release/darwin/Blender.app/Contents/Plugins/blender-thumbnailer.appex/Contents/Info.plist

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+	<dict>
+		<key>CFBundleDevelopmentRegion</key>
+		<string>en</string>
+		<key>CFBundleName</key>
+		<string>blender-thumbnailer</string>
+		<key>CFBundleDisplayName</key>
+		<string>blender_thumbnailer</string>
+		<key>CFBundleExecutable</key>
+		<string>blender-thumbnailer</string>
+		<key>CFBundleIdentifier</key>
+		<string>org.blenderfoundation.blender.thumbnailer</string>
+		<key>CFBundleInfoDictionaryVersion</key>
+		<string>6.0</string>
+		<key>CFBundlePackageType</key>
+		<string>XPC!</string>
+		<key>CFBundleSupportedPlatforms</key>
+		<array>
+			<string>MacOSX</string>
+		</array>
+		<key>CFBundleShortVersionString</key>
+		<string>${MACOSX_BUNDLE_SHORT_VERSION_STRING}</string>
+		<key>CFBundleVersion</key>
+		<string>${MACOSX_BUNDLE_LONG_VERSION_STRING}</string>
+		<key>CFBundleGetInfoString</key>
+		<string>${MACOSX_BUNDLE_LONG_VERSION_STRING}, Blender Foundation</string>
+		<key>LSMinimumSystemVersion</key>
+		<string>10.15</string>
+		<key>NSExtension</key>
+		<dict>
+			<key>NSExtensionAttributes</key>
+			<dict>
+				<key>QLSupportedContentTypes</key>
+				<array>
+					<!-- The supported file UTIs. Not inherited from parent bundle. -->
+					<string>org.blenderfoundation.blender.file</string>
+				</array>
+				<key>QLThumbnailMinimumDimension</key>
+				<integer>0</integer>
+			</dict>
+			<key>NSExtensionPointIdentifier</key>
+			<string>com.apple.quicklook.thumbnail</string>
+			<key>NSExtensionPrincipalClass</key>
+			<!-- Must be the same as the class implementing the reply method. -->
+			<string>ThumbnailProvider</string>
+		</dict>
+	</dict>
+</plist>

release/darwin/thumbnail_entitlements.plist

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <!-- Extension must be codesigned even locally. -->
+    <key>com.apple.security.app-sandbox</key>
+    <true/>
+    <key>com.apple.security.files.user-selected.read-only</key>
+    <true/>
+</dict>
+</plist>

source/blender/blendthumb/CMakeLists.txt

@@ -39,7 +39,23 @@ if(WIN32)
   target_link_libraries(BlendThumb bf_blenlib dbghelp.lib Version.lib)
   set_target_properties(BlendThumb PROPERTIES LINK_FLAGS_DEBUG "/NODEFAULTLIB:msvcrt")
 
-else()
+elseif(APPLE)
+  # -----------------------------------------------------------------------------
+  # Build `blender-thumbnailer.appex` app extension.
+  set(SRC_APPEX
+    src/thumbnail_provider.mm
+    src/thumbnail_provider.h
+  )
+
+  add_executable(blender-thumbnailer MACOSX_BUNDLE ${SRC} ${SRC_APPEX})
+  setup_platform_linker_flags(blender-thumbnailer)
+  target_link_libraries(blender-thumbnailer
+    bf_blenlib
+    # Avoid linker error about undefined _main symbol.
+    "-e _NSExtensionMain"
+    "-framework QuickLookThumbnailing"
+  )
+elseif(UNIX)
   # -----------------------------------------------------------------------------
   # Build `blender-thumbnailer` executable
 

