DragDropTreeCtrl.h
#if !defined(AFX_DRAGDROPTREECTRL_H__63AC05AD_E0DC_11D1_8E53_006008A82731__INCLUDED_)
#define AFX_DRAGDROPTREECTRL_H__63AC05AD_E0DC_11D1_8E53_006008A82731__INCLUDED_
#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000
// DragDropTreeCtrl.h : header file
/////////////////////////////////////////////////////////////////////////////
// CDragDropTreeCtrl window
class CDragDropTreeCtrl : public CTreeCtrl
{
// Construction
public:
CDragDropTreeCtrl();
// Attributes
public:
// Operations
public:
// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CDragDropTreeCtrl)
protected:
virtual BOOL PreCreateWindow(CREATESTRUCT& cs);
//}}AFX_VIRTUAL
// Implementation
public:
virtual ~CDragDropTreeCtrl();
// Generated message map functions
protected:
HTREEITEM HighlightDropTarget (CPoint point);
int m_nDelayInterval;
BOOL IsItemExpanded (HTREEITEM hItem);
int m_nScrollMargin;
int m_nScrollInterval;
void CopyChildren (HTREEITEM hDest, HTREEITEM hSrc);
void CopyTree (HTREEITEM hDest, HTREEITEM hSrc);
void MoveTree (HTREEITEM hDest, HTREEITEM hSrc);
BOOL IsChildOf (HTREEITEM hItem1, HTREEITEM hItem2);
BOOL m_bDragging;
CImageList* m_pImageList;
HTREEITEM m_hDragItem;
//{{AFX_MSG(CDragDropTreeCtrl)
afx_msg void OnBeginDrag(NMHDR* pNMHDR, LRESULT* pResult);
afx_msg void OnMouseMove(UINT nFlags, CPoint point);
afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
afx_msg void OnTimer(UINT nIDEvent);
//}}AFX_MSG
DECLARE_MESSAGE_MAP()
};
/////////////////////////////////////////////////////////////////////////////
//{{AFX_INSERT_LOCATION}}
// Microsoft Developer Studio will insert additional declarations immediately
// before the previous line.
#endif
// !defined(AFX_DRAGDROPTREECTRL_H__63AC05AD_E0DC_11D1_8E53_006008A82731__INCLUDED_)DragDropTreeCtrl.cpp
// DragDropTreeCtrl.cpp : implementation file
#include "stdafx.h"
#include "TreeDemo.h"
#include "DragDropTreeCtrl.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
/////////////////////////////////////////////////////////////////////////////
// CDragDropTreeCtrl
CDragDropTreeCtrl::CDragDropTreeCtrl()
{
m_hDragItem = NULL;
m_pImageList = NULL;
m_bDragging = FALSE;
m_nDelayInterval = 500; // Default delay interval = 500 milliseconds
m_nScrollInterval = 200; // Default scroll interval = 200 milliseconds
m_nScrollMargin = 10; // Default scroll margin = 10 pixels
}
CDragDropTreeCtrl::~CDragDropTreeCtrl()
{
// Delete the image list created by CreateDragImage.
//
if (m_pImageList != NULL)
delete m_pImageList;
}
BEGIN_MESSAGE_MAP(CDragDropTreeCtrl, CTreeCtrl)
//{{AFX_MSG_MAP(CDragDropTreeCtrl)
ON_NOTIFY_REFLECT(TVN_BEGINDRAG, OnBeginDrag)
ON_WM_MOUSEMOVE()
ON_WM_LBUTTONUP()
ON_WM_TIMER()
//}}AFX_MSG_MAP
END_MESSAGE_MAP()
/////////////////////////////////////////////////////////////////////////////
// CDragDropTreeCtrl message handlers
BOOL CDragDropTreeCtrl::PreCreateWindow(CREATESTRUCT& cs)
{
// Make sure the control's TVS_DISABLEDRAGDROP flag is not set.
// If you subclass an existing tree view control rather than create
// a CDragDropTreeCtrl outright, it's YOUR responsibility to see that
// this flag isn't set.
cs.style &= ~TVS_DISABLEDRAGDROP;
return CTreeCtrl::PreCreateWindow(cs);
}
void CDragDropTreeCtrl::OnBeginDrag(NMHDR* pNMHDR, LRESULT* pResult)
{
*pResult = 0;
NM_TREEVIEW* pNMTreeView = (NM_TREEVIEW*) pNMHDR;
//
// Do nothing if the user is attempting to drag a top-level item.
//
HTREEITEM hItem = pNMTreeView->itemNew.hItem;
if (GetParentItem (hItem) == NULL)
return;
// Create a drag image. If the assertion fails, you probably forgot
// to assign an image list to the control with SetImageList. Create-
// DragImage will not work if the control hasn't been assigned an
// image list!
m_pImageList = CreateDragImage (hItem);
ASSERT (m_pImageList != NULL);
if (m_pImageList != NULL) { // Just to be sure
// Compute the coordinates of the "hot spot"--the location of the
// cursor relative to the upper left corner of the item rectangle.
