1# Graphics Subsystem 2 3The Graphics subsystem mainly consists of user interface (UI) components, layout, animator, font, input event, window management, and rendering and drawing modules. It is an application framework that can be built on the LiteOS to develop OpenHarmony applications for Internet of Things (IoT) devices with limited hardware resources or on the standard OS to develop OpenHarmony applications for standard- and large-system devices. 4 5## Mini System 6 7### Introduction 8 9The Graphics subsystem mainly consists of UI components, layout, animator, font, input event, window management, and rendering and drawing modules. It is an application framework that can be built on the LiteOS to develop OpenHarmony applications for IoT devices with limited hardware resources. 10 11**Figure 1** Graphics subsystem architecture 12![](figures/graphics-subsystem-architecture.png "graphics subsystem architecture") 13 14The related modules are described as follows: 15 16- View: provides application components, including **UIView**, **UIViewGroup**, **UIButton**, **UILabel**, **UILabelButton**, **UIList**, and **UISlider**. 17- Animator: defines functions for customizing animations. 18- Layout: lays out components, including **FlexLayout**, **GridLayout**, and **ListLayout**. 19- Transform: rotates, translates, or scales images. 20- Event: processes basic events, including click, press, drag, and long press events. 21- Rendering engine: performs rendering and drawing operations. 22- 2D graphics library: draws 2D graphical elements including lines, rectangles, circles, arcs, images, and texts. Functions of this module include interconnection with the software drawing and hardware acceleration capabilities. 23- Multi-language: processes the line feed and shaping of texts in different languages. 24- Image library: parses and operates images of different types and formats, such as PNG, JPEG, ARGB8888, and ARGB565. 25- WindowManager: manages windows, including creating, showing, hiding, and combining windows. 26- InputManager: processes input events. 27 28### Directory Structure 29 30``` 31/foundation/arkui 32├── ui_lite # UI module, including UI components, animations, and fonts 33 34/foundation/graphic 35├── surface_lite # Shared memory 36├── graphic_utils_lite # Basic graphics library and hardware adaptation layer 37 38/foundation/window 39└── window_manager_lite # Window and input event management 40``` 41 42### Constraints 43 44- The Graphics subsystem does not support multi-thread concurrent operations. You are advised to perform related operations in UI threads. 45- The **utils/interfaces/innerkits/graphic\_config.h** file provides the configuration information about macro switches that can be used to enable or disable graphics features. You need to configure these switches before compilation. Note that some switches are configured depending on the platform. 46 47### Usage 48 49For details, see the README and **test** directory of each repository. 50 51### Repositories Involved 52 53**Graphics subsystem** 54 55[graphic\_surface_lite](https://gitee.com/openharmony/graphic_surface_lite) 56 57[arkui\_ui_lite](https://gitee.com/openharmony/arkui_ui_lite) 58 59[window\_window_manager_lite](https://gitee.com/openharmony/window_window_manager_lite) 60 61[graphic\_graphic_utils_lite](https://gitee.com/openharmony/graphic_graphic_utils_lite) 62 63## Standard System 64 65### Introduction 66 67The Graphics subsystem provides graphics APIs. 68 69The following figure shows the architecture of the Graphics subsystem. 70 71![Graphics subsystem architecture](figures/graphic_rosen_architecture.jpg) 72 73The OpenHarmony graphics stack is divided into the following layers: 74 75Interface layer: provides native APIs for the Graphics subsystem, including WebGL, native drawing, and OpenGL command-level drawing. 76 77Framework layer: consists of the Render Service, Drawing, Animation, Effect, and Display and Memory Management modules. 78| Module | Description | 79|------------------------|--------------------------------------------------------------------------------------------| 80| Render Service| Performs UI framework drawing. This module converts the ArkUI component description into drawing tree information and renders the optimal path based on the corresponding rendering policy. It also provides the core underlying mechanism for multi-window smoothness and spatial UI sharing. | 81| Drawing | Provides standard internal interfaces in the Graphics subsystem to implement 2D rendering, 3D rendering, and rendering engine management. | 82| Animation | Provides capabilities related to the animation engine. | 83| Effect | Processes image effects and rendering effects, including cascading and parallel processing of multiple effects, and adding rendering effects and component interaction effects during layout. | 84| Display and Memory Management | Decouples the graphics stack from hardware and provides OpenHarmony display and memory management. OEMs need to adapt the HDIs defined by this module.| 85 86Engine layer: consists of the 2D graphics library and 3D graphics engine. The 2D graphics library provides bottom-layer APIs for 2D graphics drawing (including text drawing). The 3D graphics engine capability is being developed. 87 88 89### Directory Structure 90 91``` 92foundation/graphic/standard/ 93├── figures # Images referenced by Markdown 94├── frameworks # Framework code 95│ ├── animation_server # Animation server code 96│ ├── bootanimation # Boot animation 97│ ├── dumper # Graphic dumper code 98│ ├── fence # Fence code 99│ ├── surface # Surface code 100│ ├── vsync # Vsync code 101├── rosen # Framework code 102│ ├── build # Build description 103│ ├── doc # doc 104│ ├── include # Code of external header files 105│ ├── lib # lib 106│ ├── modules # Graphic subsystem code, organized by module 107│ ├── samples # Sample code 108│ ├── test # Development and test code 109│ ├── tools # Tool code 110├── interfaces # Graphics APIs 111│ ├── innerkits # Native APIs 112│ └── kits # JS APIs and native APIs 113└── utils # Utilities 114``` 115 116### Constraints 117 118Programming language version: C++ 11 or later 119 120### Compilation and Building 121 122### Usage 123 124For details, see the README and **test** directory of each repository. 125 126### Repositories Involved 127 128**Graphics subsystem** 129 130- [**graphic_graphic_2d**](https://gitee.com/openharmony/graphic_graphic_2d) 131- [arkui_ace_engine](https://gitee.com/openharmony/arkui_ace_engine) 132- [ability_ability_runtime](https://gitee.com/openharmony/ability_ability_runtime) 133- [multimedia_player_framework](https://gitee.com/openharmony/multimedia_player_framework) 134- [multimedia_image_standard](https://gitee.com/openharmony/multimedia_image_standard) 135- [Windowmanager](https://gitee.com/openharmony/windowmanager) 136- [third_party_egl](https://gitee.com/openharmony/third_party_egl) 137- [third_party_opengles](https://gitee.com/openharmony/third_party_opengles) 138- [third_party_skia](https://gitee.com/openharmony/third_party_skia) 139- [third_party_giflib](https://gitee.com/openharmony/third_party_giflib) 140