You may find that a pure free HMI graphics library lacks niche components (e.g., a specific model of a VFD or a bottling line capping machine).
Use the free library as a template layer. Take a generic "Motor" SVG from a free pack, duplicate it, and overlay a PNG of your specific motor brand. In many jurisdictions, this "derivative work" remains covered by the original free license.
| Library / Source | Main Format | License | Industrial-ready? | Cost | Best usage | |----------------|-------------|---------|-------------------|------|-------------| | Qt Quick Controls | QML/C++ | (L)GPL | Medium (basic) | Free for open-source | Embedded, cross-platform | | Material/Iconfiy SVG | SVG | MIT | High (if icons exist) | Free | Any HMI (via image assets) | | HMI Project (GitHub) | SVG + XML | MIT | Medium (some assets) | Free | Python Tk/PyQt proof-of-concept | | OpenSCADA widgets | SVG | GPL | High (process mimics) | Free | Linux SCADA systems | | Apache ECharts | JS/Canvas | Apache 2.0 | Medium (gauges only) | Free | Web-based HMI dashboards |
| Criterion | Weight | Description | |-----------|--------|-------------| | License compatibility | High | Allows commercial use? Requires attribution? Copyleft (GPL) risk? | | Quality & scalability | High | Vector (SVG) vs raster; resolution independence; anti-aliasing | | Platform compatibility | Medium | Works with common HMI runtimes (C++, Python, C#, Web) | | Customizability | Medium | Source SVG/PSD files available; styling via CSS/QSS/XML | | Documentation & examples | Low | Clear API, demo projects | | Maintenance & community | Low | Recent commits, active forum, issue tracking |
Since truly complete and free off-the-shelf HMI libraries are rare, the most practical approach combines:
When selecting a library, evaluate these criteria:
| Feature | Why It Matters | |--------|----------------| | Vector format (SVG) | Scales from 2" to 4K without pixelation | | State-based styling | Shows “pump running” (green) vs “alarm” (red) without swapping images | | Touch-friendly sizing | Minimum 40×40px hit area for finger operation | | Tool compatibility | Works with Ignition Maker, Grafana, Node-RED, FUXA, or your custom Web HMI | | No restrictive license | Avoid GPL if building proprietary hardware – prefer MIT, CC0, or Apache 2.0 |