example.c

一个国人自己实现图像库的程序（有参考价值）

    deflateParams(&c_stream, Z_BEST_COMPRESSION, Z_FILTERED);
    c_stream.next_in = uncompr;
    c_stream.avail_in = (uInt)uncomprLen;
    err = deflate(&c_stream, Z_NO_FLUSH);
    CHECK_ERR(err, "deflate");

    err = deflate(&c_stream, Z_FINISH);
    if (err != Z_STREAM_END) {
        fprintf(stderr, "deflate should report Z_STREAM_END\n");
	exit(1);
    }
    err = deflateEnd(&c_stream);
    CHECK_ERR(err, "deflateEnd");
}

/* ===========================================================================
 * Test inflate() with large buffers
 */
void test_large_inflate(compr, comprLen, uncompr, uncomprLen)
    Byte *compr, *uncompr;
    uLong comprLen, uncomprLen;
{
    int err;
    z_stream d_stream; /* decompression stream */

    strcpy((char*)uncompr, "garbage");

    d_stream.zalloc = (alloc_func)0;
    d_stream.zfree = (free_func)0;
    d_stream.opaque = (voidpf)0;

    d_stream.next_in  = compr;
    d_stream.avail_in = (uInt)comprLen;

    err = inflateInit(&d_stream);
    CHECK_ERR(err, "inflateInit");

    for (;;) {
        d_stream.next_out = uncompr;            /* discard the output */
	d_stream.avail_out = (uInt)uncomprLen;
        err = inflate(&d_stream, Z_NO_FLUSH);
        if (err == Z_STREAM_END) break;
        CHECK_ERR(err, "large inflate");
    }

    err = inflateEnd(&d_stream);
    CHECK_ERR(err, "inflateEnd");

    if (d_stream.total_out != 2*uncomprLen + comprLen/2) {
        fprintf(stderr, "bad large inflate: %ld\n", d_stream.total_out);
	exit(1);
    } else {
        printf("large_inflate(): OK\n");
    }
}

/* ===========================================================================
 * Test deflate() with full flush
 */
void test_flush(compr, comprLen)
    Byte *compr;
    uLong *comprLen;
{
    z_stream c_stream; /* compression stream */
    int err;
    int len = strlen(hello)+1;

    c_stream.zalloc = (alloc_func)0;
    c_stream.zfree = (free_func)0;
    c_stream.opaque = (voidpf)0;

    err = deflateInit(&c_stream, Z_DEFAULT_COMPRESSION);
    CHECK_ERR(err, "deflateInit");

    c_stream.next_in  = (Bytef*)hello;
    c_stream.next_out = compr;
    c_stream.avail_in = 3;
    c_stream.avail_out = (uInt)*comprLen;
    err = deflate(&c_stream, Z_FULL_FLUSH);
    CHECK_ERR(err, "deflate");

    compr[3]++; /* force an error in first compressed block */
    c_stream.avail_in = len - 3;

    err = deflate(&c_stream, Z_FINISH);
    if (err != Z_STREAM_END) {
        CHECK_ERR(err, "deflate");
    }
    err = deflateEnd(&c_stream);
    CHECK_ERR(err, "deflateEnd");

    *comprLen = c_stream.total_out;
}

/* ===========================================================================
 * Test inflateSync()
 */
void test_sync(compr, comprLen, uncompr, uncomprLen)
    Byte *compr, *uncompr;
    uLong comprLen, uncomprLen;
{
    int err;
    z_stream d_stream; /* decompression stream */

    strcpy((char*)uncompr, "garbage");

    d_stream.zalloc = (alloc_func)0;
    d_stream.zfree = (free_func)0;
    d_stream.opaque = (voidpf)0;

    d_stream.next_in  = compr;
    d_stream.avail_in = 2; /* just read the zlib header */

    err = inflateInit(&d_stream);
    CHECK_ERR(err, "inflateInit");

    d_stream.next_out = uncompr;
    d_stream.avail_out = (uInt)uncomprLen;

    inflate(&d_stream, Z_NO_FLUSH);
    CHECK_ERR(err, "inflate");

    d_stream.avail_in = (uInt)comprLen-2;   /* read all compressed data */
    err = inflateSync(&d_stream);           /* but skip the damaged part */
    CHECK_ERR(err, "inflateSync");

    err = inflate(&d_stream, Z_FINISH);
    if (err != Z_DATA_ERROR) {
        fprintf(stderr, "inflate should report DATA_ERROR\n");
        /* Because of incorrect adler32 */
	exit(1);
    }
    err = inflateEnd(&d_stream);
    CHECK_ERR(err, "inflateEnd");

