ActiveX Controls and Visual FoxPro 5.0
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ActiveX Controls and Visual FoxPro 5.0 |
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ActiveX controls are installed by default if you choose the Complete installation option when you install Visual FoxPro. If you did not choose this option, you can run Visual FoxPro Setup again at any time and install only the ActiveX controls. ActiveX controls are installed in the SYSTEM directory in Windows 95 or the SYSTEM32 directory in Windows NT®.
ActiveX Controls included in Visual FoxPro 5.0
The following table lists the .OCX files shipped with Visual FoxPro and the ActiveX controls contained in each file.
| File | Controls |
| COMCTRL32.OCX | ImageList ListView ProgressBar Slider StatusBar TabStrip Toolbar TreeView |
| COMDLG32.OCX | Common Dialogs |
| DBLIST32.OCX | MSDataCombo MSDataList |
| FOXHWND.OCX | Visual FoxPro HWND |
| FOXTLIB.OCX | Visual FoxPro Foxtlib |
| GRID32.OCX | Grid |
| MCI32.OCX | Microsoft Multimedia |
| MSACAL70.OCX | Calendar |
| MSCOMM32.OCX | Microsoft Comm |
| MSMAPI32.OCX | Microsoft MAPI Message Microsoft MAPI Session |
| MSOUTL32.OCX | Outline |
| PICCLP32.OCX | PicClip |
| RICHTX32.OCX | Rich Textbox |
| SYSINFO.OCX | SysInfo |
| TABCTL32.OCX | SSTab |
| THREED32.OCX | Threed Checkbox Threed Command Button Threed Frame Threed Group Push Button Threed Option Button Threed Panel |
For additional information about adding ActiveX controls to your applications, see Chapter 16, "Adding OLE," in the Developer's Guide.
Distributing ActiveX Controls included with Visual FoxPro
Note The MediaView 1.41 ActiveX control (MEDV141N.OCX), installed with the Visual FoxPro
online documentation, cannot be added to or distributed with your applications. This ActiveX control is intended only for browsing the Visual FoxPro online documentation in an interactive Visual
FoxPro session.
Distribution rights of an ActiveX control is determined by the control's creator. Be sure you have distribution rights
for any ActiveX controls you distribute with a Visual FoxPro application. All of the ActiveX controls included with Visual FoxPro can be distributed with the applications you create.
Using ActiveX Controls in Visual FoxPro
The OLE Container Control
ActiveX controls can also be added to a form by choosing the View Classes button on the Form Controls toolbar, and then choosing ActiveX Controls. An icon for each registered ActiveX control appears on the toolbar. (To register an installed ActiveX control, choose Options from the Tools menu, then choose the Controls tab. Check the box next to the ActiveX control to register, then choose the Set As Default button.) To place an ActiveX control on the form, click its icon and then click the form where you'd like the ActiveX control to appear.
ActiveX Tips and Tricks
The following sections discuss tips and tricks for applications that utilize ActiveX controls.
Object Keyword
A new Object keyword has been added to Visual FoxPro 5.0 so you can specify properties for ActiveX controls in class
definitions defined programmatically. Class definitions are processed before the ActiveX control is instantiated; the Object keyword indicates to Visual FoxPro that a property value should be applied when the ActiveX control is instantiated. If the Object keyword is not included, a custom property for the ActiveX control is created when the control is instantiated. Note that the Object keyword must be immediately preceded by a period.
The following example adds the ActiveX Outline control (MSOUTL32.OCX) to a form. The Object keyword is used to specify the BackColor property for the Outline control before the control is instantiated. Run the example, remove the Object keyword from the program line containing the BackColor property, and run the example again to see the effect of the Object keyword on the Outline control.
