io.c

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/*
    This file is part of the Ansel project.
    Copyright (C) 2026 Aurélien PIERRE.
    Copyright (C) 2026 Guillaume Stutin.
 
    Ansel 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.
 
    Ansel 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 Ansel.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#include "system/macros.h"
#include "system/mem_alloc.h"
#include "system/openmp.h"
#include "iop/drawlayer/io.h"
 
#include "colorprofiles/colorspaces.h"
#include "common/image.h"
#include "imageio/imageio_core.h"
#include "imageio/imageio_module.h"
#include "control/jobs.h"
#include "iop/drawlayer/cache.h"
 
#include <glib/gstdio.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <tiffio.h>
 
static inline float _clamp01(const float value)
{
  return fminf(fmaxf(value, 0.0f), 1.0f);
}
 
typedef union dt_drawlayer_io_fp32_t
{
  uint32_t u;
  float f;
} dt_drawlayer_io_fp32_t;
 
static inline float _half_to_float(const uint16_t h)
{
  static const dt_drawlayer_io_fp32_t magic = { 113u << 23 };
  static const uint32_t shifted_exp = 0x7c00u << 13;
  dt_drawlayer_io_fp32_t out;
 
  out.u = (h & 0x7fffu) << 13;
  const uint32_t exp = shifted_exp & out.u;
  out.u += (127u - 15u) << 23;
 
  if(exp == shifted_exp)
    out.u += (128u - 16u) << 23;
  else if(exp == 0)
  {
    out.u += 1u << 23;
    out.f -= magic.f;
  }
 
  out.u |= (h & 0x8000u) << 16;
  return out.f;
}
 
static inline uint16_t _float_to_half(float value)
{
  dt_drawlayer_io_fp32_t in = { .f = value };
  const uint32_t sign = (in.u >> 16) & 0x8000u;
  const uint32_t exponent = (in.u >> 23) & 0xffu;
  uint32_t mantissa = in.u & 0x007fffffu;
 
  if(exponent == 0xffu)
  {
    if(mantissa) return (uint16_t)(sign | 0x7e00u);
    return (uint16_t)(sign | 0x7c00u);
  }
 
  const int32_t half_exponent = (int32_t)exponent - 127 + 15;
 
  if(half_exponent >= 0x1f) return (uint16_t)(sign | 0x7c00u);
  if(half_exponent <= 0)
  {
    if(half_exponent < -10) return (uint16_t)sign;
 
    mantissa |= 0x00800000u;
    const uint32_t shift = (uint32_t)(1 - half_exponent);
    uint32_t half_mantissa = mantissa >> (shift + 13);
    const uint32_t round_bit = 1u << (shift + 12);
 
    if((mantissa & round_bit) && ((mantissa & (round_bit - 1u)) || (half_mantissa & 1u)))
      half_mantissa++;
 
    return (uint16_t)(sign | half_mantissa);
  }
 
  uint32_t half_exp = (uint32_t)half_exponent << 10;
  uint32_t half_mantissa = mantissa >> 13;
 
  if((mantissa & 0x00001000u) && ((mantissa & 0x00001fffu) || (half_mantissa & 1u)))
  {
    half_mantissa++;
 
    if(half_mantissa == 0x0400u)
    {
      half_mantissa = 0;
      half_exp += 0x0400u;
      if(half_exp >= 0x7c00u) return (uint16_t)(sign | 0x7c00u);
    }
  }
 
  return (uint16_t)(sign | half_exp | half_mantissa);
}
 
static inline void _clear_transparent_half(uint16_t *pixels, const size_t pixel_count)
{
  if(IS_NULL_PTR(pixels)) return;
  memset(pixels, 0, pixel_count * 4 * sizeof(uint16_t));
}
 
static inline void _load_half_pixel_rgba(const uint16_t *src, float rgba[4])
{
  rgba[0] = _half_to_float(src[0]);
  rgba[1] = _half_to_float(src[1]);
  rgba[2] = _half_to_float(src[2]);
  rgba[3] = _half_to_float(src[3]);
}
 
typedef struct drawlayer_tiff_export_params_t
{
  dt_imageio_module_data_t global;
  int bpp;
  int compress;
  int compresslevel;
  int shortfile;
} drawlayer_tiff_export_params_t;
 
static gboolean dt_drawlayer_layer_name_non_empty(const char *name)
{
  if(IS_NULL_PTR(name)) return FALSE;
  char tmp[DT_DRAWLAYER_IO_NAME_SIZE] = { 0 };
  g_strlcpy(tmp, name, sizeof(tmp));
  g_strstrip(tmp);
  return tmp[0] != '\0';
}
 
static int64_t dt_drawlayer_sidecar_timestamp_from_path(const char *path)
{
  if(IS_NULL_PTR(path) || path[0] == '\0' || !g_file_test(path, G_FILE_TEST_EXISTS)) return 0;
 