    printf("after inflateSync(): hel%s\n", (char *)uncompr);
}

/* ===========================================================================
 * Test deflate() with preset dictionary
 */
void test_dict_deflate(compr, comprLen)
    Byte *compr;
    uLong comprLen;
{
    z_stream c_stream; /* compression stream */
    int err;

    c_stream.zalloc = (alloc_func)0;
    c_stream.zfree = (free_func)0;
    c_stream.opaque = (voidpf)0;

    err = deflateInit(&c_stream, Z_BEST_COMPRESSION);
    CHECK_ERR(err, "deflateInit");

    err = deflateSetDictionary(&c_stream,
			       (const Bytef*)dictionary, sizeof(dictionary));
    CHECK_ERR(err, "deflateSetDictionary");

    dictId = c_stream.adler;
    c_stream.next_out = compr;
    c_stream.avail_out = (uInt)comprLen;

    c_stream.next_in = (Bytef*)hello;
    c_stream.avail_in = (uInt)strlen(hello)+1;

    err = deflate(&c_stream, Z_FINISH);
    if (err != Z_STREAM_END) {
        fprintf(stderr, "deflate should report Z_STREAM_END\n");
	exit(1);
    }
    err = deflateEnd(&c_stream);
    CHECK_ERR(err, "deflateEnd");
}

/* ===========================================================================
 * Test inflate() with a preset dictionary
 */
void test_dict_inflate(compr, comprLen, uncompr, uncomprLen)
    Byte *compr, *uncompr;
    uLong comprLen, uncomprLen;
{
    int err;
    z_stream d_stream; /* decompression stream */

    strcpy((char*)uncompr, "garbage");

    d_stream.zalloc = (alloc_func)0;
    d_stream.zfree = (free_func)0;
    d_stream.opaque = (voidpf)0;

    d_stream.next_in  = compr;
    d_stream.avail_in = (uInt)comprLen;

    err = inflateInit(&d_stream);
    CHECK_ERR(err, "inflateInit");

    d_stream.next_out = uncompr;
    d_stream.avail_out = (uInt)uncomprLen;

    for (;;) {
        err = inflate(&d_stream, Z_NO_FLUSH);
        if (err == Z_STREAM_END) break;
	if (err == Z_NEED_DICT) {
	    if (d_stream.adler != dictId) {
		fprintf(stderr, "unexpected dictionary");
		exit(1);
	    }
	    err = inflateSetDictionary(&d_stream, (const Bytef*)dictionary,
				       sizeof(dictionary));
	}
        CHECK_ERR(err, "inflate with dict");
    }

    err = inflateEnd(&d_stream);
    CHECK_ERR(err, "inflateEnd");

    if (strcmp((char*)uncompr, hello)) {
        fprintf(stderr, "bad inflate with dict\n");
	exit(1);
    } else {
        printf("inflate with dictionary: %s\n", (char *)uncompr);
    }
}

/* ===========================================================================
 * Usage:  example [output.gz  [input.gz]]
 */

int main(argc, argv)
    int argc;
    char *argv[];
{
    Byte *compr, *uncompr;
    uLong comprLen = 10000*sizeof(int); /* don't overflow on MSDOS */
    uLong uncomprLen = comprLen;
    static const char* myVersion = ZLIB_VERSION;

    if (zlibVersion()[0] != myVersion[0]) {
        fprintf(stderr, "incompatible zlib version\n");
        exit(1);

    } else if (strcmp(zlibVersion(), ZLIB_VERSION) != 0) {
        fprintf(stderr, "warning: different zlib version\n");
    }

    compr    = (Byte*)calloc((uInt)comprLen, 1);
    uncompr  = (Byte*)calloc((uInt)uncomprLen, 1);
    /* compr and uncompr are cleared to avoid reading uninitialized
     * data and to ensure that uncompr compresses well.
     */
    if (compr == Z_NULL || uncompr == Z_NULL) {
        printf("out of memory\n");
	exit(1);
    }
    test_compress(compr, comprLen, uncompr, uncomprLen);

    test_gzio((argc > 1 ? argv[1] : TESTFILE),
              (argc > 2 ? argv[2] : TESTFILE),
	      uncompr, (int)uncomprLen);

    test_deflate(compr, comprLen);
    test_inflate(compr, comprLen, uncompr, uncomprLen);

    test_large_deflate(compr, comprLen, uncompr, uncomprLen);
    test_large_inflate(compr, comprLen, uncompr, uncomprLen);

    test_flush(compr, &comprLen);
    test_sync(compr, comprLen, uncompr, uncomprLen);
    comprLen = uncomprLen;

    test_dict_deflate(compr, comprLen);
    test_dict_inflate(compr, comprLen, uncompr, uncomprLen);

    exit(0);
    return 0; /* to avoid warning */
}