Grab 0.9.0

Screen capture application for NEXTSPACE on GNU/Linux (X11). Original author: Andres Morales (armm77). Modular refactoring: clean architecture, ARC, NEXTSPACE integration.

This application is intended to be a recreation of the excellent and original Grab application created by Keith Bernstein and developed for the NeXTSTEP/OPENSTEP.

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Capture Options:

• Full screen.
• Full screen with 10 second timer.
• Specific window.
• Screen selection portion.

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Platform:

• GNU/Linux (X11)

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Requirements

Dependency	Version	Notes
SoundKit Back	0.1	NEXTSPACE
DesktopKit	0.6	NEXTSPACE — NXTSavePanel, NXTRunAlertPanel
SystemKit	0.3	NEXTSPACE — required at link time
libobjc2	≥ 2.0	ARC runtime (-fobjc-arc, dispatch_once)
libdispatch	6.0.2	GCD — dispatch_once, dispatch_async, main queue
X11 / libX11	21.1.21	Screen capture
libXcomposite	0.4.6	Window capture compositing
libXcursor	1.2.3	Custom cursors

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Building

# Source the NEXTSPACE environment
. /usr/NextSpace/Makefiles/GNUstep.sh

# Build — must use clang (same compiler as all NEXTSPACE apps)
make CC=clang

# Install to /Applications
make install

Launching

# From terminal
openapp Grab.app

# From NEXTSPACE Workspace — double-click works correctly

Running the binary directly (./Grab.app/Grab) is not supported. GNUstep requires the .app bundle so that NSBundle mainBundle resolves resources correctly.

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Architecture

Grab/
├── Grab_main.m                  Entry point (NSApplicationMain)
│
├── Controllers/
│   ├── GrabController           Application delegate · UI coordinator.
│   │                            Owns NIB outlets, dispatches IBActions.
│   │                            No X11, no I/O, no preferences logic.
│   └── GrabAnimationController  Floating NSPanel icon + animation timers.
│                                Drives blinking-eye and pie-piece countdown.
│
├── Managers/
│   ├── GrabPreferencesManager   NSUserDefaults wrapper (singleton).
│   │                            Keys: audio enabled, timer duration,
│   │                            cursor type.
│   ├── GrabAudioManager         Sound playback (singleton).
│   ├── GrabSession              Current capture state (singleton).
│   │                            Holds captured NSImage; posts
│   │                            GrabSessionDidUpdateImageNotification.
│   └── GrabResourceManager      .tiff asset loader + compositor (singleton).
│
├── Capture/
│   ├── GrabCaptureManager       Capture orchestrator (singleton).
│   │                            Spawns NSThreads, runs X11 event loops,
│   │                            dispatches UI work to main queue via GCD,
│   │                            writes to GrabSession, calls GrabDraw.
│   └── GrabImageProcessor       Stateless X11 → NSImage converter.
│                                XImage → NSBitmapImageRep → NSImage.
│
├── Views/
│   ├── GrabDraw                 Stateless display + save layer.
│   │                            Creates GrabImageWindow, manages window
│   │                            lifetime via _openWindows array,
│   │                            handles NXTSavePanel + NSData encoding.
│   ├── GrabImageWindow          NSWindow subclass — close button delegate.
│   │                            Shows NXTRunAlertPanel (Save / Don't Save
│   │                            / Cancel) on window close.
│   │                            Calls GrabDraw_releaseWindow on close.
│   └── DraggableImageView       NSImageView with click-drag pan.
│                                Cursor managed via NSTimer polling.
│
├── English.lproj/
│   ├── Grab.gorm                Main menu (English)
│   └── Localizable.strings      Runtime strings
│
├── Spanish.lproj/
│   ├── Grab.gorm                Main menu (Spanish)
│   └── Localizable.strings      Runtime strings
│
└── Resources/                   .gorm, .tiff, .wav, .plist assets.

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Technical notes

Memory management — ARC This project uses Automatic Reference Counting (-fobjc-arc) targeting libobjc2 ≥ 2.0. All retain/release/autorelease calls are inserted by the compiler. Background threads use @autoreleasepool { } blocks. See CHANGELOG.md [0.8.0] for full migration details.

Singletons All singletons use dispatch_once_t. This is thread-safe, executes exactly once, and has zero overhead after the first call.

Threading Background captures use NSThread detachNewThreadSelector:. Each thread is wrapped in @autoreleasepool { }. All AppKit work (window creation, session update) is dispatched to the main thread via dispatch_async(dispatch_get_main_queue(), ^{ ... }) after XCloseDisplay.

Window lifetime under ARC GrabDraw retains every open result window in a static NSMutableArray (_openWindows). With setReleasedWhenClosed:NO (required under ARC to prevent double-free), windows have no implicit AppKit owner; the array provides the strong reference until GrabDraw_releaseWindow is called from GrabImageWindow -windowShouldClose:.

Workspace launch / DISPLAY When launched by double-click from NEXTSPACE Workspace, $DISPLAY may not be inherited. GrabController -applicationWillFinishLaunching: reads GSDisplayName from NSUserDefaults and injects it via setenv() before any X11 call. GNUmakefile.postamble patches NSMainNibFile in Info-gnustep.plist if gnustep-make leaves it empty.

DesktopKit integration GrabDraw uses NXTSavePanel for the save dialog. GrabImageWindow uses NXTRunAlertPanel for the close confirmation dialog. Both are linked directly via -lDesktopKit in GNUmakefile.preamble.

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Capture flow — full-screen example

User clicks "Screen" in the Grab menu
        │
        ▼
GrabController -captureFullScreen:
        │  loads resources via GrabResourceManager
        ▼
GrabCaptureManager -captureFullScreenFromMenuOrigin:
        │  animates icon panel from menu origin (GrabAnimationController)
        │  waits for user click on panel
        ▼
User clicks the icon panel button
        │
        ▼
GrabCaptureManager -_activateFullScreenCursor  [main thread]
        │  starts motion-driven eye animation
        │  detaches _fullScreenCaptureThread
        ▼
GrabCaptureManager -_fullScreenCaptureThread  [NSThread]
        │  @autoreleasepool
        │  XOpenDisplay → XGrabPointer → wait ButtonPress
        │  XUngrabPointer · XFreeCursor
        │  shows CameraEyeFlash · sleeps 0.8s · closes panel
        │  XGetWindowAttributes → XGetImage
        │  GrabImageProcessor +captureRect:display:rootWindow: → NSImage
        │  XCloseDisplay
        │  plays OpenShutter sound (blocks until complete)
        │  dispatch_async(main_queue, ^{
        │      GrabSession -setCapturedImage:
        │      GrabDraw +showImage:           ← main thread only
        │      plays CloseShutter (async, non-blocking)
        │  })
        ▼
Result window (GrabImageWindow) appears with the captured image

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Localization

Grab supports English and Spanish. The active language is determined by the system setting (NSLanguages).

Testing a specific language

# Switch to Spanish
defaults write Grab NSLanguages '(Spanish)'

# Restore to English
defaults write Grab NSLanguages '(English)'

Adding a new language

1. Copy English.lproj/ to NewLang.lproj/
2. Translate Localizable.strings
3. Create a localized Grab.gorm with translated menu titles
4. Add the language name to Grab_LANGUAGES in GNUmakefile

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Acknowledgments:

• GNUstep: to all the developers who have contributed to the project and to others who do not appear in the list of members but have still contributed.
• NEXTSPACE: to Sergii Stonian for his project and recreating the desktop again.

Examples

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License

GNU General Public License v2 or later. See LICENSE.