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+# lib_ui
+
+A cross-platform C++/Qt UI framework library — part of the [Desktop App Toolkit](https://github.com/desktop-app) used to build [Telegram Desktop](https://github.com/telegramdesktop/tdesktop).
+
+`lib_ui` provides the foundational UI layer: reusable widgets, a custom styling/theming engine, rich text rendering, animations, emoji support, OpenGL rendering, and platform-specific window management.
+
+## Architecture Overview
+
+```
+lib_ui/
+├── ui/
+│   ├── widgets/        # Core UI components (buttons, inputs, menus, scrolling, etc.)
+│   ├── effects/        # Animation system (fade, slide, ripple, radial, spoiler, etc.)
+│   ├── text/           # Rich text engine with BiDi, entities, custom emoji
+│   ├── style/          # Custom theming via .style/.palette DSL (colors, fonts, icons, scaling)
+│   ├── layers/         # Overlay/dialog system (box content, layer manager)
+│   ├── platform/       # Platform-specific code (Windows, macOS, Linux)
+│   ├── gl/             # OpenGL rendering (shaders, surfaces, primitives)
+│   ├── paint/          # Paint helpers (blob animations, arcs)
+│   ├── wrap/           # Layout wrappers (vertical, table, slide, fade, padding)
+│   ├── toast/          # Toast notification system
+│   ├── accessible/     # Accessibility (screen reader support)
+│   ├── image/          # Image preparation and processing
+│   └── dpr/            # Device pixel ratio aware icons/images
+├── emoji_suggestions/  # Emoji autocomplete engine + dataset
+├── emoji_old/          # Legacy emoji data files (data3–data7)
+├── fonts/              # Bundled fonts (OpenSans, Vazirmatn)
+├── icons/              # UI icons with @1x/@2x/@3x HiDPI variants
+├── cmake/              # Code generators for palette, styles, and emoji
+├── qt_conf/            # Qt/GPU driver config for Windows (win.qrc)
+├── emoji.txt           # Emoji source data for code generation
+└── CMakeLists.txt
+```
+
+## Key Modules
+
+### Widgets (`ui/widgets/`)
+Ready-to-use UI components: buttons, checkboxes, labels, input fields (text, password, number, time), dropdown and popup menus, scroll areas, tooltips, separate panels, and more.
+
+### Effects & Animations (`ui/effects/`)
+A rich animation system including fade, slide, ripple, radial, cross, panel, and show animations. Also provides gradient utilities, spoiler effects, and a frame generator.
+
+### Text Rendering (`ui/text/`)
+Full-featured text engine supporting BiDi (right-to-left) layout, text entities (bold, italic, links, etc.), custom emoji rendering, word-level parsing, and a stack-based layout engine.
+
+### Styling & Theming (`ui/style/`)
+Custom DSL-based theming system using `.style` and `.palette` files. Manages colors, fonts, icons, DPI scaling, and supports runtime palette colorization for theme switching.
+
+### Platform Integration (`ui/platform/`)
+Native window management for each OS:
+- **Windows** — custom title bar, window shadows, direct manipulation, native event filters
+- **macOS** — native window and title bar integration (Objective-C++)
+- **Linux** — window and title bar support
+
+### OpenGL (`ui/gl/`)
+GPU-accelerated rendering with shader management, GL surfaces, image rendering, and math utilities.
+
+### Emoji (`emoji_suggestions/`)
+Autocomplete engine that suggests emoji as users type. Powered by a comprehensive JSON dataset.
+
+## Build System
+
+`lib_ui` is built as a **static CMake library** and uses Qt's `AUTOMOC` for meta-object compilation. It includes custom CMake scripts that generate:
+
+- **Palette code** from `ui/colors.palette`
+- **Style code** from `.style` files
+- **Emoji data** from `emoji.txt` and `emoji_autocomplete.json`
+
+## Dependencies
+
+| Dependency | Linkage | Purpose |
+|---|---|---|
+| `desktop-app::lib_base` | Public | Core base library |
+| zlib | Private | Compression |
+| libjpeg | Private | JPEG image handling |
+| lz4 | Private | Fast compression |
+| xxhash | Private | Hashing |
+| ANGLE | Private | OpenGL ES on Windows (Qt < 6 only) |
+
+## Bundled Fonts
+
+- **OpenSans** — Regular, Italic, SemiBold, SemiBold Italic
+- **Vazirmatn UI NL** — Regular, SemiBold (for Persian/RTL text)
+
+Packaged font usage can be toggled via the `DESKTOP_APP_USE_PACKAGED_FONTS` CMake option.
+
+## License
+
+For license and copyright information, see [desktop-app/legal](https://github.com/desktop-app/legal/blob/master/LEGAL).