vpImageIoLibpng.cpp

/*
 * ViSP, open source Visual Servoing Platform software.
 * Copyright (C) 2005 - 2025 by Inria. All rights reserved.
 *
 * This software is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * See the file LICENSE.txt at the root directory of this source
 * distribution for additional information about the GNU GPL.
 *
 * For using ViSP with software that can not be combined with the GNU
 * GPL, please contact Inria about acquiring a ViSP Professional
 * Edition License.
 *
 * See https://visp.inria.fr for more information.
 *
 * This software was developed at:
 * Inria Rennes - Bretagne Atlantique
 * Campus Universitaire de Beaulieu
 * 35042 Rennes Cedex
 * France
 *
 * If you have questions regarding the use of this file, please contact
 * Inria at visp@inria.fr
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Description:
 * Libpng backend for PNG image I/O operations.
 */

 
#include "vpImageIoBackend.h"
#include <visp3/core/vpImageConvert.h>
 
#if defined(VISP_HAVE_PNG)
#include <png.h>
#endif
 
//--------------------------------------------------------------------------
// PNG
//--------------------------------------------------------------------------
 
#if defined(VISP_HAVE_PNG)
 
BEGIN_VISP_NAMESPACE
void writePNGLibpng(const vpImage<unsigned char> &I, const std::string &filename)
{
  FILE *file;
 
  // Test the filename
  if (filename.empty()) {
    throw(vpImageException(vpImageException::ioError, "Cannot create PNG file: filename empty"));
  }
 
  file = fopen(filename.c_str(), "wb");
 
  if (file == nullptr) {
    throw(vpImageException(vpImageException::ioError, "Cannot create PNG file \"%s\"", filename.c_str()));
  }
 
  /* create a png info struct */
  png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
  if (!png_ptr) {
    fclose(file);
    throw(vpImageException(vpImageException::ioError, "PNG write error"));
  }
 
  png_infop info_ptr = png_create_info_struct(png_ptr);
  if (!info_ptr) {
    fclose(file);
    png_destroy_write_struct(&png_ptr, nullptr);
    throw(vpImageException(vpImageException::ioError, "PNG write error"));
  }
 
  /* initialize the setjmp for returning properly after a libpng error occurred
   */
  if (setjmp(png_jmpbuf(png_ptr))) {
    fclose(file);
    png_destroy_write_struct(&png_ptr, &info_ptr);
    throw(vpImageException(vpImageException::ioError, "PNG write error"));
  }
 
  /* setup libpng for using standard C fwrite() function with our FILE pointer
   */
  png_init_io(png_ptr, file);
 
  unsigned int width = I.getWidth();
  unsigned int height = I.getHeight();
  int bit_depth = 8;
  int color_type = PNG_COLOR_TYPE_GRAY;
  /* set some useful information from header */
 
  if (setjmp(png_jmpbuf(png_ptr))) {
    fclose(file);
    png_destroy_write_struct(&png_ptr, &info_ptr);
    throw(vpImageException(vpImageException::ioError, "PNG write error"));
  }
 
  png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
               PNG_FILTER_TYPE_BASE);
 
  png_write_info(png_ptr, info_ptr);
 
  png_bytep *row_ptrs = new png_bytep[height];
  for (unsigned int i = 0; i < height; ++i)
    row_ptrs[i] = new png_byte[width];
 
  unsigned char *input = (unsigned char *)I.bitmap;
 
  for (unsigned int i = 0; i < height; ++i) {
    png_byte *row = row_ptrs[i];
    for (unsigned int j = 0; j < width; ++j) {
      row[j] = *(input);
      input++;
    }
  }
 
  png_write_image(png_ptr, row_ptrs);
 
  png_write_end(png_ptr, nullptr);
 
  for (unsigned int j = 0; j < height; ++j)
    delete[] row_ptrs[j];
 
  delete[] row_ptrs;
 
  png_destroy_write_struct(&png_ptr, &info_ptr);
 
  fclose(file);
}

void writePNGLibpng(const vpImage<vpRGBa> &I, const std::string &filename)
{
  FILE *file;
 
  // Test the filename
  if (filename.empty()) {
    throw(vpImageException(vpImageException::ioError, "Cannot create PNG file: filename empty"));
  }
 
  file = fopen(filename.c_str(), "wb");
 
  if (file == nullptr) {
    throw(vpImageException(vpImageException::ioError, "Cannot create PNG file \"%s\"", filename.c_str()));
  }
 