PUBLIC frmOLETestfrmOLETest = CREATEOBJECT('Form') && Create a form
frmOLETest.Visible = .T. && Display the form* The following line adds the Outline control to the form
frmOLETest.ADDOBJECT ( 'OCXTest', 'BlueOLEControl',
; 'MSOutl.Outline')frmOLETest.OCXTest.AddItem( 'Item One' ) && Add an item to the control
frmOLETest.OCXTest.AddItem( 'Item Two' ) && Add an item to the controlDEFINE CLASS BlueOLEControl AS OLEControl
* Use the Object keyword to set the Backcolor
* property for the Outline control.Object.Backcolor = 16776960 && Light blue
Set properties of the OLE Container Control
Height = 100 Width = 200 Visible = .T.
ENDDEFINE
Passing Arrays to ActiveX Controls
If you pass an array to an ActiveX control - for example, if you call one of the control's methods and want to pass it an array - you must pass the array by reference. If you pass the array by value (the default), only the first element will be passed.
Programmatically Adding ActiveX Controls to an OLE Container
Control
The following example demonstrates how you can programmatically add the ActiveX ProgressBar control contained in COMCTRL32.OCX to a form. Note the third argument of ADDOBJECT( ) (COMCTL.ProgCtrl.1) that specifies the OLE class ID for the ActiveX ProgressBar control.
You can use ADDOBJECT( ) to add an ActiveX control to an OLE Container control programmatically at run time. The third argument in ADDOBJECT( ) is the OLE class ID for the ActiveX control. To determine the OLE class ID for an ActiveX control, add the ActiveX control to a form. The class ID for the ActiveX control appears in the OLEClass property in the Properties window.
PUBLIC oForm
* The following line adds the ProgessBar control to the form
oForm.ADDOBJECT("OleProgress", "OLEControl", "COMCTL.ProgCtrl.1")
* The following lines specify the location
oForm.OleProgress.Top = 5
oForm.OleProgress.Visible = .T. && Display the ProgessBar
FOR i = 1 to 10
You can register an ActiveX control used by your Visual FoxPro application during the installation of that application. Include the ActiveX control and any supporting files it requires in the list of distributed files specified in the Setup Wizard. In the "Change File Settings" step of the Setup Wizard, check the ActiveX checkbox for each ActiveX control that you distribute. This instructs Setup to register the control when the distributed application is installed. Note that the list of supporting files required for each of the ActiveX Control shipped with Visual FoxPro is listed in the control's help file or help topic.
The preferred method for distributing an application utilizing the ActiveX controls included with Visual FoxPro is to add ActiveX controls to .VCX visual class libraries. The .VCX visual class libraries are included in the Setup Wizard distribution directory, and the setup created by the Setup Wizard will automatically register the ActiveX controls on the computer on which the distributed application is installed.
For more information about distributing ActiveX controls with your applications, see "Including ActiveX Components" in Chapter 25, "Building an Application for Distribution" in the Developer's Guide.
oForm = CREATEOBJECT("Form") && Create a form
* and size of the ProgressBar control
oForm.OleProgress.Left = 5
oForm.OleProgress.Height = 25
oForm.OleProgress.Width = 289
oForm.Visible = .T. && Display the Form
oForm.OleProgress.Value=i*10 && Update the ProgressBar
= INKEY(1) && Wait one second
ENDFOR
Licensing
Many ActiveX Controls, including those shipped with Visual FoxPro 5.0, require both a design time and runtime license. The design time license is located and read by the control when it is instantiated. The runtime license is provided to Visual FoxPro by the control when the control is saved with a form or visual class. The legal agreement provided with the ActiveX controls specifies that the design time license may not be distributed with custom applications developed in Visual FoxPro 5.0.
To distribute ActiveX Controls which enforce this type of licensing scheme with your application, create a visual class library which contains a visual class for each of the controls you wish to distribute. Include this visual class and the ActiveX controls (.OCX files) and the supporting files they require with your custom application. In your code, instantiate the ActiveX controls you add to your forms from these class libraries. Because the visual class libraries are created and saved on your computer have a design time license, they also contain the correct runtime license, and your code will run without errors in your distributed applications. Note that ActiveX controls saved in visual class libraries and forms do not need to be registered to run correctly. It is not necessary to specify to the Setup Wizard that the ActiveX controls you distribute are ActiveX components.
