eglQuerySurface - EGL Reference Pages

Name

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_GL_COLORSPACE + +: +
+ Returns the color space used by OpenGL and OpenGL ES + when rendering to the surface, either + EGL_GL_COLORSPACE_SRGB or + EGL_GL_COLORSPACE_LINEAR. +
+
+ + 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_VG_ALPHA_FORMAT + +: +
+ Returns the interpretation of alpha values used by + OpenVG when rendering to the surface, either + EGL_VG_ALPHA_FORMAT_NONPRE or + EGL_VG_ALPHA_FORMAT_PRE. +
+
+ + EGL_VG_COLORSPACE + +: +
+ Returns the color space used by OpenVG when rendering to + the surface, either + EGL_VG_COLORSPACE_sRGB or + EGL_VG_COLORSPACE_LINEAR. +
+
+ + EGL_WIDTH + +: +
+ Returns the width of the surface in pixels. +
+

Notes

+ Attribute EGL_GL_COLORSPACE is supported + only if the EGL version is 1.5 or greater. +

+ 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. +