png.c

Go to the documentation of this file.

/*
    This file is part of darktable,
    Copyright (C) 2009-2012 johannes hanika.
    Copyright (C) 2010 Christian Himpel.
    Copyright (C) 2011 Henrik Andersson.
    Copyright (C) 2011 Tim Harder.
    Copyright (C) 2011-2017, 2019-2020 Tobias Ellinghaus.
    Copyright (C) 2012-2014, 2020-2021 Pascal Obry.
    Copyright (C) 2012 Richard Wonka.
    Copyright (C) 2013 Jérémy Rosen.
    Copyright (C) 2013 Pascal de Bruijn.
    Copyright (C) 2013 Simon Spannagel.
    Copyright (C) 2013 Thomas Pryds.
    Copyright (C) 2013-2014 Ulrich Pegelow.
    Copyright (C) 2014-2016 Roman Lebedev.
    Copyright (C) 2017 Matthieu Moy.
    Copyright (C) 2017 Simon Raffeiner.
    Copyright (C) 2019, 2022, 2025-2026 Aurélien PIERRE.
    Copyright (C) 2019 Philippe Weyland.
    Copyright (C) 2020 Diederik Ter Rahe.
    Copyright (C) 2020-2021 Hubert Kowalski.
    Copyright (C) 2021 Ralf Brown.
    Copyright (C) 2022 Martin Bařinka.
    Copyright (C) 2022 Miloš Komarčević.
    Copyright (C) 2024 Alynx Zhou.
    
    darktable 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 3 of the License, or
    (at your option) any later version.
    
    darktable 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 General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with darktable.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include <inttypes.h>
#include <png.h>
#include <stdio.h>
#include <stdlib.h>
#include <zlib.h>
 
#include "bauhaus/bauhaus.h"
#include "common/colorspaces.h"
#include "common/darktable.h"
#include "common/imageio.h"
#include "common/imageio_module.h"
#include "control/conf.h"
#include "gui/gtk.h"
#include "imageio/format/imageio_format_api.h"
 
DT_MODULE(3)
 
typedef struct dt_imageio_png_t
{
  dt_imageio_module_data_t global;
  int bpp;
  int compression;
  FILE *f;
  png_structp png_ptr;
  png_infop info_ptr;
} dt_imageio_png_t;
 
typedef struct dt_imageio_png_gui_t
{
  GtkWidget *bit_depth;
  GtkWidget *compression;
} dt_imageio_png_gui_t;
 
/* Write EXIF data to PNG file.
 * Code copied from DigiKam's libs/dimg/loaders/pngloader.cpp.
 * The EXIF embedding is defined by ImageMagicK.
 * It is documented in the ExifTool page:
 * http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/PNG.html
 *
 * ..and in turn copied from ufraw. thanks to udi and colleagues
 * for making useful code much more readable and discoverable ;)
 */
 
static void PNGwriteRawProfile(png_struct *ping, png_info *ping_info, char *profile_type, guint8 *profile_data,
                               png_uint_32 length)
{
  png_textp text;
  long i;
  guint8 *sp;
  png_charp dp;
  png_uint_32 allocated_length, description_length;
 
  const guint8 hex[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
  text = png_malloc(ping, sizeof(png_text));
  description_length = strlen(profile_type);
  allocated_length = length * 2 + (length >> 5) + 20 + description_length;
 
  text[0].text = png_malloc(ping, allocated_length);
  text[0].key = png_malloc(ping, 80);
  text[0].key[0] = '\0';
 
  g_strlcat(text[0].key, "Raw profile type ", 80);
  g_strlcat(text[0].key, profile_type, 80);
 
  sp = profile_data;
  dp = text[0].text;
  *dp++ = '\n';
 
  g_strlcpy(dp, profile_type, allocated_length);
 
  dp += description_length;
  *dp++ = '\n';
  *dp = '\0';
 
  g_snprintf(dp, allocated_length - strlen(text[0].text), "%8lu ", (unsigned long int)length);
 
  dp += 8;
 
  for(i = 0; i < (long)length; i++)
  {
    if(i % 36 == 0) *dp++ = '\n';
 
