An independent, enhanced reimplementation of PowerToys Crop And Lock.
We've completely rewritten the Thumbnail Mode (Ctrl+Alt+C), breaking through the limits of the Windows DWM API to deliver features you won't find anywhere else:
- Strict Proportional Scaling: Resize the cropped thumbnail freely via window edges or third-party tools like AltSnap. ZenCrop mathematically locks the aspect ratio so your crop never stretches and never shows black bars.
- Engine-Defeating Invisible Rendering: Hide the original target window from your screen and taskbar entirely! Using a groundbreaking "1-pixel anchor" hack combined with COM interface manipulation, we trick modern engines (Chromium, Electron, WinUI) into rendering at a full 60 FPS in the background without pausing. Meanwhile, V2.2.1 brings back the ZenCrop taskbar icon for the Thumbnail window itself, making it effortlessly easy to manage and bring to the front when buried behind other apps.
📖 Deep dive: ZenCrop Thumbnail Scaling & Hiding Technology
While the official PowerToys module suffers from an "all-white/black screen" known issue when trying to reparent modern Windows applications (UWP/WinUI/XAML apps like Calculator or Settings), ZenCrop has completely solved this.
ZenCrop successfully supports interactive cropping of applications that the original PowerToys Crop And Lock explicitly cannot handle, utilizing two distinct cutting-edge rendering engines:
1. Native Viewport Cropping Technology:
- Windows Calculator, Settings, Microsoft To Do (Modern UWP apps)
- Completely bypasses the "all-white screen" rendering bug by manipulating the window region instead of forcing a cross-process DWM visual tree attachment. 📖 Deep dive: ZenCrop Viewport Technology Implementation Report
2. Deep Visual Tree Radar & Advanced Reparenting:
- Windows 11 Paint (Modern
DesktopChildSiteBridgeWinUI 3 apps) - Magpie and other traditional Win32 apps nesting modern XAML components (
DesktopWindowContentBridge) - Intelligently circumvents fragile DWM composition rules, applies smart dark-mode background camouflage to prevent washed-out colors, and utilizes inverse coordinate compensation to perfectly align the crop without triggering fallback titlebars or crashes. 📖 Deep dive: WinUI 3 Reparenting Technical Report
PowerToys Crop And Lock is a module in the Microsoft PowerToys toolkit that allows users to crop any window into a sub-window and pin it on screen. However, the original project is deeply tied to the PowerToys framework, making it difficult to use independently or customize.
ZenCrop is rebuilt from scratch, runs completely standalone without PowerToys, and provides a lighter solution while preserving and exceeding the core functionality.
- Smart Reparent Mode: Crops a target window into an independent child window. ZenCrop automatically detects modern UWP/WinUI applications (like Calculator or Settings) and seamlessly falls back to a special Viewport mode. This prevents the "all-white" rendering bug associated with standard reparenting, ensuring all apps remain interactive.
- Thumbnail Mode: Displays a live DWM thumbnail of the target window with a cornflower blue border. New in V2.2.0 & V2.2.1: the target window is stealthily hidden from the taskbar and screen while keeping Chromium/Electron engines rendering at 60 FPS, and the thumbnail itself displays its own taskbar icon for easy window management. Supports strict proportional scaling via native window edge dragging or third-party tools like AltSnap. 📖 Deep dive: ZenCrop Thumbnail Scaling & Hiding Technology
- Always On Top: Press
Alt+Tto pin any window on top of all others, with a customizable border (color, opacity, thickness, rounded corners) - Customizable Hotkeys: All hotkeys can be customized in Settings — click the input field and press your desired key combo
- Crop On Top: Optionally auto-pin cropped windows on top (configurable in Settings)
- Smart Window Detection: The crop overlay automatically follows the mouse, dynamically highlighting the window under the cursor — crop any window on screen
- Smart Content Detection: UI Automation-based element detection — the overlay automatically identifies the UI element under the cursor (browser title bar, address bar, content area, etc.) and suggests a crop region with a red dashed border
