JpegEncode.c

/*
 * The Python Imaging Library.
 * $Id$
 *
 * coder for JPEG data
 *
 * history:
 * 1996-05-06 fl   created
 * 1996-07-16 fl   don't drop last block of encoded data
 * 1996-12-30 fl   added quality and progressive settings
 * 1997-01-08 fl   added streamtype settings
 * 1998-01-31 fl   adapted to libjpeg 6a
 * 1998-07-12 fl   added YCbCr support
 * 2001-04-16 fl   added DPI write support
 *
 * Copyright (c) 1997-2001 by Secret Labs AB
 * Copyright (c) 1995-1997 by Fredrik Lundh
 *
 * See the README file for details on usage and redistribution.
 */

#include "Imaging.h"

#ifdef HAVE_LIBJPEG

#undef HAVE_PROTOTYPES
#undef HAVE_STDLIB_H
#undef HAVE_STDDEF_H
#undef UINT8
#undef UINT16
#undef UINT32
#undef INT16
#undef INT32

#include "Jpeg.h"

/* -------------------------------------------------------------------- */
/* Suspending output handler                                            */
/* -------------------------------------------------------------------- */

METHODDEF(void)
stub(j_compress_ptr cinfo) { /* empty */ }

METHODDEF(boolean)
empty_output_buffer(j_compress_ptr cinfo) {
    /* Suspension */
    return FALSE;
}

GLOBAL(void)
jpeg_buffer_dest(j_compress_ptr cinfo, JPEGDESTINATION *destination) {
    cinfo->dest = (void *)destination;

    destination->pub.init_destination = stub;
    destination->pub.empty_output_buffer = empty_output_buffer;
    destination->pub.term_destination = stub;
}

/* -------------------------------------------------------------------- */
/* Error handler                                                        */
/* -------------------------------------------------------------------- */

METHODDEF(void)
error(j_common_ptr cinfo) {
    JPEGERROR *error;
    error = (JPEGERROR *)cinfo->err;
    (*cinfo->err->output_message)(cinfo);
    longjmp(error->setjmp_buffer, 1);
}

/* -------------------------------------------------------------------- */
/* Encoder                                                              */
/* -------------------------------------------------------------------- */

int
ImagingJpegEncode(Imaging im, ImagingCodecState state, UINT8 *buf, int bytes) {
    JPEGENCODERSTATE *context = (JPEGENCODERSTATE *)state->context;
    int ok;

    if (setjmp(context->error.setjmp_buffer)) {
        /* JPEG error handler */
        jpeg_destroy_compress(&context->cinfo);
        state->errcode = IMAGING_CODEC_BROKEN;
        return -1;
    }

    if (!state->state) {
        /* Setup compression context (very similar to the decoder) */
        context->cinfo.err = jpeg_std_error(&context->error.pub);
        context->error.pub.error_exit = error;
        jpeg_create_compress(&context->cinfo);
        jpeg_buffer_dest(&context->cinfo, &context->destination);

        context->extra_offset = 0;

        /* Ready to encode */
        state->state = 1;
    }

    /* Load the destination buffer */
    context->destination.pub.next_output_byte = buf;
    context->destination.pub.free_in_buffer = bytes;

    switch (state->state) {
        case 1:

            context->cinfo.image_width = state->xsize;
            context->cinfo.image_height = state->ysize;

            switch (state->bits) {
                case 8:
                    context->cinfo.input_components = 1;
                    context->cinfo.in_color_space = JCS_GRAYSCALE;
                    break;
                case 24:
                    context->cinfo.input_components = 3;
                    if (strcmp(im->mode, "YCbCr") == 0) {
                        context->cinfo.in_color_space = JCS_YCbCr;
                    } else {
                        context->cinfo.in_color_space = JCS_RGB;
                    }
                    break;
                case 32:
                    context->cinfo.input_components = 4;
                    context->cinfo.in_color_space = JCS_CMYK;
#ifdef JCS_EXTENSIONS
                    if (strcmp(context->rawmode, "RGBX") == 0) {
                        context->cinfo.in_color_space = JCS_EXT_RGBX;
                    }
#endif
                    break;
                default:
                    state->errcode = IMAGING_CODEC_CONFIG;
                    return -1;
            }