  /* create a png info struct */
  png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
  if (!png_ptr) {
    fclose(file);
    throw(vpImageException(vpImageException::ioError, "PNG write error"));
  }
 
  png_infop info_ptr = png_create_info_struct(png_ptr);
  if (!info_ptr) {
    fclose(file);
    png_destroy_write_struct(&png_ptr, nullptr);
    throw(vpImageException(vpImageException::ioError, "PNG write error"));
  }
 
  /* initialize the setjmp for returning properly after a libpng error occurred
   */
  if (setjmp(png_jmpbuf(png_ptr))) {
    fclose(file);
    png_destroy_write_struct(&png_ptr, &info_ptr);
    throw(vpImageException(vpImageException::ioError, "PNG write error"));
  }
 
  /* setup libpng for using standard C fwrite() function with our FILE pointer
   */
  png_init_io(png_ptr, file);
 
  unsigned int width = I.getWidth();
  unsigned int height = I.getHeight();
  int bit_depth = 8;
  int color_type = PNG_COLOR_TYPE_RGB;
  /* set some useful information from header */
 
  if (setjmp(png_jmpbuf(png_ptr))) {
    fclose(file);
    png_destroy_write_struct(&png_ptr, &info_ptr);
    throw(vpImageException(vpImageException::ioError, "PNG write error"));
  }
 
  png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
               PNG_FILTER_TYPE_BASE);
 
  png_write_info(png_ptr, info_ptr);
 
  png_bytep *row_ptrs = new png_bytep[height];
  for (unsigned int i = 0; i < height; ++i)
    row_ptrs[i] = new png_byte[3 * width];
 
  unsigned char *input = (unsigned char *)I.bitmap;
 
  for (unsigned int i = 0; i < height; ++i) {
    png_byte *row = row_ptrs[i];
    for (unsigned int j = 0; j < width; ++j) {
      row[3 * j] = *(input);
      input++;
      row[3 * j + 1] = *(input);
      input++;
      row[3 * j + 2] = *(input);
      input++;
      input++;
    }
  }
 
  png_write_image(png_ptr, row_ptrs);
 
  png_write_end(png_ptr, nullptr);
 
  for (unsigned int j = 0; j < height; ++j)
    delete[] row_ptrs[j];
 
  delete[] row_ptrs;
 
  png_destroy_write_struct(&png_ptr, &info_ptr);
 
  fclose(file);
}

void readPNGLibpng(vpImage<unsigned char> &I, const std::string &filename)
{
  FILE *file;
  png_byte magic[8];
  // Test the filename
  if (filename.empty()) {
    throw(vpImageException(vpImageException::ioError, "Cannot read PNG image: filename empty"));
  }
 
  file = fopen(filename.c_str(), "rb");
 
  if (file == nullptr) {
    throw(vpImageException(vpImageException::ioError, "Cannot read file \"%s\"", filename.c_str()));
  }
 
  /* read magic number */
  if (fread(magic, 1, sizeof(magic), file) != sizeof(magic)) {
    fclose(file);
    throw(vpImageException(vpImageException::ioError, "Cannot read magic number in file \"%s\"", filename.c_str()));
  }
 
  /* check for valid magic number */
  if (png_sig_cmp(magic, 0, sizeof(magic))) {
    fclose(file);
    throw(vpImageException(vpImageException::ioError, "Cannot read PNG file: \"%s\" is not a valid PNG image",
                           filename.c_str()));
  }
 
  /* create a png read struct */
  // printf("version %s\n", PNG_LIBPNG_VER_STRING);
  png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
  if (png_ptr == nullptr) {
    fprintf(stderr, "error: can't create a png read structure!\n");
    fclose(file);
    throw(vpImageException(vpImageException::ioError, "error reading png file"));
  }
 
  /* create a png info struct */
  png_infop info_ptr = png_create_info_struct(png_ptr);
  if (info_ptr == nullptr) {
    fprintf(stderr, "error: can't create a png info structure!\n");
    fclose(file);
    png_destroy_read_struct(&png_ptr, nullptr, nullptr);
    throw(vpImageException(vpImageException::ioError, "error reading png file"));
  }
 
  /* initialize the setjmp for returning properly after a libpng error occurred
   */
  if (setjmp(png_jmpbuf(png_ptr))) {
    fclose(file);
    png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
    throw(vpImageException(vpImageException::ioError, "PNG read error"));
  }
 
