SAMPLE: Odvhlb.exe Demos Owner-Draw Variable-Height List Box

ID: Q86333

The information in this article applies to:

SUMMARY

Odvhlb.exe is a smaple in the Microsoft Software Library that demonstrates how to use an owner-draw variable-height list box in an application for the Microsoft Windows environment.

In the ODVHLB application, the user can add a short string (one line of text), long string (two lines of text), or an icon to a list box. Because the list box has the LBS_MULTIPLESEL style, the user can select multiple items in the list box simultaneously.

MORE INFORMATION

The following file is available for download from the Microsoft Software Library: 

 ~ Odvhlb.exe (size: 26949 bytes)
For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from
               Online Services
To implement an owner-draw variable-height list box, an application must process the WM_MEASUREITEM and WM_DRAWITEM messages in the window procedure for the list box's parent window. When the list box has the LBS_OWNERDRAWVARIABLE style, the parent window receives a WM_MEASUREITEM and a WM_DRAWITEM message each time the application updates an item in the list box.

When the parent of the list box receives a WM_MEASUREITEM message, lParam points to a MEASUREITEMSTRUCT data structure. The application must specify values for the itemHeight and itemWidth members of this structure to indicate how much space in the list box Windows must allocate for the item. Through the WM_MEASUREITEM message, the application can individually specify the height of each item in the list box.

The parent of the list box receives a WM_DRAWITEM message when an item in the list box needs to be drawn. The lParam parameter points to a DRAWITEMSTRUCT data structure. The itemAction member indicates the required drawing action and itemState member indicates the visual state of the item. For example, when the itemAction member is ODA_SELECT and the itemState member has the ODS_SELECTED flag set, the selection state has changed and the item is gaining selection. Conversely, if the itemState member has the ODS_SELECTED flag clear, the item is losing selection.

The itemData member of the DRAWITEMSTRUCT data structure identifies the item in the list box, either through a pointer to a string or a 32-bit identifier. An application specifies an appropriate identifier when it uses the LB_ADDSTRING or LB_INSERTSTRING message to add an item to the list box.

Additional query words: listbox Keywords : kbfile kbsample kb16bitonly kbCtrl kbListBox kbGrpUser kbWinOS310

Last Reviewed: December 26, 1998