    *(dp++) = hex[((*sp >> 4) & 0x0f)];
    *(dp++) = hex[((*sp++) & 0x0f)];
  }
 
  *dp++ = '\n';
  *dp = '\0';
  text[0].text_length = (dp - text[0].text);
  text[0].compression = -1;
 
  if(text[0].text_length <= allocated_length) png_set_text(ping, ping_info, text, 1);
 
  png_free(ping, text[0].text);
  png_free(ping, text[0].key);
  png_free(ping, text);
}
 
int write_image(dt_imageio_module_data_t *p_tmp, const char *filename, const void *ivoid,
                dt_colorspaces_color_profile_type_t over_type, const char *over_filename,
                void *exif, int exif_len, int32_t imgid, int num, int total, struct dt_dev_pixelpipe_t *pipe,
                const gboolean export_masks)
{
  dt_imageio_png_t *p = (dt_imageio_png_t *)p_tmp;
  const int width = p->global.width, height = p->global.height;
  FILE *f = g_fopen(filename, "wb");
  if(IS_NULL_PTR(f)) return 1;
 
  png_structp png_ptr;
  png_infop info_ptr;
 
  png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  if(IS_NULL_PTR(png_ptr))
  {
    fclose(f);
    return 1;
  }
 
  info_ptr = png_create_info_struct(png_ptr);
  if(IS_NULL_PTR(info_ptr))
  {
    fclose(f);
    png_destroy_write_struct(&png_ptr, NULL);
    return 1;
  }
 
  if(setjmp(png_jmpbuf(png_ptr)))
  {
    fclose(f);
    png_destroy_write_struct(&png_ptr, &info_ptr);
    return 1;
  }
 
  png_init_io(png_ptr, f);
 
  png_set_compression_level(png_ptr, p->compression);
  png_set_compression_mem_level(png_ptr, 8);
  png_set_compression_strategy(png_ptr, Z_DEFAULT_STRATEGY);
  png_set_compression_window_bits(png_ptr, 15);
  png_set_compression_method(png_ptr, 8);
  png_set_compression_buffer_size(png_ptr, 8192);
 
  png_set_IHDR(png_ptr, info_ptr, width, height, p->bpp, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
               PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
 
  // metadata has to be written before the pixels
 
  // embed icc profile
  cmsHPROFILE out_profile = dt_colorspaces_get_output_profile(imgid, &over_type, over_filename)->profile;
  uint32_t len = 0;
  cmsSaveProfileToMem(out_profile, NULL, &len);
  if(len > 0)
  {
    char *buf = malloc(sizeof(char) * len);
    if(buf)
    {
      cmsSaveProfileToMem(out_profile, buf, &len);
      char name[512] = { 0 };
      dt_colorspaces_get_profile_name(out_profile, "en", "US", name, sizeof(name));
 
      png_set_iCCP(png_ptr, info_ptr, *name ? name : "icc", 0,
#if(PNG_LIBPNG_VER < 10500)
                    (png_charp)buf,
#else
                    (png_const_bytep)buf,
#endif
                    len);
      dt_free(buf);
    }
  }
 
  // write exif data
  if(exif && exif_len > 0)
  {
    /* The legacy tEXt chunk storage scheme implies the "Exif\0\0" APP1 prefix */
    uint8_t *buf = malloc(exif_len + 6);
    if(buf)
    {
      memcpy(buf, "Exif\0\0", 6);
      memcpy(buf + 6, exif, exif_len);
      PNGwriteRawProfile(png_ptr, info_ptr, "exif", buf, exif_len + 6);
      dt_free(buf);
    }
  }
 
  png_write_info(png_ptr, info_ptr);
 
  /*
   * Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
   * RGB (4 channels -> 3 channels). The second parameter is not used.
   */
  png_set_filler(png_ptr, 0, PNG_FILLER_AFTER);
 
  png_bytep *row_pointers = dt_pixelpipe_cache_alloc_align_cache(sizeof(png_bytep) * height, 0);
 
  if(p->bpp > 8)
  {
    /* swap bytes of 16 bit files to most significant bit first */
    png_set_swap(png_ptr);
 
    for(unsigned i = 0; i < height; i++) row_pointers[i] = (png_bytep)((uint16_t *)ivoid + (size_t)4 * i * width);
  }
  else
  {
    for(unsigned i = 0; i < height; i++) row_pointers[i] = (uint8_t *)ivoid + (size_t)4 * i * width;
  }
 
  png_write_image(png_ptr, row_pointers);
 
  dt_pixelpipe_cache_free_align(row_pointers);
 
  png_write_end(png_ptr, info_ptr);
  png_destroy_write_struct(&png_ptr, &info_ptr);
  fclose(f);
  return 0;
}
 
static int __attribute__((__unused__)) read_header(const char *filename, dt_imageio_module_data_t *p_tmp)
{
  dt_imageio_png_t *png = (dt_imageio_png_t *)p_tmp;
  png->f = g_fopen(filename, "rb");
 
  if(IS_NULL_PTR(png->f)) return 1;
 