  GStatBuf st = { 0 };
  if(g_stat(path, &st) != 0) return 0;
  return (int64_t)st.st_mtime;
}
 
static gboolean _export_pre_module_fullres_to_tiff(const int32_t imgid, const char *filter, const char *path)
{
  if(imgid <= 0 || IS_NULL_PTR(path) || path[0] == '\0') return FALSE;
 
  dt_imageio_module_format_t *format = dt_imageio_get_format_by_name("tiff");
  if(IS_NULL_PTR(format)) return FALSE;
 
  dt_imageio_module_data_t *format_params = format->get_params(format);
  if(IS_NULL_PTR(format_params)) return FALSE;
 
  format_params->max_width = 0;
  format_params->max_height = 0;
  format_params->width = 0;
  format_params->height = 0;
  format_params->style[0] = '\0';
 
  if(format->params_size(format) >= sizeof(drawlayer_tiff_export_params_t))
  {
    drawlayer_tiff_export_params_t *const tiff_params = (drawlayer_tiff_export_params_t *)format_params;
    tiff_params->bpp = 32;
    tiff_params->compress = 0;
    tiff_params->compresslevel = 0;
    tiff_params->shortfile = 0;
  }
 
  const int rc = dt_imageio_export_with_flags(
      imgid, path, format, format_params, TRUE, FALSE, TRUE, FALSE, FALSE, FALSE, (filter && filter[0]) ? filter : NULL,
      FALSE, FALSE, DT_COLORSPACE_NONE, NULL, DT_INTENT_PERCEPTUAL, NULL, NULL, 0, 0, NULL, NULL);
 
  format->free_params(format, format_params);
  return rc == 0;
}
 
static gboolean _icc_blob_from_profile_key(const char *work_profile, uint8_t **icc_data, uint32_t *icc_len)
{
  if(icc_data) *icc_data = NULL;
  if(!IS_NULL_PTR(icc_len)) *icc_len = 0;
  if(IS_NULL_PTR(work_profile) || work_profile[0] == '\0' || IS_NULL_PTR(icc_data) || !icc_len) return FALSE;
 
  const char *sep0 = strchr(work_profile, '|');
  if(IS_NULL_PTR(sep0)) return FALSE;
  const char *sep1 = strchr(sep0 + 1, '|');
  if(IS_NULL_PTR(sep1)) return FALSE;
 
  char *endptr = NULL;
  const long type_long = strtol(work_profile, &endptr, 10);
  if(endptr != sep0) return FALSE;
 
  const dt_colorspaces_color_profile_type_t type = (dt_colorspaces_color_profile_type_t)type_long;
  const char *filename = sep1 + 1;
  const dt_colorspaces_color_profile_t *profile = dt_colorspaces_get_profile(type, filename, DT_PROFILE_ROLE_ANY);
  if(IS_NULL_PTR(profile) || IS_NULL_PTR(profile->profile)) return FALSE;
 
  cmsUInt32Number len = 0;
  cmsSaveProfileToMem(profile->profile, NULL, &len);
  if(len == 0) return FALSE;
 
  uint8_t *buf = g_malloc(len);
  if(IS_NULL_PTR(buf)) return FALSE;
 
  if(!cmsSaveProfileToMem(profile->profile, buf, &len) || len == 0)
  {
    dt_free(buf);
    return FALSE;
  }
 
  *icc_data = buf;
  *icc_len = (uint32_t)len;
  return TRUE;
}
 
static gboolean _set_directory_tags(TIFF *tiff, const uint32_t width, const uint32_t height, const char *name,
                                    const char *work_profile)
{
  const uint16_t extrasamples[] = { EXTRASAMPLE_ASSOCALPHA };
 
  if(!TIFFSetField(tiff, TIFFTAG_IMAGEWIDTH, width)) return FALSE;
  if(!TIFFSetField(tiff, TIFFTAG_IMAGELENGTH, height)) return FALSE;
  if(!TIFFSetField(tiff, TIFFTAG_BITSPERSAMPLE, 16)) return FALSE;
  if(!TIFFSetField(tiff, TIFFTAG_SAMPLEFORMAT, SAMPLEFORMAT_IEEEFP)) return FALSE;
  if(!TIFFSetField(tiff, TIFFTAG_SAMPLESPERPIXEL, 4)) return FALSE;
  if(!TIFFSetField(tiff, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG)) return FALSE;
  if(!TIFFSetField(tiff, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_RGB)) return FALSE;
  if(!TIFFSetField(tiff, TIFFTAG_EXTRASAMPLES, 1, extrasamples)) return FALSE;
 
  if(!TIFFSetField(tiff, TIFFTAG_COMPRESSION, COMPRESSION_ADOBE_DEFLATE)
     && !TIFFSetField(tiff, TIFFTAG_COMPRESSION, COMPRESSION_DEFLATE)
     && !TIFFSetField(tiff, TIFFTAG_COMPRESSION, COMPRESSION_LZW))
    TIFFSetField(tiff, TIFFTAG_COMPRESSION, COMPRESSION_NONE);
 
  TIFFSetField(tiff, TIFFTAG_ROWSPERSTRIP, TIFFDefaultStripSize(tiff, 0));
  if(!IS_NULL_PTR(name) && name[0]) TIFFSetField(tiff, TIFFTAG_PAGENAME, name);
  if(!IS_NULL_PTR(work_profile) && work_profile[0]) TIFFSetField(tiff, TIFFTAG_IMAGEDESCRIPTION, work_profile);
  return TRUE;
}
 
static gboolean _read_scanline_rgba(TIFF *tiff, const uint32_t width, const uint32_t row, uint16_t *out)
{
  uint16_t bpp = 0;
  uint16_t spp = 0;
  uint16_t sampleformat = SAMPLEFORMAT_UINT;
 
