jbig2_image_pbm.c.svn-base

来自「SumatraPDF是一款小型开源的pdf阅读工具。虽然玲珑小巧（只有800多K」· SVN-BASE 代码 · 共 143 行

/*
    jbig2dec
    
    Copyright (C) 2002 Artifex Software, Inc.
    
    This software is distributed under license and may not
    be copied, modified or distributed except as expressly
    authorized under the terms of the license contained in
    the file LICENSE in this distribution.
                                                                                
    For information on commercial licensing, go to
    http://www.artifex.com/licensing/ or contact
    Artifex Software, Inc.,  101 Lucas Valley Road #110,
    San Rafael, CA  94903, U.S.A., [phone].

    $Id: jbig2_image_pbm.c 461 2008-05-07 21:37:02Z giles $
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif 
#include "os_types.h"

#include <stdio.h>
#include <ctype.h>

#include "jbig2.h"
#include "jbig2_image.h"

/* take an image structure and write it to a file in pbm format */

int jbig2_image_write_pbm_file(Jbig2Image *image, char *filename)
{
    FILE *out;
    int	error;
    
    if ((out = fopen(filename, "wb")) == NULL) {
        fprintf(stderr, "unable to open '%s' for writing", filename);
        return 1;
    }
    
    error = jbig2_image_write_pbm(image, out);
    
    fclose(out);
    return (error);
}

/* write out an image struct as a pbm stream to an open file pointer */

int jbig2_image_write_pbm(Jbig2Image *image, FILE *out)
{
        /* pbm header */
        fprintf(out, "P4\n%d %d\n", image->width, image->height);
        
        /* pbm format pads to a byte boundary, so we can
           just write out the whole data buffer
           NB: this assumes minimal stride for the width */
        fwrite(image->data, 1, image->height*image->stride, out);
        
        /* success */
	return 0;
}

/* take an image from a file in pbm format */
Jbig2Image *jbig2_image_read_pbm_file(Jbig2Ctx *ctx, char *filename)
{
    FILE *in;
    Jbig2Image *image;
    
    if ((in = fopen(filename, "rb")) == NULL) {
		fprintf(stderr, "unable to open '%s' for reading\n", filename);
		return NULL;
    }
    
    image = jbig2_image_read_pbm(ctx, in);
    
    return (image);
}

/* FIXME: should handle multi-image files */
Jbig2Image *jbig2_image_read_pbm(Jbig2Ctx *ctx, FILE *in)
{
    int i, dim[2];
    int done;
    Jbig2Image *image;
    int c;
    char buf[32];
    
    /* look for 'P4' magic */
    while ((c = fgetc(in)) != 'P') {
        if (feof(in)) return NULL;
    }
    if ((c = fgetc(in)) != '4') {
        fprintf(stderr, "not a binary pbm file.\n");
        return NULL;
    }
    /* read size. we must find two decimal numbers representing
       the image dimensions. 'done' will index whether we're
       looking for the width or the height and 'i' will be our
       array index for copying strings into our buffer */
    done = 0;
    i = 0;
    while (done < 2) {
        c = fgetc(in);
        /* skip whitespace */
        if (c == ' ' || c == '\t' || c == '\r' || c == '\n') continue;
        /* skip comments */
        if (c == '#') {
            while ((c = fgetc(in)) != '\n');
            continue;
        }
        if (isdigit(c)) {
            buf[i++] = c;
            while (isdigit(buf[i++] = fgetc(in))) {
                if (feof(in) || i >= 32) {
                    fprintf(stderr, "pbm parsing error\n");
                    return NULL;
                }
            }
            buf[i] = '\0';
            sscanf(buf, "%d", &dim[done]);
            i = 0;
            done++;
        }
    }
    /* allocate image structure */
    image = jbig2_image_new(ctx, dim[0], dim[1]);
    if (image == NULL) {
        fprintf(stderr, "could not allocate %dx%d image for pbm file\n", dim[0], dim[1]);
        return NULL;
    }
    /* the pbm data is byte-aligned, so we can
       do a simple block read */
    fread(image->data, 1, image->height*image->stride, in);
    if (feof(in)) {
        fprintf(stderr, "unexpected end of pbm file.\n");
        jbig2_image_release(ctx, image);
        return NULL;
    }    
    /* success */
    return image;
}