter checking/processing) */
            jinit_c_master_control(true /* transcode only */);

            /* Entropy encoding: only Huffman coding supported. */
            if (m_progressive_mode)
                m_entropy = new phuff_entropy_encoder(this);
            else
                m_entropy = new huff_entropy_encoder(this);

            /* We need a special coefficient buffer controller. */
            m_coef = new my_trans_c_coef_controller(this, coef_arrays);
            m_marker = new jpeg_marker_writer(this);

            /* Write the datastream header (SOI, JFIF) immediately.
            * Frame and scan headers are postponed till later.
            * This lets application insert special markers after the SOI.
            */
            m_marker.write_file_header();
        }
Ejemplo n.º 2
0
        /// <summary>
        /// Master selection of compression modules for transcoding.
        /// </summary>
        private void transencode_master_selection(jvirt_array<JBLOCK>[] coef_arrays)
        {
            /* Initialize master control (includes parameter checking/processing) */
            jinit_c_master_control(true /* transcode only */);

            /* Entropy encoding: only Huffman or arithmetic coding. */
            if (arith_code)
                m_entropy = new arith_entropy_encoder(this);
            else
                m_entropy = new huff_entropy_encoder(this);

            /* We need a special coefficient buffer controller. */
            m_coef = new my_trans_c_coef_controller(this, coef_arrays);
            m_marker = new jpeg_marker_writer(this);

            /* Write the datastream header (SOI, JFIF) immediately.
            * Frame and scan headers are postponed till later.
            * This lets application insert special markers after the SOI.
            */
            m_marker.write_file_header();
        }
        /// <summary>
        /// Master selection of compression modules.
        /// This is done once at the start of processing an image.  We determine
        /// which modules will be used and give them appropriate initialization calls.
        /// This routine is in charge of selecting the modules to be executed and
        /// making an initialization call to each one.
        /// </summary>
        private void jinit_compress_master()
        {
            /* Initialize master control (includes parameter checking/processing) */
            jinit_c_master_control(false /* full compression */);

            /* Preprocessing */
            if (!m_raw_data_in)
            {
                m_cconvert = new jpeg_color_converter(this);
                m_downsample = new jpeg_downsampler(this);
                m_prep = new jpeg_c_prep_controller(this);
            }

            /* Forward DCT */
            m_fdct = new jpeg_forward_dct(this);

            /* Entropy encoding: only Huffman coding supported. */
            if (m_progressive_mode)
                m_entropy = new phuff_entropy_encoder(this);
            else
                m_entropy = new huff_entropy_encoder(this);

            /* Need a full-image coefficient buffer in any multi-pass mode. */
            m_coef = new my_c_coef_controller(this, (bool)(m_num_scans > 1 || m_optimize_coding));
            jinit_c_main_controller(false /* never need full buffer here */);
            m_marker = new jpeg_marker_writer(this);

            /* Write the datastream header (SOI) immediately.
            * Frame and scan headers are postponed till later.
            * This lets application insert special markers after the SOI.
            */
            m_marker.write_file_header();
        }
Ejemplo n.º 4
0
        /// <summary>
        /// Master selection of compression modules.
        /// This is done once at the start of processing an image.  We determine
        /// which modules will be used and give them appropriate initialization calls.
        /// This routine is in charge of selecting the modules to be executed and
        /// making an initialization call to each one.
        /// </summary>
        private void jinit_compress_master()
        {
            /* Sanity check on image dimensions */
            if (m_image_height <= 0 || m_image_width <= 0 || m_input_components <= 0)
                ERREXIT(J_MESSAGE_CODE.JERR_EMPTY_IMAGE);

            /* Initialize master control (includes parameter checking/processing) */
            jinit_c_master_control(false /* full compression */);

            /* Preprocessing */
            if (!m_raw_data_in)
            {
                m_cconvert = new jpeg_color_converter(this);
                m_downsample = new jpeg_downsampler(this);
                m_prep = new jpeg_c_prep_controller(this);
            }

            /* Forward DCT */
            m_fdct = new jpeg_forward_dct(this);

            /* Entropy encoding: either Huffman or arithmetic coding. */
            if (arith_code)
                m_entropy = new arith_entropy_encoder(this);
            else
                m_entropy = new huff_entropy_encoder(this);

            /* Need a full-image coefficient buffer in any multi-pass mode. */
            m_coef = new my_c_coef_controller(this, (bool)(m_num_scans > 1 || m_optimize_coding));
            jinit_c_main_controller(false /* never need full buffer here */);
            m_marker = new jpeg_marker_writer(this);

            /* Write the datastream header (SOI) immediately.
            * Frame and scan headers are postponed till later.
            * This lets application insert special markers after the SOI.
            */
            m_marker.write_file_header();
        }