added fotn change API and examples

README.md

@@ -25,6 +25,7 @@ PyWebLayout is a Python library for HTML-like layout and rendering to paginated
 ### Text and HTML Support
 - 📝 **HTML Parsing** - Parse HTML content into structured document blocks
 - 🔤 **Font Support** - Multiple font sizes, weights, and styles
+- 🎨 **Dynamic Font Families** - Switch between Sans, Serif, and Monospace fonts on-the-fly
 - ↔️ **Text Alignment** - Left, center, right, and justified text
 - 📖 **Rich Content** - Headings, paragraphs, bold, italic, and more
 - 📊 **Table Rendering** - Full HTML table support with headers, borders, and styling
@@ -138,6 +139,13 @@ The library supports various page layouts and configurations:
       <em>All 14 form field types with validation</em>
     </td>
   </tr>
+  <tr>
+    <td align="center" colspan="2">
+      <b>🆕 Dynamic Font Family Switching</b><br>
+      <img src="docs/images/font_family_switching_vertical.png" width="600" alt="Font Switching"><br>
+      <em>Switch between Sans, Serif, and Monospace fonts instantly</em>
+    </td>
+  </tr>
 </table>
 
 ## Examples
@@ -151,11 +159,13 @@ The `examples/` directory contains working demonstrations:
 - **[04_table_rendering.py](examples/04_table_rendering.py)** - HTML table rendering with styling
 - **[05_html_table_with_images.py](examples/05_html_table_with_images.py)** - Tables with embedded images
 - **[06_functional_elements_demo.py](examples/06_functional_elements_demo.py)** - Interactive buttons and forms with callbacks
+- **[08_bundled_fonts_demo.py](examples/08_bundled_fonts_demo.py)** - Using the bundled DejaVu font families
 
 ### 🆕 Advanced Features (NEW)
 - **[08_pagination_demo.py](examples/08_pagination_demo.py)** - Multi-page documents with PageBreak ([11 tests](tests/examples/test_08_pagination_demo.py))
 - **[09_link_navigation_demo.py](examples/09_link_navigation_demo.py)** - All link types and navigation ([10 tests](tests/examples/test_09_link_navigation_demo.py))
 - **[10_forms_demo.py](examples/10_forms_demo.py)** - All 14 form field types ([9 tests](tests/examples/test_10_forms_demo.py))
+- **[11_font_family_switching_demo.py](examples/11_font_family_switching_demo.py)** - 🆕 Dynamic font switching in ereader
 
 Run any example:
 ```bash
@@ -176,9 +186,46 @@ python -m pytest tests/examples/ -v  # 30 tests, all passing ✅
 
 See **[examples/README.md](examples/README.md)** for detailed documentation.
 
+## Font Family Switching (NEW ✨)
+
+PyWebLayout now supports dynamic font family switching in the ereader, allowing readers to change fonts on-the-fly without losing their reading position!
+
+### Quick Example
+
+```python
+from pyWebLayout.style.fonts import BundledFont
+from pyWebLayout.layout.ereader_manager import create_ereader_manager
+
+# Create an ereader
+manager = create_ereader_manager(blocks, page_size=(600, 800))
+
+# Switch to serif font
+manager.set_font_family(BundledFont.SERIF)
+
+# Switch to monospace font
+manager.set_font_family(BundledFont.MONOSPACE)
+
+# Restore original fonts
+manager.set_font_family(None)
+
+# Query current font
+current = manager.get_font_family()
+```
+
+### Features
+
+- **3 Bundled Fonts**: Sans, Serif, and Monospace (DejaVu font family)
+- **Instant Switching**: Change fonts without recreating the document
+- **Position Preservation**: Reading position maintained across font changes
+- **Attribute Preservation**: Bold, italic, size, and color are preserved
+- **Smart Caching**: Automatic cache invalidation for optimal performance
+
+**Learn more**: See [FONT_SWITCHING_FEATURE.md](FONT_SWITCHING_FEATURE.md) for complete documentation.
+
 ## Documentation
 
 - **[ARCHITECTURE.md](ARCHITECTURE.md)** - Abstract/Concrete architecture guide
+- **[FONT_SWITCHING_FEATURE.md](FONT_SWITCHING_FEATURE.md)** - 🆕 Font family switching guide
 - **[examples/README.md](examples/README.md)** - Complete examples guide with tests
 - **[docs/images/README.md](docs/images/README.md)** - Visual documentation index
 - **[pyWebLayout/layout/README_EREADER_API.md](pyWebLayout/layout/README_EREADER_API.md)** - EbookReader API reference