  TIFFGetField(tiff, TIFFTAG_BITSPERSAMPLE, &bpp);
  TIFFGetField(tiff, TIFFTAG_SAMPLESPERPIXEL, &spp);
  TIFFGetFieldDefaulted(tiff, TIFFTAG_SAMPLEFORMAT, &sampleformat);
 
  if(spp != 4) return FALSE;
 
  const tsize_t scanline = TIFFScanlineSize(tiff);
  tdata_t buffer = _TIFFmalloc((tsize_t)scanline);
  if(IS_NULL_PTR(buffer)) return FALSE;
 
  const int ok = TIFFReadScanline(tiff, buffer, row, 0);
  if(ok == -1)
  {
    _TIFFfree(buffer);
    return FALSE;
  }
 
  if(bpp == 16 && sampleformat == SAMPLEFORMAT_IEEEFP)
    memcpy(out, buffer, (size_t)width * 4 * sizeof(uint16_t));
  else
  {
    _TIFFfree(buffer);
    return FALSE;
  }
 
  _TIFFfree(buffer);
  return TRUE;
}
 
static gboolean _write_scanline_rgba(TIFF *tiff, const uint32_t row, const uint16_t *in)
{
  return TIFFWriteScanline(tiff, (tdata_t)in, row, 0) != -1;
}
 
static void _overlay_patch_row_rgba(uint16_t *dst_row, const uint32_t width, const int offset_x,
                                    const int raw_y, const dt_drawlayer_io_patch_t *patch)
{
  if(IS_NULL_PTR(dst_row) || IS_NULL_PTR(patch) || IS_NULL_PTR(patch->pixels) || raw_y < patch->y || raw_y >= patch->y + patch->height) return;
 
  const int dst_x0 = MAX(0, patch->x - offset_x);
  const int dst_x1 = MIN((int)width, patch->x + patch->width - offset_x);
  if(dst_x0 >= dst_x1) return;
 
  const float *patch_row = patch->pixels + 4 * (size_t)(raw_y - patch->y) * patch->width;
  __OMP_FOR_SIMD__()
  for(int dst_x = dst_x0; dst_x < dst_x1; dst_x++)
  {
    const float *src_pixel = patch_row + 4 * (size_t)(dst_x + offset_x - patch->x);
    dst_row[4 * dst_x + 0] = _float_to_half(src_pixel[0]);
    dst_row[4 * dst_x + 1] = _float_to_half(src_pixel[1]);
    dst_row[4 * dst_x + 2] = _float_to_half(src_pixel[2]);
    dst_row[4 * dst_x + 3] = _float_to_half(src_pixel[3]);
  }
}
 
static void _scan_directories(TIFF *tiff, const char *target_name, const int target_order,
                              dt_drawlayer_io_layer_info_t *info)
{
  memset(info, 0, sizeof(*info));
  info->index = -1;
 
  if(IS_NULL_PTR(tiff)) return;
  if(!TIFFSetDirectory(tiff, 0)) return;
 
  const gboolean has_target_name = (target_name && target_name[0] != '\0');
  const gboolean has_target_order = (target_order >= 0);
  gboolean exact_found = FALSE;
  gboolean named_found = FALSE;
  gboolean order_found = FALSE;
  dt_drawlayer_io_layer_info_t exact = { 0 };
  dt_drawlayer_io_layer_info_t named = { 0 };
  dt_drawlayer_io_layer_info_t ordered = { 0 };
  exact.index = -1;
  named.index = -1;
  ordered.index = -1;
 
  int index = 0;
  do
  {
    char *page_name = NULL;
    char *page_profile = NULL;
    uint32_t width = 0;
    uint32_t height = 0;
    TIFFGetField(tiff, TIFFTAG_IMAGEWIDTH, &width);
    TIFFGetField(tiff, TIFFTAG_IMAGELENGTH, &height);
    TIFFGetField(tiff, TIFFTAG_PAGENAME, &page_name);
    TIFFGetField(tiff, TIFFTAG_IMAGEDESCRIPTION, &page_profile);
 
    const gboolean order_match = (has_target_order && index == target_order);
    const gboolean name_match = (has_target_name && !g_strcmp0(page_name ? page_name : "", target_name));
    const gboolean exact_match = (name_match && order_match);
 
    if(exact_match && !exact_found)
    {
      exact_found = TRUE;
      exact.found = TRUE;
      exact.index = index;
      exact.width = width;
      exact.height = height;
      g_strlcpy(exact.name, page_name ? page_name : "", sizeof(exact.name));
      g_strlcpy(exact.work_profile, page_profile ? page_profile : "", sizeof(exact.work_profile));
    }
 
    if(name_match && !named_found)
    {
      named_found = TRUE;
      named.found = TRUE;
      named.index = index;
      named.width = width;
      named.height = height;
      g_strlcpy(named.name, page_name ? page_name : "", sizeof(named.name));
      g_strlcpy(named.work_profile, page_profile ? page_profile : "", sizeof(named.work_profile));
    }
 
    if(order_match && !order_found)
    {
      order_found = TRUE;
      ordered.found = TRUE;
      ordered.index = index;
      ordered.width = width;
      ordered.height = height;
      g_strlcpy(ordered.name, page_name ? page_name : "", sizeof(ordered.name));
      g_strlcpy(ordered.work_profile, page_profile ? page_profile : "", sizeof(ordered.work_profile));
    }
 
    index++;
  } while(TIFFReadDirectory(tiff));
 