Working with ActiveX controls
This section discusses three ActiveX controls that ship with Visual FoxPro: the Outline control, the MAPI Session
control and the MAPI Messages control.
The Outline Control
The Outline control is a special type of ListBox control that shows list information in hierarchical order. It is useful for showing a myriad of information from files and directories (much like File Manager in Microsoft Windows) to sales by territory, and much more. Basically, any information based on ownership or containership can be shown in hierarchical order with the Outline control.
Registering ActiveX Controls
ActiveX controls can be used like any other control, provided they have been registered with Visual FoxPro.
You register ActiveX controls in the Options dialog box as shown below.
Options Dialog Box
To see the list of the ActiveX controls available on your system, select the ActiveX Controls option button and make sure that the Controls check box is selected. In this case, the Insertable Objects check box (which refers to OLE applications such as Microsoft Word for Windows) is cleared to keep the list more readable and manageable.
Note, in this example, the five controls shown. All of these controls ship with Visual FoxPro and are installed with the full installation. You can, of course, opt not to install these. If you do not see these controls in your list, you can install them from the Visual FoxPro installation diskettes. See the Visual FoxPro Installation Guide for more information.
To permanently register a control with Visual FoxPro (so that it is always available in designers), select the desired controls and then click Set As Default. The controls will then always appear in the list of ActiveX controls in the designers.
If you acquire additional ActiveX controls and install them, use the Options dialog box to register them for use with Visual FoxPro.
Using ActiveX Controls
Once the ActiveX controls are registered, you can access them with the Form Controls toolbar. To show the registered controls, click the View Classes button on the toolbar and select ActiveX Controls. The registered ActiveX controls appear on the toolbar. Click the desired object and drop it on the container (for example, a form, a page frame or a grid). From that point on, you can work with the ActiveX control like any other control.
Working with ActiveX Control Properties
The properties of an ActiveX control can be accessed in two ways:
ActiveX Control Shortcut Menu
The Properties window brought up by selecting the Properties option from this menu shows only those properties
programmed into the control. The dialog below shows the Properties window for the Outline control.
Outline Control Properties Window
Note that this dialog only allows access to properties of the control; events and methods are not accessible. The standard Properties dialog box, on the other hand, allows access to all Visual FoxPro standard properties, events and methods, as well as the properties specific to the control. The reason for this is interesting. Visual FoxPro wraps the ActiveX control in an OLE container that allows the developer access to the standard properties, events, and methods as well as the properties specific to the ActiveX control. This wrapping means that you can subclass ActiveX controls. This feature is unique to Visual FoxPro.
Now that we have discussed the issues relating to working with ActiveX controls in general, the next step is to discuss the particulars of the Outline control.
An Outline Example
The following figure is an example of a form using the Outline control. It shows customers and the products they have ordered. The data for this example comes from the TESTDATA database that ships with Visual FoxPro.
Customer Orders Form
As you can see, this is a powerful way of looking at data. Only the detail for the companies the user specifically expands are shown. This gives the user the ability to limit the information they see on the form.
Here's the code for this form:
* Class.............: Frmcustord*
DataSession = 2
ADD OBJECT oleoutline AS olecontrol WITH ;
LOCAL lcCompany
DO WHILE lcCompany == _cCustOrders.Company
PROCEDURE Init
PROCEDURE Load
ENDPROC
PROCEDURE oleoutline.Collapse
PROCEDURE oleoutline.Expand
PROCEDURE cmdok.Click
ENDDEFINE
The list is populated in the LoadData method, which is a custom method to this form. This method simply scans through the result set. Customers are added at the default indent level (1) whereas the products they ordered are added at level 2. Indenting items to level 2 makes them subitems of the immediately prior level 1 item. Products are also set to have the "document" icon by setting the PictureType property for that element to 2.
When the list is expanded and contracted, the picture for the main item has to be changed from the "closed" folder to the "open" folder icon. This is accomplished in the Expand and Collapse event methods which are part of the Outline control.
As you can see, the amount of code needed to work with Outline control lists is minimal.