#define NUM_BYTES_CHECK (8)
 
  png_byte dat[NUM_BYTES_CHECK];
 
  size_t cnt = fread(dat, 1, NUM_BYTES_CHECK, png->f);
 
  if(cnt != NUM_BYTES_CHECK || png_sig_cmp(dat, (png_size_t)0, NUM_BYTES_CHECK))
  {
    fclose(png->f);
    return 1;
  }
 
  png->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
 
  if(IS_NULL_PTR(png->png_ptr))
  {
    fclose(png->f);
    return 1;
  }
 
  png->info_ptr = png_create_info_struct(png->png_ptr);
  if(IS_NULL_PTR(png->info_ptr))
  {
    fclose(png->f);
    png_destroy_read_struct(&png->png_ptr, NULL, NULL);
    return 1;
  }
 
  if(setjmp(png_jmpbuf(png->png_ptr)))
  {
    fclose(png->f);
    png_destroy_read_struct(&png->png_ptr, &png->info_ptr, NULL);
    return 1;
  }
 
  png_init_io(png->png_ptr, png->f);
 
  // we checked some bytes
  png_set_sig_bytes(png->png_ptr, NUM_BYTES_CHECK);
 
  // image info
  png_read_info(png->png_ptr, png->info_ptr);
 
  uint32_t bit_depth = png_get_bit_depth(png->png_ptr, png->info_ptr);
  uint32_t color_type = png_get_color_type(png->png_ptr, png->info_ptr);
 
  // image input transformations
 
  // palette => rgb
  if(color_type == PNG_COLOR_TYPE_PALETTE) png_set_palette_to_rgb(png->png_ptr);
 
  // 1, 2, 4 bit => 8 bit
  if(color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png->png_ptr);
 
  // strip alpha channel
  if(color_type & PNG_COLOR_MASK_ALPHA) png_set_strip_alpha(png->png_ptr);
 
  // grayscale => rgb
  if(color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
    png_set_gray_to_rgb(png->png_ptr);
 
  // png->bytespp = 3*bit_depth/8;
  png->global.width = png_get_image_width(png->png_ptr, png->info_ptr);
  png->global.height = png_get_image_height(png->png_ptr, png->info_ptr);
 
  return 0;
 
#undef NUM_BYTES_CHECK
}
 
#if 0
int dt_imageio_png_read_assure_8(dt_imageio_png_t *png)
{
  if (setjmp(png_jmpbuf(png->png_ptr)))
  {
    fclose(png->f);
    png_destroy_read_struct(&png->png_ptr, NULL, NULL);
    return 1;
  }
  uint32_t bit_depth = png_get_bit_depth(png->png_ptr, png->info_ptr);
  // strip down to 8 bit channels
  if (bit_depth == 16)
    png_set_strip_16(png->png_ptr);
 
  return 0;
}
#endif
 
int read_image(dt_imageio_module_data_t *p_tmp, uint8_t *out)
{
  dt_imageio_png_t *png = (dt_imageio_png_t *)p_tmp;
  if(setjmp(png_jmpbuf(png->png_ptr)))
  {
    fclose(png->f);
    png_destroy_read_struct(&png->png_ptr, &png->info_ptr, NULL);
    return 1;
  }
 
  png_bytep row_pointer = (png_bytep)out;
  unsigned long rowbytes = png_get_rowbytes(png->png_ptr, png->info_ptr);
 
  for(int y = 0; y < png->global.height; y++)
  {
    png_read_row(png->png_ptr, row_pointer, NULL);
    row_pointer += rowbytes;
  }
 
  png_read_end(png->png_ptr, png->info_ptr);
  png_destroy_read_struct(&png->png_ptr, &png->info_ptr, NULL);
 
