OnChange

Declaration:	TMatrix.OnChange: TNotifyEvent; { TNotifyEvent = procedure (Sender: TObject); }
The OnChange event specifies which event handler should be executed when the contents of a matrix changes. OnChange occurs when any element of the matrix is modified.

Example:

The following tiny program shows how to set up and use an OnChange event. When the matrix is changed it issues the OnChange event which is assigned to the event handler MyMatOnChangeEvent. This event handler simply shows a mesagebox. The event handling can be removed again by assigning a nil value to the OnChange event: program MatrixEvents; procedure MyMatOnChangeEvent (Sender: TObject); // event handler begin MessageDlg ('Bingo! Matrix has changed', mtInformation, [mbOK]); end; var MyMat : TMatrix; begin // main program MyMat := TMatrix.Create (nil); MyMat.Resize (10,5); MyMat.Fill (0,0,0,0,100); MyMat.OnChange := @MyMatOnChangeEvent; // assign event handler Pause; MyMat.Elem [1,1] := 99; // this triggers the OnChange event Pause; MyMat.OnChange := nil; // remove event handling MyMat.Elem [1,1] := 55; // this does not trigger the OnChange event any more Pause; MyMat.Free; end.