  /* setup libpng for using standard C fread() function with our FILE pointer
   */
  png_init_io(png_ptr, file);
 
  /* tell libpng that we have already read the magic number */
  png_set_sig_bytes(png_ptr, sizeof(magic));
 
  /* read png info */
  png_read_info(png_ptr, info_ptr);
 
  unsigned int width = png_get_image_width(png_ptr, info_ptr);
  unsigned int height = png_get_image_height(png_ptr, info_ptr);
 
  unsigned int bit_depth, channels, color_type;
  /* get some useful information from header */
  bit_depth = png_get_bit_depth(png_ptr, info_ptr);
  channels = png_get_channels(png_ptr, info_ptr);
  color_type = png_get_color_type(png_ptr, info_ptr);
 
  /* convert index color images to RGB images */
  if (color_type == PNG_COLOR_TYPE_PALETTE)
    png_set_palette_to_rgb(png_ptr);
 
  /* convert 1-2-4 bits grayscale images to 8 bits grayscale. */
  if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
    png_set_expand(png_ptr);
 
  //  if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
  //    png_set_tRNS_to_alpha (png_ptr);
 
  if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
    png_set_strip_alpha(png_ptr);
 
  if (bit_depth == 16)
    png_set_strip_16(png_ptr);
  else if (bit_depth < 8)
    png_set_packing(png_ptr);
 
  /* update info structure to apply transformations */
  png_read_update_info(png_ptr, info_ptr);
 
  channels = png_get_channels(png_ptr, info_ptr);
 
  if ((width != I.getWidth()) || (height != I.getHeight()))
    I.resize(height, width);
 
  png_bytep *rowPtrs = new png_bytep[height];
 
  unsigned int stride = static_cast<unsigned int>(png_get_rowbytes(png_ptr, info_ptr));
  unsigned char *data = new unsigned char[stride * height];
 
  for (unsigned int i = 0; i < height; ++i)
    rowPtrs[i] = (png_bytep)data + (i * stride);
 
  png_read_image(png_ptr, rowPtrs);
 
  vpImage<vpRGBa> Ic(height, width);
  unsigned char *output;
 
  switch (channels) {
  case 1:
    output = (unsigned char *)I.bitmap;
    for (unsigned int i = 0; i < width * height; ++i) {
      *(output++) = data[i];
    }
    break;
 
  case 2:
    output = (unsigned char *)I.bitmap;
    for (unsigned int i = 0; i < width * height; ++i) {
      *(output++) = data[i * 2];
    }
    break;
 
  case 3:
    output = (unsigned char *)Ic.bitmap;
    for (unsigned int i = 0; i < width * height; ++i) {
      *(output++) = data[i * 3];
      *(output++) = data[i * 3 + 1];
      *(output++) = data[i * 3 + 2];
      *(output++) = vpRGBa::alpha_default;
    }
    vpImageConvert::convert(Ic, I);
    break;
 
  case 4:
    output = (unsigned char *)Ic.bitmap;
    for (unsigned int i = 0; i < width * height; ++i) {
      *(output++) = data[i * 4];
      *(output++) = data[i * 4 + 1];
      *(output++) = data[i * 4 + 2];
      *(output++) = data[i * 4 + 3];
    }
    vpImageConvert::convert(Ic, I);
    break;
  }
 
  delete[](png_bytep) rowPtrs;
  delete[] data;
  png_read_end(png_ptr, nullptr);
  png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
  fclose(file);
}

void readPNGLibpng(vpImage<vpRGBa> &I, const std::string &filename)
{
  FILE *file;
  png_byte magic[8];
 
  // Test the filename
  if (filename.empty()) {
    throw(vpImageException(vpImageException::ioError, "Cannot read PNG image: filename empty"));
  }
 
  file = fopen(filename.c_str(), "rb");
 
  if (file == nullptr) {
    throw(vpImageException(vpImageException::ioError, "Cannot read file \"%s\"", filename.c_str()));
  }
 
  /* read magic number */
  if (fread(magic, 1, sizeof(magic), file) != sizeof(magic)) {
    fclose(file);
    throw(vpImageException(vpImageException::ioError, "Cannot read magic number in file \"%s\"", filename.c_str()));
  }
 
  /* check for valid magic number */
  if (png_sig_cmp(magic, 0, sizeof(magic))) {
    fclose(file);
    throw(vpImageException(vpImageException::ioError, "Cannot read PNG file: \"%s\" is not a valid PNG image",
                           filename.c_str()));
  }
 