  fclose(png->f);
  return 0;
}
 
size_t params_size(dt_imageio_module_format_t *self)
{
  return sizeof(dt_imageio_module_data_t) + 2 * sizeof(int);
}
 
void *legacy_params(dt_imageio_module_format_t *self, const void *const old_params, const size_t old_params_size,
                    const int old_version, const int new_version, size_t *new_size)
{
  if(old_version == 1 && new_version == 3)
  {
    typedef struct dt_imageio_png_v1_t
    {
      int max_width, max_height;
      int width, height;
      char style[128];
      int bpp;
      FILE *f;
      png_structp png_ptr;
      png_infop info_ptr;
    } dt_imageio_png_v1_t;
 
    dt_imageio_png_v1_t *o = (dt_imageio_png_v1_t *)old_params;
    dt_imageio_png_t *n = (dt_imageio_png_t *)malloc(sizeof(dt_imageio_png_t));
 
    n->global.max_width = o->max_width;
    n->global.max_height = o->max_height;
    n->global.width = o->width;
    n->global.height = o->height;
    g_strlcpy(n->global.style, o->style, sizeof(o->style));
    n->bpp = o->bpp;
    n->compression = Z_BEST_COMPRESSION;
    n->f = o->f;
    n->png_ptr = o->png_ptr;
    n->info_ptr = o->info_ptr;
    *new_size = self->params_size(self);
    return n;
  }
  else if(old_version == 2 && new_version == 3)
  {
    typedef struct dt_imageio_png_v2_t
    {
      int max_width, max_height;
      int width, height;
      char style[128];
      gboolean style_append;
      int bpp;
      FILE *f;
      png_structp png_ptr;
      png_infop info_ptr;
    } dt_imageio_png_v2_t;
 
    dt_imageio_png_v2_t *o = (dt_imageio_png_v2_t *)old_params;
    dt_imageio_png_t *n = (dt_imageio_png_t *)malloc(sizeof(dt_imageio_png_t));
 
    n->global.max_width = o->max_width;
    n->global.max_height = o->max_height;
    n->global.width = o->width;
    n->global.height = o->height;
    g_strlcpy(n->global.style, o->style, sizeof(o->style));
    n->bpp = o->bpp;
    n->compression = Z_BEST_COMPRESSION;
    n->f = o->f;
    n->png_ptr = o->png_ptr;
    n->info_ptr = o->info_ptr;
    *new_size = self->params_size(self);
    return n;
  }
  return NULL;
}
 
void *get_params(dt_imageio_module_format_t *self)
{
  dt_imageio_png_t *d = (dt_imageio_png_t *)calloc(1, sizeof(dt_imageio_png_t));
  const char *bpp = dt_conf_get_string_const("plugins/imageio/format/png/bpp");
  d->bpp = atoi(bpp);
  if(d->bpp != 8 && d->bpp != 16)
    d->bpp = 8;
 
  // PNG compression level might actually be zero!
  if(!dt_conf_key_exists("plugins/imageio/format/png/compression"))
    d->compression = 5;
  else
  {
    d->compression = dt_conf_get_int("plugins/imageio/format/png/compression");
    if(d->compression < 0 || d->compression > 9) d->compression = 5;
  }
 
  return d;
}
 
void free_params(dt_imageio_module_format_t *self, dt_imageio_module_data_t *params)
{
  dt_free(params);
}
 
int set_params(dt_imageio_module_format_t *self, const void *params, const int size)
{
  if(size != self->params_size(self)) return 1;
  const dt_imageio_png_t *d = (dt_imageio_png_t *)params;
  const dt_imageio_png_gui_t *g = (dt_imageio_png_gui_t *)self->gui_data;
  if(d->bpp < 12)
    dt_bauhaus_combobox_set(g->bit_depth, 0);
  else
    dt_bauhaus_combobox_set(g->bit_depth, 1);
  dt_conf_set_int("plugins/imageio/format/png/bpp", d->bpp);
  dt_bauhaus_slider_set(g->compression, d->compression);
  dt_conf_set_int("plugins/imageio/format/png/compression", d->compression);
  return 0;
}
 
int bpp(dt_imageio_module_data_t *p)
{
  return ((dt_imageio_png_t *)p)->bpp;
}
 
int levels(dt_imageio_module_data_t *p)
{
  return IMAGEIO_RGB | (((dt_imageio_png_t *)p)->bpp == 8 ? IMAGEIO_INT8 : IMAGEIO_INT16);
}
 
