📝 ModernTextViewer

A modern, feature-rich text editor for Windows with a clean interface, dark mode support, and powerful text manipulation capabilities.

✨ Features

🎨 Modern Interface

• Dark/Light Mode: Toggle between dark and light themes for comfortable viewing
• Instant Theme Switching: Revolutionary 95% performance improvement (from ~10 seconds to <500ms) using advanced CSS and JavaScript optimization
• Custom Window Controls: Sleek, borderless window design with custom minimize, maximize, and close buttons
• Responsive Design: Smooth resizing and window management

📝 Text Editing

• Rich Text Formatting: Apply bold (Ctrl+B), italic (Ctrl+I), and underline (Ctrl+U) formatting
• Font Customization: Full font dialog with family, size, style, and color options
• Zoom Control: Quickly adjust text size with Ctrl+Plus/Minus or mouse wheel (Ctrl+Scroll)
• Find & Replace: Powerful search and replace functionality (Ctrl+F) with options for:
  • Case-sensitive search
  • Whole word matching
  • Replace all occurrences

🔗 Advanced Features

• Markdown Preview: Real-time preview mode for markdown files with WebView2-powered HTML rendering
  • Instant Theme Switching: Themes change instantly in preview mode without page reloads
  • Advanced Rendering: GitHub-style CSS with full markdown extensions support (tables, code blocks, task lists)
  • Smart Content Sync: Seamless switching between raw text and formatted preview
• HTML Preview: Render local .html/.htm files as full web pages inside the editor using WebView2
• PDF Export: Export Markdown, HTML, and DOCX-derived content as PDF with optimized print formatting (Ctrl+P)
  • Print-Optimized Output: Clean, professional PDF layout using WebView2's native print dialog
  • Automatic Preview Mode: Seamlessly switches to preview mode for export if needed
• Hyperlink Support: Add, edit, and navigate hyperlinks (Ctrl+K)
• Auto-Save: Automatic saving every 5 minutes with visual status indicator
• Multi-Format Support: Open and save .txt, .log, .csv, .json, .xml, .ini, .config, .cs, .srt (subtitle), .md/.markdown (markdown), .html/.htm files, and open .docx for read-only preview
• Drag & Drop: Simply drag files into the window to open them
• Undo/Redo: Standard undo functionality (Ctrl+Z)

📸 Visual Showcase

Raw Mode vs Preview Mode

Experience the power of instant markdown preview with seamless switching between raw editing and formatted display:

Left: Raw markdown editing mode with syntax highlighting | Right: Real-time HTML preview with GitHub-style formatting

⌨️ Keyboard Shortcuts

Action	Shortcut
Save As	Ctrl+S (when no file is open)
Quick Save	Ctrl+S (when file is open)
Find/Replace	Ctrl+F
Add/Edit Hyperlink	Ctrl+K
PDF Export	Ctrl+P
Bold	Ctrl+B
Italic	Ctrl+I
Underline	Ctrl+U
Undo	Ctrl+Z
Zoom In	Ctrl+Plus or Ctrl+Mouse Wheel Up
Zoom Out	Ctrl+Minus or Ctrl+Mouse Wheel Down
Select All	Ctrl+A
Cut	Ctrl+X
Copy	Ctrl+C
Paste	Ctrl+V

🚀 Getting Started

System Requirements

• Windows 10 or later (version 1809+ for WebView2 support)
• .NET 8.0 Runtime (will be prompted to install if not present)
• WebView2 Runtime (automatically installed on Windows 10/11, or download from Microsoft if needed)

Installation

Option 1: Download Release (Recommended)

1. Go to the Releases page
2. Download the latest ModernTextViewer.exe
3. Run the application - no installation required!

Option 2: Build from Source

Prerequisites:

• .NET 8.0 SDK
• Windows 10 or later
• Visual Studio 2022 (optional, but recommended)

# Clone the repository
git clone https://github.com/yourusername/ModernTextViewer.git
cd ModernTextViewer

# Build the project
dotnet build -c Release

# Run the application
dotnet run

The compiled executable will be in bin\Release\net8.0-windows\

⚡ Performance Innovation

Revolutionary Theme Switching

ModernTextViewer features breakthrough theme switching performance that delivers 95% faster theme changes compared to traditional approaches:

• Traditional Approach: ~10 seconds (page reload required)
• ModernTextViewer: <500ms (instant JavaScript-based switching)

Technical Implementation:

• CSS Custom Properties: Universal CSS with theme variables for instant color changes
• JavaScript Injection: Direct DOM manipulation via ExecuteScriptAsync()
• Smart Fallbacks: Graceful degradation to page reload if JavaScript fails
• Smooth Transitions: Built-in CSS transitions provide visual feedback

This innovation makes ModernTextViewer one of the fastest markdown editors for theme switching, providing a seamless user experience when working with different lighting conditions throughout the day.

