Visual Graph Getting Started - Callback Control Event in Script

As you know, Visual Graph allows you to declare functions in a .tbl file (via Program -> Add function... menu item), and you can call them in element's event script. Besides, it provides you with DoCommand and OnCommand matching callback mechanism.

DoCommand is a function in Visual Graph scripting language, it has two parameters, the first is current document, the second is a string that will be transfered to the document's related ActiveX control OnCommand event.

Now, we demonstrate it through a VB6 example.

1. Create a new file in Visual Graph IDE, and then draw a circle (basic element in library group) in this document.

2. Select this circle, and then double-click OnClick event in the Functions view at left to write the follow script:

DoCommand( Owner, "Hello" )

3. Save current document as h:\test.tbl.

4. Create a new project in VB6, right-click on Toolbox and select Components, and then check Visual Graph ActiveX Control and click <OK>.

5. Click vgctrl in Toolbox, and then draw an instance on Form1.

6. Write the following code in Form_Load event:

vgctrl1.Run "h:\test.tbl"

7. Write the following code in vgctrl1_OnCommand event:

MsgBox ACommand

8. Run this project, click the circle, you will get a message box with Hello prompt.