  /* create a png read struct */
  png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
  if (!png_ptr) {
    fclose(file);
    throw(vpImageException(vpImageException::ioError, "PNG read error"));
  }
 
  /* create a png info struct */
  png_infop info_ptr = png_create_info_struct(png_ptr);
  if (!info_ptr) {
    fclose(file);
    png_destroy_read_struct(&png_ptr, nullptr, nullptr);
    throw(vpImageException(vpImageException::ioError, "PNG read error"));
  }
 
  /* initialize the setjmp for returning properly after a libpng error occurred
   */
  if (setjmp(png_jmpbuf(png_ptr))) {
    fclose(file);
    png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
    throw(vpImageException(vpImageException::ioError, "PNG read error"));
  }
 
  /* setup libpng for using standard C fread() function with our FILE pointer
   */
  png_init_io(png_ptr, file);
 
  /* tell libpng that we have already read the magic number */
  png_set_sig_bytes(png_ptr, sizeof(magic));
 
  /* read png info */
  png_read_info(png_ptr, info_ptr);
 
  unsigned int width = png_get_image_width(png_ptr, info_ptr);
  unsigned int height = png_get_image_height(png_ptr, info_ptr);
 
  unsigned int bit_depth, channels, color_type;
  /* get some useful information from header */
  bit_depth = png_get_bit_depth(png_ptr, info_ptr);
  channels = png_get_channels(png_ptr, info_ptr);
  color_type = png_get_color_type(png_ptr, info_ptr);
 
  /* convert index color images to RGB images */
  if (color_type == PNG_COLOR_TYPE_PALETTE)
    png_set_palette_to_rgb(png_ptr);
 
  /* convert 1-2-4 bits grayscale images to 8 bits grayscale. */
  if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
    png_set_expand(png_ptr);
 
  //  if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
  //    png_set_tRNS_to_alpha (png_ptr);
 
  if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
    png_set_strip_alpha(png_ptr);
 
  if (bit_depth == 16)
    png_set_strip_16(png_ptr);
  else if (bit_depth < 8)
    png_set_packing(png_ptr);
 
  /* update info structure to apply transformations */
  png_read_update_info(png_ptr, info_ptr);
 
  channels = png_get_channels(png_ptr, info_ptr);
 
  if ((width != I.getWidth()) || (height != I.getHeight()))
    I.resize(height, width);
 
  png_bytep *rowPtrs = new png_bytep[height];
 
  unsigned int stride = static_cast<unsigned int>(png_get_rowbytes(png_ptr, info_ptr));
  unsigned char *data = new unsigned char[stride * height];
 
  for (unsigned int i = 0; i < height; ++i)
    rowPtrs[i] = (png_bytep)data + (i * stride);
 
  png_read_image(png_ptr, rowPtrs);
 
  vpImage<unsigned char> Ig(height, width);
  unsigned char *output;
 
  switch (channels) {
  case 1:
    output = (unsigned char *)Ig.bitmap;
    for (unsigned int i = 0; i < width * height; ++i) {
      *(output++) = data[i];
    }
    vpImageConvert::convert(Ig, I);
    break;
 
  case 2:
    output = (unsigned char *)Ig.bitmap;
    for (unsigned int i = 0; i < width * height; ++i) {
      *(output++) = data[i * 2];
    }
    vpImageConvert::convert(Ig, I);
    break;
 
  case 3:
    output = (unsigned char *)I.bitmap;
    for (unsigned int i = 0; i < width * height; ++i) {
      *(output++) = data[i * 3];
      *(output++) = data[i * 3 + 1];
      *(output++) = data[i * 3 + 2];
      *(output++) = vpRGBa::alpha_default;
    }
    break;
 
  case 4:
    output = (unsigned char *)I.bitmap;
    for (unsigned int i = 0; i < width * height; ++i) {
      *(output++) = data[i * 4];
      *(output++) = data[i * 4 + 1];
      *(output++) = data[i * 4 + 2];
      *(output++) = data[i * 4 + 3];
    }
    break;
  }
 
  delete[](png_bytep) rowPtrs;
  delete[] data;
  png_read_end(png_ptr, nullptr);
  png_destroy_read_struct(&png_ptr, &info_ptr, nullptr);
  fclose(file);
}
 
END_VISP_NAMESPACE
 
#endif