Capturing Special Keys on your DataWindow

A common requirement for applications is to capture certain keystrokes and perform special
actions when the user presses these keys. To capture keystrokes on your DataWindow, do the
following:

1. Declare an event on your DataWindow (possibly your ancestor DW, as is done here) and assign that event the pbm_dwnkey event id. This causes all keystrokes to be processed through the event.
2. Code that event to handle the special keystrokes in the desired manner. Ideally, common keystrokes (like Enter, Tab) will be captured at the ancestor level and a standard event will be called. A sample event that catches certain keystrokes is shown below.

In this sample event, the following keystrokes can be captured:

• tabs: to do so, a descendant DW sets the ib_CaptureTab instance variable to True. The
  ue_Tab or ue_BackTab event are then invoked when Tab/BackTab is pressed to allow
  the descendant to code appropriate logic.
• enter keys: to do so, a descendant DW sets the ib_CaptureEnter instance variable to True.
  The ue_Enter event is then called when Enter is pressed to allow the descendant to code
  appropriate logic.

sample ue_key event code:

// if descendent DW wants tab ... capture it
IF ib_CaptureTab AND KeyDown(KeyTab!) THEN
  // determine whether it is a tab or back-tab
  IF NOT KeyDown(KeyShift!) THEN
    This.POST ue_Tab()
  ELSE
    This.POST ue_BackTab()
  END IF
  Return 1 // have key not otherwise be ignored by PB

// if descendent DW wants enter keys ... capture it
ELSEIF ib_CaptureEnter AND KeyDown(KeyEnter!) THEN
  This.POST ue_Enter()
  Return 1 // have key not otherwise be ignored by PB

// otherwise send the key to the window-level for standard processing
ELSE
  IF IsValid(iw_ParentWin) THEN
    iw_ParentWin.TriggerEvent(Key!)
  ELSE
    // how did we get a key event for invalid parent?
    f_SignalError(0/gi_zero,"Invalid Parent Window in Key Event")
  END IF
END IF

Note: a handle to the parent window (iw_ParentWin) is obtained in the Constructor event. PFC's
of_GetParentWindow function is a good method to generically get a handle to the parent
window.