Class TDbWindow

TDbWindow

Support

Supported from 5.0

Description

Describes the desired shape of a view's pre-evaluation window.

An instance of this class is passed to the RDbView object as part of the Prepare() function. The different constructors for TDbWindow can specify a view:

• without pre-evaluation

• with full pre-evaluation

• with limited pre-evaluation.

Defined in TDbWindow:
Anonymous, ENone, EUnlimited, PreferredPos(), Size(), TDbWindow(), TUnlimited

See also:

• RDbView

TDbWindow();

Description

Constructs this object with a size of ENone. This can be used to request a view with no pre-evaluation window.

TDbWindow(TUnlimited);

Description

Constructs this object with a size of EUnlimited. This is used to request a completely pre-evaluated view. The constant KDbUnlimitedWindow is an instance of such a TDbWindow.

Parameters

TUnlimited The argument is only used to direct the compiler to construct an unlimited window.

TDbWindow(TInt aForeSlots,TInt aRearSlots);

Description

Constructs this object with the preferred shape. When fully evaluated, the view will try to have aForeSlots rows immediately available for navigation forwards, and aRearSlots rows immediately available for navigation backwards.

Parameters

TInt aForeSlots The number of rows to evaluate ahead of the current row. TInt aRearSlots The number of rows to evaluate behind the current row.

TInt PreferredPos() const;

Description

Returns the preferred position in the window of the current row marker. i.e. the position with the forward and backward slots as requested.

Return value

TInt The preferred position in the window. It is undefined if this is not a limited window.

TInt Size() const;

Description

Returns the number of rows stored by the view.

Return value

TInt The number of rows stored by the window. This could be one of the special values ENone or EUnlimited.

TUnlimited

Description

Denotes a full pre-evaluation window.

EUnlimited No limit on how many rows may be in the window.

Anonymous

Description

Denotes that no pre-evaluation window is required.

ENone Used to indicate that no pre-evaluation window is required.