Add Chromium-only Blender WebEngine parity work

blender-5.2.0/source/blender/blendthumb/CMakeLists.txt

@@ -0,0 +1,105 @@
+# SPDX-FileCopyrightText: 2006 Blender Authors
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+# -----------------------------------------------------------------------------
+# Shared Thumbnail Extraction Logic
+
+include_directories(
+  ../blenlib
+  ../blenloader_core
+  ../makesdna
+  ../../../intern/guardedalloc
+)
+
+include_directories(
+  SYSTEM
+  ${ZLIB_INCLUDE_DIRS}
+)
+
+set(SRC
+  src/blendthumb.hh
+  src/blendthumb_extract.cc
+  src/blendthumb_png.cc
+)
+
+if(WITH_BUILDINFO)
+  list(APPEND SRC
+    "$<TARGET_OBJECTS:buildinfoobj>"
+  )
+endif()
+
+if(WIN32)
+  # -----------------------------------------------------------------------------
+  # Build `BlendThumb.dll`
+
+  set(SRC_WIN32
+    src/blendthumb_win32.cc
+    src/blendthumb_win32.def
+    src/blendthumb_win32.rc
+    src/blendthumb_win32_dll.cc
+  )
+
+  add_library(BlendThumb SHARED ${SRC} ${SRC_WIN32})
+
+  setup_platform_linker_flags(BlendThumb)
+  setup_platform_linker_libs(BlendThumb)
+
+  target_link_libraries(BlendThumb PRIVATE bf_blenlib bf_blenloader_core dbghelp.lib Version.lib Comctl32.lib)
+  # `blenlib` drags in a whole bunch of dependencies on shared libraries, none of which are used
+  # by `blenthumb`, but will cause load issues since the debug linker will not eliminate them.
+  # Link with /OPT:ref to force elimination of those unused dependencies this is already
+  # enabled by default on the release mode flags.
+  set_target_properties(BlendThumb PROPERTIES LINK_FLAGS "/OPT:ref")
+  set_target_properties(BlendThumb PROPERTIES LINK_FLAGS_DEBUG "/NODEFAULTLIB:msvcrt")
+  set_target_properties(BlendThumb PROPERTIES VS_GLOBAL_VcpkgEnabled "false")
+
+elseif(APPLE)
+  # -----------------------------------------------------------------------------
+  # Build `blender-thumbnailer.appex` app extension.
+  set(SRC_APPEX
+    src/thumbnail_provider.h
+    src/thumbnail_provider.mm
+  )
+
+  add_executable(blender-thumbnailer MACOSX_BUNDLE ${SRC} ${SRC_APPEX})
+  setup_platform_linker_flags(blender-thumbnailer)
+  setup_platform_linker_libs(blender-thumbnailer)
+  target_link_libraries(blender-thumbnailer
+    bf_blenlib
+    bf_blenloader_core
+    # Avoid linker error about undefined _main symbol.
+    "-e _NSExtensionMain"
+    "-framework QuickLookThumbnailing"
+  )
+  # The RPATH here points to the main Blender Resources/lib directory.
+  # Avoid duplicating the large `dylibs` (~300MB).
+  set_target_properties(blender-thumbnailer PROPERTIES
+    INSTALL_RPATH "@loader_path/../../../../Resources/lib"
+    # Prevent Xcode from overwriting the signature.
+    XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY ""
+  )
+  # CMake needs the target defined in the same file as add_custom_command.
+  # It needs to be code-signed (ad-hoc in this case)
+  # even on developer machine to generate thumbnails.
+  # Command taken from XCode build process.
+  add_custom_command(
+    TARGET blender-thumbnailer POST_BUILD
+    COMMAND codesign --deep --force --sign -
+      --entitlements "${CMAKE_SOURCE_DIR}/release/darwin/thumbnailer_entitlements.plist"
+      --timestamp=none $<TARGET_BUNDLE_DIR:blender-thumbnailer>
+  )
+elseif(UNIX)
+  # -----------------------------------------------------------------------------
+  # Build `blender-thumbnailer` executable
+
+  set(SRC_CMD
+    src/blender_thumbnailer.cc
+  )
+
+  add_executable(blender-thumbnailer ${SRC} ${SRC_CMD})
+  setup_platform_linker_flags(blender-thumbnailer)
+  setup_platform_linker_libs(blender-thumbnailer)
+  target_link_libraries(blender-thumbnailer PRIVATE bf_blenlib bf_blenloader_core)
+  target_link_libraries(blender-thumbnailer PRIVATE bf::dependencies::pthreads)
+endif()

blender-5.2.0/source/blender/blendthumb/src/blender_thumbnailer.cc

@@ -0,0 +1,102 @@
+/* SPDX-FileCopyrightText: 2023 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \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 <iostream>
+#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"
+
+using namespace blender;
+
+/**
+ * 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<Vector<uint8_t>> png_buf_opt = blendthumb_create_png_data_from_thumb(&thumb);
+  if (!png_buf_opt) {
+    err = BT_ERROR;
+  }
+  else {
+    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);
+}

blender-5.2.0/source/blender/blendthumb/src/blendthumb.hh

@@ -0,0 +1,52 @@
+/* SPDX-FileCopyrightText: 2008-2021 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup blendthumb
+ *
+ * Shared thumbnail extraction logic.
+ *
+ * Used for both MS-Windows DLL and Unix command line.
+ */
+
+#pragma once
+
+#include <optional>
+
+#include "BLI_array.hh"
+#include "BLI_vector.hh"
+
+namespace blender {
+
+struct FileReader;
+
+struct Thumbnail {
+  Array<uint8_t> data;
+  int width;
+  int height;
+};
+
+enum eThumbStatus {
+  BT_OK = 0,
+  BT_FILE_ERR = 1,
+  BT_COMPRES_ERR = 2,
+  BT_DECOMPRESS_ERR = 3,
+  BT_INVALID_FILE = 4,
+  BT_EARLY_VERSION = 5,
+  BT_INVALID_THUMB = 6,
+  BT_ERROR = 9
+};
+
+std::optional<Vector<uint8_t>> blendthumb_create_png_data_from_thumb(const Thumbnail *thumb);
+/**
+ * This function extracts the thumbnail from the .blend file into thumb.
+ * Returns #BT_OK for success and the relevant error code otherwise.
+ */
+eThumbStatus blendthumb_create_thumb_from_file(FileReader *rawfile, Thumbnail *thumb);
+
+/* INTEGER CODES */
+/* NOTE: this is endianness-sensitive. */
+#define MAKE_ID(a, b, c, d) (int(d) << 24 | int(c) << 16 | (b) << 8 | (a))
+
+}  // namespace blender

