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How to Initialize the Image List

  • Article

Every item in a tree-view control can have two images associated with it. An item displays one image when it is selected and the other when it is not. To include images with tree-view items, first use the Image Lists functions to create an image list and add images to it. Then associate the image list with the tree-view control by using the TVM_SETIMAGELIST message.

What you need to know

Technologies

Prerequisites

  • C/C++
  • Windows User Interface Programming

Instructions

Initialize the Image List

The following example creates an image list, adds three bitmaps to the list, and associates the image list with a tree-view control.

// InitTreeViewImageLists - creates an image list, adds three bitmaps 
// to it, and associates the image list with a tree-view control. 
// Returns TRUE if successful, or FALSE otherwise. 
// hwndTV - handle to the tree-view control. 
//
// Global variables and constants: 
// g_hInst - the global instance handle.
// g_nOpen, g_nClosed, and g_nDocument - global indexes of the images. 
// CX_BITMAP and CY_BITMAP - width and height of an icon. 
// NUM_BITMAPS - number of bitmaps to add to the image list. 
// IDB_OPEN_FILE, IDB_CLOSED_FILE, IDB_DOCUMENT -
//     resource identifiers of the bitmaps.

BOOL InitTreeViewImageLists(HWND hwndTV) 
{ 
    HIMAGELIST himl;  // handle to image list 
    HBITMAP hbmp;     // handle to bitmap 

    // Create the image list. 
    if ((himl = ImageList_Create(CX_BITMAP, 
                                 CY_BITMAP,
                                 FALSE, 
                                 NUM_BITMAPS, 0)) == NULL) 
        return FALSE; 

    // Add the open file, closed file, and document bitmaps. 
    hbmp = LoadBitmap(g_hInst, MAKEINTRESOURCE(IDB_OPEN_FILE)); 
    g_nOpen = ImageList_Add(himl, hbmp, (HBITMAP)NULL); 
    DeleteObject(hbmp); 

    hbmp = LoadBitmap(g_hInst, MAKEINTRESOURCE(IDB_CLOSED_FILE)); 
    g_nClosed = ImageList_Add(himl, hbmp, (HBITMAP)NULL); 
    DeleteObject(hbmp); 

    hbmp = LoadBitmap(g_hInst, MAKEINTRESOURCE(IDB_DOCUMENT)); 
    g_nDocument = ImageList_Add(himl, hbmp, (HBITMAP)NULL); 
    DeleteObject(hbmp); 

    // Fail if not all of the images were added. 
    if (ImageList_GetImageCount(himl) < 3) 
        return FALSE; 

    // Associate the image list with the tree-view control. 
    TreeView_SetImageList(hwndTV, himl, TVSIL_NORMAL); 

    return TRUE; 
}

Using Tree-View Controls

CustDTv sample illustrates custom draw in a Tree-View control