Advanced MFC Programming

Chapter 14. Views
returned value should be the handle of the item that is currently under the mouse cursor. If the mouse is not
over any item, the function will return NULL. Please note that when calling this function, the coordinates
of the mouse cursor should be in the coordinate system of the client window. We need to call function
CWnd::ScreenToClient(…) to make the conversion.
When an Item Is Clicked
Special attention needs to be paid to directory nodes labeled with “.” and “..”. When they are clicked,
the current working directory should be changed differently. For the purpose of demonstration, in the
sample, no change will be made if the user clicks any of the two types of directories. If the user clicks a
normal directory node, we need to change the current working directory to the selected one and notify the
list view to update its contents. This notification is made through calling function
CBrowserDoc::ChangePath(), within which function CBrowserView::ChangeDir() is called. However, if
the user clicks on the currently selected directory, no change will be made. The following is the message
handler for mouse left button clicking:
void CDirView::OnClick(NMHDR *pNMHDR, LRESULT *pResult)
{
CPoint pt;
HTREEITEM hItem;
UINT nFlags;
CString szPath;
char path[_MAX_PATH];
}
::GetCursorPos(&pt);
ScreenToClient(&pt);
hItem=GetTreeCtrl().HitTest(pt, &nFlags);
if(hItem != NULL)
{
szPath=GetTreeCtrl().GetItemText(hItem);
if(szPath.Find('.') == -1)
{
szPath=GetDir(hItem);
if(szPath.GetLength())
{
if(_getcwd(path, _MAX_PATH) != NULL)
{
if(stricmp((LPCSTR)szPath, path) != 0)
{
if(_chdir((LPCSTR)szPath) == 0)
{
((CExplorerDoc *)GetDocument())->ChangePath();
}
}
}
}
}
}
*pResult=0;
When a Node Expands
When a node is expanding, we need to check the newly revealed nodes to see if they always contain
child nodes. If not, we need to add child nodes (if they have sub-directories) to them because this will
enable node button automatically. In the sample, function CDirView::AddChildrenChildren() is
implemented to let us add new nodes for all the child nodes of a given node. Within this function, we check
each child node to see if it already has child items (which means the sub-directories have already been
added for this node). If not, we call function CDirView::AddDirs(…) to add new nodes to it. A node’s child
item can be enumerated by calling function CTreeCtrl::GetChildItem(…) first then calling
CTreeCtrl::GetNextSiblingItem(…) repeatedly until it returns NULL value. Also, we can call function
CTreeCtrl::ItemHasChildren(…) to examine if a node already has child nodes. The following is the
implementation of function CDirView::AddChildrenChildren(…):
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