mapnik/src/miniz_png.cpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2012 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

// mapnik
#include <mapnik/palette.hpp>
#include <mapnik/miniz_png.hpp>
#include <mapnik/image_data.hpp>
#include <mapnik/image_view.hpp>

// miniz
#define MINIZ_NO_ARCHIVE_APIS
#define MINIZ_NO_STDIO
#define MINIZ_NO_ZLIB_COMPATIBLE_NAMES
#include "miniz.c"

// zlib
#include <zlib.h>

// stl
#include <vector>
#include <iostream>
#include <stdexcept>

namespace mapnik { namespace MiniZ {

PNGWriter::PNGWriter(int level, int strategy)
{
    buffer = NULL;
    compressor = NULL;

    if (level == -1)
    {
        level = MZ_DEFAULT_LEVEL; // 6
    }
    else if (level < 0 || level > 10)
    {
        throw std::runtime_error("compression level must be between 0 and 10");
    }
    mz_uint flags = s_tdefl_num_probes[level] | (level <= 3) ? TDEFL_GREEDY_PARSING_FLAG : 0 | TDEFL_WRITE_ZLIB_HEADER;
    if (strategy == Z_FILTERED) flags |= TDEFL_FILTER_MATCHES;
    else if (strategy == Z_HUFFMAN_ONLY) flags &= ~TDEFL_MAX_PROBES_MASK;
    else if (strategy == Z_RLE) flags |= TDEFL_RLE_MATCHES;
    else if (strategy == Z_FIXED) flags |= TDEFL_FORCE_ALL_STATIC_BLOCKS;

    buffer = (tdefl_output_buffer *)MZ_MALLOC(sizeof(tdefl_output_buffer));
    if (buffer == NULL)
    {
        throw std::bad_alloc();
    }

    buffer->m_pBuf = NULL;
    buffer->m_capacity = 8192;
    buffer->m_expandable = MZ_TRUE;
    buffer->m_pBuf = (mz_uint8 *)MZ_MALLOC(buffer->m_capacity);
    if (buffer->m_pBuf == NULL)
    {
        throw std::bad_alloc();
    }

    compressor = (tdefl_compressor *)MZ_MALLOC(sizeof(tdefl_compressor));
    if (compressor == NULL)
    {
        throw std::bad_alloc();
    }

    // Reset output buffer.
    buffer->m_size = 0;
    tdefl_status tdstatus = tdefl_init(compressor, tdefl_output_buffer_putter, buffer, flags);
    if (tdstatus != TDEFL_STATUS_OKAY)
    {
        throw std::runtime_error("tdefl_init failed");
    }

    // Write preamble.
    mz_bool status = tdefl_output_buffer_putter(preamble, 8, buffer);
    if (status != MZ_TRUE)
    {
        throw std::bad_alloc();
    }
}

PNGWriter::~PNGWriter()
{
    if (compressor)
    {
        MZ_FREE(compressor);
    }
    if (buffer)
    {
        if (buffer->m_pBuf)
        {
            MZ_FREE(buffer->m_pBuf);
        }
        MZ_FREE(buffer);
    }
}

inline void PNGWriter::writeUInt32BE(mz_uint8 *target, mz_uint32 value)
{
    target[0] = (value >> 24) & 0xFF;
    target[1] = (value >> 16) & 0xFF;
    target[2] = (value >> 8) & 0xFF;
    target[3] = value & 0xFF;
}

size_t PNGWriter::startChunk(const mz_uint8 header[], size_t length)
{
    size_t start = buffer->m_size;
    mz_bool status = tdefl_output_buffer_putter(header, length, buffer);
    if (status != MZ_TRUE)
    {
        throw std::bad_alloc();
    }
    return start;
}

void PNGWriter::finishChunk(size_t start)
{
    // Write chunk length at the beginning of the chunk.
    size_t payloadLength = buffer->m_size - start - 4 - 4;
    writeUInt32BE(buffer->m_pBuf + start, payloadLength);

