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How to Work With State Image Indexes

  • Article

There is often confusion about how to set and retrieve the state image index in a tree-view control. The following examples demonstrate the proper method for setting and retrieving the state image index. The examples assume that there are only two state image indexes in the tree-view control, unchecked and checked. If your application contains more than two, these functions will need to be modified to handle that case.

What you need to know

Technologies

Prerequisites

  • C/C++
  • Windows User Interface Programming

Instructions

Set a Tree-View Item's Check State

The following example demonstrates how to set a tree-view item's check state.

  BOOL TreeView_SetCheckState(HWND hwndTreeView, HTREEITEM hItem, BOOL fCheck)
  {
      TVITEM tvItem;

      tvItem.mask   = TVIF_HANDLE | TVIF_STATE;
      tvItem.hItem  = hItem;
      tvItem.stateMask  = TVIS_STATEIMAGEMASK;

      // Image 1 in the tree-view check box image list is the unchecked box. 
      // Image 2 is the checked box.

      tvItem.state = INDEXTOSTATEIMAGEMASK((fCheck ? 2 : 1));

      return TreeView_SetItem(hwndTreeView, &tvItem);
  }

Retrieve a Tree-View Item's Check State

The following example demonstrates how to retrieve a tree-view item's check state.

  BOOL TreeView_GetCheckState(HWND hwndTreeView, HTREEITEM hItem)
  {
      TVITEM tvItem;

      // Prepare to receive the desired information.
      tvItem.mask   = TVIF_HANDLE | TVIF_STATE;
      tvItem.hItem  = hItem;
      tvItem.stateMask  = TVIS_STATEIMAGEMASK;

      // Request the information.
      TreeView_GetItem(hwndTreeView, &tvItem);

      // Return zero if it's not checked, or nonzero otherwise.
      return ((BOOL)(tvItem.state >> 12) - 1);
  }

Using Tree-View Controls

CustDTv sample illustrates custom draw in a Tree-View control