Chia-I WuNotes about the EGL library: The EGL code here basically consists of two things: 1. An EGL API dispatcher. This directly routes all the eglFooBar() API calls into driver-specific functions. 2. Fallbacks for EGL API functions. A driver _could_ implement all the EGL API calls from scratch. But in many cases, the fallbacks provided in libEGL (such as eglChooseConfig()) will do the job. Bootstrapping: When the apps calls eglOpenDisplay() a device driver is selected and loaded (look for dlsym() or LoadLibrary() in egldriver.c). The driver's _eglMain() function is then called. This driver function allocates, initializes and returns a new _EGLDriver object (usually a subclass of that type). As part of initialization, the dispatch table in _EGLDriver->API must be populated with all the EGL entrypoints. Typically, _eglInitDriverFallbacks() can be used to plug in default/fallback functions. Some functions like driver->API.Initialize and driver->API.Terminate _must_ be implemented with driver-specific code (no default/fallback function is possible). A bit later, the app will call eglInitialize(). This will get routed to the driver->API.Initialize() function. Any additional driver initialization that wasn't done in _eglMain() should be done at this point. Typically, this will involve setting up visual configs, etc. Special Functions: Certain EGL functions _must_ be implemented by the driver. This includes: eglCreateContext eglCreateWindowSurface eglCreatePixmapSurface eglCreatePBufferSurface eglMakeCurrent eglSwapBuffers Most of the EGLConfig-related functions can be implemented with the defaults/fallbacks. Same thing for the eglGet/Query functions. Teardown: When eglTerminate() is called, the driver->API.Terminate() function is called. The driver should clean up after itself. eglTerminate() will then close/unload the driver (shared library). Subclassing: The internal libEGL data structures such as _EGLDisplay, _EGLContext, _EGLSurface, etc should be considered base classes from which drivers will derive subclasses.