    // Write CRC32 checksum. Don't include the 4-byte length, but /do/ include
    // the 4-byte chunk name.
    mz_uint32 crc = mz_crc32(MZ_CRC32_INIT, buffer->m_pBuf + start + 4, payloadLength + 4);
    mz_uint8 checksum[] = { crc >> 24, crc >> 16, crc >> 8, crc };
    mz_bool status = tdefl_output_buffer_putter(checksum, 4, buffer);
    if (status != MZ_TRUE)
    {
        throw std::bad_alloc();
    }
}

void PNGWriter::writeIHDR(mz_uint32 width, mz_uint32 height, mz_uint8 pixel_depth)
{
    // Write IHDR chunk.
    size_t IHDR = startChunk(IHDR_tpl, 21);
    writeUInt32BE(buffer->m_pBuf + IHDR + 8, width);
    writeUInt32BE(buffer->m_pBuf + IHDR + 12, height);

    if (pixel_depth == 32)
    {
        // Alpha full color image.
        buffer->m_pBuf[IHDR + 16] = 8; // bit depth
        buffer->m_pBuf[IHDR + 17] = 6; // color type (6 == true color with alpha)
    }
    else if (pixel_depth == 24)
    {
        // Full color image.
        buffer->m_pBuf[IHDR + 16] = 8; // bit depth
        buffer->m_pBuf[IHDR + 17] = 2; // color type (2 == true color without alpha)
    }
    else
    {
        // Paletted image.
        buffer->m_pBuf[IHDR + 16] = pixel_depth; // bit depth
        buffer->m_pBuf[IHDR + 17] = 3; // color type (3 == indexed color)
    }

    buffer->m_pBuf[IHDR + 18] = 0; // compression method
    buffer->m_pBuf[IHDR + 19] = 0; // filter method
    buffer->m_pBuf[IHDR + 20] = 0; // interlace method
    finishChunk(IHDR);
}

void PNGWriter::writePLTE(std::vector<rgb> const& palette)
{
    // Write PLTE chunk.
    size_t PLTE = startChunk(PLTE_tpl, 8);
    const mz_uint8 *colors = reinterpret_cast<const mz_uint8 *>(&palette[0]);
    mz_bool status = tdefl_output_buffer_putter(colors, palette.size() * 3, buffer);
    if (status != MZ_TRUE)
    {
        throw std::bad_alloc();
    }
    finishChunk(PLTE);
}

void PNGWriter::writetRNS(std::vector<unsigned> const& alpha)
{
    if (alpha.size() == 0)
    {
        return;
    }

    std::vector<unsigned char> transparency(alpha.size());
    unsigned char transparencySize = 0; // Stores position of biggest to nonopaque value.
    for(unsigned i = 0; i < alpha.size(); i++)
    {
        transparency[i] = alpha[i];
        if (alpha[i] < 255)
        {
            transparencySize = i + 1;
        }
    }
    if (transparencySize > 0)
    {
        // Write tRNS chunk.
        size_t tRNS = startChunk(tRNS_tpl, 8);
        mz_bool status = tdefl_output_buffer_putter(&transparency[0], transparencySize, buffer);
        if (status != MZ_TRUE)
        {
            throw std::bad_alloc();
        }
        finishChunk(tRNS);
    }
}

template<typename T>
void PNGWriter::writeIDAT(T const& image)
{
    // Write IDAT chunk.
    size_t IDAT = startChunk(IDAT_tpl, 8);
    mz_uint8 filter_type = 0;
    tdefl_status status;

    int bytes_per_pixel = sizeof(typename T::pixel_type);
    int stride = image.width() * bytes_per_pixel;

    for (unsigned int y = 0; y < image.height(); y++)
    {
        // Write filter_type
        status = tdefl_compress_buffer(compressor, &filter_type, 1, TDEFL_NO_FLUSH);
        if (status != TDEFL_STATUS_OKAY)
        {
            throw std::runtime_error("failed to compress image");
        }

