TcxTreeListStyles.OnGetPreviewStyle Event

Occurs whenever the node preview section needs repainting.

Declaration

property OnGetPreviewStyle: TcxTreeListGetPreviewStyleEvent read; write;

Remarks

This event occurs every time the TreeList node preview section is about to be painted. This allows you to substitute the assigned style by 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 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.

Sender specifies the TreeList control.

AColumn specifies the column whose data is displayed in the preview section.

Note

The node preview section is not visible by default. To set up the preview section, use the Preview property.

The initial style for the preview section is determined by the TcxTreeListStyles.Preview property.