Odvhlb.exe Demos Owner-Draw Variable-Height List Box |
Q86333
The information in this article applies to:
- Microsoft Windows Software Development Kit (SDK)
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 files are available for download from the Microsoft Download Center:
Odvhlb.exe
For additional information about how to download Microsoft Support files, click the article number below to view the article in the Microsoft Knowledge Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
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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 kbGrpDSUser kbOSWin310
Issue type :
Technology : kbAudDeveloper kbSDKSearch kbWinSDKSearch
Last Reviewed: December 9, 1999 |