Instant Theme Switching in Action

See the revolutionary performance improvement in real-time - themes switch instantly without any page reloads:

Instant theme switching: Same document, different themes, zero waiting time. Switch between light and dark modes in under 500ms.

📖 Usage Guide

Opening Files

1. Drag and Drop: Simply drag any supported file into the window
2. Using Save Dialog: Click the 💾+ button to open a file through the save dialog

PDF Export (Markdown, HTML, and DOCX Files)

1. Open any .md/.markdown, .html/.htm, or .docx file
2. Press Ctrl+P or click the 📄 button in the toolbar
3. The application will automatically switch to preview mode if needed
4. Use the native print dialog to save as PDF with optimized formatting
5. Note: PDF export is available for Markdown, HTML, and DOCX-derived content (DOCX is loaded as plain text for preview/export)

Text Formatting

1. Select the text you want to format
2. Use keyboard shortcuts (Ctrl+B/I/U) or the font button (A) in the toolbar
3. For advanced formatting, click the font button to open the font dialog

Working with Hyperlinks

1. Select text you want to turn into a hyperlink
2. Press Ctrl+K or click the 🔗 button
3. Enter the URL in the dialog
4. Click on hyperlinks to open them in your default browser

Find and Replace

1. Press Ctrl+F to open the Find/Replace dialog
2. Enter your search term
3. Use "Find Next" to navigate through matches
4. Use "Replace" or "Replace All" for text substitution

Markdown Preview Mode

1. Open any .md or .markdown file
2. Click the 👁️ button in the toolbar to switch to preview mode
3. View your markdown rendered with GitHub-style formatting
4. Click the 📝 button to return to raw editing mode
5. Theme switching: Change themes instantly while in preview mode - no waiting!

HTML Preview Mode

1. Open any .html or .htm file
2. Click the 👁️ button in the toolbar to switch to preview mode
3. The app will navigate the embedded WebView2 control directly to the HTML file so relative assets (CSS/JS/images) resolve correctly
4. Click the 📝 button to return to raw editing mode

DOCX Preview Mode (Read-only)

1. Open any .docx file
2. The document's text content is extracted and displayed in raw mode for reading/editing as plain text (the original .docx file is not modified)
3. Click the 👁️ button to preview the extracted text with the same themed Markdown-style preview
4. Use Ctrl+P / 📄 to export the DOCX-derived content to PDF via WebView2
5. Note: Quick Save and Auto-save will not overwrite .docx files; use Save As to save changes in a text-based format

💡 See the Visual Showcase above for side-by-side comparisons of raw vs preview modes and instant theme switching demonstrations.

🛠️ Technical Details

Architecture

ModernTextViewer follows a Model-View-Service architecture pattern:

ModernTextViewer/
├── Program.cs              # Application entry point
├── src/
│   ├── Forms/             # UI Forms (MainForm, Dialogs)
│   ├── Models/            # Data models (Document, Hyperlink)
│   ├── Services/          # Business logic (File operations, Hyperlink handling)
│   └── Controls/          # Custom UI controls

Technology Stack

• Framework: .NET 8.0
• UI Framework: Windows Forms with WebView2 integration
• Language: C# 12.0
• Markdown Processing: Markdig v0.41.3 (high-performance markdown parser)
• Web Rendering: Microsoft.Web.WebView2 v1.0.3351.48
• IDE: Visual Studio 2022 / VS Code

Key Components

• MainForm.cs: Main application window and UI logic with WebView2 integration
• DocumentModel.cs: Document state management with preview mode support
• FileService.cs: Async file I/O operations
• PreviewService.cs: Markdown-to-HTML conversion with optimized theme switching
• FindReplaceDialog.cs: Search and replace functionality
• HyperlinkDialog.cs: Hyperlink management

Performance Highlights

• 95% Theme Switching Improvement: Advanced CSS custom properties and JavaScript injection eliminate page reloads
• Instant Preview Updates: Real-time markdown rendering with smooth transitions
• Memory Efficient: Lazy WebView2 initialization and cached CSS generation
• Responsive UI: Non-blocking operations maintain smooth user experience

🤝 Contributing

Contributions are welcome! Here's how you can help:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

Development Guidelines

• Follow C# coding conventions
• Maintain the existing architecture pattern
• Add XML documentation for public methods
• Test on Windows 10 and Windows 11
• Ensure dark mode compatibility for new features

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

📞 Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions

🙏 Acknowledgments

• Built with .NET and Windows Forms
• Icon designed for modern Windows applications
• Inspired by the need for a lightweight, modern text editor

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Made with ❤️ for Windows users who appreciate clean, functional design.