diff -r ebc84c812384 -r 46218c8b8afa Symbian3/PDK/Source/GUID-41802B91-26B3-5F3C-AE04-B6954F3804B7.dita --- a/Symbian3/PDK/Source/GUID-41802B91-26B3-5F3C-AE04-B6954F3804B7.dita Thu Mar 11 15:24:26 2010 +0000 +++ b/Symbian3/PDK/Source/GUID-41802B91-26B3-5F3C-AE04-B6954F3804B7.dita Thu Mar 11 18:02:22 2010 +0000 @@ -1,87 +1,87 @@ - - - - - -Scene -ElementsThis topic provides an introduction to the concept of scene -elements within the context of graphics composition. Scene elements are -sometimes referred to as layers. -

Variant: ScreenPlay. Target audience: Device creators.

-

Within a composition scene, elements map surfaces to screen rectangles. -Depth ordering (z-order) is used to resolve how the elements overlap each -other. The elements support some basic pixel rectangle transformations such -as scaling and rotation in 90 degree increments.

-

The following diagram shows the three elements in a video telephony use -case. The uppermost element (with a red border) contains the UI content (called -the UI surface). This is semi-transparent and is owned by the Window Server. -The next element down is the camera viewfinder (green border). The surface -associated with this element is owned by the camera. The final element (blue -border) shows a video of the caller. The surface associated with this element -is owned by the video renderer.

- - The elements in a video telephony use case - - -

A similar principle applies when a game is running on the phone. The semi-transparent -UI surface would overlay the element containing the EGL-owned surface. When -the game or a video is in full screen mode, the composition engine can enter fast -path mode. This indicates to the LCD controller that there is no UI content -to blend with the background element.

- - Fast path mode - - -

-

The z-order of an element is determined by its position in the list of -elements. Several additional pieces of positional information are stored as -element metadata. The element maps the surface to the device screen. More -specifically it maps a part of the surface, the source rectangle, to -a destination rectangle on the screen. The destination rectangle defines -the position and size of the element itself.

- - Element terminology - - -

The source rectangle corresponds to the viewport in the Window Server -documentation and the destination rectangle corresponds to the extent.

-

The source and destination rectangles do not have to be the same size—the -composition engine can clip or scale the data to fit.

-

The following concepts are related to elements:

- -

This distinction between the scene structure and scene content is important. -The architecture is split so that the Window Server deals only with the scene -structure and UI content and not with the scene content. This allows optimal -data and control paths. For example, it has the advantage that the Window -Server does not need to take any action when the content of a video surface -changes but the UI does not change.

-

The components in the Graphics Composition collection are divided between -those that manage the scene structure and those that manage scene content:

- - - -Composition -Concepts -Graphics -Composition Collection Overview + + + + + +Scene +ElementsThis topic provides an introduction to the concept of scene +elements within the context of graphics composition. Scene elements are +sometimes referred to as layers. +

Variant: ScreenPlay. Target audience: Device creators.

+

Within a composition scene, elements map surfaces to screen rectangles. +Depth ordering (z-order) is used to resolve how the elements overlap each +other. The elements support some basic pixel rectangle transformations such +as scaling and rotation in 90 degree increments.

+

The following diagram shows the three elements in a video telephony use +case. The uppermost element (with a red border) contains the UI content (called +the UI surface). This is semi-transparent and is owned by the Window Server. +The next element down is the camera viewfinder (green border). The surface +associated with this element is owned by the camera. The final element (blue +border) shows a video of the caller. The surface associated with this element +is owned by the video renderer.

+ + The elements in a video telephony use case + + +

A similar principle applies when a game is running on the phone. The semi-transparent +UI surface would overlay the element containing the EGL-owned surface. When +the game or a video is in full screen mode, the composition engine can enter fast +path mode. This indicates to the LCD controller that there is no UI content +to blend with the background element.

+ + Fast path mode + + +

+

The z-order of an element is determined by its position in the list of +elements. Several additional pieces of positional information are stored as +element metadata. The element maps the surface to the device screen. More +specifically it maps a part of the surface, the source rectangle, to +a destination rectangle on the screen. The destination rectangle defines +the position and size of the element itself.

+ + Element terminology + + +

The source rectangle corresponds to the viewport in the Window Server +documentation and the destination rectangle corresponds to the extent.

+

The source and destination rectangles do not have to be the same size—the +composition engine can clip or scale the data to fit.

+

The following concepts are related to elements:

+
    +

  • Scene structure

    A +set of elements, all with a specific size, visible region and z-order, which +when composed form an entire scene.

    • +

  • Scene content

    A +set of surfaces bound with elements that contain the pixels to be composed +according to the structure described by the scene structure.

    • +
+

This distinction between the scene structure and scene content is important. +The architecture is split so that the Window Server deals only with the scene +structure and UI content and not with the scene content. This allows optimal +data and control paths. For example, it has the advantage that the Window +Server does not need to take any action when the content of a video surface +changes but the UI does not change.

+

The components in the Graphics Composition collection are divided between +those that manage the scene structure and those that manage scene content:

+
    +

  • The composition engine +manages scene structure. This means that the composition engine mainly deals +in elements and dictates how the scene is composed.

    • +

  • The Surface Manager +and the Surface Update Server manage scene content. This means that they mainly +deal in surfaces.

    • +
+ + +Composition +Concepts +Graphics +Composition Collection Overview \ No newline at end of file