- Click to Accept: Single-click accepts the smart suggestion; drag to manually draw a rectangle
- Crop Area Adjustment: After drawing the crop rectangle, you can resize it by dragging edges/corners, move it by dragging inside, and double-click to confirm — no more accidental crops
- Arrow Key Control: Fine-tune the crop box with keyboard in adjust mode — Arrow keys move 1px, Ctrl+Arrow expands, Shift+Arrow shrinks, Enter confirms
- Coordinate Display: Shows real-time coordinates and dimensions at the top-left corner (e.g.,
1077, 864 — 320 x 240 px)
- Borderless / Titlebar Toggle: Windows are borderless by default; toggle titlebar visibility via the tray menu
- Stale Window Cleanup: Automatically removes Reparent/Thumbnail windows whose target has been closed externally
- System Tray: Runs in the background; right-click the tray icon for the menu
| Hotkey | Action |
|---|---|
Ctrl+Alt+X |
Start Smart Reparent crop mode |
Ctrl+Alt+C |
Start Thumbnail crop mode |
Ctrl+Alt+V |
Force Viewport crop mode (Manual fallback) |
Ctrl+Alt+Z |
Close all active crop windows |
Alt+T |
Toggle Always On Top for the foreground window |
ESC |
Cancel current crop rectangle / cancel entire crop mode / close focused Thumbnail window |
| Right-click tray icon | Open menu (toggle titlebar / settings / exit) |
All hotkeys are customizable in Settings (right-click tray → Settings → ZenCrop / Always On Top tab).
- Press
Ctrl+Alt+XorCtrl+Alt+Cto enter crop mode - Move the mouse — a red dashed border highlights the detected UI element under the cursor (smart detection via UI Automation)
- Click to accept the smart suggestion and enter adjust mode, or drag to manually draw a crop rectangle
- In adjust mode:
- Drag edges/corners to resize
- Drag inside the rectangle to move
- Double-click inside the rectangle to confirm the crop
- Arrow keys (↑↓←→) to move the crop box by 1px
- Ctrl+Arrow keys to expand the corresponding edge by 1px
- Shift+Arrow keys to shrink the corresponding edge by 1px
- Enter to confirm (same as double-click)
- Press
ESCto cancel the rectangle and redraw, pressESCagain to exit - Click outside the rectangle to cancel and redraw
- Press
Ctrl+Alt+Zto close all Reparent windows - Press
Alt+Tto toggle Always On Top for any window
Note: The desktop background cannot be selected as a crop target. Clicking on the desktop will automatically exit crop mode.
Right-click the tray icon → Settings to open the tabbed settings dialog:
- ZenCrop tab: Overlay color & thickness, Crop On Top toggle, Reparent/Thumbnail/Close Reparent hotkey customization
- Always On Top tab: Border visibility, color (system accent or custom), opacity, thickness, rounded corners, AOT hotkey customization
- Language: C++17
- Framework: Native Windows Win32 API
- Dependencies: user32, gdi32, dwmapi, shcore, shell32, ole32, oleaut32, shlwapi, comctl32, comdlg32, advapi32
- Visual Studio 2022 (with vcvars64)
- Windows SDK
# Using build.bat (recommended)
build.bat
# Or using CMake
cmake -B build && cmake --build buildThe output is ZenCrop.exe.
zencrop/
├── main.cpp # Entry point, system tray, message loop
├── Utils.h/cpp # Utility functions
├── SmartDetector.h/cpp # UI Automation smart content detection
├── OverlayWindow.h/cpp # Crop area selection overlay
├── ReparentWindow.h/cpp # Reparent mode window
├── ThumbnailWindow.h/cpp # Thumbnail mode window
├── ViewportWindow.h/cpp # Viewport mode window (for modern apps)
├── AlwaysOnTop.h/cpp # Always On Top manager & border window
├── Settings.h/cpp # Unified settings dialog (AOT, overlay, hotkeys)
├── app.ico # Application icon
├── resources.rc # Dialog templates & icon resource
├── app.manifest # DPI awareness & compatibility
├── build.bat # MSVC build script
├── CMakeLists.txt # CMake configuration
├── AGENTS.md # AI development guide
├── README.md
└── doc/
├── CHANGELOG.md # Detailed changelog
├── README_zh.md # Chinese documentation
├── viewport_technology_report.md # Tech report on Viewport mode (CN)
└── viewport_technology_report_en.md # Tech report on Viewport mode (EN)
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MIT License