Advanced MFC Programming

Chapter 5. Common Controls
This function also has several versions. The following is the one that has the simplest format:
int CTreeCtrl::InsertItem(LPTV_INSERTSTRUCT lpInsertStruct);
The only parameter to this function is a TV_INSERTSTRUCT type pointer:
typedef struct _TV_INSERTSTRUCT{
HTREEITEM hParent;
HTREEITEM hInsertAfter;
TV_ITEM item;
} TV_INSERTSTRUCT;
In a tree control, nodes are managed through handles. After a node is created, it will be assigned an
HTREEITEM type handle. Each node has a different handle, so we can use the handle to access a specific
node. In the above structure, member hParent indicates which node is the parent of the new node. If we
assign NULL to this member, the new node will become the root node. Likewise, member hInsertAfter is
used to indicate where the new node should be inserted. We can specify a node handle, or we can use
predefined parameters TVI_FIRST, TVI_LAST or TVI_SORT to insert the new node after the first node, last
node or let the nodes be sorted automatically.
Member item is a TV_ITEM type object, and the structure contains the information of the new node:
typedef struct _TV_ITEM {
UINT mask;
HTREEITEM hItem;
UINT state;
UINT stateMask;
LPSTR pszText;
int cchTextMax;
int iImage;
int iSelectedImage;
int cChildren;
LPARAM lParam;
} TV_ITEM;
In order to add new nodes, we need to understand how to use the following four members of this
structure: mask, pszText, iImage and iSelectedImage.
Member mask indicates which of the other members in the structure contain valid data. Besides mask,
every member of this structure has a corresponding mask flag listed as follows:
Member
Mask Flag
hItem TVIF_HANDLE
state, stateMask TVIF_STATE
pszText, cchTextMax TVIF_TEXT
iImage TVIF_IMAGE
iImage, iSelectedImage TVIF_SELECTEDIMAGE
cChildren TVIF_CHILDREN
lParam TVIF_PARAM
In order to use members pszText, iImage and iSelectedImage, we need to set the following bits of
member mask:
TVIF_IMAGE | TVIF_SELECTEDIMAGE | TVIF_TEXT
Member pszText is a pointer to a null-terminated string text that will be used to label this node.
Member iImage and iSelectedImage are indices to two images contained in the image list that will be
used to represent the node’s normal and selected state respectively.
By calling function CTreeCtrl::InsertItem(…) repeatedly, we could create a tree structure with
desired number of nodes.
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