            /* Compressor configuration */
            jpeg_set_defaults(&context->cinfo);

            /* Prevent RGB -> YCbCr conversion */
            if (context->keep_rgb) {
                switch (context->cinfo.in_color_space) {
                    case JCS_RGB:
#ifdef JCS_EXTENSIONS
                    case JCS_EXT_RGBX:
#endif
                        switch (context->subsampling) {
                            case -1:  /* Default */
                            case 0:   /* No subsampling */
                                break;
                            default:
                                /* Would subsample the green and blue
                                   channels, which doesn't make sense */
                                state->errcode = IMAGING_CODEC_CONFIG;
                                return -1;
                        }
                        jpeg_set_colorspace(&context->cinfo, JCS_RGB);
                        break;
                    default:
                        break;
                }
            }

            /* Use custom quantization tables */
            if (context->qtables) {
                int i;
                int quality = 100;
                int last_q = 0;
                if (context->quality != -1) {
                    quality = context->quality;
                }
                for (i = 0; i < context->qtablesLen; i++) {
                    jpeg_add_quant_table(
                        &context->cinfo,
                        i,
                        &context->qtables[i * DCTSIZE2],
                        quality,
                        FALSE);
                    context->cinfo.comp_info[i].quant_tbl_no = i;
                    last_q = i;
                }
                if (context->qtablesLen == 1) {
                    // jpeg_set_defaults created two qtables internally, but we only
                    // wanted one.
                    jpeg_add_quant_table(
                        &context->cinfo, 1, &context->qtables[0], quality, FALSE);
                }
                for (i = last_q; i < context->cinfo.num_components; i++) {
                    context->cinfo.comp_info[i].quant_tbl_no = last_q;
                }
            } else if (context->quality != -1) {
                jpeg_set_quality(&context->cinfo, context->quality, TRUE);
            }

            /* Set subsampling options */
            switch (context->subsampling) {
                case 0: /* 1x1 1x1 1x1 (4:4:4) : None */
                {
                    context->cinfo.comp_info[0].h_samp_factor = 1;
                    context->cinfo.comp_info[0].v_samp_factor = 1;
                    context->cinfo.comp_info[1].h_samp_factor = 1;
                    context->cinfo.comp_info[1].v_samp_factor = 1;
                    context->cinfo.comp_info[2].h_samp_factor = 1;
                    context->cinfo.comp_info[2].v_samp_factor = 1;
                    break;
                }
                case 1: /* 2x1, 1x1, 1x1 (4:2:2) : Medium */
                {
                    context->cinfo.comp_info[0].h_samp_factor = 2;
                    context->cinfo.comp_info[0].v_samp_factor = 1;
                    context->cinfo.comp_info[1].h_samp_factor = 1;
                    context->cinfo.comp_info[1].v_samp_factor = 1;
                    context->cinfo.comp_info[2].h_samp_factor = 1;
                    context->cinfo.comp_info[2].v_samp_factor = 1;
                    break;
                }
                case 2: /* 2x2, 1x1, 1x1 (4:2:0) : High */
                {
                    context->cinfo.comp_info[0].h_samp_factor = 2;
                    context->cinfo.comp_info[0].v_samp_factor = 2;
                    context->cinfo.comp_info[1].h_samp_factor = 1;
                    context->cinfo.comp_info[1].v_samp_factor = 1;
                    context->cinfo.comp_info[2].h_samp_factor = 1;
                    context->cinfo.comp_info[2].v_samp_factor = 1;
                    break;
                }
                default: {
                    /* Use the lib's default */
                    break;
                }
            }
            if (context->progressive) {
                jpeg_simple_progression(&context->cinfo);
            }
            context->cinfo.smoothing_factor = context->smooth;
            context->cinfo.optimize_coding = (boolean)context->optimize;
            context->cinfo.restart_interval = context->restart_marker_blocks;
            context->cinfo.restart_in_rows = context->restart_marker_rows;
            if (context->xdpi > 0 && context->ydpi > 0) {
                context->cinfo.write_JFIF_header = TRUE;
                context->cinfo.density_unit = 1; /* dots per inch */
                context->cinfo.X_density = context->xdpi;
                context->cinfo.Y_density = context->ydpi;
            }
            switch (context->streamtype) {
                case 1:
                    /* tables only */
                    jpeg_write_tables(&context->cinfo);
                    goto cleanup;
                case 2:
                    /* image only */
                    jpeg_suppress_tables(&context->cinfo, TRUE);
                    jpeg_start_compress(&context->cinfo, FALSE);
                    /* suppress extra section */
                    context->extra_offset = context->extra_size;
                    break;
                default:
                    /* interchange stream */
                    jpeg_start_compress(&context->cinfo, TRUE);
                    break;
            }
            state->state++;
            /* fall through */