blender-5.2.0/source/blender/blendthumb/src/blendthumb_extract.cc

@@ -0,0 +1,181 @@
+/* SPDX-FileCopyrightText: 2008 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup blendthumb
+ *
+ * Expose #blendthumb_create_thumb_from_file that creates the PNG data
+ * but does not write it to a file.
+ */
+
+#include <cctype>
+#include <cstring>
+
+#include "BLI_alloca.h"
+#include "BLI_endian_defines.h"
+#include "BLI_fileops.h"
+#include "BLI_filereader.h"
+#include "BLI_string.h"
+
+#include "BLO_core_bhead.hh"
+#include "BLO_core_blend_header.hh"
+#include "BLO_core_file_reader.hh"
+
+#include "blendthumb.hh"
+
+namespace blender {
+
+BLI_STATIC_ASSERT(ENDIAN_ORDER == L_ENDIAN, "Blender only builds on little endian systems")
+
+static void thumb_data_vertical_flip(Thumbnail *thumb)
+{
+  uint32_t *rect = reinterpret_cast<uint32_t *>(thumb->data.data());
+  int x = thumb->width, y = thumb->height;
+  uint32_t *top = rect;
+  uint32_t *bottom = top + ((y - 1) * x);
+  uint32_t *line = static_cast<uint32_t *>(malloc(x * sizeof(uint32_t)));
+
+  y >>= 1;
+  for (; y > 0; y--) {
+    memcpy(line, top, x * sizeof(uint32_t));
+    memcpy(top, bottom, x * sizeof(uint32_t));
+    memcpy(bottom, line, x * sizeof(uint32_t));
+    bottom -= x;
+    top += x;
+  }
+  free(line);
+}
+
+static int32_t bytes_to_native_i32(const uint8_t bytes[4])
+{
+  int32_t data;
+  memcpy(&data, bytes, 4);
+  /* NOTE: this is endianness-sensitive. */
+  /* PNG is always little-endian, and would require switching on a big-endian system. */
+  return data;
+}
+
+static bool file_read(FileReader *file, uint8_t *buf, size_t buf_len)
+{
+  return (file->read(file, buf, buf_len) == buf_len);
+}
+
+static bool file_seek(FileReader *file, size_t len)
+{
+  if (file->seek != nullptr) {
+    if (file->seek(file, len, SEEK_CUR) == -1) {
+      return false;
+    }
+    return true;
+  }
+
+  /* File doesn't support seeking (e.g. gzip), so read and discard in chunks. */
+  constexpr size_t dummy_data_size = 4096;
+  Array<char> dummy_data(dummy_data_size);
+  while (len > 0) {
+    const size_t len_chunk = std::min(len, dummy_data_size);
+    if (size_t(file->read(file, dummy_data.data(), len_chunk)) != len_chunk) {
+      return false;
+    }
+    len -= len_chunk;
+  }
+  return true;
+}
+
+static eThumbStatus blendthumb_extract_from_file_impl(FileReader *file,
+                                                      Thumbnail *thumb,
+                                                      const BlenderHeader &header)
+{
+  BLI_assert(header.endian == L_ENDIAN);
+  /* Iterate over file blocks until we find the thumbnail or run out of data. */
+  while (true) {
+    /* Read next BHead. */
+    const std::optional<BHead> bhead = BLO_readfile_read_bhead(file, header.bhead_type());
+    if (!bhead.has_value()) {
+      /* File has ended. */
+      return BT_INVALID_THUMB;
+    }
+    if (bhead->len < 0) {
+      /* Avoid parsing bad data. */
+      return BT_INVALID_THUMB;
+    }
+    switch (bhead->code) {
+      case MAKE_ID('T', 'E', 'S', 'T'): {
+        uint8_t shape[8];
+        if (!file_read(file, shape, sizeof(shape))) {
+          return BT_INVALID_THUMB;
+        }
+        thumb->width = bytes_to_native_i32(&shape[0]);
+        thumb->height = bytes_to_native_i32(&shape[4]);
+
+        /* Verify that image dimensions and data size make sense. */
+        size_t data_size = bhead->len - sizeof(shape);
+        const uint64_t expected_size = uint64_t(thumb->width) * uint64_t(thumb->height) * 4;
+        if (thumb->width < 0 || thumb->height < 0 || data_size != expected_size) {
+          return BT_INVALID_THUMB;
+        }
+
+        thumb->data = Array<uint8_t>(data_size);
+        if (!file_read(file, thumb->data.data(), data_size)) {
+          return BT_INVALID_THUMB;
+        }
+        return BT_OK;
+      }
+      case MAKE_ID('R', 'E', 'N', 'D'): {
+        if (!file_seek(file, bhead->len)) {
+          return BT_INVALID_THUMB;
+        }
+        /* Check the next block. */
+        break;
+      }
+      default: {
+        /* Early exit if there are no `TEST` or `REND` blocks.
+         * This saves scanning the entire blend file which could be slow. */
+        return BT_INVALID_THUMB;
+      }
+    }
+  }
+  return BT_INVALID_THUMB;
+}
+
+eThumbStatus blendthumb_create_thumb_from_file(FileReader *rawfile, Thumbnail *thumb)
+{
+  FileReader *file = BLO_file_reader_uncompressed(rawfile);
+
+  if (file == nullptr) {
+    return BT_ERROR;
+  }
+
+  const BlenderHeaderVariant header_variant = BLO_readfile_blender_header_decode(file);
+  if (!std::holds_alternative<BlenderHeader>(header_variant)) {
+    file->close(file);
+    return BT_ERROR;
+  }
+  const BlenderHeader &header = std::get<BlenderHeader>(header_variant);
+
+  /* Check if the file is new enough to contain a thumbnail. */
+  if (header.file_version < 250) {
+    file->close(file);
+    return BT_EARLY_VERSION;
+  }
+
+  /* Check if the file was written from a big-endian build. */
+  if (header.endian != L_ENDIAN) {
+    file->close(file);
+    return BT_INVALID_FILE;
+  }
+  BLI_assert(header.endian == ENDIAN_ORDER);
+
+  /* Read the thumbnail. */
+  eThumbStatus err = blendthumb_extract_from_file_impl(file, thumb, header);
+  file->close(file);
+  if (err != BT_OK) {
+    return err;
+  }
+
+  thumb_data_vertical_flip(thumb);
+  return BT_OK;
+}
+
+}  // namespace blender

