EGL +Functions with Symbian-Specific Behavior

The functions that have Symbian-specific behavior are:

eglQueryString()
eglCreatePixmapSurface()
eglChooseConfig()
eglSurfaceAttrib()

eglQueryString() const char *eglQueryString( + EGLDisplay dpy, + EGLint name)

When name is EGL_EXTENSIONS, +the function returns the list of extensions supported by the implementation. +The platform-specific strings are as follows:

+ + + +String +Description + + + + +

EGL_SYMBIAN_COMPOSITION

Indicates that the ScreenPlay variant is in use.

+ + +

EGL_KHR_reusable_sync

Indicates that the EGL reusable sync extension is supported.

+ + +EGL_NOK_resource_profiling +

Indicates that the EGL resource profiling extension is supported.

+ + +EGL_NOK_resource_profiling2 +

Indicates that the EGL resource profiling2 extension is supported.

+ + + +

Example

if ( NULL == strstr(eglQueryString(display, EGL_EXTENSIONS), "EGL_SYMBIAN_COMPOSITION") ) + { + RDebug::Printf("ScreenPlay not in use."); + error = KErrNotSupported; + }

eglCreatePixmapSurface() EGLSurface eglCreatePixmapSurface( + EGLDisplay dpy, + EGLConfig config, + EGLNativePixmapType pixmap, + const EGLint *attrib_list)

EGLNativePixmapType is +a CFbsBitmap* . See Symbian-Specific +Behavior for more information.

You must choose <config> using +the attribute EGL_MATCH_NATIVE_PIXMAP when calling eglChooseConfig() in +order to ensure compatibility with the Symbian pixmap.

Preconditions

<pixmap> has +been initialized.
The EGL_VG_ALPHA_FORMAT attribute +must be set to EGL_VG_ALPHA_FORMAT_PRE if the following conditions +are all true:
- The pixel format of <pixmap> specifies +premultiplied alpha—such as EColor16MAP.
- The EGL_RENDERABLE_TYPE of <config> includes EGL_OPENVG_BIT.

Error conditions

+ + + +Error +Description + + + + +

EGL_NO_SURFACE

Returned if any of the preconditions are violated.

+ + +

EGL_BAD_NATIVE_PIXMAP

Error generated when <pixmap> is not initialized.

+ + +

EGL_BAD_MATCH

Error generated when any of the following occur:

The attributes of <pixmap> do +not correspond to those of <config>.
<config> does +not support rendering to pixmaps (the EGL_SURFACE_TYPE attribute +does not contain the EGL_PIXMAP_BIT).
The EGL_VG_ALPHA_FORMAT attribute +is not set to EGL_VG_ALPHA_FORMAT_PRE for the cases described +in the preconditions section above.

+ + + +

eglChooseConfig() EGLBoolean eglChooseConfig( + EGLDisplay dpy, + const EGLint *attrib_list, + EGLConfig *configs, + EGLint config_size, + EGLint *num_config)

The EGLNativePixmapType value +corresponding to the EGL_MATCH_NATIVE_PIXMAP attribute is CFbsBitmap*. +See Symbian-Specific +Behavior for more information.

The configuration attribute EGL_SWAP_BEHAVIOR_PRESERVED_BIT is +set by default on window surfaces. This bit is not relevant to pixmap and +pbuffer surfaces because they are single-buffered.

Postconditions

The +following apply to the EGLNativePixmapType value only.

The EGL_SURFACE_TYPE of +each matching config contains EGL_VG_ALPHA_FORMAT_PRE_BIT if +the following conditions are all true:
- The pixel format of +the pixmap specifies premultiplied alpha—such as EColor16MAP.
- The EGL_RENDERABLE_TYPE of +the config includes EGL_OPENVG_BIT.

Note: The EGL_RENDERABLE_TYPE can be used +as an input to eglChooseConfig() to further filter the set +of configs returned.

eglSurfaceAttrib()EGLBoolean eglSurfaceAttrib( + EGLDisplay dpy, + EGLSurface surface, + EGLint attribute, + EGLint value);

If the attribute is EGL_SWAP_BEHAVIOR, +the value can be one of the following:.

EGL_BUFFER_DESTROYED: Indicates that posting a surface +with eglSwapBuffers() changes or destroys the back buffer +content.
EGL_BUFFER_PRESERVED: Indicates that posting a surface +with eglSwapBuffers() preserves the back buffer content.

The preserve buffer feature is relevant only to window surfaces. +It is not relevant to pbuffer or pixmap surfaces because they are single-buffered. +Therefore setting the swap behavior to preserve buffer is not allowed for +these surface types, as shown in the following table.

+Configuration behaviors + + + +Configuration Mask +Default EGL_SWAP_BEHAVIOR +Set Destroyed Allowed? +Set Preserved Allowed? + + + + +EGL_SWAP_BEHAVIOR_PRESERVED_BIT|EGL_WINDOW_BIT +Destroyed +Yes +Yes + + +EGL_WINDOW_BIT +Destroyed +Yes +Yes + + + EGL_PIXMAP_BIT +Preserved +Yes +No + + + EGL_PBUFFER_BIT +Preserved +Yes +No + + + +

Error conditions

This applies to attempting to set +the EGL_SWAP_BEHAVIOR attribute to EGL_BUFFER_PRESERVED. +If the surface configuration does not match EGL_SWAP_BEHAVIOR_PRESERVED_BIT, +this function returns EGL_FALSE and generates an error of EGL_BAD_MATCH.