  if(exact_found)
  {
    info->found = TRUE;
    info->index = exact.index;
    info->width = exact.width;
    info->height = exact.height;
    g_strlcpy(info->name, exact.name, sizeof(info->name));
    g_strlcpy(info->work_profile, exact.work_profile, sizeof(info->work_profile));
  }
  else if(named_found)
  {
    info->found = TRUE;
    info->index = named.index;
    info->width = named.width;
    info->height = named.height;
    g_strlcpy(info->name, named.name, sizeof(info->name));
    g_strlcpy(info->work_profile, named.work_profile, sizeof(info->work_profile));
  }
  else if(order_found)
  {
    info->found = TRUE;
    info->index = ordered.index;
    info->width = ordered.width;
    info->height = ordered.height;
    g_strlcpy(info->name, ordered.name, sizeof(info->name));
    g_strlcpy(info->work_profile, ordered.work_profile, sizeof(info->work_profile));
  }
 
  info->count = index;
  TIFFSetDirectory(tiff, 0);
}
 
static gboolean _write_page(TIFF *dst, TIFF *src, const int src_dir, const char *name, const char *work_profile,
                            const dt_drawlayer_io_patch_t *patch, const int layer_width, const int layer_height)
{
  uint32_t width = patch ? (uint32_t)patch->width : (uint32_t)layer_width;
  uint32_t height = patch ? (uint32_t)patch->height : (uint32_t)layer_height;
  const char *page_profile = work_profile;
  uint8_t *icc_profile = NULL;
  uint32_t icc_profile_len = 0;
 
  if(!IS_NULL_PTR(src))
  {
    if(!TIFFSetDirectory(src, (tdir_t)src_dir)) return FALSE;
    if(IS_NULL_PTR(patch))
    {
      TIFFGetField(src, TIFFTAG_IMAGEWIDTH, &width);
      TIFFGetField(src, TIFFTAG_IMAGELENGTH, &height);
    }
    if(IS_NULL_PTR(name))
    {
      char *src_name = NULL;
      TIFFGetField(src, TIFFTAG_PAGENAME, &src_name);
      name = src_name;
    }
    if(IS_NULL_PTR(page_profile))
    {
      char *src_profile = NULL;
      TIFFGetField(src, TIFFTAG_IMAGEDESCRIPTION, &src_profile);
      page_profile = src_profile;
    }
  }
 
  if(!_set_directory_tags(dst, width, height, name, page_profile)) return FALSE;
  if(page_profile && page_profile[0] && _icc_blob_from_profile_key(page_profile, &icc_profile, &icc_profile_len))
    TIFFSetField(dst, TIFFTAG_ICCPROFILE, icc_profile_len, icc_profile);
 
  uint16_t *src_row = g_malloc_n((gsize)width * 4, sizeof(uint16_t));
  uint16_t *dst_row = g_malloc_n((gsize)width * 4, sizeof(uint16_t));
  if(IS_NULL_PTR(src_row) || IS_NULL_PTR(dst_row))
  {
    dt_free(icc_profile);
    dt_free(src_row);
    dt_free(dst_row);
    return FALSE;
  }
 
  const int offset_x = (layer_width - (int)width) / 2;
  const int offset_y = (layer_height - (int)height) / 2;
 
  for(uint32_t y = 0; y < height; y++)
  {
    if(!IS_NULL_PTR(src))
    {
      if(!_read_scanline_rgba(src, width, y, src_row))
      {
        dt_free(icc_profile);
        dt_free(src_row);
        dt_free(dst_row);
        return FALSE;
      }
      memcpy(dst_row, src_row, (size_t)width * 4 * sizeof(uint16_t));
    }
    else
      _clear_transparent_half(dst_row, (size_t)width);
 
    if(!IS_NULL_PTR(patch))
    {
      const int layer_y = (int)y + offset_y;
      _overlay_patch_row_rgba(dst_row, width, offset_x, layer_y, patch);
    }
 
    if(!_write_scanline_rgba(dst, y, dst_row))
    {
      dt_free(icc_profile);
      dt_free(src_row);
      dt_free(dst_row);
      return FALSE;
    }
  }
 
  dt_free(icc_profile);
  dt_free(src_row);
  dt_free(dst_row);
  return TIFFWriteDirectory(dst) != 0;
}
 
static gboolean _rewrite_sidecar(const char *path, const char *target_name, const int target_order,
                                 const char *work_profile, const dt_drawlayer_io_patch_t *patch, const int layer_width,
                                 const int layer_height, const gboolean delete_target, const int insert_order,
                                 int *final_order)
{
  if(!IS_NULL_PTR(final_order)) *final_order = -1;
 
  TIFF *src = NULL;
  dt_drawlayer_io_layer_info_t info;
  memset(&info, 0, sizeof(info));
  info.index = -1;
 
  if(g_file_test(path, G_FILE_TEST_EXISTS))
  {
    src = TIFFOpen(path, "rb");
    if(IS_NULL_PTR(src)) return FALSE;
    _scan_directories(src, target_name, target_order, &info);
  }
 
  if(delete_target && (IS_NULL_PTR(src) || !info.found))
  {
    if(!IS_NULL_PTR(src)) TIFFClose(src);
    return TRUE;
  }
 
  if(delete_target && !IS_NULL_PTR(src) && info.found && info.count == 1)
  {
    TIFFClose(src);
    return g_unlink(path) == 0;
  }
 
