src/core/SkFlate.cpp

/*
 * Copyright (C) 2010 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "SkFlate.h"
#include "SkStream.h"

#ifndef SK_ZLIB_INCLUDE
bool SkFlate::HaveFlate() { return false; }
bool SkFlate::Deflate(SkStream*, SkDynamicMemoryWStream*) { return false; }
bool SkFlate::Inflate(SkStream*, SkDynamicMemoryWStream*) { return false; }
#else

// static
const size_t SkFlate::kBufferSize = 1024;

// static
bool SkFlate::HaveFlate() {
    return true;
}

namespace {

#include SK_ZLIB_INCLUDE

bool doFlate(bool compress, const size_t kBufferSize, SkStream* src,
             SkDynamicMemoryWStream* dst) {
    uint8_t inputBuffer[kBufferSize];
    uint8_t outputBuffer[kBufferSize];
    z_stream flateData;
    flateData.zalloc = NULL;
    flateData.zfree = NULL;
    flateData.next_in = NULL;
    flateData.avail_in = 0;
    flateData.next_out = outputBuffer;
    flateData.avail_out = kBufferSize;
    int rc;
    if (compress)
        rc = deflateInit(&flateData, Z_DEFAULT_COMPRESSION);
    else
        rc = inflateInit(&flateData);
    if (rc != Z_OK)
        return false;

    uint8_t* input = (uint8_t*)src->getMemoryBase();
    size_t inputLength = src->getLength();
    if (input == NULL || inputLength < 0) {
        input = NULL;
        flateData.next_in = inputBuffer;
        flateData.avail_in = 0;
    } else {
        flateData.next_in = input;
        flateData.avail_in = inputLength;
    }

    rc = Z_OK;
    while (true) {
        if (flateData.avail_out < kBufferSize) {
            if (!dst->write(outputBuffer, kBufferSize - flateData.avail_out)) {
                rc = Z_BUF_ERROR;
                break;
            }
            flateData.next_out = outputBuffer;
            flateData.avail_out = kBufferSize;
        }
        if (flateData.avail_in == 0) {
            if (input != NULL)
                break;
            size_t read = src->read(&inputBuffer, kBufferSize);
            if (read == 0)
                break;
            flateData.next_in = inputBuffer;
            flateData.avail_in = read;
        }
        if (compress)
            rc = deflate(&flateData, Z_NO_FLUSH);
        else
            rc = inflate(&flateData, Z_NO_FLUSH);
        if (rc != Z_OK)
            break;
    }
    while (rc == Z_OK) {
        if (compress)
            rc = deflate(&flateData, Z_FINISH);
        else
            rc = inflate(&flateData, Z_FINISH);
        if (flateData.avail_out > 0) {
            if (!dst->write(outputBuffer, kBufferSize - flateData.avail_out))
                return false;
            flateData.next_out = outputBuffer;
            flateData.avail_out = kBufferSize;
        }
    }

    if (compress)
        deflateEnd(&flateData);
    else
        inflateEnd(&flateData);
    if (rc == Z_STREAM_END)
        return true;
    return false;
}

}

// static
bool SkFlate::Deflate(SkStream* src, SkDynamicMemoryWStream* dst) {
    return doFlate(true, kBufferSize, src, dst);
}

// static
bool SkFlate::Inflate(SkStream* src, SkDynamicMemoryWStream* dst) {
    return doFlate(false, kBufferSize, src, dst);
}

#endif