blender-5.2.0/source/blender/blendthumb/src/blendthumb_png.cc

@@ -0,0 +1,147 @@
+/* SPDX-FileCopyrightText: 2008 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup blendthumb
+ *
+ * Expose #blendthumb_create_png_data_from_thumb that creates the PNG data
+ * but does not write it to a file.
+ */
+
+#include <cstring>
+#include <optional>
+#include <zlib.h>
+
+#include "blendthumb.hh"
+
+#include "BLI_endian_defines.h"
+#include "BLI_endian_switch.h"
+#include "BLI_vector.hh"
+
+namespace blender {
+
+static void png_extend_native_int32(Vector<uint8_t> &output, int32_t data)
+{
+  /* NOTE: this is endianness-sensitive. */
+  /* PNG is big-endian, its values need to be switched on little-endian systems. */
+  BLI_endian_switch_int32(&data);
+  output.extend_unchecked(Span(reinterpret_cast<uint8_t *>(&data), 4));
+}
+
+/** The number of bytes each chunk uses on top of the data that's written. */
+#define PNG_CHUNK_EXTRA 12
+
+static void png_chunk_create(Vector<uint8_t> &output,
+                             const uint32_t tag,
+                             const Vector<uint8_t> &data)
+{
+  uint32_t crc = crc32(0, nullptr, 0);
+  crc = crc32(crc, reinterpret_cast<uint8_t *>(const_cast<uint32_t *>(&tag)), sizeof(tag));
+  crc = crc32(crc, const_cast<uint8_t *>(data.data()), data.size());
+
+  png_extend_native_int32(output, data.size());
+  output.extend_unchecked(
+      Span(reinterpret_cast<uint8_t *>(const_cast<uint32_t *>(&tag)), sizeof(tag)));
+  output.extend_unchecked(data);
+  png_extend_native_int32(output, crc);
+}
+
+static Vector<uint8_t> filtered_rows_from_thumb(const Thumbnail *thumb)
+{
+  /* In the image data sent to the compression step, each scan-line is preceded by a filter type
+   * byte containing the numeric code of the filter algorithm used for that scan-line. */
+  const size_t line_size = thumb->width * 4;
+  Vector<uint8_t> filtered;
+  size_t final_size = thumb->height * (line_size + 1);
+  filtered.reserve(final_size);
+  for (int i = 0; i < thumb->height; i++) {
+    filtered.append_unchecked(0x00);
+    filtered.extend_unchecked(Span(&thumb->data[i * line_size], line_size));
+  }
+  BLI_assert(final_size == filtered.size());
+  return filtered;
+}
+
+static std::optional<Vector<uint8_t>> zlib_compress(const Vector<uint8_t> &data)
+{
+  ulong uncompressed_size = data.size();
+  uLongf compressed_size = compressBound(uncompressed_size);
+
+  Vector<uint8_t> compressed(compressed_size, 0x00);
+
+  int return_value = compress2(static_cast<uchar *>(compressed.data()),
+                               &compressed_size,
+                               const_cast<uchar *>(data.data()),
+                               uncompressed_size,
+                               Z_NO_COMPRESSION);
+  if (return_value != Z_OK) {
+    /* Something went wrong with compression of data. */
+    return std::nullopt;
+  }
+  compressed.resize(compressed_size);
+  return compressed;
+}
+
+std::optional<Vector<uint8_t>> blendthumb_create_png_data_from_thumb(const Thumbnail *thumb)
+{
+  if (thumb->data.is_empty()) {
+    return std::nullopt;
+  }
+
+  /* Create `IDAT` chunk data. */
+  Vector<uint8_t> image_data;
+  {
+    auto image_data_opt = zlib_compress(filtered_rows_from_thumb(thumb));
+    if (image_data_opt == std::nullopt) {
+      return std::nullopt;
+    }
+    image_data = *image_data_opt;
+  }
+
+  /* Create the IHDR chunk data. */
+  Vector<uint8_t> ihdr_data;
+  {
+    const size_t ihdr_data_final_size = 4 + 4 + 5;
+    ihdr_data.reserve(ihdr_data_final_size);
+    png_extend_native_int32(ihdr_data, thumb->width);
+    png_extend_native_int32(ihdr_data, thumb->height);
+    ihdr_data.extend_unchecked({
+        0x08, /* Bit Depth. */
+        0x06, /* Color Type. */
+        0x00, /* Compression method. */
+        0x00, /* Filter method. */
+        0x00, /* Interlace method. */
+    });
+    BLI_assert(size_t(ihdr_data.size()) == ihdr_data_final_size);
+  }
+
+  /* Join it all together to create a PNG image. */
+  Vector<uint8_t> png_buf;
+  {
+    const size_t png_buf_final_size = (
+        /* Header. */
+        8 +
+        /* `IHDR` chunk. */
+        (ihdr_data.size() + PNG_CHUNK_EXTRA) +
+        /* `IDAT` chunk. */
+        (image_data.size() + PNG_CHUNK_EXTRA) +
+        /* `IEND` chunk. */
+        PNG_CHUNK_EXTRA);
+
+    png_buf.reserve(png_buf_final_size);
+
+    /* This is the standard PNG file header. Every PNG file starts with it. */
+    png_buf.extend_unchecked({0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A});
+
+    png_chunk_create(png_buf, MAKE_ID('I', 'H', 'D', 'R'), ihdr_data);
+    png_chunk_create(png_buf, MAKE_ID('I', 'D', 'A', 'T'), image_data);
+    png_chunk_create(png_buf, MAKE_ID('I', 'E', 'N', 'D'), {});
+
+    BLI_assert(size_t(png_buf.size()) == png_buf_final_size);
+  }
+
+  return png_buf;
+}
+
+}  // namespace blender