* Notes.............: Exported code from Class Browser.
**************************************************
*-- Form: frmcustord
*-- ParentClass: form
*-- BaseClass: form
*
DEFINE CLASS frmcustord AS form
Height = 358
Width = 588
DoCreate = .T.
AutoCenter = .T.
BackColor = RGB(192,192,192)
BorderStyle = 2
Caption = "Customer Orders"
Name = "frmcustord"
Top = 12, ;
Left = 12, ;
Height = 301, ;
Width = 565, ;
Name = "oleOutline"
ADD OBJECT cmdok AS commandbutton WITH ;
Top = 324, ;
Left = 240, ;
Height = 29, ;
Width = 94, ;
Cancel = .T., ;
Caption = "\<OK", ;
Default = .T., ;
Name = "cmdOK"
*-- Loads the customer orders into the Outline Control
PROCEDURE LoadData
SET TALK OFF
WAIT WINDOW NOWAIT "Loading information. Please stand by..."
SELECT _cCustOrders
GO TOP
SCAN
lcCompany = _cCustOrders.Company
THISFORM.OleOutline.AddItem(lcCompany)
IF !EMPTY(_cCustOrders.Product)
THIS.OleOutline.AddItem(Product)
THIS.OleOutline.Indent(THIS.OleOutline.listcount-1) = 2
THIS.oleOutline.PictureType(THIS.OleOutline.listcount-1)= 2
ENDIF
SKIP
ENDDO
ENDSCAN
ENDPROC
THISFORM.LoadData()
ENDPROC
OPEN DATABASE home()+"SAMPLES\DATA\TESTDATA"
SELECT Customer.company, ;
Products.prod_name AS Product;
FROM testdata!customer, ;
testdata!orders, ;
testdata!orditems, ;
testdata!products ;
WHERE Customer.cust_id = Orders.cust_id ;
AND Orders.order_id = Orditems.order_id ;
AND Products.product_id = Orditems.product_id ;
AND Customer.Country = "Germany" ;
UNION
ALL ;
SELECT Customer.company, ;
"" ;
FROM testdata!customer ;
WHERE Customer.cust_id NOT IN ;
(SELECT Orders.cust_id FROM testdata!orders ;)
AND Customer.Country = "Germany" ;
ORDER BY 1,2 ;
INTO CURSOR _cCustOrders
GO TOP
*** OLE Control Event ***
LPARAMETERS listindex
IF this.HasSubitems(listindex)
this.PictureType(listindex) = 0
ENDIF
ENDPROC
*** OLE Control Event ***
LPARAMETERS listindex
IF THIS.HasSubitems(listindex)
THIS.PictureType(listindex) = 1
ENDIF
ENDPROC
RELEASE THISFORM
ENDPROC
*
*-- EndDefine: frmcustord
**************************************************
The Load event run a SELECT - SQL statement from the information in the TESTDATA database to extract the names of customer in Germany and the products they have purchased. The list is ordered by company name and then by product name.
Outline Control: A Final Word
The Outline control is a wonderful example of how an ActiveX control can enhance a system. The ability to translate data into a visual, hierarchical display is a powerful way to allow users to view and work with data. However, ActiveX controls can add much more than display features to an application. The two MAPI controls that ship with Visual FoxPro provide an example of how ActiveX controls can add functionality to your applications.
Creating Mail-Enabled Applications with the MAPI Controls
Creating mail-enabled applications is becoming a requirement in many business settings. The MAPI controls make this requirement easy to accomplish.
Visual FoxPro ships two controls designed to enable applications to interact with MAPI-compliant mail systems. These two controls, the MAPI Session control and the MAPI Messages control, work in tandem to allow an application to send, respond and reply to messages in addition to managing the e-mail system.
Managing E-Mail Sessions
Before you can work with e-mail, you have to establish a session with the e-mail system. You can think of a session
in e-mail as being similar to working with an Automated Teller Machine (ATM). In order to work with the ATM, you first have to establish a session. Part of establishing a session includes logging into the system. Once you have a session established, you can initiate and complete many transactions. The same is true of an e-mail system.
