Winnow - A multiplatform in-place image editor

A simplified online version is available here. The full desktop version is available for mac, windows, and linux from the releases page here. Features:

• Edits to crop, resize, rename, and rotate images, applied immediately on disk (there is an undo queue kept in the temp directory (/tmp on linux, %TEMP% on windows) which is cleared on shutdown).
• Intelligent initial selection based on detected people.
• You will be prompted for an image directory on first launch, this will be saved to a config file in your user directory (i.e. ~/.winnow.conf on linux, %userprofile%/.winnow.conf on windows) so you will not be prompted again. The directory can be changed at any time by clicking or touching the directory path in the control window.
• The image file can be renamed by typing a new name in the combo box at the bottom, which is populated with frequently chosen values from the directory. If there is a filename pattern this will attempt to parse it and break the input into multiple selection boxes if necessary, predicting the most likely name based on frequency. Additional components can be added dynamically via the "+" button before the file extension. To turn off predictive editing and use a single text field instead of combo boxes, set useSimpleFilenameEditor=true in the config file.

Controls:

Action	Key	Mouse	Touchpad
Previous Image	Left Arrow	Ctrl + Drag Right	Swipe Right
Next Image	Right Arrow	Ctrl + Drag Left	Swipe Left
Zoom In	Dash/Minus	Wheel Forward	Pinch
Zoom Out	Equals/Plus	Wheel Backwards	Expand
Rotate Right	Ctrl + E	Drag Top Right Clockwise	Drag Top RightClockwise
Rotate Left	Ctrl + Q	Drag Top Right Counterclockwise	Drag Top Right Counterclockwise
Expand Right Selection Right	Ctrl + D	Drag Bottom Right Rectangle Right	Drag Bottom Right Rectangle Right
Reduce Right Selection Left	Ctrl + A	Drag Bottom Right Rectangle Left	Drag Bottom Right Rectangle Left
Expand Bottom Selection Down	Ctrl + S	Drag a Bottom Rectangle Down	Drag a Bottom Rectangle Down
Reduce Bottom Selection Up	Ctrl + W	Drag a Bottom Rectangle Up	Drag a Bottom Rectangle Up
Expand Left Selection Right	Shift + Ctrl + D	Drag a Left Rectangle Right	Drag a Left Rectangle Right
Reduce Left Selection Left	Shift + Ctrl + A	Drag a Left Rectangle Left	Drag a Left Rectangle Left
Expand Top Selection Down	Shift + Ctrl + S	Drag a Top Rectangle Down	Drag a Top Rectangle Down
Reduce Top Selection Up	Shift + Ctrl + W	Drag a Top Rectangle Up	Drag a Top Rectangle Up
Undo	Ctrl + Z	Press Undo Button	Press Undo Button

Focus between fields on the control window can be cycled via tab. Focus can be shifted between the control and image windows via Ctrl+Tab. The selection rectangle can be moved by dragging the green selection handle.

Design

• Uses the ImageJ library to do a lot of the heavy lifting of image processing and manipulation
• Uses JavaFX because it has out of the box support for multitouch
• ImageJ uses swing, so this requires converting the buffered image to JavaFX (as embedding a swing component in JavaFX can be slow) and maintaining our own ROI. BufferedImage → JavaFX Image conversion happens at render time to avoid Swing/JavaFX mixing issues

Classes

Core (org.win.core)

Business logic (image operations, selection state, interaction control) for sharing between desktop and web platforms.

• PixelImage: Platform-independent ARGB pixel array representation for image manipulation.
• PixelImageOps: Shared image operations (crop, rotate, resize) using ARGB pixel manipulation.
• SelectionModel: Platform-neutral selection rectangle state management.
• InteractionController: Manages zoom, selection, and image manipulation state across platforms.
• ImageUndo: Unified undo interface with InMemoryImageUndo for browser undo history.
• ControlViewModel: Platform-neutral control state (filename, navigation, action bindings).