source/blender/blendthumb/src/thumbnail_provider.h

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

source/blender/blendthumb/src/thumbnail_provider.mm

@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <AppKit/NSImage.h>
+#include <CoreGraphics/CGDataProvider.h>
+#include <CoreGraphics/CoreGraphics.h>
+#include <Foundation/Foundation.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 sandboxed environment and should call the handler with a reply.
+ *
+ * # Plugin Info.plist
+ * The Info.plist file should be properly configured. See the template Info.plist
+ * under release/darwin for more info.
+ *
+ * # 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 even to run the plugin locally.
+ * com.apple.security.get-task-allow 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
+ *
+ * # 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.
+ *
+ * # Troubleshooting
+ * - Is it registered with lsregister and there isn't a conflict with another plugin taking
+ *   precedence? `lsregister -dump | grep blender-thumbnailer.appex`
+ * - Is it codesigned and sandboxed?
+ *   `codesign -d --entitlements ent.plist -f -s - /path/to/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 /path/to/file.blend
+ * - qlmanage -t -s 512 -o /tmp/ /path/to/file.blend
+ */
+
+class FileDescriptorRAII : blender::NonCopyable, blender::NonMovable {
+  int src_file_ = -1;
+
+ public:
+  explicit FileDescriptorRAII(const char *file_path)
+  {
+    src_file_ = BLI_open(file_path, O_BINARY | O_RDONLY, 0);
+  }
+
+  ~FileDescriptorRAII()
+  {
+    if (good()) {
+      close(src_file_);
+    }
+  }
+
+  bool good()
+  {
+    return src_file_ != -1;
+  }
+
+  int get()
+  {
+    return src_file_;
+  }
+};
+
+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;
+  }
+
+  FileReader *file_content = 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. */
+  Thumbnail thumb;
+  eThumbStatus err = blendthumb_create_thumb_from_file(file_content, &thumb);
+  if (err != 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()];
+  CGDataProviderRef provider = CGDataProviderCreateWithCFData((CFDataRef)ns_data);
+  CGColorRenderingIntent intent = kCGRenderingIntentDefault;
+  bool should_interpolate = true;
+  CGFloat *decode = nullptr;
+  CGImageRef image_ref = CGImageCreateWithPNGDataProvider(
+      provider, decode, should_interpolate, intent);
+  NSImage *ns_image = [[NSImage alloc] initWithCGImage:image_ref size:NSZeroSize];
+  CGImageRelease(image_ref);
+  CGDataProviderRelease(provider);
+  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 *ns_image = generate_nsimage_for_file(request.fileURL.path.UTF8String, &error);
+    if (ns_image == nil) {
+      handler(nil, error);
+      return;
+    }
+    handler([QLThumbnailReply replyWithContextSize:request.maximumSize
+                        currentContextDrawingBlock:^BOOL {
+                          [ns_image drawInRect:NSMakeRect(0,
+                                                          0,
+                                                          request.maximumSize.width,
+                                                          request.maximumSize.height)];
+                          return YES;
+                        }],
+            nil);
+  }
+}
+
+@end

source/creator/CMakeLists.txt

@@ -1317,6 +1317,16 @@ elseif(APPLE)
     MACOSX_BUNDLE_LONG_VERSION_STRING "${BLENDER_VERSION}.${BLENDER_VERSION_PATCH} ${BLENDER_DATE}"
   )
 
+  if(WITH_BLENDER_THUMBNAILER)
+    set(OSX_THUMBNAILER_SOURCEDIR ${OSX_APP_SOURCEDIR}/Contents/PlugIns/blender-thumbnailer.appex)
+    set_target_properties(blender-thumbnailer PROPERTIES
+      BUNDLE_EXTENSION appex
+      MACOSX_BUNDLE_INFO_PLIST ${OSX_THUMBNAILER_SOURCEDIR}/Contents/Info.plist
+      MACOSX_BUNDLE_SHORT_VERSION_STRING "${BLENDER_VERSION}.${BLENDER_VERSION_PATCH}"
+      MACOSX_BUNDLE_LONG_VERSION_STRING "${BLENDER_VERSION}.${BLENDER_VERSION_PATCH} ${BLENDER_DATE}"
+    )
+  endif()
+
   # Gather the date in finder-style.
   execute_process(
     COMMAND date "+%m/%d/%Y/%H:%M"
@@ -1352,7 +1362,14 @@ elseif(APPLE)
   if(WITH_BLENDER_THUMBNAILER)
     install(
       TARGETS blender-thumbnailer
-      DESTINATION Blender.app/Contents/MacOS/
+      DESTINATION Blender.app/Contents/Plugins
+    )
+    set(THUMBNAIL_ENTITLEMENTS "${CMAKE_SOURCE_DIR}/release/darwin/thumbnail_entitlements.plist")
+    install(CODE
+      "execute_process(COMMAND codesign
+        --deep --force --sign - --entitlements \"${THUMBNAIL_ENTITLEMENTS}\" --timestamp=none
+        \"${EXECUTABLE_OUTPUT_PATH}/Blender.app/Contents/Plugins/blender-thumbnailer.appex\"
+      )"
     )
   endif()