FileDescriptorRAII Class Reference

Inherits blender::NonCopyable, and blender::NonMovable.

Public Member Functions
	FileDescriptorRAII (const char *file_path)
	~FileDescriptorRAII ()
bool	good ()
int	get ()

Detailed Description

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

Definition at line 71 of file thumbnail_provider.mm.

Constructor & Destructor Documentation

FileDescriptorRAII()

FileDescriptorRAII::FileDescriptorRAII ( const char * file_path )

inlineexplicit

Definition at line 76 of file thumbnail_provider.mm.

References BLI_open(), and O_BINARY.

~FileDescriptorRAII()

FileDescriptorRAII::~FileDescriptorRAII ( )

inline

Definition at line 81 of file thumbnail_provider.mm.

References good().

Member Function Documentation

get()

int FileDescriptorRAII::get ( )

inline

Definition at line 96 of file thumbnail_provider.mm.

Referenced by generate_nsimage_for_file().

good()

bool FileDescriptorRAII::good ( )

inline

Definition at line 91 of file thumbnail_provider.mm.

Referenced by generate_nsimage_for_file(), and ~FileDescriptorRAII().

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The documentation for this class was generated from the following file:

• thumbnail_provider.mm