Establishing the Session
Establishing a session with the MAPI Session control is a simple matter. Place the control on a form and put the following code in its Init( ) event:
THIS.LogonUI = .T.
THIS.SignOn()
The Signon( ) method accesses the mail system and attempts to establish a mail session. Since the LogonUI property is set to .T., if the user is not logged in yet, a dialog box is displayed for the user to enter a user name and password.
The session is terminated with the SignOff( ) method.
Each MAPI session has an ID. The ID of the session is stored in the SessionId property of the Session control. The
ID is important for the Message control to be able to communicate with the session.
Composing Messages
MAILME.SCX is a sample form that illustrates well how messages with attachments can be composed and sent using the MAPI Message control. The figure below shows the form in the designer followed by the code to the form.
Composing message with the MAPI Message control is straightforward. The control has a series of methods and properties
that a developer can modify and work with in order to compose messages to be sent through the mail system. For example, the
MsgNoteText property holds the text of the message. Placing text in that property will put the text into the body of the message. The control also allows you to attach files, work with address books, and read messages as well.
DoCreate = .T.
ADD OBJECT olesession AS olecontrol WITH ;
ADD OBJECT olemessage AS olecontrol WITH ;
ADD OBJECT cmdmailme AS commandbutton WITH ;
PROCEDURE olesession.Init
THIS.LogonUI = .T.
PROCEDURE olesession.Destroy
PROCEDURE olemessage.Init
PROCEDURE cmdmailme.Click
*-- First, save this as a class to JUNKME.VCX
LOCAL lcOldSafety
THISFORM.SaveAsClass("JunkMe.VCX", "MailMe")
*-- Set the address book caption
*-- Clear the compose buffer.
*-- Get the recipient's address.
*-- Set the message subject and the body text.
*-- Add first attachment
THISFORM m.oleMessage.AttachmentIndex = ;
*-- Now the second attachment
*-- Diplay the Send dialog before sending
*-- Reset SET SAFETY and finish
ENDDEFINE
Form MAILME
* Form..............: MAILME.SCX
* Notes.............: Exported code from Class Browser.
**************************************************
*
*-- Form: form1
*-- ParentClass: form
*-- BaseClass: form
DEFINE CLASS form1 AS form
Caption = "Form1"
Name = "Form1"
Top = 204, ;
Left = 120, ;
Height = 100, ;
Width = 100, ;
Name = "oleSession"
Top = 204, ;
Left = 180, ;
Height = 100, ;
Width = 100, ;
AddressModifiable = .T., ;
AddressResolveUI = .T., ;
Name = "oleMessage"
Top = 36, ;
Left = 36, ;
Height = 133, ;
Width = 253, ;
Caption = "Mail Me!", ;
Name = "cmdMailMe"
*-- Establish a session
THIS.Signon()
ENDPROC
THIS.signoff()
ENDPROC
THIS.SessionID = THISFORM.oleSession.SessionID
ENDPROC
lcOldSafety = SET("safety")
SET SAFETY OFF
THISFORM.oleMessage.AddressCaption = "Select Recipient(s)"
THISFORM.oleMessage.Compose()
THISFORM.oleMessage.Show()
THISFORM.oleMessage.msgNoteText = ;
"Please see that these files get into the class libraries " + ;
REPL(chr(13)+chr(10), 3) + " "
THISFORM.oleMessage.msgSubject = "Attached Files"
THISFORM.oleMessage.AttachmentCount
THISFORM.oleMessage.AttachmentType = 0
THISFORM.oleMessage.AttachmentPathName = "JUNKME.VCX"
THISFORM.oleMessage.AttachmentPosition = ;
LEN(THISFORM.oleMessage.msgNoteText)-2
THISFORM.oleMessage.AttachmentIndex = THISFORM.oleMessage.AttachmentCount
THISFORM.oleMessage.AttachmentType = 0 THISFORM.oleMessage.AttachmentPathName =
"JUNKME.VCT"
THISFORM.oleMessage.AttachmentPosition = ;
LEN(THISFORM.oleMessage.msgNoteText)-1
THISFORM.oleMessage.Send(.T.)
