SAMPLE: Setting Tab Stops in a Windows List Box

• Microsoft Windows Software Development Kit (SDK) versions 3.0 and 3.1
• Microsoft Win32 Application Programming Interface (API) included with:

      - Microsoft Windows NT versions 3.5 and 3.51
      - Microsoft Windows 95 version 4.0
  

SUMMARY

Tab stops can be used in a list box to align columns of information. This article describes how to set tab stops in a list box and provides a code example that demonstrates the process.

MORE INFORMATION

To set tab stops in a list box, perform the following three steps:

1. Specify the LBS_USETABSTOPS style when creating the list box.

2. Assign the desired tab stops to an integer array.

   a. The tab stop values must be in increasing order -- back tab

         stops are not allowed. The tabs work the same as typewriter
         tabs: once a tab stop is overrun, a tab character will move
         the cursor to the next tab stop. If the tab stop list is
         overrun (that is, the current position is greater than the last
         tab stop value), the default tab of eight characters is used.
   

   b. The tab stops should be specified in dialog units. On the

         average, each character is about four horizontal dialog units in
         width.
   

   c. It is possible to hide columns of text from the user by

         specifying tab stops beyond the right side of the list box. This
         can be a useful way to hide information used for the
         application's internal processing.
   

3. Send an LB_SETTABSTOPS message to the list box to set the tab stops. For example, in Windows 3.1:

         SendMessage(GetDlgItem(hDlg, IDD_LISTBOX),
                     LB_SETTABSTOPS,
                     TOTAL_TABS,
                     (LONG)(LPSTR)TabStopList);
   
      a. If wParam is set to 0 (zero) and lParam to NULL, the tab stops are
         set to two dialog units by default.
   
      b. SendMessage() will return TRUE if all of the tab stops are set
         successfully; otherwise, SendMessage() returns FALSE.
   
   

Example

Below is an example of the process. Tab stops are set at character positions 16, 32, 58, and 84.

   int     TabStopList[TOTAL_TABS]; /*  Array to store tabs */

   TabStopList[0] = 16 * 4;          /* 16 spaces */
   TabStopList[1] = 32 * 4;          /* 32 spaces */
   TabStopList[2] = 58 * 4;          /* 58 spaces */
   TabStopList[3] = 84 * 4;          /* 84 spaces */

   SendMessage(GetDlgItem(hDlg, IDD_LISTBOX),
               LB_SETTABSTOPS,
               TOTAL_TABS,
               (LONG)(LPSTR)TabStopList);

If the desired unit of measure is character position, then specifying tab positions in dialog units is recommended. Dialog units are independent of the current font; they are loosely based on the average width of the system font. Each character takes approximately four dialog units.

NOTE: Under Windows 95, dialog base units for dialogs based on non-system fonts are calculated in a different way than under Windows 3.1. For more information, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q125681
   TITLE     : How to Calculate Dialog Base Units with Non-system-based
               Font

   TabStopList[n] = 4 * DesiredPixelPosition /
                     LOWORD(GetDialogBaseUnits());

Download TABSTOPS.EXE, a self-extracting file, from the Microsoft Software Library (MSL) on the following services:

• Microsoft Download Service (MSDL)

        Dial (206) 936-6735 to connect to MSDL
        Download TABSTOPS.EXE (size: 22641 bytes) 
  

• Internet (anonymous FTP)

        ftp ftp.microsoft.com
        Change to the \SOFTLIB\MSLFILES directory
        Get TABSTOPS.EXE (size: 22641 bytes)