public my_2pass_cquantizer(jpeg_decompress_struct cinfo)
{
m_cinfo = cinfo;
/* Make sure jdmaster didn't give me a case I can't handle */
if (cinfo.m_out_color_components != 3)
cinfo.ERREXIT(J_MESSAGE_CODE.JERR_NOTIMPL);
/* Allocate the histogram/inverse colormap storage */
m_histogram = new ushort[HIST_C0_ELEMS][];
for (int i = 0; i < HIST_C0_ELEMS; i++)
m_histogram[i] = new ushort[HIST_C1_ELEMS * HIST_C2_ELEMS];
m_needs_zeroed = true; /* histogram is garbage now */
/* Allocate storage for the completed colormap, if required.
* We do this now since it is FAR storage and may affect
* the memory manager's space calculations.
*/
if (cinfo.m_enable_2pass_quant)
{
/* Make sure color count is acceptable */
int desired_local = cinfo.m_desired_number_of_colors;
/* Lower bound on # of colors ... somewhat arbitrary as long as > 0 */
if (desired_local < 8)
cinfo.ERREXIT(J_MESSAGE_CODE.JERR_QUANT_FEW_COLORS, 8);
/* Make sure colormap indexes can be represented by JSAMPLEs */
if (desired_local > MAXNUMCOLORS)
cinfo.ERREXIT(J_MESSAGE_CODE.JERR_QUANT_MANY_COLORS, MAXNUMCOLORS);
m_sv_colormap = jpeg_common_struct.AllocJpegSamples(desired_local, 3);
m_desired = desired_local;
}
/* Only F-S dithering or no dithering is supported. */
/* If user asks for ordered dither, give him F-S. */
if (cinfo.m_dither_mode != J_DITHER_MODE.JDITHER_NONE)
cinfo.m_dither_mode = J_DITHER_MODE.JDITHER_FS;
/* Allocate Floyd-Steinberg workspace if necessary.
* This isn't really needed until pass 2, but again it is FAR storage.
* Although we will cope with a later change in dither_mode,
* we do not promise to honor max_memory_to_use if dither_mode changes.
*/
if (cinfo.m_dither_mode == J_DITHER_MODE.JDITHER_FS)
{
m_fserrors = new short[(cinfo.m_output_width + 2) * 3];
/* Might as well create the error-limiting table too. */
init_error_limit();
}
}
