OpenWF -Composition Interface Overview

OpenWF -Composition Interface OverviewThe OpenWF Composition Interface Component provides the Symbian -platform with a consistent interface to the open-source, cross-platform OpenWF -Composition (OpenWF-C) APIs defined by the Khronos Group. The OpenWF-C Interface -component includes the Khronos-released header files and some Symbian-specific -files. It does not provide any implementations of the APIs. -

Target audience: Device creators.

Introduction to OpenWF-C on Symbian

OpenWF-C provides -a hardware abstraction layer that allows power-efficient hardware-accelerated -composition on a wide variety of hardware platforms including blitter (memory-memory) -and overlay (memory-less) hardware. OpenWF-C is particularly aimed at systems -with limited memory bandwidth, such as mobile devices. OpenWF-C enables the -UI and the window system stack to be independent of the hardware used to achieve -the composition.

OpenWF-C uses a number of opaque handle types (WFCHandle) -to represent the following key concepts:

Device. An abstract -device that is capable of performing composition operations. Typically this -corresponds to a unit of graphics hardware. All composition operations and -resources are associated with a device. The WFCDevice subtype -represents an opaque handle to a device.
Context. A visual -description of a scene that is applied to a specific target. The context represents -the state required for the composition of the scene. A context can be on-screen -or off-screen but only one on-screen context per screen can render. The WFCContext subtype -represents an opaque handle to a composition context.
Element. Represents -the positioning and other attributes of content within the composition context. -An element is sometimes referred to as a layer. The WFCElement subtype -represents an opaque handle to an element.
Source. Supplies -the image data that an element can reference as the primary source of its -color data. A source is created from a stream. The WFCSource subtype -represents an opaque handle to a source.
Stream. A container -for multiple image buffers that share the same properties. Streams encapsulate -the queuing state of the internal buffers. Streams are used for both input -and output pixel data and can be connected to multiple contexts simultaneously. -Ultimately renderers use streams to pass image data to the composition engine. -The stream format is defined as platform-specific. Streams are therefore sometimes -referred to as native streams. The WFCNativeStreamType subtype -represents the opaque handle to a stream.

Note: The OpenWF-C APIs are system-level APIs and are not -intended for use by application developers.

Architectural relationships

The following diagram -shows the key OpenWF-C architectural component relationships within the Symbian -platform.

- OpenWF-C and related Symbian platform components - - -

Window -Server. The Symbian window management and rendering component.
Render -Stages. An abstraction layer below the Window Server.
OpenWF-C -Engine. The implementation of the OpenWF-C interface.
OpenWF-C -Support. Abstracts communication between the OpenWF-C engine and the -Surface Manager, Surface Update Server and the render stage framework and -provides a reference implementation of native stream in terms of Symbian composition surfaces.
Surface -Manager. Allocates and manages the lifetime and use of composition -surfaces in system memory. Composition surfaces are identified by a 128-bit -identifier (TSurfaceId).
Surface -Update Server. Provides a communication mechanism between the composition -engine and its clients.
Display -Driver. Low-level abstraction of display hardware.
EGL (not -shown on diagram). The OpenWF-C engine and support components use EGL sync -objects for synchronization. In addition OpenWF-C clients obtain any extension -functions that the engine implements by using the EGL function, eglGetProcAddress().

Description

OpenWF-C is a standard defined by the -Khronos Group (www.khronos.org) -which defines a C API. The following table provides a link to the relevant -specification.

- - - -API -Specification - - - - -OpenWF-C 1.0 - http://www.khronos.org/registry/wf/specs/OpenWF_Composition_1_0_Specification.pdf - - - -

Header files

The OpenWF-C Interface component includes -the Khronos-released header files shown in the following table. Use of these -standard header files helps to ensure binary compatibility for applications -across different Symbian platforms. It also provides source compatibility -between different operating systems.

- - - -Filename -Description - - - - -wfc.h -Type definitions and function prototypes. - - -wfcext.h -Defines additional values, functions and data types that may be available -on a platform. - - -wfcplatform.h -Platform-specific elements of the specification. - - -openwfcuids.hrh -Symbian-defined constants for representing UIDs in MMP files and elsewhere. - - - - -

Library file

The OpenWF-C Interface component generates -a LIB file called libWFC.lib.

DEF files

The following definition (DEF) files -are delivered by the OpenWF-C Interface component in order to ensure binary -compatibility.

