The TVM_GETVISIBLECOUNT message obtains the number of items that are fully visible in the client window of a tree-view control. You can send this message explicitly, or by using the TreeView_GetVisibleCount macro.
TVM_GETVISIBLECOUNT
wParam = 0;
lParam = 0;
Return Values
Returns the number of items that are fully visible in the client window of the tree-view control.
Remarks
Note that the return value is the number of fully-visible items. If you can see all of 20 items, and part of one more item, the return value is 20, not 21.
See Also