ComfyUI-WatchPoint
Multi-monitor preview with external window (zoom, pan, save), floating in-browser preview, and prompt monitoring. Features stable threading, customizable positioning,…

👁️ ComfyUI Watch Point

Dual preview system for ComfyUI workflows
About This Project
This node was developed by a creator with limited Python experience, using AI tools like Claude, Gemini, and Kimi. While fully functional, it may not strictly adhere to all Python best practices.
We warmly invite you to fork, improve, and adapt this code—collaboration is what makes open-source thrive!
Watch Point provides two simultaneous preview methods:
- Monitor Preview: External Tkinter window on any monitor
- Floating Preview: ComfyUI's built-in preview system

🔧 Features
Monitor Preview (Tkinter)
- Display on any connected monitor
- Zoom/Pan controls with mouse
- Keyboard shortcuts
- Save images directly from preview
- Copy to clipboard
- Customizable settings
- Thread Safety: Windows minimize instead of closing to prevent ComfyUI crashes
Floating Preview (JavaScript)
- Uses ComfyUI's native preview system
- Works with existing preview extensions
- Auto-updates during workflow execution
- Configurable via browser localStorage (no file editing)
- Customizable keyboard shortcuts
- Snap-to-grid positioning
- Adjustable opacity levels
🛡️ Thread Safety & Window Protection
WatchPoint includes built-in protection against threading issues that can crash ComfyUI:
Window Minimization Protection
- Close Button Behavior: Clicking the Windows close button minimizes the window instead of closing it
- Thread Safety: Prevents
Tcl_AsyncDeleteerrors and threading conflicts - ComfyUI Stability: Ensures ComfyUI continues running even if windows are "minimized"
- Window Recovery: Minimized windows can be restored from the taskbar
Technical Details
- Uses thread-safe Tkinter operations
- Implements proper cleanup procedures
- Prevents memory leaks and threading deadlocks
- Global window management for consistent behavior
📦 Installation
- Clone into your ComfyUI custom_nodes directory:
cd ComfyUI/custom_nodes
git clone [https://github.com/gmorks/ComfyUI-WatchPoint.git](https://github.com/gmorks/ComfyUI-WatchPoint.git)
- Install dependencies (if needed):
pip install pillow screeninfo
- Restart ComfyUI
👁️ Nodes
Watch Point
The main preview node.
- Add Watch Point to your workflow.
- Connect an
IMAGEinput. - Enable/disable previews:
floating_preview: Enable ComfyUI's built-in preview.monitor_preview: Enable or pause the external monitor window (window stays alive, image updates only when True).
- Configure the target monitor via the ⚙ Settings dialog or by editing
watchpoint_settings.json(monitor_index). - The node acts as a pass-through for the
IMAGEoutput.
Optional string input
- Connect any
STRINGinput. - The text will appear in the side panel of the external window.
🎮 Controls (Monitor Preview)
Mouse
- Scroll wheel: Zoom in/out
- Left click + drag: Pan image
- Right click: Context menu
Keyboard
- R: Reset zoom and pan
- T: Toggle toolbar
- P: Toggle Text panel
- 1: Zoom 1:1 (100% actual size)
Window Close Behavior
Important: The Windows close button (❌) minimizes the window instead of closing it. This prevents threading errors and keeps ComfyUI stable. To "close" the window:
- Click the close button → Window minimizes to taskbar
- Right-click taskbar icon → "Close window" for forced closure
Toolbar Buttons
- ↻ Reset: Reset zoom and pan
- ⊕ Zoom In: Increase zoom level
- ⊖ Zoom Out: Decrease zoom level
- 1:1 (100%): View image at actual size
- Window Size: Quick resize presets
- ⛶ Fullscreen: Toggle fullscreen mode
- ⚙ Settings: Open settings dialog
⚙️ Settings
Access settings via the ⚙ Settings button in the toolbar.
Save Options
- Default format: PNG or JPEG
- JPEG quality slider (10-100)
Monitor Options
- Select the target monitor from the Monitor dropdown in the Settings dialog.
- Persist the monitor selection globally via
monitor_indexinwatchpoint_settings.json.
UI Options
- Show/hide toolbar by default
All settings are saved to watchpoint_settings.json.
🔧 Configuration Files
Monitor Preview Settings
Edit watchpoint_settings.json to customize defaults for the external Tkinter window:
{
"window_width": 800,
"window_height": 600,
"window_x": null,
"window_y": null,
"window_size_mode": "fixed",
"show_toolbar": true,
"save_format": "png",
"jpeg_quality": 90,
"monitor_index": 0
}
Settings Explained
window_x,window_y: Window position (null = auto)window_size_mode: "fixed", "Half Vertical", "Half Horizontal", or "Quarter"show_toolbar: Show toolbar on startupsave_format: Default save format ("png" or "jpeg")jpeg_quality: JPEG compression quality (10-100)monitor_index: Index of the monitor used for the external preview (0 = first monitor).
Floating Preview Configuration
The floating preview window is configured via browser localStorage. No file editing required!
Quick Start
View Current Configuration
Open browser console (F12) and run:
WatchPointFloating.getConfig()
Change Configuration
WatchPointFloating.setConfig({
window: {
defaultWidth: 500,
defaultHeight: 500,
defaultPosition: "top-right",
defaultOpacity: 80
},
shortcuts: {
toggle: "Ctrl+Alt+KeyP" // Change toggle shortcut
}
})
Reset to Defaults
