AltiaTM Design 2.3 for Windows 3.1/95/NT

This document assumes Altia Design is installed relative to the c:\usr\altia directory. Your installation directory may be different. If so, occurrences of c:\usr\altia would be replaced with your installation directory choice.

System Configuration Requirements

The first Altia specific action for this Main subroutine is to select to receive events from the Altia interface. This is accomplished with one or more calls to altiaSelectEvent(). In this example, the events selected are named "button" and "knob". As the program comments point out, the first Altia API function call automatically attempts to open a connection to the Altia interface process. This can only work if an Altia interface process is already running. The process can be an editor or runtime session. The connection is made using a DDE named "altDDE", but details such as this are taken care of automatically by the Altia API DLL.

The altiaPending() function call checks to see if any events are available. If so, a call is made to altiaNextEvent() to get the next available event. If more than one event is available, the oldest event is returned. In the above example, eventName must be a fixed length string. Since it is easier to deal with variable length strings, the line following the call to altiaNextEvent() copies just the string portion of eventName to event. Because altiaNextEvent() always terminates strings with the NULL (0) character, this is easily accomplished.

After getting a new Altia event, this example compares the event string to the strings "button" and "knob". If event matches "button", the value of the event is also tested. If value is 1, altiaSendEvent() is called to send an event back to the Altia interface. In this case, it is a request to set the state of an animation named "led" to 1. If the value for the "button" event is 0, the "led" animation is set to 0. If the incoming event is named "knob", the value for the "knob" event is used to set the state for an animation named "knob_integer". Presumably, "knob_integer" is an integer animation associated with a text i/o object (i.e., a dynamic text input/output object originating from the Altia textio.dsn models library).

A call to DoEvents completes the idle loop. The DoEvents call checks for inputs from the Visual Basic product interface.

Prior to the idle loop, you may want to include custom initialization code. For example, you may want to start the runtime version of Altia Design and have it automatically load your specific interface. This can be done with a call to altiaStartInterface(). This function searches for the Altia Runtime executable, altiart.exe, in %ALTIAHOME%\bin if the ALTIAHOME environment variable is set. Otherwise, it searches for altiart.exe in the directories specified in the PATH environment variable, then it searches in the current working directory, and finally it looks in \usr\altia\bin if all previous searches failed. In the above example, it would be placed before the altiaSelectEvent() calls and immediately after the Dim quit As Integer statement. For example:

If the function call returns -1, then the Altia interface startup failed. In this particular example, a return of -1 will force the program to end. For much more detail on altiaStartInterface() and all of the other functions supported by the Altia API DLL, refer to the comments found in the declarations portion of the code module created from the c:\usr\altia\lib\altiaapi.txt or altia32.txt file.

As your program grows, you can partition it into additional subroutines and call these subroutines from the Main subroutine or each other. New subroutines are created in the same manner as the Main subroutine (i.e., type: Sub New_Sub_Name<Enter> in the code module window).

Several examples are supplied with Altia Design that demonstrate integration with Visual Basic programs. The first is a version of the standard Stress Monitor demo. To load the project for this demo into Visual Basic, select Open Project... from the File menu, change directory to c:\usr\altia\demos\stress\vbasic[16] in the Open Project dialog, and double-click on stress.mak. Or, an even easier method is to simply double-click on stress.mak from a file browser window (e.g., File Manager in Windows 3.1 or Windows Explorer in Windows 95). The easier method assumes that the Windows file type registry is mapping .mak files to the Visual Basic project file type. Under c:\usr\altia\demos\vbasic[16] is a second demonstration - a simple blood meter prototype. This demo shows how a state machine can be built and how timer events are used. To load this project, open c:\usr\altia\demos\vbasic[16]\meter.mak. If you are using a 16-bit Visual Basic development environment, then open the project files in the vbasic16 directories while 32-bit Visual Basic users should open the project files in the vbasic directories.

As discussed earlier, the file c:\usr\altia\lib\altiaapi.txt contains declarations for all of the functions supported by the 16-bit Altia API DLL. It also includes documentation for each function. A copy of altiaapi.txt is actually included in the declarations portion of the ALTIAAPI.BAS code module for each 16-bit Visual Basic demonstration project.

The c:\usr\altia\lib\altia32.txt file contains the 32-bit DLL function declarations. A copy of altia32.txt is actually included in the declarations portion of the ALTIA32.TXT code module in each 32-bit Visual Basic demonstration project.