TcxTreeListStyles.OnGetBandBackgroundStyle Event

Occurs whenever the band’s background needs repainting.

Declaration

property OnGetBandBackgroundStyle: TcxTreeListGetBandStyleEvent read; write;

Remarks

This event occurs every time the TreeList band’s background is repainted. This allows you to substitute the assigned band background style to another style.

To change the style, you should write an event handler that passes the existing instance of the TcxStyle class to the control via the AStyle parameter. Note that the AStyle parameter doesn’t represent any TcxStyle instance and is nil by default. So you can’t implement the following code:

AStyle.Color := clBlack

before you assign a TcxStyle instance to it.

The following code is not recommended either:

AStyle := TcxStyle.Create;

In this case, a TcxStyle instance will be created every time the event occurs and it will never be removed until application termination. Implementing the above code creates excessive TcxStyle instances and excessive memory usage as the result. The correct method is to create a TcxStyle instance outside the event handler and pass it to the control via the AStyle parameter within the event handler. For instance, you can use the StyleRepository to create and store your custom styles.

The Sender parameter of the event contains the TreeList control instance that owns the style collection.

The ABand parameter contains the TreeList band whose background is being repainted.

Additionally, you can use the OnGetBandContentStyle and OnGetBandHeaderStyle events to redefine the style settings for a band’s content and header respectively.