/// <summary>
/// Master selection of decompression modules.
/// This is done once at jpeg_start_decompress time. We determine
/// which modules will be used and give them appropriate initialization calls.
/// We also initialize the decompressor input side to begin consuming data.
///
/// Since jpeg_read_header has finished, we know what is in the SOF
/// and (first) SOS markers. We also have all the application parameter
/// settings.
/// </summary>
private void master_selection()
{
/* Initialize dimensions and other stuff */
m_cinfo.jpeg_calc_output_dimensions();
prepare_range_limit_table();
/* Width of an output scanline must be representable as int. */
long samplesperrow = m_cinfo.m_output_width * m_cinfo.m_out_color_components;
int jd_samplesperrow = (int)samplesperrow;
if ((long)jd_samplesperrow != samplesperrow)
{
m_cinfo.ERREXIT(J_MESSAGE_CODE.JERR_WIDTH_OVERFLOW);
}
/* Initialize my private state */
m_pass_number = 0;
m_using_merged_upsample = m_cinfo.use_merged_upsample();
/* Color quantizer selection */
m_quantizer_1pass = null;
m_quantizer_2pass = null;
/* No mode changes if not using buffered-image mode. */
if (!m_cinfo.m_quantize_colors || !m_cinfo.m_buffered_image)
{
m_cinfo.m_enable_1pass_quant = false;
m_cinfo.m_enable_external_quant = false;
m_cinfo.m_enable_2pass_quant = false;
}
if (m_cinfo.m_quantize_colors)
{
if (m_cinfo.m_raw_data_out)
{
m_cinfo.ERREXIT(J_MESSAGE_CODE.JERR_NOTIMPL);
}
/* 2-pass quantizer only works in 3-component color space. */
if (m_cinfo.m_out_color_components != 3)
{
m_cinfo.m_enable_1pass_quant = true;
m_cinfo.m_enable_external_quant = false;
m_cinfo.m_enable_2pass_quant = false;
m_cinfo.m_colormap = null;
}
else if (m_cinfo.m_colormap != null)
{
m_cinfo.m_enable_external_quant = true;
}
else if (m_cinfo.m_two_pass_quantize)
{
m_cinfo.m_enable_2pass_quant = true;
}
else
{
m_cinfo.m_enable_1pass_quant = true;
}
if (m_cinfo.m_enable_1pass_quant)
{
m_cinfo.m_cquantize = new my_1pass_cquantizer(m_cinfo);
m_quantizer_1pass = m_cinfo.m_cquantize;
}
/* We use the 2-pass code to map to external colormaps. */
if (m_cinfo.m_enable_2pass_quant || m_cinfo.m_enable_external_quant)
{
m_cinfo.m_cquantize = new my_2pass_cquantizer(m_cinfo);
m_quantizer_2pass = m_cinfo.m_cquantize;
}
/* If both quantizers are initialized, the 2-pass one is left active;
* this is necessary for starting with quantization to an external map.
*/
}
/* Post-processing: in particular, color conversion first */
if (!m_cinfo.m_raw_data_out)
{
if (m_using_merged_upsample)
{
/* does color conversion too */
m_cinfo.m_upsample = new my_merged_upsampler(m_cinfo);
}
else
{
m_cinfo.m_cconvert = new jpeg_color_deconverter(m_cinfo);
m_cinfo.m_upsample = new my_upsampler(m_cinfo);
}
m_cinfo.m_post = new jpeg_d_post_controller(m_cinfo, m_cinfo.m_enable_2pass_quant);
}
/* Inverse DCT */
m_cinfo.m_idct = new jpeg_inverse_dct(m_cinfo);
if (m_cinfo.m_progressive_mode)
{
m_cinfo.m_entropy = new phuff_entropy_decoder(m_cinfo);
}
else
{
m_cinfo.m_entropy = new huff_entropy_decoder(m_cinfo);
}
/* Initialize principal buffer controllers. */
bool use_c_buffer = m_cinfo.m_inputctl.HasMultipleScans() || m_cinfo.m_buffered_image;
m_cinfo.m_coef = new jpeg_d_coef_controller(m_cinfo, use_c_buffer);
if (!m_cinfo.m_raw_data_out)
{
m_cinfo.m_main = new jpeg_d_main_controller(m_cinfo);
}
/* Initialize input side of decompressor to consume first scan. */
m_cinfo.m_inputctl.start_input_pass();
/* If jpeg_start_decompress will read the whole file, initialize
* progress monitoring appropriately. The input step is counted
* as one pass.
*/
if (m_cinfo.m_progress != null && !m_cinfo.m_buffered_image && m_cinfo.m_inputctl.HasMultipleScans())
{
/* Estimate number of scans to set pass_limit. */
int nscans;
if (m_cinfo.m_progressive_mode)
{
/* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
nscans = 2 + 3 * m_cinfo.m_num_components;
}
else
{
/* For a non progressive multiscan file, estimate 1 scan per component. */
nscans = m_cinfo.m_num_components;
}
m_cinfo.m_progress.Pass_counter = 0;
m_cinfo.m_progress.Pass_limit = m_cinfo.m_total_iMCU_rows * nscans;
m_cinfo.m_progress.Completed_passes = 0;
m_cinfo.m_progress.Total_passes = (m_cinfo.m_enable_2pass_quant ? 3 : 2);
/* Count the input pass as done */
m_pass_number++;
}
}