MarkLatex

A lightweight desktop application for academics to grade PDF assignments with styled text annotations.

Features

• Batch Processing: Recursively load all PDFs from a folder
• Moodle Folder Support: Detect Moodle-style submission folders and label PDFs by student name
• Non-Destructive Editing: Annotations saved in separate .mlat files, original PDFs remain untouched
• Custom Styled Text: Add annotations with custom fonts, sizes, and text wrapping
• LaTeX Support: Render mathematical formulas using Matplotlib
• Smart Export: Automatically expand PDF canvas if annotations go out of bounds
• Export All: Batch-export all PDFs and warn about unmarked files
• Undo: Ctrl+Z and toolbar undo button for per-PDF edits (max depth 20)
• Enhanced Navigation: Use Page Up/Down keys for easy page switching
• High DPI Rendering: Sharp annotations at 300 DPI
• Remarks Tree: Sidebar shows remark subitems under each PDF for quick jumping

Quick Start

1. Install Dependencies

   pip install PyQt6 PyMuPDF matplotlib

2. Run the Application

   python main.py

3. Open a Folder

   • Click "Open Folder" in the toolbar
   • Select a folder containing PDF files, or a Moodle-unzipped submission folder
   • The application will load all PDFs recursively or map Moodle submissions by student

4. Add Annotations

   • Double-click on any PDF page to add a new annotation
   • Customize font, size, and text wrapping in the dialog
   • Drag annotations to reposition them
   • Double-click existing annotations to edit them

5. Export Marked PDFs

   • Click "Export PDF" to save a new PDF with all annotations
   • Click "Export All" to export every PDF in the list (warnings shown for unmarked files)
   • Exported files use the _marked.pdf suffix

User Interface

• Left Sidebar: Tree of PDFs with remark subitems (click a remark to jump to its page)
• Main Area: PDF page display with annotations
• Toolbar: Navigation buttons, Moodle mode indicator, export tools, and undo
• Keyboard Shortcuts:
  • Page Up/Down: Navigate between pages
  • Delete: Remove selected annotations
  • Ctrl+Z: Undo last change (per PDF)
  • Ctrl + Mouse Wheel: Zoom in/out
  • Shift + Mouse Wheel: Horizontal scrolling

File Structure

• Main Application: main.py
• Developer Documentation: DEVELOPER.md
• Dependencies: Listed in requirements.txt

Export Process

When exporting, the application:

1. Renders each annotation as a transparent PNG
2. Places annotations at their specified coordinates
3. Expands the PDF canvas if annotations extend beyond page boundaries
4. Saves the result as a new PDF file

Requirements

• Python 3.7+
• PyQt6
• PyMuPDF (fitz)
• Matplotlib

Known Issues

• Memory usage increases with large numbers of PDFs
• Stylus support is limited

License

This project is open source. Feel free to contribute or modify for your needs.