VIEWING THE POSSIBLE API CALLS

You can view API calls immediately in a couple of ways. One way is by using the API Viewer that comes with Microsoft Office Developer. The other is to copy the example in the text file called Win32api.txt.

Using the API Viewer to Locate Calls

A good source for API calls is the API Viewer that comes with Microsoft Office Developer. The API Viewer that comes with the MOD is useful for getting an idea of the available API calls. To use the API Viewer, follow these steps:

The Available Items list box then is populated with API call names (see Figure 15.1).

The API Type drop-down list allows you to choose from Constants, Declares, and Types. Constants and Types are actually used with the arguments used in declarations.

Cutting and Pasting Calls from the API Viewer

To copy and paste calls from the API Viewer, follow these steps:

Now you need to load Access and pull the declarations into the actual module where they're needed. To do so, open Access and then follow these steps:

The full declarations should be pasted in the module. It saves a lot of hassle not having to remember the correct syntax. You can see the full declarations that were copied, as follows:

Declare Function GetSystemDirectory Lib "kernel32" Alias _
   "GetSystemDirectoryA" (ByVal lpBuffer As String, _
   ByVal nSize As Long) As Long
Declare Function GetWindowsDirectory Lib "kernel32" Alias _
   "GetWindowsDirectoryA" (ByVal lpBuffer As String, _
   ByVal nSize As Long) As Long

Now all you need to do is place wu_ on the front of the name of the declarations. They would then look like this:

Declare Function wu_GetSystemDirectory Lib "kernel32" Alias _
   "GetSystemDirectoryA" (ByVal lpBuffer As String, _
   ByVal nSize As Long) As Long
Declare Function wu_GetWindowsDirectory Lib "kernel32" Alias _
   "GetWindowsDirectoryA" (ByVal lpBuffer As String, _
   ByVal nSize As Long) As Long

You'll look at these two declarations again later in the section “Looking at Some Examples of API Calls,” where they're used in actual calls to display the Windows main folder and system folder.

Finding API Calls in the Win32api.txt File

You can lookat API calls in another way, by using the Win32api.txt available with the ODE and on the CD-ROM accompanying this book. From Explorer, access the ExamplesChap15 folder on the CD. Then double-click the Win32api.txt file. It will then appear in Notepad or WordPad, depending on how much memory you have available.

In addition to the disclaimer about it being royalty-free and unsupported, notice that the name of the file is Win32 API Declarations for Visual Basic. This is what I meant when I said earlier that these declarations are literally identical in the two products, VB and Access.

As you page down through the file, notice the constants, user-defined type declarations, and the API declarations themselves.

To use the declarations given in the Win32api.txt file, simply copy and paste as you would with any other text into the Declarations section of an Access module.

Another great feature is being able to grab the type declarations right out of this file. The type declaration shown in Figure 15.4, WNDCLASS, is used in the API call declaration that follows it.