SET SAFETY &lcOldSafety
ENDPROC
*
*-- EndDefine: form1
**************************************************
This form has both a MAPI Session and a MAPI Message control on it.
The Init( ) event of the MAPI Message control sets the SessionId property of the Message control to the SessionId of the Session control. In this way, our messages are linked to the current open mail session. Most of the work happens in the Click( ) event of the cmdMailMe command button:
That's all there is to it. The figure below shows the dialog box that displays at the end of this process.
Composed Message
MAPI Controls: Conclusion
The MAPI controls show another side to working with ActiveX controls. They provide a host of possible additions to
the capabilities of Visual FoxPro applications. These controls, although non-visual, reduce the complexity and tedium of mail-enabling applications to setting a few properties and calling a few methods. This is, in essence, what easy development is all about.
ActiveX Troubleshooting
The following sections discuss problems you might encounter with ActiveX controls and suggest workarounds for the problems.
Support for ActiveX Controls
For example, Visual FoxPro treats ISimpleFrame controls as true containers. Visual FoxPro also supports the ability to subclass ActiveX controls. Both of these features affect the language used when working with ActiveX controls. Some of the samples that you find in the control's documentation might need to be modified
to work correctly in Visual FoxPro.
If you are experiencing a problem with a control, you might find that a workaround or a more recent version of the
control is available. For the most up-to-date information, search the Visual FoxPro Knowledge Base using the keyword "ActiveX." The Knowledge Base contains sample code, version information,
and known issues concerning ActiveX controls.
Because ActiveX controls are independent modules, not developed in or specifically for Visual FoxPro, they might
exhibit behavior different than that of native Visual FoxPro controls. You might also experience problems when using them in Visual FoxPro or find that they work differently than they do in other programs.
Automatically Resizing Panel Controls in Forms
If you add an ActiveX Threed Panel Control (as an OLE Container control) to a form and then set its AutoSize property
to 2 - AutoSize Panel Height To Caption, you might experience problems in redrawing the control. The control might appear very thin, and might not allow you to reset its height. To correct this problem, reset its Caption property by double-clicking it
in the Properties window. This causes the Caption property to be set to "(None)," and allows you to resize the panel as required.
Binding RichTextBox Controls to Memo Fields
If you attempt to bind a Microsoft RichTextBox control directly to a memo field in a table (by setting the control's
ControlSource property to the name of the memo field), Visual FoxPro displays an error when you run the form, and unbinds the control. To work around this problem, you can copy the contents of the field to a variable that is updated whenever the record pointer is moved. Then bind the control to the variable instead of directly to the memo field. For an example of how to create this type of binding, see "Use the RichText Control" in the Solutions Sample.
ToolTips for Controls Inside ISimpleFrame Controls
To display ToolTip text for a control inside an ISimpleFrame ActiveX control (for example, for a command button inside an ActiveX SSTab control) set the ShowTips property of the ActiveX control itself to True. For controls outside of ISimpleFrame ActiveX controls, set the ShowTips property of the form to True.
Getting Help for Controls Inside ISimpleFrame Controls
If you put a native Visual FoxPro control inside
an ISimpleFrame control (for example, if you put a command button
inside an ActiveX SSTab control), you cannot display context-sensitive
Help (What's This Help) for that control.
Moving Between SSTab Control Tabs in Design Mode
If you create a form that contains an SSTab control,
then run the form from the Form Designer, and then return to design
mode, you might not be able to display the first tab in the control
by clicking it. If this occurs, you can try clicking it several
times, or you can click on the very edge of the tab.
Using ISimpleFrame Controls in Page Frames
If you place an ISimpleFrame control on one page in a page frame and then display the form, the control might initially
appear on all pages. To prevent the control from appearing on any page except the page on which you placed it, set the control's Visible property to true in the page's Activate method and to false in its Deactivate method. Depending on what page is initially active when the form is run, you might also have to set the control's Visible property to false in the Activate method of the page that first appears.