  gchar *tmp_path = g_strdup_printf("%s.tmp", path);
  TIFF *dst = TIFFOpen(tmp_path, "wb");
  if(IS_NULL_PTR(dst))
  {
    if(!IS_NULL_PTR(src)) TIFFClose(src);
    dt_free(tmp_path);
    return FALSE;
  }
 
  int written_index = 0;
  gboolean ok = TRUE;
 
  if(!IS_NULL_PTR(src))
  {
    for(int dir = 0; dir < info.count && ok; dir++)
    {
      if(!delete_target && !info.found && insert_order >= 0 && written_index == insert_order)
      {
        ok = _write_page(dst, NULL, -1, target_name, work_profile, patch, layer_width, layer_height);
        if(ok && final_order) *final_order = written_index;
        if(ok) written_index++;
      }
 
      const gboolean is_target = info.found && dir == info.index;
      if(is_target && delete_target) continue;
 
      const dt_drawlayer_io_patch_t *page_patch = (is_target && !delete_target) ? patch : NULL;
      const char *page_label = is_target ? target_name : NULL;
 
      ok = _write_page(dst, src, dir, page_label, is_target ? work_profile : NULL, page_patch, layer_width,
                       layer_height);
      if(ok && is_target && !delete_target && final_order) *final_order = written_index;
      if(ok) written_index++;
    }
  }
 
  if(ok && !delete_target && (IS_NULL_PTR(src) || !info.found))
  {
    const gboolean append_at_end = (insert_order < 0 || insert_order >= written_index || !src);
    if(append_at_end)
    {
      ok = _write_page(dst, NULL, -1, target_name, work_profile, patch, layer_width, layer_height);
      if(ok && !IS_NULL_PTR(final_order)) *final_order = written_index;
    }
  }
 
  TIFFClose(dst);
  if(!IS_NULL_PTR(src)) TIFFClose(src);
 
  if(ok)
    ok = (g_rename(tmp_path, path) == 0);
  else
    g_unlink(tmp_path);
 
  dt_free(tmp_path);
  return ok;
}
 
gboolean dt_drawlayer_io_layer_name_exists(const char *path, const char *candidate, const int ignore_index)
{
  if(IS_NULL_PTR(path) || !candidate || candidate[0] == '\0' || !g_file_test(path, G_FILE_TEST_EXISTS)) return FALSE;
 
  TIFF *tiff = TIFFOpen(path, "rb");
  if(IS_NULL_PTR(tiff)) return FALSE;
 
  gboolean exists = FALSE;
  int index = 0;
  if(TIFFSetDirectory(tiff, 0))
  {
    do
    {
      char *page_name = NULL;
      TIFFGetField(tiff, TIFFTAG_PAGENAME, &page_name);
      if(index != ignore_index && !g_strcmp0(page_name ? page_name : "", candidate))
      {
        exists = TRUE;
        break;
      }
      index++;
    } while(TIFFReadDirectory(tiff));
  }
 
  TIFFClose(tiff);
  return exists;
}
 
gboolean dt_drawlayer_io_sidecar_path(const int32_t imgid, char *path, const size_t path_size)
{
  gboolean from_cache = FALSE;
  if(IS_NULL_PTR(path) || path_size == 0) return FALSE;
  dt_image_full_path(imgid, path, path_size, &from_cache, __FUNCTION__);
  if(path[0] == '\0') return FALSE;
  g_strlcat(path, ".ansel.tiff", path_size);
  return TRUE;
}
 
gboolean dt_drawlayer_io_find_layer(const char *path, const char *target_name, const int target_order,
                                    dt_drawlayer_io_layer_info_t *info)
{
  if(!IS_NULL_PTR(info)) memset(info, 0, sizeof(*info));
  if(IS_NULL_PTR(path) || !g_file_test(path, G_FILE_TEST_EXISTS)) return FALSE;
 
  TIFF *tiff = TIFFOpen(path, "rb");
  if(IS_NULL_PTR(tiff)) return FALSE;
  _scan_directories(tiff, target_name, target_order, info);
  TIFFClose(tiff);
  return info && info->found;
}
 
gboolean dt_drawlayer_io_load_layer(const char *path, const char *target_name, const int target_order,
                                    const int layer_width, const int layer_height, dt_drawlayer_io_patch_t *patch)
{
  if(IS_NULL_PTR(patch) || IS_NULL_PTR(patch->pixels) || patch->width <= 0 || patch->height <= 0) return FALSE;
  dt_drawlayer_cache_clear_transparent_float(patch->pixels, (size_t)patch->width * patch->height);
 
  if(!g_file_test(path, G_FILE_TEST_EXISTS)) return TRUE;
 
  TIFF *tiff = TIFFOpen(path, "rb");
  if(IS_NULL_PTR(tiff)) return FALSE;
 
  dt_drawlayer_io_layer_info_t info;
  _scan_directories(tiff, target_name, target_order, &info);
  if(!info.found)
  {
    TIFFClose(tiff);
    return TRUE;
  }
 
  if(!TIFFSetDirectory(tiff, (tdir_t)info.index))
  {
    TIFFClose(tiff);
    return FALSE;
  }
 
  uint16_t *row = g_malloc_n((gsize)info.width * 4, sizeof(uint16_t));
  if(IS_NULL_PTR(row))
  {
    TIFFClose(tiff);
    return FALSE;
  }
 
  const int offset_x = (layer_width - (int)info.width) / 2;
  const int offset_y = (layer_height - (int)info.height) / 2;
 
