[Overview][Constants][Types][Classes][Procedures and functions][Index] | Reference for unit 'ComCtrls' (#lcl)

# TCustomListView.OnDataHint

Event handler signalled to load a range of cached list items in the virtual storage for the control.

## Declaration

Source position: comctrls.pp line 1608

`protected property TCustomListView.OnDataHint : TLVDataHintEvent read FOnDataHint write FOnDataHint;`

## Description

OnDataHint is a TLVDataHintEvent property with the event handler signalled when a caching hint is received for the list view control.

In virtual mode (OwnerData = True), only the most recently accessed virtual list item exists in the list view control. Data hinting, or pre-fetch caching, allows a range of values to be loaded into the virtual storage for the list items.

Arguments passed to the event handler identify the starting and ending positions for the list items needed for the visible area on the control.

OnDataHint is signalled from the DoOwnerDataHint method, and occurs when a cache hint is received and handled in the widgetset class.

Use the OnData event handler to load the values for the selected list item from the virtual storage.

Remark: | OnDataHint is signalled for the Windows platform only. Cache hint information is not provided by other widgetsets.

## See also

TCustomListView.OnData |  | Event handler signalled to the value(s) for a list item when OwnerData (virtual mode) has been enabled.
TCustomListView.OwnerData |  | Enables or disables owner data (virtual) mode for the list view control.
TLVDataHintEvent |  | Specifies a handler routine for data hint events in TListView.