        case 2:
            // check for exif len + 'APP1' header bytes
            if (context->rawExifLen + 5 > context->destination.pub.free_in_buffer) {
                break;
            }
            // add exif header
            if (context->rawExifLen > 0) {
                jpeg_write_marker(
                    &context->cinfo,
                    JPEG_APP0 + 1,
                    (unsigned char *)context->rawExif,
                    context->rawExifLen);
            }

            state->state++;
            /* fall through */
        case 3:

            if (context->extra) {
                /* copy extra buffer to output buffer */
                unsigned int n = context->extra_size - context->extra_offset;
                if (n > context->destination.pub.free_in_buffer) {
                    n = context->destination.pub.free_in_buffer;
                }
                memcpy(
                    context->destination.pub.next_output_byte,
                    context->extra + context->extra_offset,
                    n);
                context->destination.pub.next_output_byte += n;
                context->destination.pub.free_in_buffer -= n;
                context->extra_offset += n;
                if (context->extra_offset >= context->extra_size) {
                    state->state++;
                } else {
                    break;
                }
            } else {
                state->state++;
            }

        case 4:

            if (context->comment) {
                jpeg_write_marker(&context->cinfo, JPEG_COM, (unsigned char *)context->comment, context->comment_size);
            }
            state->state++;

        case 5:
            if (1024 > context->destination.pub.free_in_buffer) {
                break;
            }

            ok = 1;
            while (state->y < state->ysize) {
                state->shuffle(
                    state->buffer,
                    (UINT8 *)im->image[state->y + state->yoff] +
                        state->xoff * im->pixelsize,
                    state->xsize);
                ok = jpeg_write_scanlines(&context->cinfo, &state->buffer, 1);
                if (ok != 1) {
                    break;
                }
                state->y++;
            }

            if (ok != 1) {
                break;
            }
            state->state++;
            /* fall through */

        case 6:

            /* Finish compression */
            if (context->destination.pub.free_in_buffer < 100) {
                break;
            }
            jpeg_finish_compress(&context->cinfo);

cleanup:
            /* Clean up */
            if (context->comment) {
                free(context->comment);
                context->comment = NULL;
            }
            if (context->extra) {
                free(context->extra);
                context->extra = NULL;
            }
            if (context->rawExif) {
                free(context->rawExif);
                context->rawExif = NULL;
            }
            if (context->qtables) {
                free(context->qtables);
                context->qtables = NULL;
            }

            jpeg_destroy_compress(&context->cinfo);
            /* if (jerr.pub.num_warnings) return BROKEN; */
            state->errcode = IMAGING_CODEC_END;
            break;
    }

    /* Return number of bytes in output buffer */
    return context->destination.pub.next_output_byte - buf;
}

const char *
ImagingJpegVersion(void) {
    static char version[20];
    sprintf(version, "%d.%d", JPEG_LIB_VERSION / 10, JPEG_LIB_VERSION % 10);
    return version;
}

#endif