sixel_dither_new(
    sixel_dither_t    /* out */ **ppdither, /* dither object to be created */
    int               /* in */  ncolors,    /* required colors */
    sixel_allocator_t /* in */  *allocator) /* allocator, null if you use
                                               default allocator */
{
    SIXELSTATUS status = SIXEL_FALSE;
    size_t headsize;
    size_t datasize;
    size_t wholesize;
    int quality_mode;

    if (ppdither == NULL) {
        sixel_helper_set_additional_message(
            "sixel_dither_new: ppdither is null.");
        status = SIXEL_BAD_ARGUMENT;
        goto end;
    }

    if (allocator == NULL) {
        status = sixel_allocator_new(&allocator, NULL, NULL, NULL, NULL);
        if (SIXEL_FAILED(status)) {
            *ppdither = NULL;
            goto end;
        }
    } else {
        sixel_allocator_ref(allocator);
    }

    if (ncolors < 0) {
        ncolors = 256;
        quality_mode = SIXEL_QUALITY_HIGHCOLOR;
    } else {
        if (ncolors > SIXEL_PALETTE_MAX) {
            ncolors = 256;
        } else if (ncolors < 2) {
            ncolors = 2;
        }
        quality_mode = SIXEL_QUALITY_LOW;
    }
    headsize = sizeof(sixel_dither_t);
    datasize = (size_t)(ncolors * 3);
    wholesize = headsize + datasize;

    *ppdither = (sixel_dither_t *)sixel_allocator_malloc(allocator, wholesize);
    if (*ppdither == NULL) {
        sixel_allocator_unref(allocator);
        sixel_helper_set_additional_message(
            "sixel_dither_new: sixel_allocator_malloc() failed.");
        status = SIXEL_BAD_ALLOCATION;
        goto end;
    }

    (*ppdither)->ref = 1;
    (*ppdither)->palette = (unsigned char*)(*ppdither + 1);
    (*ppdither)->cachetable = NULL;
    (*ppdither)->reqcolors = ncolors;
    (*ppdither)->ncolors = ncolors;
    (*ppdither)->origcolors = (-1);
    (*ppdither)->keycolor = (-1);
    (*ppdither)->optimized = 0;
    (*ppdither)->optimize_palette = 0;
    (*ppdither)->complexion = 1;
    (*ppdither)->bodyonly = 0;
    (*ppdither)->method_for_largest = SIXEL_LARGE_NORM;
    (*ppdither)->method_for_rep = SIXEL_REP_CENTER_BOX;
    (*ppdither)->method_for_diffuse = SIXEL_DIFFUSE_FS;
    (*ppdither)->quality_mode = quality_mode;
    (*ppdither)->pixelformat = SIXEL_PIXELFORMAT_RGB888;
    (*ppdither)->allocator = allocator;

    status = SIXEL_OK;

end:
    return status;
}
Unknown