blender-5.2.0/source/blender/blendthumb/src/blendthumb_win32.cc

@@ -0,0 +1,226 @@
+/* SPDX-FileCopyrightText: 2023 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup blendthumb
+ *
+ * Thumbnail from Blend file extraction for MS-Windows.
+ */
+
+#include <cmath>
+#include <new>
+#include <shlwapi.h>
+#include <string>
+#include <thumbcache.h> /* for #IThumbnailProvider */
+
+#include "Wincodec.h"
+
+#include "blendthumb.hh"
+
+#include "BLI_filereader.h"
+
+#pragma comment(lib, "shlwapi.lib")
+
+using namespace blender;
+
+/**
+ * This thumbnail provider implements #IInitializeWithStream to enable being hosted
+ * in an isolated process for robustness.
+ */
+class CBlendThumb : public IInitializeWithStream, public IThumbnailProvider {
+ public:
+  CBlendThumb() : _cRef(1), _pStream(nullptr) {}
+
+  virtual ~CBlendThumb()
+  {
+    if (_pStream) {
+      _pStream->Release();
+    }
+  }
+
+  IFACEMETHODIMP QueryInterface(REFIID riid, void **ppv)
+  {
+    static const QITAB qit[] = {
+        QITABENT(CBlendThumb, IInitializeWithStream),
+        QITABENT(CBlendThumb, IThumbnailProvider),
+        {0},
+    };
+    return QISearch(this, qit, riid, ppv);
+  }
+
+  IFACEMETHODIMP_(ULONG) AddRef()
+  {
+    return InterlockedIncrement(&_cRef);
+  }
+
+  IFACEMETHODIMP_(ULONG) Release()
+  {
+    ULONG cRef = InterlockedDecrement(&_cRef);
+    if (!cRef) {
+      delete this;
+    }
+    return cRef;
+  }
+
+  /** IInitializeWithStream */
+  IFACEMETHODIMP Initialize(IStream *pStream, DWORD grfMode);
+
+  /** IThumbnailProvider */
+  IFACEMETHODIMP GetThumbnail(UINT cx, HBITMAP *phbmp, WTS_ALPHATYPE *pdwAlpha);
+
+ private:
+  long _cRef;
+  IStream *_pStream; /* provided in Initialize(). */
+};
+
+HRESULT CBlendThumb_CreateInstance(REFIID riid, void **ppv)
+{
+  CBlendThumb *pNew = new (std::nothrow) CBlendThumb();
+  HRESULT hr = pNew ? S_OK : E_OUTOFMEMORY;
+  if (SUCCEEDED(hr)) {
+    hr = pNew->QueryInterface(riid, ppv);
+    pNew->Release();
+  }
+  return hr;
+}
+
+IFACEMETHODIMP CBlendThumb::Initialize(IStream *pStream, DWORD)
+{
+  if (_pStream != nullptr) {
+    /* Can only be initialized once. */
+    return E_UNEXPECTED;
+  }
+  /* Take a reference to the stream. */
+  return pStream->QueryInterface(&_pStream);
+}
+
+/**
+ * #FileReader compatible wrapper around the Windows stream that gives access to the .blend file.
+ */
+struct StreamReader {
+  FileReader reader;
+
+  IStream *_pStream;
+};
+
+static int64_t stream_read(FileReader *reader, void *buffer, size_t size)
+{
+  StreamReader *stream = reinterpret_cast<StreamReader *>(reader);
+
+  ULONG readsize;
+  stream->_pStream->Read(buffer, size, &readsize);
+  stream->reader.offset += readsize;
+
+  return int64_t(readsize);
+}
+
+static off64_t stream_seek(FileReader *reader, off64_t offset, int whence)
+{
+  StreamReader *stream = reinterpret_cast<StreamReader *>(reader);
+
+  DWORD origin = STREAM_SEEK_SET;
+  switch (whence) {
+    case SEEK_CUR:
+      origin = STREAM_SEEK_CUR;
+      break;
+    case SEEK_END:
+      origin = STREAM_SEEK_END;
+      break;
+  }
+  LARGE_INTEGER offsetI;
+  offsetI.QuadPart = offset;
+  ULARGE_INTEGER newPos;
+  stream->_pStream->Seek(offsetI, origin, &newPos);
+  stream->reader.offset = newPos.QuadPart;
+
+  return stream->reader.offset;
+}
+
+static void stream_close(FileReader *reader)
+{
+  StreamReader *stream = reinterpret_cast<StreamReader *>(reader);
+  delete stream;
+}
+
+IFACEMETHODIMP CBlendThumb::GetThumbnail(UINT cx, HBITMAP *phbmp, WTS_ALPHATYPE *pdwAlpha)
+{
+  HRESULT hr = S_FALSE;
+
+  StreamReader *file = new StreamReader;
+  file->reader.read = stream_read;
+  file->reader.seek = stream_seek;
+  file->reader.close = stream_close;
+  file->reader.offset = 0;
+  file->_pStream = _pStream;
+
+  file->reader.seek(&file->reader, 0, SEEK_SET);
+
+  /* Extract thumbnail from stream. */
+  Thumbnail thumb;
+  if (blendthumb_create_thumb_from_file(&file->reader, &thumb) != BT_OK) {
+    return S_FALSE;
+  }
+
+  /* Convert to BGRA for Windows. */
+  for (int i = 0; i < thumb.width * thumb.height; i++) {
+    std::swap(thumb.data[4 * i], thumb.data[4 * i + 2]);
+  }
+
+  *phbmp = CreateBitmap(thumb.width, thumb.height, 1, 32, thumb.data.data());
+  if (!*phbmp) {
+    return E_FAIL;
+  }
+  *pdwAlpha = WTSAT_ARGB;
+
+  /* Scale up the thumbnail if required. */
+  if (uint(thumb.width) < cx && uint(thumb.height) < cx) {
+    float scale = 1.0f / (std::max(thumb.width, thumb.height) / float(cx));
+    LONG NewWidth = LONG(thumb.width * scale);
+    LONG NewHeight = LONG(thumb.height * scale);
+
+    IWICImagingFactory *pImgFac;
+    hr = CoCreateInstance(
+        CLSID_WICImagingFactory, nullptr, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pImgFac));
+
+    IWICBitmap *WICBmp;
+    hr = pImgFac->CreateBitmapFromHBITMAP(*phbmp, 0, WICBitmapUseAlpha, &WICBmp);
+
+    BITMAPINFO bmi = {};
+    bmi.bmiHeader.biSize = sizeof(bmi.bmiHeader);
+    bmi.bmiHeader.biWidth = NewWidth;
+    bmi.bmiHeader.biHeight = -NewHeight;
+    bmi.bmiHeader.biPlanes = 1;
+    bmi.bmiHeader.biBitCount = 32;
+    bmi.bmiHeader.biCompression = BI_RGB;
+
+    BYTE *pBits;
+    HBITMAP ResizedHBmp = CreateDIBSection(
+        nullptr, &bmi, DIB_RGB_COLORS, (void **)&pBits, nullptr, 0);
+    hr = ResizedHBmp ? S_OK : E_OUTOFMEMORY;
+    if (SUCCEEDED(hr)) {
+      IWICBitmapScaler *pIScaler;
+      hr = pImgFac->CreateBitmapScaler(&pIScaler);
+      hr = pIScaler->Initialize(WICBmp, NewWidth, NewHeight, WICBitmapInterpolationModeFant);
+
+      WICRect rect = {0, 0, NewWidth, NewHeight};
+      hr = pIScaler->CopyPixels(&rect, NewWidth * 4, NewWidth * NewHeight * 4, pBits);
+
+      if (SUCCEEDED(hr)) {
+        DeleteObject(*phbmp);
+        *phbmp = ResizedHBmp;
+      }
+      else {
+        DeleteObject(ResizedHBmp);
+      }
+
+      pIScaler->Release();
+    }
+    WICBmp->Release();
+    pImgFac->Release();
+  }
+  else {
+    hr = S_OK;
+  }
+  return hr;
+}