WatchPointFloating.resetConfig()
Show Help
WatchPointFloating.showHelp()
Note: Reload the page after changing config to apply changes.
Available Configuration Options
Window Settings
{
window: {
defaultWidth: 320, // Width in pixels
defaultHeight: 320, // Height in pixels
defaultPosition: "middle-right", // Initial position
defaultOpacity: 100 // 0-100 (percentage)
}
}
Available Positions:
"top-left","top-center","top-right""middle-left","middle-center","middle-right""bottom-left","bottom-center","bottom-right"
Opacity Settings
{
opacity: {
levels: [20, 40, 60, 80, 100], // Available opacity levels (%)
showIndicator: true, // Show opacity % when changing
indicatorDuration: 1000 // How long indicator shows (ms)
}
}
UI Settings
{
ui: {
showHeader: true, // Show title bar
showTitle: true, // Show "👁️ Watch Point" title
showCloseButton: true, // Show X button
dragFromAnywhere: false // Drag from image area (only if header=false)
}
}
Keyboard Shortcuts
{
shortcuts: {
// Main controls
toggle: "Ctrl+Alt+KeyW",
increaseOpacity: "Ctrl+Alt+Equal", // or Ctrl+Alt++
decreaseOpacity: "Ctrl+Alt+Minus", // or Ctrl+Alt+-
// Arrow navigation (relative)
snapUp: "Ctrl+Alt+ArrowUp",
snapDown: "Ctrl+Alt+ArrowDown",
snapLeft: "Ctrl+Alt+ArrowLeft",
snapRight: "Ctrl+Alt+ArrowRight",
// Numpad navigation (absolute positions)
snapToPosition7: "Ctrl+Alt+Numpad7", // Top-left
snapToPosition8: "Ctrl+Alt+Numpad8", // Top-center
snapToPosition9: "Ctrl+Alt+Numpad9", // Top-right
snapToPosition4: "Ctrl+Alt+Numpad4", // Middle-left
snapToPosition5: "Ctrl+Alt+Numpad5", // Middle-center
snapToPosition6: "Ctrl+Alt+Numpad6", // Middle-right
snapToPosition1: "Ctrl+Alt+Numpad1", // Bottom-left
snapToPosition2: "Ctrl+Alt+Numpad2", // Bottom-center
snapToPosition3: "Ctrl+Alt+Numpad3" // Bottom-right
}
}
Default Keyboard Shortcuts
| Action | Shortcut | Description |
| --- | --- | --- |
| Toggle window | Ctrl+Alt+W | Show/hide floating preview |
| Increase opacity | Ctrl+Alt++ | Make more opaque |
| Decrease opacity | Ctrl+Alt+- | Make more transparent |
| Move up | Ctrl+Alt+↑ | Snap to position above |
| Move down | Ctrl+Alt+↓ | Snap to position below |
| Move left | Ctrl+Alt+← | Snap to position left |
| Move right | Ctrl+Alt+→ | Snap to position right |
| Snap to corner | Ctrl+Alt+Numpad[1-9] | Jump to specific position |
Storage Location
Configuration is stored in browser localStorage under the key:
watchpoint-floating-config
Use Cases
Dual Monitor Setup
Perfect for users with multiple monitors:
- Work on ComfyUI on main monitor
- View live preview on secondary monitor
- No need to switch windows or tabs
Quality Control
Use 1:1 zoom to inspect:
- Image quality at pixel level
- Upscaling artifacts
- Detail preservation
Live Monitoring
Watch your workflow progress in real-time:
- Both previews update simultaneously
- Choose the view that works best for your setup
- Keep an eye on intermediate results
Requirements
- Python 3.7+
- tkinter (usually included with Python)
- PIL/Pillow
- screeninfo (optional, for multi-monitor detection)
Optional Dependencies
For clipboard support (Windows):
pip install pywin32
🛠️ Troubleshooting
Window doesn't appear
- Check if
monitor_previewis enabled (True). - Open the ⚙ Settings dialog and verify that a valid monitor is selected.
- Alternatively, check that
monitor_indexinwatchpoint_settings.jsonpoints to an existing monitor. - Check console for error messages.
Window appears in wrong location
- Set explicit X, Y coordinates in settings
- Use
window_x: 0, window_y: 0for top-left
Image not updating
- Ensure workflow is executing.
- Check that image is connected to Watch Point input.
- Verify that
monitor_previewis enabled (True); when False, the window stays open but the image will not refresh. - Try disabling/re-enabling monitor preview.
Window snapping (Win + Arrows) doesn't work in Fullscreen
- Reason: To guarantee that fullscreen mode activates on the correct monitor (avoiding a Windows bug that forces it to Monitor 0), we use a custom "borderless window" approach.
- Solution: To move the window to another monitor, exit fullscreen (F11 or toolbar button), drag the window to the desired monitor, and re-enable fullscreen. Alternatively, use the Monitor selector in Settings.
Floating preview not working
- Ensure
floating_previewis enabled (True) - Check if other preview extensions are conflicting
- Restart ComfyUI
Credits
Vibe Coded for ComfyUI by gmorks using AI.
License
MIT License - Feel free to use and modify!
🚧 Development Status
Note: This extension is not yet compatible with ComfyUI Nodes 2.0. Support for the new node system is on our to-do list and will be implemented in a future update.
Known Issues
- Fullscreen Mode: Currently, toggling fullscreen (F11) may default to the primary monitor (Monitor 0) regardless of the window's current position. We are actively working on a fix to ensure fullscreen activates on the correct monitor. [WIP]
Recent Changes
v2.0.0 - Cleanup & Optimization
- Removed debug nodes and utilities
- Integrated Signal Scout text feature into main node
- Simplified codebase while preserving stability
v1.0.0 - Initial Release
- Dual preview system (Monitor + Floating)
- Basic window controls and settings
- Multi-monitor support