TCustomListBox.OnMeasureItem property
Handler invoked when the height for an item is needed.
Declaration
property OnMeasureItem: TMeasureItemEvent read FOnMeasureItem write FOnMeasureItem;Description
OnMeasureItem is a
TMeasureItemEvent property with the
event handler signalled to get the height for specified item in the list box
control. OnMeasureItem is signalled (when assigned) from the
MeasureItem method, and occurs when the
LM_MeasureItem
message is handled for the control. MeasureItem provides the arguments passed
to the event handler, while the message handler stores the calculated height
in
ItemHeight when it is not 0 (zero).
An application must implement an object procedure to respond to the event
notification. Index contains the position in Items with
the string to examine in the event handler. On entry, TheHeight
contains the text height for the current Font calculated using the
Canvas in the control. The value in TheHeight can be updated with
the value derived in the event handler.
See also
An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.