blender-5.2.0/source/blender/blendthumb/src/blendthumb_win32.def

@@ -0,0 +1,5 @@
+EXPORTS
+    DllGetClassObject       PRIVATE
+    DllCanUnloadNow         PRIVATE
+    DllRegisterServer       PRIVATE
+    DllUnregisterServer     PRIVATE

blender-5.2.0/source/blender/blendthumb/src/blendthumb_win32.rc

@@ -0,0 +1,26 @@
+#define IDR_VERSION1 1
+
+IDR_VERSION1 VERSIONINFO
+FILEVERSION 1,4,0,0
+PRODUCTVERSION 2,78,0,0
+FILEOS 0x00000004
+FILETYPE 0x00000002
+BEGIN
+  BLOCK "StringFileInfo"
+  BEGIN
+    BLOCK "FFFF04B0"
+    BEGIN
+      VALUE "FileVersion", "1.4\0"
+      VALUE "ProductVersion", "2.78\0"
+      VALUE "FileDescription", "Blender Thumbnail Handler\0"
+      VALUE "OriginalFilename", "BlendThumb.dll\0"
+      VALUE "ProductName", "Blender\0"
+      VALUE "LegalCopyright", "GPL2, 2016\0"
+    END
+  END
+  BLOCK "VarFileInfo"
+  BEGIN
+    VALUE "Translation", 0x0409, 0x04B0
+  END
+END
+