If you place an ISimpleFrame control on a page in a form-based class, the control might appear on the Windows® desktop when you create an instance of the class and show it. If so, you can correct the problem using this code in the Init
method of the form:
You might experience the following problems when working with ISimpleFrame controls (such as a Threed Frame Control)
in pages in a page frame:
* On the following line,2 represents
* the page on which the control appears
THIS.PageFrame1.ActivePage = 2
THIS.Draw
THIS.PageFrame1.ActivePage = 1 && default page
Dragging and Dropping ActiveX Controls
You might not be able to establish drag and drop behavior for certain ActiveX controls. For example, you cannot
drag ISimpleFrame controls. In other cases, you might find that establishing drag and drop between ActiveX controls results in an error.
Disabling or Enabling VTABLE Binding
Some ActiveX controls are documented to support VTABLE binding but do not fully do so. VTABLE binding allows the control's host to bind "early" to its members (properties and methods) for better performance. If the control does not support VTABLE binding, Visual FoxPro might experience a fatal error in the module OLEAUT32.DLL, or you might see a message such as "Not enough storage space is available to complete this operation."
If so, you can temporarily disable VTABLE binding by calling the new SYS(2333) function. The syntax is:
SYS(2333, 0)
After disabling VTABLE binding, you can create an
instance of the control. Then reset VTABLE binding by calling SYS(2333,1) so that other ActiveX controls can take advantage
of the speed increases offered by VTABLE binding.
Note If you are testing ActiveX controls in Visual Basic® 4.0, you will not encounter this problem because that version of Visual Basic does not support VTABLE binding.
You can also create an entry in the Windows Registry
to disable VTABLE binding for individual controls, which saves
you the trouble of disabling it each time you want to create another
instance of the control. To do so, create an entry using the following
Registry key, in which clsid represents the class id of the control
for which you are disabling VTABLE binding:
HKEY_CLASSES_ROOT\NoDualInterface\{clsid}
HKEY_CLASSES_ROOT\NoDualInterface\{EAB22AC3-30C1-11CF-A7EB-0000C05BAE0B}
ActiveX Control Help
If you place the SysInfo ActiveX control on a form, there is no Help available for the control through F1. For information about this control, see the SysInfo control Help file (SYSINFO.HLP) in the SYSTEM or SYSTEM32 directory.
The Visual FoxPro HWND (FOXHWND.OCX) and Visual FoxPro Foxtlib (FOXTLIB.OCX) ActiveX controls were created for use with Visual FoxPro. Visual FoxPro Help contains information about these controls.
ActiveX Interfaces Supported by Visual FoxPro
For additional information about creating ActiveX controls for applications such as Visual FoxPro, see "For
Developer's Only" at the Microsoft Internet web site at www.microsoft.com/devonly/.
By adding ActiveX support to Visual FoxPro, Microsoft has opened the door to a flood of additional functionality. With support for this powerful feature, Visual FoxPro has no limits on what it can do.
The information contained in this document represents the current view of Microsoft Corporation on the issues discussed as of the date of publication. Because Microsoft must respond
to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the date of publication.
This document is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS OR IMPLIED, IN THIS DOCUMENT.
For example, you can disable VTABLE binding for the Internet Explorer Shell control by making this entry in the Registry:
Many of the ActiveX controls that ship with Visual FoxPro were originally created for use with
other applications such as Microsoft Visual Basic® and Microsoft Access. When an ActiveX control is placed on a form and you press F1 for Help on the control, the Help that displays is from the
original application, not Visual FoxPro.
The following table lists the ActiveX features and interfaces supported by Visual FoxPro. These features and interfaces will be of interest to developers of ActiveX controls designed for use with Visual FoxPro.
Supported Features
Supported Interfaces
ActiveX Controls: Conclusion
Extensibility. Once it was an option in a development language. Today, it's the key to success. As technology has become
more advanced, users expect more from their applications. No single software vendor can anticipate all the needs and desires of the user market. However, many vendors can address a much broader range of needs.
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