The EGL Reference Implementation component implements the minimum EGL functionality to support OpenWF composition. It does not implement the EGL functionality required to support the use of the Khronos rendering APIs, such as OpenGL ES and OpenVG. Typically device creators replace the reference implementation with a fully functional implementation of their own.
Target audience: Device creators.
The EGL Reference Implementation implements the following EGL 1.4 APIs:
eglGetError()eglGetDisplay()eglInitialize()eglTerminate()eglReleaseThread()eglQueryString()eglGetProcAddress()The EGL Reference Implementation also implements the following reusable sync extension functions:
eglCreateSyncKHR()eglDestroySyncKHR()eglClientWaitSyncKHR()eglSignalSyncKHR()eglGetSyncAttribKHR()The Reference Implementation implements eglGetProcAddress() ,
which supports retrieving OpenWF-C extension functions.
Calling any
of the unsupported APIs panics the client with the EEglPanicNotSupported panic
code and the return value and EGL error code are undefined. This behavior
deliberately does not conform to the EGL specification. It is intended to
make it easy to detect errors in the platform configuration—for example, where
the intention was to use a fully-functional EGL implementation instead of
the Reference Implementation.
The Reference Implementation returns the following implementation-specific strings:
The Reference Implementation allows the supported EGL APIs to be used from multiple threads within the same process. The Reference Implementation maintains the process and thread state in order to conform to the correct behavior described in the EGL specification. Access to process-wide objects is serialized and protected by mutex to prevent race conditions.
The Reference Implementation
uses its own heap to allow the creation, access and destruction of process-wide
objects from any thread. This includes the EGLDisplay and EGLSync objects.
The heap is created in a local chunk.
For simplicity, the Reference
Implementation supports only one display: EGL_DEFAULT_DISPLAY.
A request to obtain any other EGLDisplay returns EGL_NO_DISPLAY. EGLDisplay is
a process-wide resource that can be accessed from any thread. Its behavior
follows the EGL specification for eglGetDisplay(), eglInitialize() and eglTerminate().
Each
client thread can have its own EGL error. Error handling and thread state
management follows the EGL specification for eglGetError() and eglReleaseThread().
| DLL | Description |
|---|---|
libegl_ref.dll |
The EGL reference implementation. |
libEGL.dll |
In the emulator, this provides a mechanism that switches among different EGL implementation DLLs used in different scenarios, including the Reference Implementation mentioned above. For ARM builds, the file above is renamed to this during the ROM build process. This is controlled by IBY files. |
To allow different EGL implementations to be used on a platform,
the Reference Implementation is built with a target name of libegl_ref.dll.
However, EGL Clients should link their code against libEGL.lib.
Emulator
To enable the
ScreenPlay OpenWF-C components and the EGL Reference Implementation in the
emulator, add the following lines to the \epoc32\data\epoc.ini file:
SYMBIAN_GRAPHICS_USE_OPENWF SYMBIAN_GRAPHICS_USE_EGL_REF