Chapter 20: Using External Functions and Other Processing Extensions

Message object properties

Table 20-3 lists the properties of the Message object and the datatype and uses of each. The first four properties of the Message object correspond to the first four properties of the Microsoft Windows message structure.

**Table 20-3: Message object properties**
Property	Datatype	Use
Handle	Integer	The handle of the window or control.
Number	Integer	The number that identifies the event (this number comes from Windows).
WordParm	UnsignedInt	The word parameter for the event (this parameter comes from Windows). The parameter’s value and meaning are determined by the event.
LongParm	Long	The long parameter for the event (this number comes from Windows). The parameter’s value and meaning are determined by the event.
DoubleParm	Double	A numeric or numeric variable.
StringParm	String	A string or string variable.
PowerObjectParm	PowerObject	Any PocketBuilder object type, including structures.
Processed	Boolean	A boolean value set in the script for the user-defined event: true – the script processed the event. Do not call the default window Proc (DefWindowProc) after the event has been processed. false (default) – call DefWindowProc after the event has been processed.
ReturnValue	Long	The value you want returned to Windows when Message.Processed is true. When Message.Processed is false, this attribute is ignored.

Use the values in the Message object in the event script that caused the Message object to be populated. For example, suppose the FileExists event contains the following script. OpenWithParm displays a response window that asks the user if it is OK to overwrite the file. The return value from FileExists determines whether the file is saved:

OpenWithParm( w_question, &
   "The specified file already exists. " + &
   "Do you want to overwrite it?" )
IF Message.StringParm = "Yes" THEN
   RETURN 0  // File is saved
ELSE
   RETURN -1 // Saving is canceled
END IF

When processing messages, Windows CE supports both system-defined messages and application-defined messages. Windows CE does not support hooking messages. For information on Microsoft message numbers and parameters, see the Microsoft documentation in the MSDN library.

Chapter 21: Managing Initialization Files and the Windows CE Registry

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