Add Flatpak packaging support for UltiMaker Cura

README.md

@@ -29,6 +29,14 @@
 **Contribute Printer Profiles?** -- Please [look here](https://github.com/Ultimaker/Cura/wiki/Adding-new-machine-profiles-to-Cura) first. <br>
 **Contribute Translations?** -- Please [look here](https://github.com/Ultimaker/Cura/wiki/Translating-Cura) first.
 
+## Installation & Packaging
+
+Cura supports multiple packaging formats for different platforms:
+- **Windows**: MSI installers and NSIS packages (`/packaging/msi`, `/packaging/NSIS`)  
+- **macOS**: Native macOS applications (`/packaging/MacOS`)
+- **Linux**: AppImage packages (`/packaging/AppImage`, `/packaging/AppImage-builder`)
+- **Linux**: Flatpak packages (`/packaging/Flatpak`) - *New!*
+
 <br>
 
 [![Button Building]][Building]   

packaging/Flatpak/LIMITATIONS.md

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+# Flatpak Packaging Limitations
+
+This document outlines current limitations and future improvements for the UltiMaker Cura Flatpak packaging.
+
+## Current Status
+
+The Flatpak implementation follows the same build workflow as AppImage packaging:
+- ✅ **Conan Integration**: Uses Conan for dependency management
+- ✅ **PyInstaller Distribution**: Creates application using PyInstaller
+- ✅ **Desktop Integration**: Full desktop environment integration
+- ✅ **Cross-distribution Support**: Works on any Linux with Flatpak
+
+## Known Limitations
+
+### 1. Build Complexity
+
+**Issue**: The build process requires multiple tools (Conan, PyInstaller, Flatpak Builder) and can be complex for contributors.
+
+**Impact**: Higher barrier to entry for building and testing Flatpak packages.
+
+**Future Work**: 
+- Containerized build environment using Docker
+- Pre-built dependency caches to speed up builds
+- Integration with existing CI/CD pipelines
+
+### 2. Size Optimization
+
+**Issue**: PyInstaller bundles can be large due to including all Python dependencies and libraries.
+
+**Impact**: Larger download size compared to distribution-specific packages.
+
+**Future Work**:
+- Investigate using Flatpak base apps to share common dependencies
+- Optimize PyInstaller exclusions to reduce bundle size
+- Consider using separate extension packages for optional components
+
+### 3. Sandboxing Limitations
+
+**Issue**: Some advanced features may be limited by Flatpak's security model.
+
+**Specific Areas**:
+- Access to certain system hardware may be restricted
+- Network printer discovery might be limited
+- Serial/USB device access requires additional permissions
+
+**Future Work**:
+- Fine-tune permissions based on user feedback
+- Implement portal-based solutions where appropriate
+- Document any feature limitations clearly
+
+### 4. Distribution and Updates
+
+**Issue**: Currently builds local Flatpak packages, not distributed through a repository.
+
+**Impact**: Users must build locally, no automatic updates.
+
+**Future Work**:
+- Publish to Flathub or other Flatpak repositories
+- Implement automatic update mechanisms
+- Provide signed packages for security
+
+## Performance Considerations
+
+### Startup Time
+
+**Current**: PyInstaller applications can have slower startup times due to unpacking.
+
+**Mitigation**: Most impact is only on first startup; subsequent launches benefit from filesystem caching.
+
+### Resource Usage
+
+**Current**: Flatpak adds some memory overhead for sandboxing.
+
+**Mitigation**: Modern systems typically have sufficient resources; benefits of isolation outweigh costs.
+
+## Testing Coverage
+
+### Tested Platforms
+- ✅ Ubuntu 22.04 (development environment)
+
+### Needs Testing
+- Other Ubuntu versions (20.04, 24.04)
+- Fedora (38, 39, 40)
+- Arch Linux
+- openSUSE
+- Other distributions with Flatpak support
+
+### Test Areas
+- Basic application functionality
+- File format support and import/export
+- Printer connectivity and management
+- Plugin system functionality
+- System integration (file associations, etc.)
+
+## Future Improvements
+
+### Short Term (Next Release)
+
+1. **CI Integration**: Add Flatpak build to GitHub Actions workflow
+2. **Error Handling**: Improve error messages in build script
+3. **Documentation**: Add troubleshooting guides for common issues
+4. **Testing**: Expand testing coverage to more distributions
+
+### Medium Term (Next 2-3 Releases)
+
+1. **Repository Publishing**: Submit to Flathub for distribution
+2. **Size Optimization**: Reduce package size through better bundling
+3. **Feature Parity**: Ensure all Cura features work within Flatpak sandbox
+4. **Performance**: Optimize startup time and resource usage
+
+### Long Term
+
+1. **Modular Architecture**: Split into base app + extensions for optional features
+2. **Shared Dependencies**: Use Flatpak extension system for common libraries
+3. **Advanced Integration**: Better system integration while maintaining security
+4. **Alternative Runtimes**: Evaluate different base runtimes for optimization
+
+## Development Workflow Integration
+
+### Current Process
+
+The Flatpak build now follows the same process as AppImage:
+1. Use Conan to install and build all dependencies
+2. Use PyInstaller to create the application distribution
+3. Package the PyInstaller output with Flatpak
+
+### Integration Points
+
+1. **Shared Dependencies**: Uses the same Conan packages as AppImage
+2. **Same Build Tools**: Uses PyInstaller like other Cura packages
+3. **Consistent Metadata**: Shares desktop files, icons, and AppData
+4. **Version Alignment**: Uses the same versioning scheme
+
+## Community Feedback Areas
+
+We are particularly interested in feedback on:
+
+1. **Build Process**: Is it easy enough to build locally?
+2. **Feature Completeness**: Are there missing features compared to other packages?
+3. **Performance**: How does it compare to native packages?
+4. **Distribution Compatibility**: Does it work on your Linux distribution?
+5. **Integration**: How well does it integrate with your desktop environment?
+
+## Contributing
+
+To help improve the Flatpak packaging:
+
+1. **Test on Different Distributions**: Try building and running on various Linux distros
+2. **Report Issues**: File GitHub issues for any problems encountered
+3. **Optimize Build Process**: Suggest improvements to the build scripts
+4. **Documentation**: Help improve documentation and troubleshooting guides
+
+## Technical Debt
+
+### Areas for Refactoring
+
+1. **Build Script**: The current build.sh could be modularized for better maintainability
+2. **Error Handling**: More graceful handling of build failures
+3. **Configuration**: Better support for customizing build options
+4. **Logging**: Improved logging and debugging capabilities
+
+### Code Quality
+
+1. **Testing**: Automated testing of the build process
+2. **Validation**: Validation of the final Flatpak package
+3. **Documentation**: Inline documentation in scripts and manifests