External_Message - DfBaseWindow

Assigns Windows messages to DataFlex messages

Type: Procedure Set

Data Type: Integer

Parameters: Integer iWindowsMessage Integer iVDFMessage

ParameterDescription
iWindowsMessageWindows message ID
iVDFMessageDataFlex message ID


Syntax 
Procedure Set External_Message Integer iWindowsMessage Integer iVDFMessage


Description

External_message is used to assign Windows messages to DataFlex messages. This is an advanced technique which requires knowledge of both the Windows API and the DataFlex method of "wrapping" classes. This used in conjunction with the external_class_name message.

// from dfline.pkg
Register_Procedure WMSG_Paint integer wParam integer lParam
// make it a benign object.
Set External_Class_Name "DFLine" To 'DFUserControl'
// We want to trap WM_PAINT for efficient painting.
Set External_Message WM_PAINT To msg_WMSG_Paint
 
 
// from DfTreeVw.Pkg
Set External_Class_Name 'DFTreeView' To 'SysTreeView32'
Set External_Message WM_SETFOCUS To msg_OnSetFocus
Set External_Message WM_KILLFOCUS To msg_OnKillFocus