1 files changed, 113 insertions, 0 deletions
diff --git a/source/blender/blendthumb/src/blender_thumbnailer.cc b/source/blender/blendthumb/src/blender_thumbnailer.cc
new file mode 100644
index 00000000000..8dd9d5c0c0a
--- /dev/null
+++ b/source/blender/blendthumb/src/blender_thumbnailer.cc
@@ -0,0 +1,113 @@
+/*
+ * This program 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.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup blendthumb
+ *
+ * This file defines the thumbnail generation command (typically used on UNIX).
+ *
+ * To run automatically with a file manager such as Nautilus, save this file
+ * in a directory that is listed in PATH environment variable, and create
+ * `blender.thumbnailer` file in `${HOME}/.local/share/thumbnailers/` directory
+ * with the following contents:
+ *
+ * \code{.txt}
+ * [Thumbnailer Entry]
+ * TryExec=blender-thumbnailer
+ * Exec=blender-thumbnailer %u %o
+ * MimeType=application/x-blender;
+ * \endcode
+ */
+
+#include <fstream>
+#include <optional>
+
+#include <fcntl.h>
+#ifndef WIN32
+#  include <unistd.h> /* For read close. */
+#else
+#  include "BLI_winstuff.h"
+#  include "winsock2.h"
+#  include <io.h> /* For open close read. */
+#endif
+
+#include "BLI_fileops.h"
+#include "BLI_filereader.h"
+#include "BLI_vector.hh"
+
+#include "blendthumb.hh"
+
+/**
+ * This function opens .blend file from src_blend, extracts thumbnail from file if there is one,
+ * and writes `.png` image into `dst_png`.
+ * Returns exit code (0 if successful).
+ */
+static eThumbStatus extract_png_from_blend_file(const char *src_blend, const char *dst_png)
+{
+  eThumbStatus err;
+
+  /* Open source file `src_blend`. */
+  const int src_file = BLI_open(src_blend, O_BINARY | O_RDONLY, 0);
+  if (src_file == -1) {
+    return BT_FILE_ERR;
+  }
+
+  /* Thumbnail reading is responsible for freeing `file` and closing `src_file`. */
+  FileReader *file = BLI_filereader_new_file(src_file);
+  if (file == nullptr) {
+    close(src_file);
+    return BT_FILE_ERR;
+  }
+
+  /* Extract thumbnail from file. */
+  Thumbnail thumb;
+  err = blendthumb_create_thumb_from_file(file, &thumb);
+  if (err != BT_OK) {
+    return err;
+  }
+
+  /* Write thumbnail to `dst_png`. */
+  const int dst_file = BLI_open(dst_png, O_BINARY | O_WRONLY | O_CREAT | O_TRUNC, 0666);
+  if (dst_file == -1) {
+    return BT_FILE_ERR;
+  }
+
+  std::optional<blender::Vector<uint8_t>> png_buf_opt = blendthumb_create_png_data_from_thumb(
+      &thumb);
+  if (png_buf_opt == std::nullopt) {
+    err = BT_ERROR;
+  }
+  else {
+    blender::Vector<uint8_t> png_buf = *png_buf_opt;
+    err = (write(dst_file, png_buf.data(), png_buf.size()) == png_buf.size()) ? BT_OK :
+                                                                                BT_FILE_ERR;
+  }
+  close(dst_file);
+
+  return err;
+}
+
+int main(int argc, char *argv[])
+{
+  if (argc < 3) {
+    std::cerr << "Usage: blender-thumbnailer <input.blend> <output.png>" << std::endl;
+    return -1;
+  }
+
+  eThumbStatus ret = extract_png_from_blend_file(argv[1], argv[2]);
+
+  return (int)ret;
+}