Desktop (org.win)

• UndoManager: Manages undo queue using byte-for-byte file copying to preserve image quality. Creates temp directories per session with automatic cleanup via shutdown hooks.
• ConfigManager: Handles persistent user settings (last directory, last position, filename editor mode) in ~/.winnow.conf using Java Properties format.
• Window: Main UI container managing the filename editor, crop/resize/undo buttons, destination directory selector, and file operations. Provides editable image dimensions with resize button. Consolidates common image save/rename operations. Supports saving images to a destination directory. Dynamically selects between simple and predictive filename editors based on config.
• PredictiveFilenameEditor: Parses filenames into components with dropdown suggestions. Displays editable separators between components. Includes a "+" button to dynamically add new filename components.
• SimpleFilenameEditor: Single text field filename editor with non-editable extension label.
• CustomImageCanvas: Interactive JavaFX Canvas for image display with selection ROI, rotation, and resizing. Converts ImageJ BufferedImages to JavaFX format. Maintains original image copy for quality-preserving rotation. Uses bicubic interpolation for high-quality resizing. Implements intelligent selection rectangle clamping when zoomed past window bounds.
• InputDispatcher: Centralizes keyboard shortcuts, mouse/touchscreen gestures, and zoom controls. Uses event filtering to support modifier key combinations.
• Main: JavaFX Application that manages the image directory, file navigation, per-image undo managers, and application lifecycle.

Web (org.win.browser)

• BrowserMain: Browser entry point using TeaVM transpilation. Handles DOM manipulation, File API, and event wiring.
• WebCanvasAdapter: Canvas rendering adapter for web platform using HTML5 Canvas API and shared interaction state.

Image Quality Preservation

• Undo operations use Files.copy() for byte-for-byte file copying instead of re-encoding images
• Rotation always transforms from the original unrotated image to avoid cumulative quality loss
• Cumulative rotation tracking prevents canvas size drift during rotation
• Resize operations use bicubic interpolation for high-quality scaling

Per-Image State Management

• Each image gets its own UndoManager instance (tracked by position index)
• File renames tracked through undo operations to support correct restoration
• Config file remembers last directory and position for seamless session resumption

Zoom and Selection Management

• Selection rectangle visibility is maintained when zooming beyond window bounds
• Visible canvas bounds calculated dynamically based on scene size and zoom scale
• Selection dimensions in control panel reflect actual visible image area, not full selection
• Canvas coordinates used for drawing while visible bounds clamp what appears on screen

Building and Packaging

Web Version

Build and run the web version locally:

# Build web version (compiles Java to JavaScript via TeaVM)
./gradlew buildWeb

# Run local web server on http://localhost:8080
./gradlew runWeb

The web build output is located at build/web/dist/. The runWeb task starts a Python HTTP server (Python 3 required).

Desktop Version

Follow these steps to manually create packages you can install on linux, mac, and windows for testing.

Prerequisites

• JDK 17 or later (with jpackage support)
• Gradle 8.0+ (included via wrapper)
• For windows builds, as administrator you will first need to install: winget install --id=WiXToolset.WiXToolset

Release Process

Before creating a release:

1. Update the version in build.gradle:

   version = 'N.N.N'

2. Update the README screenshot (requires graphical environment):

   ./gradlew updateReadmeScreenshot

   This generates a fresh screenshot showing the current UI and automatically updates the README.

3. Build and test:

   ./gradlew build

4. Commit changes:

   git add -A
   git commit -m "Release vN.N.N"

5. Create and push the release tag:

   git tag vN.N.N
   git push origin main --tags

GitHub Actions will automatically build platform-specific installers and create the release.

Manual Installer Creation

You can also create installers manually for specific platforms:

./gradlew jpackage -PinstallerType=deb   # Linux (Debian/Ubuntu)
./gradlew jpackage -PinstallerType=rpm   # Linux (Fedora/RHEL)
./gradlew.bat jpackage -PinstallerType=msi  # Windows
./gradlew jpackage -PinstallerType=dmg   # macOS

Output Locations

• Runtime image: build/image/bin/winnow
• Installers: build/jpackage/
• JAR: build/libs/

Troubleshooting

On linux, if the installed application doesn't launch, run it from the terminal:

dpkg -L winnow | grep bin
# Use the path from that here, for example:
/opt/winnow/bin/Winnow

When using the web app in browsers with fingerprint protection, you will need to enable this: