Reference Manual

  • 15.0
  • 07/23/2021
  • Public Content

Adding Code to Your Application

The structure of your application remains the same as when using a dialog box that does not contain an ActiveX control. See Writing a Dialog Application Overview for details. This section discusses programming specific to ActiveX controls.
Your application must call
before calling
with a dialog box that contains an ActiveX control. Your application must include the statement
to access COMINITIALIZE. Your application must call
when you are done using ActiveX controls, but not before calling
for the dialog box that contains the ActiveX control.
You can call the methods of an ActiveX control and set and retrieve its property values using the interfaces generated by the Intel Fortran Module Wizard or by using the IFAUTO routines. To do this, you must have the object's IDispatch interface pointer. Use the
function with the ActiveX control's name, the DLG_IDISPATCH control index, and an integer variable to receive the IDispatch pointer. For example:
retlog = DlgGet( dlg, IDC_ACTIVEX, idispatch, DLG_IDISPATCH )
You do not need to specify the index DLG_IDISPATCH because it is the default integer index for an ActiveX control.
However, the control's IDispatch pointer is not available until after the control has been created and is only valid until the dialog box is closed. The control is created during the call to
or . If you call
to retrieve the IDispatch pointer before calling
, the value returned will be 0.
Do not call
with the iDispatch pointer returned by
. The dialog procedures use a reference counting optimization since the lifetime of the control is guaranteed to be less than the lifetime of the dialog box.
If you want to use a method or property of a control before the dialog box is displayed to your application's user, you can use a DLG_INIT callback. Call
using the dialog box name and the DLG_INIT index to define the callback. For example:
retlog = DlgSetSub( dlg, IDD_DIALOG, DlgSub, DLG_INIT )
callback is called after the dialog box is created but before it is displayed (with callbacktype=DLG_INIT) and immediately before the dialog box is destroyed (with callbacktype=DLG_DESTROY). The
callback is the soonest that the control's IDispatch pointer is available. The
callback is the latest that this pointer is valid. After the
callback, the ActiveX control is destroyed.
The following example shows using a
callback to reset the state of a control property before it is destroyed:
SUBROUTINE mmplayerSub( dlg, id, callbacktype ) !DEC$ ATTRIBUTES DEFAULT :: mmplayerSub use iflogm use ifcom use ifauto implicit none type (dialog) dlg integer id, callbacktype include 'resource.fd' integer obj, iret logical lret if (callbacktype == dlg_init) then lret = DlgGet(dlg, IDC_ACTIVEMOVIECONTROL1, obj) ! Add any method or property calls here before the ! dialog box is displayed else if (callbacktype == dlg_destroy) then ! Reset the filename to "" to "close" the current file lret = DlgGet(dlg, IDC_ACTIVEMOVIECONTROL1, obj) iret = AUTOSETPROPERTY(obj, "FileName", "") endif END SUBROUTINE mmplayerSub
The module generated by the Fortran Module Wizard for an ActiveX control contains a number of sections:
  • ! CLSIDs
    Parameters of derived type GUID which identify the ActiveX control class. Your application typically doesn't need to use this parameter.
  • ! IIDs
    Parameters of derived type GUID which identify source (event) interfaces of the ActiveX control. Your application can use these values in calls to DLGSETCTRLEVENTHANDLER (see below).
  • ! Enums
    Parameters of type integer that identify constants used in the ActiveX control's interfaces.
  • ! Interfaces
    Interfaces for the source (event) interfaces that are defined by the ActiveX control. There may be 0, 1, or more source interfaces implemented by the control. A control does not have to support events.
  • ! Module Procedures
    Wrapper routines that make it easy to call the control's methods and get or retrieve the control's properties.
See the
Language Reference
for more information on using the method and property interfaces generated by the Intel Fortran Module Wizard.
In addition to methods and properties, ActiveX controls also define events to notify your application that something has happened to the control. The dialog procedures provide a routine,
, that allows you to define a routine to be executed when an event occurs.
function has the following interface:
integer DlgSetCtrlEventHandler( dlg, controlid, handler, dispid, iid )
The arguments are as follows:
(Input) Derived type DIALOG. Contains dialog box parameters.
(Input) Integer. Specifies the identifier of a control within the dialog box (from the .FD file).
(Input) EXTERNAL. Name of the routine to be called when the event occurs.
(Input) Integer. Specifies the member id of the method in the event interface that identifies the event
(Input, Optional) Derived type (GUID). Specifies the Interface identifier of the source (event) interface. If not supplied, the default source interface of the ActiveX control is used.
Consider the following function call:
ret = DlgSetCtrlEventHandler( dlg, IDC_ACTIVEMOVIECONTROL1, & ActiveMovie_ReadyStateChange, -609, IID_DActiveMovieEvents2 )
In this function call:
    identifies an ActiveMovie control in the dialog box.
  • ActiveMovie_ReadyStateChange
    is the name of the event handling routine.
  • -609
    is the member id of the ActiveMovie's control ReadyStateChange event. You can get this number from:
    • The module that the Fortran Module Wizard generated. There is a "MEMBERID = nn" comment generated for each method in a source interface (see the example below).
    • The documentation of the ActiveX control.
    • A tool that allows you to examine the type information of the ActiveX control, for example, the OLE/COM Object Viewer in the Microsoft Visual Studio* IDE.
  • IID_DActiveMovieEvents2
    is the identifier of the source (event) interface.
The interface generated by the Intel Fortran Module Wizard for the ReadyStateChange event follows:
INTERFACE !Reports that the ReadyState property of the ActiveMovie Control !has changed ! MEMBERID = -609 SUBROUTINE DActiveMovieEvents2_ReadyStateChange($OBJECT, ReadyState) INTEGER(4), INTENT(IN) :: $OBJECT ! Object Pointer !DEC$ ATTRIBUTES VALUE :: $OBJECT INTEGER(4) :: ReadyState !DEC$ ATTRIBUTES VALUE :: ReadyState !DEC$ ATTRIBUTES STDCALL :: DActiveMovieEvents2_ReadyStateChange END SUBROUTINE DActiveMovieEvents2_ReadyStateChange END INTERFACE
The handler that you define in your application must have the same interface. Otherwise, your application will likely crash in unexpected ways because of the application's stack getting corrupted.
Note that an object is always the first parameter in an event handler. This object value is a pointer to the control's source (event) interface, not the IDispatch pointer of the control. You can use
as described above to retrieve the control's IDispatch pointer.

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