2003-2014
The Khronos Group Inc.
eglQuerySurface
3G
eglQuerySurface
return EGL surface information
C Specification
EGLBoolean eglQuerySurface
EGLDisplay display
EGLSurface surface
EGLint attribute
EGLint * value
Parameters
display
Specifies the EGL display connection.
surface
Specifies the EGL surface to query.
attribute
Specifies the EGL surface attribute to be returned.
value
Returns the requested value.
Description
eglQuerySurface returns in
value the value of
attribute for surface.
attribute can be one of the following:
EGL_CONFIG_ID
Returns the ID of the EGL frame buffer configuration
with respect to which the surface was created.
EGL_HEIGHT
Returns the height of the surface in pixels.
EGL_HORIZONTAL_RESOLUTION
Returns the horizontal dot pitch of the display on
which a window surface is visible. The value
returned is equal to the actual dot pitch, in
pixels/meter, multiplied by the constant value
EGL_DISPLAY_SCALING.
EGL_LARGEST_PBUFFER
Returns the same attribute value specified when the
surface was created with
eglCreatePbufferSurface.
For a window or pixmap surface,
value is not modified.
EGL_MIPMAP_LEVEL
Returns which level of the mipmap to render to, if
texture has mipmaps.
EGL_MIPMAP_TEXTURE
Returns EGL_TRUE if texture has
mipmaps, EGL_FALSE otherwise.
EGL_MULTISAMPLE_RESOLVE
Returns the filter used when resolving the
multisample buffer. The filter may be either
EGL_MULTISAMPLE_RESOLVE_DEFAULT
or EGL_MULTISAMPLE_RESOLVE_BOX,
as described for
eglSurfaceAttrib.
EGL_PIXEL_ASPECT_RATIO
Returns the aspect ratio of an individual pixel (the
ratio of a pixel's width to its height). The value
returned is equal to the actual aspect ratio
multiplied by the constant value
EGL_DISPLAY_SCALING.
EGL_RENDER_BUFFER
Returns the buffer which client API rendering is
requested to use. For a window surface, this is the
same attribute value specified when the surface was
created. For a pbuffer surface, it is always
EGL_BACK_BUFFER. For a pixmap
surface, it is always
EGL_SINGLE_BUFFER. To determine
the actual buffer being rendered to by a context,
call
eglQueryContext.
EGL_SWAP_BEHAVIOR
Returns the effect on the color buffer when posting
a surface with
eglSwapBuffers.
Swap behavior may be either
EGL_BUFFER_PRESERVED or
EGL_BUFFER_DESTROYED, as
described for
eglSurfaceAttrib.
EGL_TEXTURE_FORMAT
Returns format of texture. Possible values are
EGL_NO_TEXTURE,
EGL_TEXTURE_RGB, and
EGL_TEXTURE_RGBA.
EGL_TEXTURE_TARGET
Returns type of texture. Possible values are
EGL_NO_TEXTURE, or
EGL_TEXTURE_2D.
EGL_VERTICAL_RESOLUTION
Returns the vertical dot pitch of the display on
which a window surface is visible. The value
returned is equal to the actual dot pitch, in
pixels/meter, multiplied by the constant value
EGL_DISPLAY_SCALING.
EGL_WIDTH
Returns the width of the surface in pixels.
Notes
Attribute EGL_MULTISAMPLE_RESOLVE is
supported only if the EGL version is 1.4 or greater.
Attributes EGL_DISPLAY_SCALING.
EGL_HORIZONTAL_RESOLUTION,
EGL_PIXEL_ASPECT_RATIO,
EGL_RENDER_BUFFER,
EGL_SWAP_BEHAVIOR, and
EGL_VERTICAL_RESOLUTION are supported
only if the EGL version is 1.2 or greater.
Querying attributes EGL_TEXTURE_FORMAT,
EGL_TEXTURE_TARGET,
EGL_MIPMAP_TEXTURE, or
EGL_MIPMAP_LEVEL for a non-pbuffer
surface is not an error, but value is
not modified.
EGL_DISPLAY_SCALING is the constant
value 10000. Floating-point values such as resolution and
pixel aspect ratio are scaled by this value before being
returned as integers so that sufficient precision to be
meaningful will be retained in the returned value.
For an offscreen (pbuffer or pixmap) surface, or a surface
whose pixel dot pitch or aspect ratio are unknown, querying
EGL_HORIZONTAL_RESOLUTION,
EGL_PIXEL_ASPECT_RATIO, or
EGL_VERTICAL_RESOLUTION will return the
constant value EGL_UNKNOWN (-1).
Errors
EGL_FALSE is returned on failure,
EGL_TRUE otherwise.
value is not modified when
EGL_FALSE is returned.
EGL_BAD_DISPLAY is generated if
display is not an EGL display connection.
EGL_NOT_INITIALIZED is generated if
display has not been initialized.
EGL_BAD_SURFACE is generated if
surface is not an EGL surface.
EGL_BAD_ATTRIBUTE is generated if
attribute is not a valid surface attribute.
See Also
eglCreatePbufferSurface,
eglCreatePixmapSurface,
eglCreateWindowSurface,
eglSurfaceAttrib,
eglSwapBuffers