  for(int py = 0; py < patch->height; py++)
  {
    const int layer_y = patch->y + py;
    const int src_y = layer_y - offset_y;
    if(src_y < 0 || src_y >= (int)info.height) continue;
    if(!_read_scanline_rgba(tiff, info.width, (uint32_t)src_y, row))
    {
      dt_free(row);
      TIFFClose(tiff);
      return FALSE;
    }
 
    for(int px = 0; px < patch->width; px++)
    {
      const int layer_x = patch->x + px;
      const int src_x = layer_x - offset_x;
      if(src_x < 0 || src_x >= (int)info.width) continue;
      float *dst = patch->pixels + 4 * ((size_t)py * patch->width + px);
      _load_half_pixel_rgba(row + 4 * src_x, dst);
    }
  }
 
  dt_free(row);
  TIFFClose(tiff);
  return TRUE;
}
 
gboolean dt_drawlayer_io_load_flat_rgba(const char *path, float **pixels, int *width, int *height)
{
  if(pixels) *pixels = NULL;
  if(width) *width = 0;
  if(height) *height = 0;
  if(IS_NULL_PTR(path) || IS_NULL_PTR(pixels) || !width || IS_NULL_PTR(height) || !g_file_test(path, G_FILE_TEST_EXISTS)) return FALSE;
 
  TIFF *tiff = TIFFOpen(path, "rb");
  if(IS_NULL_PTR(tiff)) return FALSE;
 
  uint32_t w = 0, h = 0;
  uint16_t spp = 0, bpp = 0, sampleformat = SAMPLEFORMAT_UINT;
  TIFFGetField(tiff, TIFFTAG_IMAGEWIDTH, &w);
  TIFFGetField(tiff, TIFFTAG_IMAGELENGTH, &h);
  TIFFGetFieldDefaulted(tiff, TIFFTAG_SAMPLESPERPIXEL, &spp);
  TIFFGetFieldDefaulted(tiff, TIFFTAG_BITSPERSAMPLE, &bpp);
  TIFFGetFieldDefaulted(tiff, TIFFTAG_SAMPLEFORMAT, &sampleformat);
 
  if(w == 0 || h == 0 || spp < 1)
  {
    TIFFClose(tiff);
    return FALSE;
  }
 
  float *out = g_malloc_n((size_t)w * h * 4, sizeof(float));
  if(IS_NULL_PTR(out))
  {
    TIFFClose(tiff);
    return FALSE;
  }
  dt_drawlayer_cache_clear_transparent_float(out, (size_t)w * h);
 
  const tsize_t scanline = TIFFScanlineSize(tiff);
  tdata_t row = _TIFFmalloc((tsize_t)scanline);
  if(IS_NULL_PTR(row))
  {
    dt_free(out);
    TIFFClose(tiff);
    return FALSE;
  }
 
  gboolean ok = TRUE;
  for(uint32_t y = 0; y < h && ok; y++)
  {
    if(TIFFReadScanline(tiff, row, y, 0) == -1)
    {
      ok = FALSE;
      break;
    }
 
    for(uint32_t x = 0; x < w; x++)
    {
      float r = 0.0f, g = 0.0f, b = 0.0f, a = 1.0f;
 
      if(bpp == 32 && sampleformat == SAMPLEFORMAT_IEEEFP)
      {
        const float *src = (const float *)row + (size_t)x * spp;
        if(spp >= 3)
        {
          r = src[0];
          g = src[1];
          b = src[2];
        }
        else
        {
          r = g = b = src[0];
        }
        if(spp >= 4) a = src[3];
      }
      else if(bpp == 16 && sampleformat == SAMPLEFORMAT_IEEEFP)
      {
        const uint16_t *src = (const uint16_t *)row + (size_t)x * spp;
        if(spp >= 3)
        {
          r = _half_to_float(src[0]);
          g = _half_to_float(src[1]);
          b = _half_to_float(src[2]);
        }
        else
        {
          r = g = b = _half_to_float(src[0]);
        }
        if(spp >= 4) a = _half_to_float(src[3]);
      }
      else if(bpp == 16)
      {
        const uint16_t *src = (const uint16_t *)row + (size_t)x * spp;
        if(spp >= 3)
        {
          r = src[0] / 65535.0f;
          g = src[1] / 65535.0f;
          b = src[2] / 65535.0f;
        }
        else
        {
          r = g = b = src[0] / 65535.0f;
        }
        if(spp >= 4) a = src[3] / 65535.0f;
      }
      else if(bpp == 8)
      {
        const uint8_t *src = (const uint8_t *)row + (size_t)x * spp;
        if(spp >= 3)
        {
          r = src[0] / 255.0f;
          g = src[1] / 255.0f;
          b = src[2] / 255.0f;
        }
        else
        {
          r = g = b = src[0] / 255.0f;
        }
        if(spp >= 4) a = src[3] / 255.0f;
      }
      else
      {
        ok = FALSE;
        break;
      }
 
      float *dst = out + 4 * ((size_t)y * w + x);
      dst[0] = r;
      dst[1] = g;
      dst[2] = b;
      dst[3] = _clamp01(a);
    }
  }
 
  _TIFFfree(row);
  TIFFClose(tiff);
  if(!ok)
  {
    dt_free(out);
    return FALSE;
  }
 