blender-5.2.0/source/blender/blendthumb/src/blendthumb_win32_dll.cc

@@ -0,0 +1,281 @@
+/* SPDX-FileCopyrightText: 2023 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup blendthumb
+ *
+ * Thumbnail from Blend file extraction for MS-Windows (DLL).
+ */
+
+#include <new>
+#include <objbase.h>
+#include <shlobj.h> /* For #SHChangeNotify */
+#include <shlwapi.h>
+#include <thumbcache.h> /* For IThumbnailProvider */
+
+extern HRESULT CBlendThumb_CreateInstance(REFIID riid, void **ppv);
+
+#define SZ_CLSID_BLENDTHUMBHANDLER L"{D45F043D-F17F-4e8a-8435-70971D9FA46D}"
+#define SZ_BLENDTHUMBHANDLER L"Blender Thumbnail Handler"
+const CLSID CLSID_BlendThumbHandler = {
+    0xd45f043d, 0xf17f, 0x4e8a, {0x84, 0x35, 0x70, 0x97, 0x1d, 0x9f, 0xa4, 0x6d}};
+
+typedef HRESULT (*PFNCREATEINSTANCE)(REFIID riid, void **ppvObject);
+struct CLASS_OBJECT_INIT {
+  const CLSID *pClsid;
+  PFNCREATEINSTANCE pfnCreate;
+};
+
+/* Add classes supported by this module here. */
+const CLASS_OBJECT_INIT c_rgClassObjectInit[] = {
+    {&CLSID_BlendThumbHandler, CBlendThumb_CreateInstance}};
+
+long g_cRefModule = 0;
+
+/** Handle the DLL's module */
+HINSTANCE g_hInst = nullptr;
+
+/** Standard DLL functions. */
+STDAPI_(BOOL) DllMain(HINSTANCE hInstance, DWORD dwReason, void *)
+{
+  if (dwReason == DLL_PROCESS_ATTACH) {
+    g_hInst = hInstance;
+    DisableThreadLibraryCalls(hInstance);
+  }
+  return TRUE;
+}
+
+STDAPI DllCanUnloadNow()
+{
+  /* Only allow the DLL to be unloaded after all outstanding references have been released. */
+  return (g_cRefModule == 0) ? S_OK : S_FALSE;
+}
+
+void DllAddRef()
+{
+  InterlockedIncrement(&g_cRefModule);
+}
+
+void DllRelease()
+{
+  InterlockedDecrement(&g_cRefModule);
+}
+
+class CClassFactory final : public IClassFactory {
+ public:
+  static HRESULT CreateInstance(REFCLSID clsid,
+                                const CLASS_OBJECT_INIT *pClassObjectInits,
+                                size_t cClassObjectInits,
+                                REFIID riid,
+                                void **ppv)
+  {
+    *ppv = nullptr;
+    HRESULT hr = CLASS_E_CLASSNOTAVAILABLE;
+    for (size_t i = 0; i < cClassObjectInits; i++) {
+      if (clsid == *pClassObjectInits[i].pClsid) {
+        IClassFactory *pClassFactory = new (std::nothrow)
+            CClassFactory(pClassObjectInits[i].pfnCreate);
+        hr = pClassFactory ? S_OK : E_OUTOFMEMORY;
+        if (SUCCEEDED(hr)) {
+          hr = pClassFactory->QueryInterface(riid, ppv);
+          pClassFactory->Release();
+        }
+        /* Match found. */
+        break;
+      }
+    }
+    return hr;
+  }
+
+  CClassFactory(PFNCREATEINSTANCE pfnCreate) : _cRef(1), _pfnCreate(pfnCreate)
+  {
+    DllAddRef();
+  }
+
+  /** #IUnknown */
+  IFACEMETHODIMP QueryInterface(REFIID riid, void **ppv)
+  {
+    static const QITAB qit[] = {QITABENT(CClassFactory, IClassFactory), {0}};
+    return QISearch(this, qit, riid, ppv);
+  }
+
+  IFACEMETHODIMP_(ULONG) AddRef()
+  {
+    return InterlockedIncrement(&_cRef);
+  }
+
+  IFACEMETHODIMP_(ULONG) Release()
+  {
+    long cRef = InterlockedDecrement(&_cRef);
+    if (cRef == 0) {
+      delete this;
+    }
+    return cRef;
+  }
+
+  /** #IClassFactory */
+  IFACEMETHODIMP CreateInstance(IUnknown *punkOuter, REFIID riid, void **ppv)
+  {
+    return punkOuter ? CLASS_E_NOAGGREGATION : _pfnCreate(riid, ppv);
+  }
+
+  IFACEMETHODIMP LockServer(BOOL fLock)
+  {
+    if (fLock) {
+      DllAddRef();
+    }
+    else {
+      DllRelease();
+    }
+    return S_OK;
+  }
+
+ private:
+  ~CClassFactory()
+  {
+    DllRelease();
+  }
+
+  long _cRef;
+  PFNCREATEINSTANCE _pfnCreate;
+};
+
+STDAPI DllGetClassObject(REFCLSID clsid, REFIID riid, void **ppv)
+{
+  return CClassFactory::CreateInstance(
+      clsid, c_rgClassObjectInit, ARRAYSIZE(c_rgClassObjectInit), riid, ppv);
+}
+
+/**
+ * A struct to hold the information required for a registry entry.
+ */
+struct REGISTRY_ENTRY {
+  HKEY hkeyRoot;
+  PCWSTR pszKeyName;
+  PCWSTR pszValueName;
+  DWORD dwValueType;