        // Write scanline
        status = tdefl_compress_buffer(compressor, (mz_uint8 *)image.getRow(y), stride, TDEFL_NO_FLUSH);
        if (status != TDEFL_STATUS_OKAY)
        {
            throw std::runtime_error("failed to compress image");
        }
    }

    status = tdefl_compress_buffer(compressor, NULL, 0, TDEFL_FINISH);
    if (status != TDEFL_STATUS_DONE)
    {
        throw std::runtime_error("failed to compress image");
    }

    finishChunk(IDAT);
}

template<typename T>
void PNGWriter::writeIDATStripAlpha(T const& image) {
    // Write IDAT chunk.
    size_t IDAT = startChunk(IDAT_tpl, 8);
    mz_uint8 filter_type = 0;
    tdefl_status status;

    size_t stride = image.width() * 3;
    size_t i, j;
    mz_uint8 *scanline = (mz_uint8 *)MZ_MALLOC(stride);

    for (unsigned int y = 0; y < image.height(); y++) {
        // Write filter_type
        status = tdefl_compress_buffer(compressor, &filter_type, 1, TDEFL_NO_FLUSH);
        if (status != TDEFL_STATUS_OKAY)
        {
            MZ_FREE(scanline);
            throw std::runtime_error("failed to compress image");
        }

        // Strip alpha bytes from scanline
        mz_uint8 *row = (mz_uint8 *)image.getRow(y);
        for (i = 0, j = 0; j < stride; i += 4, j += 3) {
            scanline[j] = row[i];
            scanline[j+1] = row[i+1];
            scanline[j+2] = row[i+2];
        }

        // Write scanline
        status = tdefl_compress_buffer(compressor, scanline, stride, TDEFL_NO_FLUSH);
        if (status != TDEFL_STATUS_OKAY) {
            MZ_FREE(scanline);
            throw std::runtime_error("failed to compress image");
        }
    }

    MZ_FREE(scanline);

    status = tdefl_compress_buffer(compressor, NULL, 0, TDEFL_FINISH);
    if (status != TDEFL_STATUS_DONE) throw std::runtime_error("failed to compress image");

    finishChunk(IDAT);
}

void PNGWriter::writeIEND()
{
    // Write IEND chunk.
    size_t IEND = startChunk(IEND_tpl, 8);
    finishChunk(IEND);
}

void PNGWriter::toStream(std::ostream& stream)
{
    stream.write((char *)buffer->m_pBuf, buffer->m_size);
}

const mz_uint8 PNGWriter::preamble[] = {
    0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a
};

const mz_uint8 PNGWriter::IHDR_tpl[] = {
    0x00, 0x00, 0x00, 0x0D, // chunk length
    'I', 'H', 'D', 'R',     // "IHDR"
    0x00, 0x00, 0x00, 0x00, // image width (4 bytes)
    0x00, 0x00, 0x00, 0x00, // image height (4 bytes)
    0x00,                   // bit depth (1 byte)
    0x00,                   // color type (1 byte)
    0x00,                   // compression method (1 byte), has to be 0
    0x00,                   // filter method (1 byte)
    0x00                    // interlace method (1 byte)
};

const mz_uint8 PNGWriter::PLTE_tpl[] = {
    0x00, 0x00, 0x00, 0x00, // chunk length
    'P', 'L', 'T', 'E'      // "IDAT"
};

const mz_uint8 PNGWriter::tRNS_tpl[] = {
    0x00, 0x00, 0x00, 0x00, // chunk length
    't', 'R', 'N', 'S'      // "IDAT"
};

const mz_uint8 PNGWriter::IDAT_tpl[] = {
    0x00, 0x00, 0x00, 0x00, // chunk length
    'I', 'D', 'A', 'T'      // "IDAT"
};

const mz_uint8 PNGWriter::IEND_tpl[] = {
    0x00, 0x00, 0x00, 0x00, // chunk length
    'I', 'E', 'N', 'D'      // "IEND"
};

template void PNGWriter::writeIDAT<image_data_8>(image_data_8 const& image);
template void PNGWriter::writeIDAT<image_view<image_data_8> >(image_view<image_data_8> const& image);
template void PNGWriter::writeIDAT<image_data_32>(image_data_32 const& image);
template void PNGWriter::writeIDAT<image_view<image_data_32> >(image_view<image_data_32> const& image);
template void PNGWriter::writeIDATStripAlpha<image_data_32>(image_data_32 const& image);
template void PNGWriter::writeIDATStripAlpha<image_view<image_data_32> >(image_view<image_data_32> const& image);

}}