  *pixels = out;
  *width = (int)w;
  *height = (int)h;
  return TRUE;
}
 
gboolean dt_drawlayer_io_store_layer(const char *path, const char *target_name, const int target_order,
                                     const char *work_profile, const dt_drawlayer_io_patch_t *patch,
                                     const int layer_width, const int layer_height, const gboolean delete_target,
                                     int *final_order)
{
  if(IS_NULL_PTR(target_name) || target_name[0] == '\0') return FALSE;
  return _rewrite_sidecar(path, target_name, target_order, work_profile, patch, layer_width, layer_height,
                          delete_target, -1, final_order);
}
 
gboolean dt_drawlayer_io_insert_layer(const char *path, const char *target_name, const int insert_after_order,
                                      const char *work_profile, const dt_drawlayer_io_patch_t *patch,
                                      const int layer_width, const int layer_height, int *final_order)
{
  if(IS_NULL_PTR(target_name) || target_name[0] == '\0') return FALSE;
  const int insert_order = (insert_after_order >= 0) ? (insert_after_order + 1) : -1;
  return _rewrite_sidecar(path, target_name, -1, work_profile, patch, layer_width, layer_height, FALSE, insert_order,
                          final_order);
}
 
gboolean dt_drawlayer_io_rename_layer(const char *path, const char *current_name, const char *new_name,
                                      const char *work_profile, const int layer_width, const int layer_height,
                                      dt_drawlayer_io_layer_info_t *info)
{
  if(!IS_NULL_PTR(info)) memset(info, 0, sizeof(*info));
  if(IS_NULL_PTR(path) || IS_NULL_PTR(current_name) || current_name[0] == '\0' || IS_NULL_PTR(new_name) || new_name[0] == '\0') return FALSE;
  if(!g_file_test(path, G_FILE_TEST_EXISTS)) return FALSE;
 
  dt_drawlayer_io_layer_info_t current = { 0 };
  if(!dt_drawlayer_io_find_layer(path, current_name, -1, &current)) return FALSE;
  if(dt_drawlayer_io_layer_name_exists(path, new_name, current.index)) return FALSE;
 
  int final_order = current.index;
  if(!dt_drawlayer_io_store_layer(path, new_name, current.index, work_profile, NULL, layer_width, layer_height, FALSE,
                                  &final_order))
    return FALSE;
 
  if(!IS_NULL_PTR(info))
  {
    *info = current;
    info->found = TRUE;
    info->index = final_order;
    g_strlcpy(info->name, new_name, sizeof(info->name));
    if(!IS_NULL_PTR(work_profile) && work_profile[0] != '\0')
      g_strlcpy(info->work_profile, work_profile, sizeof(info->work_profile));
  }
  return TRUE;
}
 
gboolean dt_drawlayer_io_delete_layer(const char *path, const char *target_name, const int layer_width,
                                      const int layer_height)
{
  if(IS_NULL_PTR(path) || IS_NULL_PTR(target_name) || target_name[0] == '\0') return FALSE;
  if(!g_file_test(path, G_FILE_TEST_EXISTS)) return FALSE;
 
  dt_drawlayer_io_layer_info_t info = { 0 };
  if(!dt_drawlayer_io_find_layer(path, target_name, -1, &info)) return FALSE;
 
  return dt_drawlayer_io_store_layer(path, target_name, info.index, NULL, NULL, layer_width, layer_height, TRUE,
                                     NULL);
}
 
void dt_drawlayer_io_make_unique_name_plain(const char *path, const char *requested, char *name, const size_t name_size)
{
  if(IS_NULL_PTR(name) || name_size == 0) return;
  name[0] = '\0';
  if(!IS_NULL_PTR(requested)) g_strlcpy(name, requested, name_size);
  g_strstrip(name);
  if(name[0] == '\0') return;
  if(!dt_drawlayer_io_layer_name_exists(path, name, -1)) return;
 
  char base[DT_DRAWLAYER_IO_NAME_SIZE] = { 0 };
  g_strlcpy(base, name, sizeof(base));
 
  for(int suffix = 2; suffix < 100000; suffix++)
  {
    g_snprintf(name, name_size, "%.*s %d", MAX((int)name_size - 12, 1), base, suffix);
    if(!dt_drawlayer_io_layer_name_exists(path, name, -1)) return;
  }
}
 
gboolean dt_drawlayer_io_list_layer_names(const char *path, char ***names, int *count)
{
  if(names) *names = NULL;
  if(!IS_NULL_PTR(count)) *count = 0;
  if(IS_NULL_PTR(path) || IS_NULL_PTR(names) || !count || !g_file_test(path, G_FILE_TEST_EXISTS)) return FALSE;
 
  TIFF *tiff = TIFFOpen(path, "rb");
  if(IS_NULL_PTR(tiff)) return FALSE;
 
  GPtrArray *arr = g_ptr_array_new_with_free_func(g_free);
  if(TIFFSetDirectory(tiff, 0))
  {
    do
    {
      char *page_name = NULL;
      TIFFGetField(tiff, TIFFTAG_PAGENAME, &page_name);
      g_ptr_array_add(arr, g_strdup(page_name ? page_name : ""));
    } while(TIFFReadDirectory(tiff));
  }
  TIFFClose(tiff);
 