+  /** These two fields could/should have been a union, but C++ */
+  PCWSTR pszData;
+  /** Only lets you initialize the first field in a union. */
+  DWORD dwData;
+};
+
+/**
+ * Creates a registry key (if needed) and sets the default value of the key.
+ */
+HRESULT CreateRegKeyAndSetValue(const REGISTRY_ENTRY *pRegistryEntry)
+{
+  HKEY hKey;
+  HRESULT hr = HRESULT_FROM_WIN32(RegCreateKeyExW(pRegistryEntry->hkeyRoot,
+                                                  pRegistryEntry->pszKeyName,
+                                                  0,
+                                                  nullptr,
+                                                  REG_OPTION_NON_VOLATILE,
+                                                  KEY_SET_VALUE,
+                                                  nullptr,
+                                                  &hKey,
+                                                  nullptr));
+  if (SUCCEEDED(hr)) {
+    /* All this just to support #REG_DWORD. */
+    DWORD size;
+    DWORD data;
+    BYTE *lpData = (LPBYTE)pRegistryEntry->pszData;
+    switch (pRegistryEntry->dwValueType) {
+      case REG_SZ:
+        size = ((DWORD)wcslen(pRegistryEntry->pszData) + 1) * sizeof(WCHAR);
+        break;
+      case REG_DWORD:
+        size = sizeof(DWORD);
+        data = pRegistryEntry->dwData;
+        lpData = (BYTE *)&data;
+        break;
+      default:
+        return E_INVALIDARG;
+    }
+
+    hr = HRESULT_FROM_WIN32(RegSetValueExW(
+        hKey, pRegistryEntry->pszValueName, 0, pRegistryEntry->dwValueType, lpData, size));
+    RegCloseKey(hKey);
+  }
+  return hr;
+}
+
+/**
+ * Registers this COM server.
+ */
+STDAPI DllRegisterServer()
+{
+  HRESULT hr;
+
+  WCHAR szModuleName[MAX_PATH];
+
+  if (!GetModuleFileNameW(g_hInst, szModuleName, ARRAYSIZE(szModuleName))) {
+    hr = HRESULT_FROM_WIN32(GetLastError());
+  }
+  else {
+    const REGISTRY_ENTRY rgRegistryEntries[] = {
+        /* `RootKey KeyName ValueName ValueType Data` */
+        {HKEY_CURRENT_USER,
+         L"Software\\Classes\\CLSID\\" SZ_CLSID_BLENDTHUMBHANDLER,
+         nullptr,
+         REG_SZ,
+         SZ_BLENDTHUMBHANDLER},
+        {HKEY_CURRENT_USER,
+         L"Software\\Classes\\CLSID\\" SZ_CLSID_BLENDTHUMBHANDLER L"\\InProcServer32",
+         nullptr,
+         REG_SZ,
+         szModuleName},
+        {HKEY_CURRENT_USER,
+         L"Software\\Classes\\CLSID\\" SZ_CLSID_BLENDTHUMBHANDLER L"\\InProcServer32",
+         L"ThreadingModel",
+         REG_SZ,
+         L"Apartment"},
+        {HKEY_CURRENT_USER,
+         L"Software\\Classes\\.blend\\",
+         L"Treatment",
+         REG_DWORD,
+         0,
+         0}, /* This doesn't appear to do anything. */
+        {HKEY_CURRENT_USER,
+         L"Software\\Classes\\.blend\\ShellEx\\{e357fccd-a995-4576-b01f-234630154e96}",
+         nullptr,
+         REG_SZ,
+         SZ_CLSID_BLENDTHUMBHANDLER},
+    };
+
+    hr = S_OK;
+    for (int i = 0; i < ARRAYSIZE(rgRegistryEntries) && SUCCEEDED(hr); i++) {
+      hr = CreateRegKeyAndSetValue(&rgRegistryEntries[i]);
+    }
+  }
+  if (SUCCEEDED(hr)) {
+    /* This tells the shell to invalidate the thumbnail cache.
+     * This is important because any `.blend` files viewed before registering this handler
+     * would otherwise show cached blank thumbnails. */
+    SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST, nullptr, nullptr);
+  }
+  return hr;
+}
+
+/**
+ * Unregisters this COM server
+ */
+STDAPI DllUnregisterServer()
+{
+  HRESULT hr = S_OK;
+
+  const PCWSTR rgpszKeys[] = {
+      L"Software\\Classes\\CLSID\\" SZ_CLSID_BLENDTHUMBHANDLER,
+      L"Software\\Classes\\.blend\\ShellEx\\{e357fccd-a995-4576-b01f-234630154e96}"};
+
+  /* Delete the registry entries. */
+  for (int i = 0; i < ARRAYSIZE(rgpszKeys) && SUCCEEDED(hr); i++) {
+    hr = HRESULT_FROM_WIN32(RegDeleteTreeW(HKEY_CURRENT_USER, rgpszKeys[i]));
+    if (hr == HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND)) {
+      /* If the registry entry has already been deleted, say S_OK. */
+      hr = S_OK;
+    }
+  }
+  return hr;
+}