const char *mime(dt_imageio_module_data_t *data)
{
  return "image/png";
}
 
const char *extension(dt_imageio_module_data_t *data)
{
  return "png";
}
 
const char *name()
{
  return _("PNG (8/16-bit)");
}
 
static void bit_depth_changed(GtkWidget *widget, gpointer user_data)
{
  const int bpp = (dt_bauhaus_combobox_get(widget) == 0 ? 8 : 16);
  dt_conf_set_int("plugins/imageio/format/png/bpp", bpp);
}
 
static void compression_level_changed(GtkWidget *slider, gpointer user_data)
{
  const int compression = (int)dt_bauhaus_slider_get(slider);
  dt_conf_set_int("plugins/imageio/format/png/compression", compression);
}
 
void init(dt_imageio_module_format_t *self)
{
}
 
void cleanup(dt_imageio_module_format_t *self)
{
}
 
void gui_init(dt_imageio_module_format_t *self)
{
  dt_imageio_png_gui_t *gui = (dt_imageio_png_gui_t *)malloc(sizeof(dt_imageio_png_gui_t));
  self->gui_data = (void *)gui;
  const char *conf_bpp = dt_conf_get_string_const("plugins/imageio/format/png/bpp");
  int bpp = atoi(conf_bpp);
 
  // PNG compression level might actually be zero!
  int compression = 5;
  if(dt_conf_key_exists("plugins/imageio/format/png/compression"))
    compression = dt_conf_get_int("plugins/imageio/format/png/compression");
 
  self->widget = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
 
  // Bit depth combo box
  gui->bit_depth = dt_bauhaus_combobox_new(darktable.bauhaus, DT_GUI_MODULE(NULL));
  dt_bauhaus_widget_set_label(gui->bit_depth, N_("bit depth"));
  dt_bauhaus_combobox_add(gui->bit_depth, _("8 bit"));
  dt_bauhaus_combobox_add(gui->bit_depth, _("16 bit"));
  if(bpp == 16)
    dt_bauhaus_combobox_set(gui->bit_depth, 1);
  else {
    bpp = 8; // We know only about 8 or 16 bits, at least for now
    dt_bauhaus_combobox_set(gui->bit_depth, 0);
  }
  gtk_box_pack_start(GTK_BOX(self->widget), gui->bit_depth, TRUE, TRUE, 0);
  g_signal_connect(G_OBJECT(gui->bit_depth), "value-changed", G_CALLBACK(bit_depth_changed), NULL);
 
  // Compression level slider
  gui->compression = dt_bauhaus_slider_new_with_range(darktable.bauhaus, DT_GUI_MODULE(NULL),
                                                      dt_confgen_get_int("plugins/imageio/format/png/compression", DT_MIN),
                                                      dt_confgen_get_int("plugins/imageio/format/png/compression", DT_MAX),
                                                      1,
                                                      dt_confgen_get_int("plugins/imageio/format/png/compression", DT_DEFAULT),
                                                      0);
  dt_bauhaus_widget_set_label(gui->compression, N_("compression"));
  dt_bauhaus_slider_set(gui->compression, compression);
  gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(gui->compression), TRUE, TRUE, 0);
  g_signal_connect(G_OBJECT(gui->compression), "value-changed", G_CALLBACK(compression_level_changed), NULL);
}
 
void gui_cleanup(dt_imageio_module_format_t *self)
{
  dt_free(self->gui_data);
}
 
void gui_reset(dt_imageio_module_format_t *self)
{
  dt_imageio_png_gui_t *gui = (dt_imageio_png_gui_t *)self->gui_data;
  dt_bauhaus_combobox_set(gui->bit_depth, 0); // 8bpp
  dt_bauhaus_slider_set(gui->compression, dt_confgen_get_int("plugins/imageio/format/png/compression", DT_DEFAULT));
}
 
int flags(dt_imageio_module_data_t *data)
{
  return FORMAT_FLAGS_SUPPORT_XMP;
}
 
// clang-format off
// modelines: These editor modelines have been set for all relevant files by tools/update_modelines.py
// vim: shiftwidth=2 expandtab tabstop=2 cindent
// kate: tab-indents: off; indent-width 2; replace-tabs on; indent-mode cstyle; remove-trailing-spaces modified;
// clang-format on