  *count = (int)arr->len;
  if(arr->len == 0)
  {
    g_ptr_array_free(arr, TRUE);
    *names = NULL;
    return TRUE;
  }
 
  const guint layer_count = arr->len;
  char **out = (char **)g_ptr_array_free(arr, FALSE);
  out = g_renew(char *, out, layer_count + 1);
  out[layer_count] = NULL;
  *names = out;
  return TRUE;
}
 
void dt_drawlayer_io_free_layer_names(char ***names, int *count)
{
  if(IS_NULL_PTR(names) || !*names) return;
  const int n = (!IS_NULL_PTR(count) && *count > 0) ? *count : 0;
  if(n > 0)
  {
    for(int i = 0; i < n; i++) dt_free((*names)[i]);
  }
  else
  {
    for(int i = 0; (*names)[i]; i++) dt_free((*names)[i]);
  }
  dt_free(*names);
  if(!IS_NULL_PTR(count)) *count = 0;
}
 
int32_t dt_drawlayer_io_background_layer_job_run(dt_job_t *job)
{
  const dt_drawlayer_io_background_job_params_t *params
      = (const dt_drawlayer_io_background_job_params_t *)dt_control_job_get_params(job);
  if(IS_NULL_PTR(params)) return 0;
 
  dt_drawlayer_io_background_job_result_t *result = g_new0(dt_drawlayer_io_background_job_result_t, 1);
  result->imgid = params->imgid;
  g_strlcpy(result->initiator_layer_name, params->initiator_layer_name, sizeof(result->initiator_layer_name));
  result->initiator_layer_order = params->initiator_layer_order;
  g_strlcpy(result->message, _("failed to create background layer from input"), sizeof(result->message));
 
  gchar *tmp_path = NULL;
  const int tmp_fd = g_file_open_tmp("ansel-drawlayer-bg-XXXXXX.tiff", &tmp_path, NULL);
  if(tmp_fd >= 0) g_close(tmp_fd, NULL);
 
  float *export_pixels = NULL;
  int export_w = 0;
  int export_h = 0;
  dt_drawlayer_io_patch_t bg_patch = { 0 };
 
  do
  {
    if(tmp_fd < 0 || IS_NULL_PTR(tmp_path)) break;
    if(!_export_pre_module_fullres_to_tiff(params->imgid, params->filter, tmp_path)) break;
    if(!dt_drawlayer_io_load_flat_rgba(tmp_path, &export_pixels, &export_w, &export_h)) break;
    if(IS_NULL_PTR(export_pixels) || export_w <= 0 || export_h <= 0) break;
 
    bg_patch.width = params->layer_width;
    bg_patch.height = params->layer_height;
    bg_patch.x = 0;
    bg_patch.y = 0;
    bg_patch.pixels = dt_drawlayer_cache_alloc_temp_buffer(
        (size_t)params->layer_width * params->layer_height * 4 * sizeof(float), "drawlayer bg layer");
    if(IS_NULL_PTR(bg_patch.pixels)) break;
    dt_drawlayer_cache_clear_transparent_float(bg_patch.pixels, (size_t)params->layer_width * params->layer_height);
 
    const int clip_x0 = MAX(params->dst_x, 0);
    const int clip_y0 = MAX(params->dst_y, 0);
    const int clip_x1 = MIN(params->dst_x + export_w, params->layer_width);
    const int clip_y1 = MIN(params->dst_y + export_h, params->layer_height);
    if(clip_x1 <= clip_x0 || clip_y1 <= clip_y0) break;
 
    const int copy_w = clip_x1 - clip_x0;
    const int copy_h = clip_y1 - clip_y0;
    const int src_x0 = clip_x0 - params->dst_x;
    const int src_y0 = clip_y0 - params->dst_y;
    for(int y = 0; y < copy_h; y++)
    {
      const float *src = export_pixels + 4 * ((size_t)(src_y0 + y) * export_w + src_x0);
      float *dst = bg_patch.pixels + 4 * ((size_t)(clip_y0 + y) * params->layer_width + clip_x0);
      memcpy(dst, src, (size_t)copy_w * 4 * sizeof(float));
    }
 
    char bg_name[DT_DRAWLAYER_IO_NAME_SIZE] = { 0 };
    dt_drawlayer_io_make_unique_name_plain(params->sidecar_path, params->requested_bg_name, bg_name,
                                           sizeof(bg_name));
    if(!dt_drawlayer_layer_name_non_empty(bg_name)) break;
 
    int final_order = -1;
    if(!dt_drawlayer_io_insert_layer(params->sidecar_path, bg_name, params->insert_after_order,
                                     params->work_profile, &bg_patch, params->layer_width, params->layer_height,
                                     &final_order))
      break;
 
    dt_drawlayer_io_layer_info_t io_info = { 0 };
    if(!dt_drawlayer_io_find_layer(params->sidecar_path, bg_name, final_order, &io_info)) break;
 
    result->success = TRUE;
    result->sidecar_timestamp = dt_drawlayer_sidecar_timestamp_from_path(params->sidecar_path);
    g_strlcpy(result->created_bg_name, bg_name, sizeof(result->created_bg_name));
    g_snprintf(result->message, sizeof(result->message), _("created background layer `%s'"), bg_name);
  } while(0);
 
  if(!IS_NULL_PTR(export_pixels)) dt_free(export_pixels);
  if(bg_patch.pixels) dt_drawlayer_cache_free_temp_buffer((void **)&bg_patch.pixels, "drawlayer bg layer");
  if(tmp_path)
  {
    g_unlink(tmp_path);
    dt_free(tmp_path);
  }
 
  if(params->done_idle)
    g_main_context_invoke(NULL, params->done_idle, result);
  else
    dt_free(result);
  return 0;
}