Class: TCompositingLayer

Declaration: CompositingLayer.h

Taxonomy Categories:

Member Functions:

Interface Category:

API.

Inherits From:

None.

Inherited By:

TSprite TCursor

Purpose:

TCompositingLayer is an abstract base class that provides the ordering information for the sprites and cursors that are its descendants. Ordering information determines whether a sprite, cursor, or rubber band moves over or underneath other composited elements on the display (other sprites, cursors, and so on.) Compositing means saving and restoring data without requiring you to write code to accomplish this. Compositing saves and restores the display data when it is temporarily covered by a composited instance that moves over the data. This object interacts with the CompositingLayer server to supply the correct order of layering for the objects in the list.

Instantiation:

Abstract class; do not allocate.

Deriving Classes:

Provided classes include TSprite and its derived classes, and TCursor. You can derive other compositing classes from TCompositingLayer or TSprite.

Concurrency:

Not multithread safe.

Resource Use:

No special requirements.

Member Function: TCompositingLayer::TCompositingLayer

TCompositingLayer ()
TCompositingLayer (const TCompositingLayer &, bool isAbove)

Interface Category:

API.

Purpose:

Default constructor.
Constructor that places the new object over or underneath the given compositing layer.

Calling Context:

Called by the stream operators or derived classes that want to display underneath all existing compositing layers.
Normally called by derived classes.

Parameters:

Takes no parameters.
const TCompositingLayer & -Another compositing layer.
bool isAbove -A Boolean flag, which, when true, places this compositing layer above the layer passed in the first parameter.

Return Value:

None.

Exceptions:

Throws no exceptions, passes all exceptions through.

Concurrency:

Not multithread safe.

Other Considerations:

None.

Member Function: TCompositingLayer::~TCompositingLayer

virtual ~ TCompositingLayer ()

Interface Category:

API.

Purpose:

Destructor.

Calling Context:

Called to destroy an object.

Parameters:

Takes no parameters.

Return Value:

None.

Exceptions:

Throws no exceptions, passes all exceptions through.

Concurrency:

Not multithread safe.

Other Considerations:

None.

Member Function: TCompositingLayer::IsAbove

virtual bool IsAbove (const TCompositingLayer & otherLayer)

Interface Category:

API.

Purpose:

Determines the relative ordering between two compositing layers, such as sprites, cursors, and other layers. This function is a query only; derived classes like TSprite define functions (such as PlaceAbove and PlaceBelow) to change the relative ordering.

Calling Context:

Call this function directly.

Parameters:

const TCompositingLayer & otherLayer -A reference to the other compositing layer, sprite, etc., which this layer is compared to.

Return Value:

Returns true if this compositing layer is above the other compositing layer; otherwise, returns false.

Exceptions:

Throws no exceptions, passes all exceptions through.

Concurrency:

Not multithread safe.

Other Considerations:

None.

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