PowerBuilder Native Interface Programmers Guide and Reference
Building PowerBuilder Extensions

You can choose to use visual extensions to implement controls with a specific purpose or that use a custom look and feel. For some examples of visual extensions, see the PowerBuilder Code Samples Web site at https://www.appeon.com/developers/library/code-samples-for-pb.

The description for a visual class follows the same rules as for a nonvisual class, but it must inherit from the UserObject system class:

PBXEXPORT LPCTSTR PBXCALL PBX_GetDescription()
{
   static const TCHAR desc[] = {
      "class myvisualext from userobject\n"
      "subroutine func_1(int arg1, int arg2)\n"
      "subroutine func_2(string arga)\n"
      "end class\n" 
   };
return desc;
}

There are no events in the preceding example, but a typical visual extension makes use of events such as mouse clicks. There are two ways to declare and handle events. See Event processing in visual extensions.

You declare native visual classes in the same way as nonvisual classes, except that you declare an ANSI C++ class that inherits from IPBX_VisualObject, which is the ancestor class for all nonvisual PowerBuilder native classes, instead of from IPBX_NonVisualObject. You can also declare global functions in a visual extension. See Step 3: Declare native classes and global functions in the section on nonvisual extensions.

You implement Invoke and Destroy methods and any class or global functions the same way for visual extensions as for nonvisual extensions. See Step 4: Implement native classes and global functions.

The major difference between visual and nonvisual extensions is in how instances of the class are created. See Creating visual class instances.

As for nonvisual extensions, you must build a PBX, import it into the application, and put the PBX in the execution path. See Step 6: Build a PBX  and Adding an extension to a PowerBuilder target in the section on nonvisual extensions.

You do not need to declare an instance of a visual class or use the CREATE statement to create an instance. The PBVM creates an instance when the window or visual control in which the visual class resides is opened, as described in Creating visual class instances. You can invoke the object's functions the same way that you invoke a nonvisual object's functions.

You can now drag the new user object from the System Tree directly onto a window or onto another visual control, such as a tab control, and use it like any other visual user object.