jpeg_calc_output_dimensions() public method

Pre-calculate output image dimensions and related values for current decompression parameters.
This is allowed for possible use by application. Hence it mustn't do anything that can't be done twice. Also note that it may be called before the master module is initialized!
public jpeg_calc_output_dimensions ( ) : void
return void
jpeg_decompress_struct Class Documentation
コード例 #1
0
        private int cur_output_row;  /* next row# to write to virtual array */

        public bmp_dest_struct(jpeg_decompress_struct cinfo, bool is_os2)
        {
            this.cinfo = cinfo;
            this.is_os2 = is_os2;

            if (cinfo.Out_color_space == J_COLOR_SPACE.JCS_GRAYSCALE)
            {
                m_putGrayRows = true;
            }
            else if (cinfo.Out_color_space == J_COLOR_SPACE.JCS_RGB)
            {
                if (cinfo.Quantize_colors)
                    m_putGrayRows = true;
                else
                    m_putGrayRows = false;
            }
            else
            {
                cinfo.ERREXIT((int)ADDON_MESSAGE_CODE.JERR_BMP_COLORSPACE);
            }

            /* Calculate output image dimensions so we can allocate space */
            cinfo.jpeg_calc_output_dimensions();

            /* Determine width of rows in the BMP file (padded to 4-byte boundary). */
            row_width = cinfo.Output_width * cinfo.Output_components;
            data_width = row_width;
            while ((row_width & 3) != 0)
                row_width++;

            pad_bytes = row_width - data_width;

            /* Allocate space for inversion array, prepare for write pass */
            whole_image = jpeg_common_struct.CreateSamplesArray(row_width, cinfo.Output_height);
            whole_image.ErrorProcessor = cinfo;

            cur_output_row = 0;
            if (cinfo.Progress != null)
            {
                cdjpeg_progress_mgr progress = cinfo.Progress as cdjpeg_progress_mgr;
                if (progress != null)
                {
                    /* count file input as separate pass */
                    progress.total_extra_passes++;
                }
            }

            /* Create decompressor output buffer. */
            buffer = jpeg_common_struct.AllocJpegSamples(row_width, 1);
            buffer_height = 1;
        }