blender-5.2.0/source/blender/blendthumb/src/thumbnail_provider.h

@@ -0,0 +1,14 @@
+/* SPDX-FileCopyrightText: 2025 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+#pragma once
+
+#import <QuickLookThumbnailing/QuickLookThumbnailing.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface ThumbnailProvider : QLThumbnailProvider
+
+@end
+
+NS_ASSUME_NONNULL_END

blender-5.2.0/source/blender/blendthumb/src/thumbnail_provider.mm

@@ -0,0 +1,186 @@
+/* SPDX-FileCopyrightText: 2025 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+#import <AppKit/NSImage.h>
+
+#include "BLI_fileops.h"
+#include "BLI_filereader.h"
+#include "BLI_utility_mixins.hh"
+#include "blendthumb.hh"
+
+#include "thumbnail_provider.h"
+/**
+ * This section intends to list the important steps for creating a thumbnail extension.
+ * qlgenerator has been deprecated and removed in platforms we support. App extensions are the way
+ * forward. But there's little guidance on how to do it outside Xcode.
+ *
+ * The process of thumbnail generation goes something like this:
+ * 1. If an app is launched, or is registered with lsregister, its plugins also get registered.
+ * 2. When a file thumbnail in Finder or QuickLook is requested, the system looks for a plugin
+ *    that supports the file type UTI.
+ * 3. The plugin is launched in a sand-boxed environment and should call the handler with a reply.
+ *
+ * # Plugin Info.plist
+ * The Info.plist file should be properly configured with supported content type.
+ *
+ * # Codesigning
+ * The plugin should be codesigned with entitlements at least for sandbox and read-only/
+ * read-write (for access to the given file). It's needed to even run the plugin locally.
+ * com.apple.security.get-task-allow entitlement is required for debugging.
+ *
+ * # Registering the plugin
+ * The plugin should be registered with lsregister. Either by calling lsregister or by launching
+ * the parent app.
+ * /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister
+ * \ -dump | grep blender-thumbnailer
+ *
+ * # Debugging
+ * Since read-only entitlement is there, creating files to log is not possible. So NSLog and
+ * viewing it in Console.app (after triggering a thumbnail) is the way to go. Interesting processes
+ * are: qlmanage, quicklookd, kernel, blender-thumbnailer, secinitd,
+ * com.apple.quicklook.ThumbnailsAgent
+ *
+ * LLDB/ Xcode etc., debuggers can be used to get extra logs than CLI invocation but breakpoints
+ * still are a pain point. /usr/bin/qlmanage is the target executable. Other args to qlmanage
+ * follow. lldb qlmanage --  -t -x a.blend
+ *
+ * # Troubleshooting
+ * - The appex shouldn't have any quarantine flag.
+ *   xattr -rl bin/Blender.app/Contents/Plugins/blender-thumbnailer.appex
+ * - Is it registered with lsregister and there isn't a conflict with another plugin taking
+ *   precedence? lsregister -dump | grep blender-thumbnailer.appex
+ * - For RBSLaunchRequest error: is the executable flag set? chmod u+x
+ * bin/Blender.app/Contents/PlugIns/blender-thumbnailer.appex/Contents/MacOS/blender-thumbnailer
+ * - Is it codesigned and sandboxed?
+ *   codesign --display --verbose --entitlements - --xml \
+ * bin/Blender.app/Contents/Plugins/blender-thumbnailer.appex codesign --deep --force --sign - \
+ * --entitlements ../blender/release/darwin/thumbnailer_entitlements.plist --timestamp=none \
+ * bin/Blender.app/Contents/Plugins/blender-thumbnailer.appex
+ * - Sometimes blender-thumbnailer running in background can be killed.
+ * - qlmanage -r && killall Finder
+ * - The code cannot attempt to do anything outside sandbox like writing to blend.
+ *
+ * # Triggering a thumbnail
+ * - qlmanage -t -x /path/to/file.blend
+ *
+ * # External resources
+ * https://developer.apple.com/library/archive/documentation/UserExperience/Conceptual/Quicklook_Programming_Guide/Introduction/Introduction.html#//apple_ref/doc/uid/TP40005020-CH1-SW1
+ */
+
+class FileDescriptorRAII : blender::NonCopyable, blender::NonMovable {
+ private:
+  int src_fd = -1;
+
+ public:
+  explicit FileDescriptorRAII(const char *file_path)
+  {
+    src_fd = blender::BLI_open(file_path, O_BINARY | O_RDONLY, 0);
+  }
+
+  ~FileDescriptorRAII()
+  {
+    if (good()) {
+      int ok = close(src_fd);
+      if (!ok) {
+        NSLog(@"Blender Thumbnailer Error: Failed to close the blend file.");
+      }
+    }
+  }
+
+  bool good()
+  {
+    return src_fd > 0;
+  }
+
+  int get()
+  {
+    return src_fd;
+  }
+};
+
+static NSError *create_nserror_from_string(NSString *errorStr)
+{
+  NSLog(@"Blender Thumbnailer Error: %@", errorStr);
+  return [NSError errorWithDomain:@"org.blenderfoundation.blender.thumbnailer"
+                             code:-1
+                         userInfo:@{NSLocalizedDescriptionKey : errorStr}];
+}
+
+static NSImage *generate_nsimage_for_file(const char *src_blend_path, NSError *error)
+{
+  /* Open source file `src_blend`. */
+  FileDescriptorRAII src_file_fd = FileDescriptorRAII(src_blend_path);
+  if (!src_file_fd.good()) {
+    error = create_nserror_from_string(@"Failed to open blend");
+    return nil;
+  }
+
+  blender::FileReader *file_content = blender::BLI_filereader_new_file(src_file_fd.get());
+  if (file_content == nullptr) {
+    error = create_nserror_from_string(@"Failed to read from blend");
+    return nil;
+  }
+
+  /* Extract thumbnail from file. */
+  blender::Thumbnail thumb;
+  blender::eThumbStatus err = blendthumb_create_thumb_from_file(file_content, &thumb);
+  if (err != blender::BT_OK) {
+    error = create_nserror_from_string(@"Failed to create thumbnail from file");
+    return nil;
+  }
+
+  std::optional<blender::Vector<uint8_t>> png_buf_opt = blendthumb_create_png_data_from_thumb(
+      &thumb);
+  if (!png_buf_opt) {
+    error = create_nserror_from_string(@"Failed to create png data from thumbnail");
+    return nil;
+  }
+
+  NSData *ns_data = [NSData dataWithBytes:png_buf_opt->data() length:png_buf_opt->size()];
+  NSImage *ns_image = [[NSImage alloc] initWithData:ns_data];
+  return ns_image;
+}
+
+@implementation ThumbnailProvider
+
+- (void)provideThumbnailForFileRequest:(QLFileThumbnailRequest *)request
+                     completionHandler:(void (^)(QLThumbnailReply *_Nullable reply,
+                                                 NSError *_Nullable error))handler
+{
+
+  NSLog(@"Generating thumbnail for %@", request.fileURL.path);
+  @autoreleasepool {
+    NSError *error = nil;
+    NSImage *image = generate_nsimage_for_file(request.fileURL.path.fileSystemRepresentation,
+                                               error);
+    if (image == nil || image.size.width <= 0 || image.size.height <= 0) {
+      handler(nil, error);
+      return;
+    }
+
+    const CGFloat width_ratio = request.maximumSize.width / image.size.width;
+    const CGFloat height_ratio = request.maximumSize.height / image.size.height;
+    const CGFloat scale_factor = MIN(width_ratio, height_ratio);
+
+    const NSSize context_size = NSMakeSize(image.size.width * scale_factor,
+                                           image.size.height * scale_factor);
+
+    const NSRect context_rect = NSMakeRect(0, 0, context_size.width, context_size.height);
+
+    QLThumbnailReply *thumbnailReply = [QLThumbnailReply replyWithContextSize:context_size
+                                                   currentContextDrawingBlock:^BOOL {
+                                                     [image drawInRect:context_rect];
+                                                     /* Release the image that was strongly
+                                                      * captured by this block. */
+                                                     [image release];
+                                                     return YES;
+                                                   }];
+
+    /* Return the thumbnail reply. */
+    handler(thumbnailReply, nil);
+  }
+  NSLog(@"Thumbnail generation successfully completed");
+}
+
+@end