- - - -Platform -DEF file - - - - -ARM - /epoc32/include/platform/def/eabi/libWFCu.def - - -WINSCW - /epoc32/include/platform/def/win32/libWFCu.def - - - -

-OpenWF Composition - -Khronos -OpenWF Website -Khronos OpenWF White Paper + + + + + +OpenWF +Composition Interface OverviewThe OpenWF Composition Interface Component provides the Symbian +platform with a consistent interface to the open-source, cross-platform OpenWF +Composition (OpenWF-C) APIs defined by the Khronos Group. The OpenWF-C Interface +component includes the Khronos-released header files and some Symbian-specific +files. It does not provide any implementations of the APIs. +

Target audience: Device creators.

Introduction to OpenWF-C on Symbian

OpenWF-C provides +a hardware abstraction layer that allows power-efficient hardware-accelerated +composition on a wide variety of hardware platforms including blitter (memory-memory) +and overlay (memory-less) hardware. OpenWF-C is particularly aimed at systems +with limited memory bandwidth, such as mobile devices. OpenWF-C enables the +UI and the window system stack to be independent of the hardware used to achieve +the composition.

OpenWF-C uses a number of opaque handle types (WFCHandle) +to represent the following key concepts:

Device. An abstract +device that is capable of performing composition operations. Typically this +corresponds to a unit of graphics hardware. All composition operations and +resources are associated with a device. The WFCDevice subtype +represents an opaque handle to a device.
Context. A visual +description of a scene that is applied to a specific target. The context represents +the state required for the composition of the scene. A context can be on-screen +or off-screen but only one on-screen context per screen can render. The WFCContext subtype +represents an opaque handle to a composition context.
Element. Represents +the positioning and other attributes of content within the composition context. +An element is sometimes referred to as a layer. The WFCElement subtype +represents an opaque handle to an element.
Source. Supplies +the image data that an element can reference as the primary source of its +color data. A source is created from a stream. The WFCSource subtype +represents an opaque handle to a source.
Stream. A container +for multiple image buffers that share the same properties. Streams encapsulate +the queuing state of the internal buffers. Streams are used for both input +and output pixel data and can be connected to multiple contexts simultaneously. +Ultimately renderers use streams to pass image data to the composition engine. +The stream format is defined as platform-specific. Streams are therefore sometimes +referred to as native streams. The WFCNativeStreamType subtype +represents the opaque handle to a stream.

Note: The OpenWF-C APIs are system-level APIs and are not +intended for use by application developers.

Architectural relationships

The following diagram +shows the key OpenWF-C architectural component relationships within the Symbian +platform.

+ OpenWF-C and related Symbian platform components + + +

Window +Server. The Symbian window management and rendering component.
Render +Stages. An abstraction layer below the Window Server.
OpenWF-C +Engine. The implementation of the OpenWF-C interface.
OpenWF-C +Support. Abstracts communication between the OpenWF-C engine and the +Surface Manager, Surface Update Server and the render stage framework and +provides a reference implementation of native stream in terms of Symbian composition surfaces.
Surface +Manager. Allocates and manages the lifetime and use of composition +surfaces in system memory. Composition surfaces are identified by a 128-bit +identifier (TSurfaceId).
Surface +Update Server. Provides a communication mechanism between the composition +engine and its clients.
Display +Driver. Low-level abstraction of display hardware.
EGL (not +shown on diagram). The OpenWF-C engine and support components use EGL sync +objects for synchronization. In addition OpenWF-C clients obtain any extension +functions that the engine implements by using the EGL function, eglGetProcAddress().

Description

OpenWF-C is a standard defined by the +Khronos Group (www.khronos.org) +which defines a C API. The following table provides a link to the relevant +specification.

+ + + +API +Specification + + + + +OpenWF-C 1.0 + http://www.khronos.org/registry/wf/specs/OpenWF_Composition_1_0_Specification.pdf + + + +

Header files

The OpenWF-C Interface component includes +the Khronos-released header files shown in the following table. Use of these +standard header files helps to ensure binary compatibility for applications +across different Symbian platforms. It also provides source compatibility +between different operating systems.

+ + + +Filename +Description + + + + +wfc.h +Type definitions and function prototypes. + + +wfcext.h +Defines additional values, functions and data types that may be available +on a platform. + + +wfcplatform.h +Platform-specific elements of the specification. + + +openwfcuids.hrh +Symbian-defined constants for representing UIDs in MMP files and elsewhere. + + + + +

Library file

The OpenWF-C Interface component generates +a LIB file called libWFC.lib.

DEF files

The following definition (DEF) files +are delivered by the OpenWF-C Interface component in order to ensure binary +compatibility.

+ + + +Platform +DEF file + + + + +ARM + /epoc32/include/platform/def/eabi/libWFCu.def + + +WINSCW + /epoc32/include/platform/def/win32/libWFCu.def + + + +

+OpenWF Composition + +Khronos +OpenWF Website +Khronos OpenWF White Paper

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