CRect rect;
GetItemRect (hItem, rect, TRUE);
CPoint point (pNMTreeView->ptDrag.x, pNMTreeView->ptDrag.y);
CPoint hotSpot = point;
hotSpot.x -= rect.left;
hotSpot.y -= rect.top;
// Convert the client coordinates in "point" to coordinates relative
// to the upper left corner of the control window.
CPoint client (0, 0);
ClientToScreen (&client);
GetWindowRect (rect);
point.x += client.x - rect.left;
point.y += client.y - rect.top;
// Capture the mouse and begin dragging.
SetCapture ();
m_pImageList->BeginDrag (0, hotSpot);
m_pImageList->DragEnter (this, point);
m_hDragItem = hItem;
m_bDragging = TRUE;
}
}
void CDragDropTreeCtrl::OnMouseMove(UINT nFlags, CPoint point)
{
CTreeCtrl::OnMouseMove(nFlags, point);
if (m_bDragging && m_pImageList != NULL) {
// Stop the scroll timer if it's running.
KillTimer (1);
// Erase the Old drag image and draw a new one.
m_pImageList->DragMove (point);
// Highlight the drop target if the cursor is over an item.
HTREEITEM hItem = HighlightDropTarget (point);
// Modify the cursor to provide visual feedback to the user.
// Note: It's important to do this AFTER the call to DragMove.
::SetCursor (hItem == NULL ?
AfxGetApp ()->LoadStandardCursor (IDC_NO) :
(HCURSOR) ::GetClassLong (m_hWnd, GCL_HCURSOR));
// Set a timer if the cursor is at the top or bottom of the window,
// or if it's over a collapsed item.
CRect rect;
GetClientRect (rect);
int cy = rect.Height ();
if ((point.y >= 0 && point.y <= m_nScrollMargin) ||
(point.y >= cy - m_nScrollMargin && point.y <= cy) ||
(hItem != NULL && ItemHasChildren (hItem) &&
!IsItemExpanded (hItem)))
SetTimer (1, m_nDelayInterval, NULL);
}
}
void CDragDropTreeCtrl::OnLButtonUp(UINT nFlags, CPoint point)
{
CTreeCtrl::OnLButtonUp(nFlags, point);
if (m_bDragging && m_pImageList != NULL) {
// Stop the scroll timer if it's running.
KillTimer (1);
// Terminate the dragging operation and release the mouse.
m_pImageList->DragLeave (this);
m_pImageList->EndDrag ();
::ReleaseCapture ();
m_bDragging = FALSE;
SelectDropTarget (NULL);
// Delete the image list created by CreateDragImage.
delete m_pImageList;
m_pImageList = NULL;
// Get the HTREEITEM of the drop target and exit now if it's NULL.
UINT nFlags;
HTREEITEM hItem = HitTest (point, &nFlags);
if (hItem == NULL)
return;
// Display an error message if the move is illegal.
if (hItem == m_hDragItem) {
MessageBox (_T ("An item can't be dropped onto itself"));
return;
}
else if (hItem == GetParentItem (m_hDragItem)) {
MessageBox (_T ("An item can't be dropped onto its parent"));
return;
}
else if (IsChildOf (hItem, m_hDragItem)) {
MessageBox (_T ("An item can't be dropped onto one of its " \
"children"));
return;
}
// Move the dragged item and its subitems (if any) to the drop point.
MoveTree (hItem, m_hDragItem);
m_hDragItem = NULL;
}
}
void CDragDropTreeCtrl::OnTimer(UINT nIDEvent)
{
CTreeCtrl::OnTimer(nIDEvent);
//
// Reset the timer.
//
SetTimer (1, m_nScrollInterval, NULL);
// Get the current cursor position and window height.
DWORD dwPos = ::GetMessagePos ();
CPoint point (LOWORD (dwPos), HIWORD (dwPos));
ScreenToClient (&point);
CRect rect;
GetClientRect (rect);
int cy = rect.Height ();
// Scroll the window if the cursor is near the top or bottom.
if (point.y >= 0 && point.y <= m_nScrollMargin) {
HTREEITEM hFirstVisible = GetFirstVisibleItem ();
m_pImageList->DragShowNolock (FALSE);
SendMessage (WM_VSCROLL, MAKEWPARAM (SB_LINEUP, 0), NULL);
m_pImageList->DragShowNolock (TRUE);
//
// Kill the timer if the window did not scroll, or redraw the
// drop target highlight if the window did scroll.
//
if (GetFirstVisibleItem () == hFirstVisible)
KillTimer (1);
else {
HighlightDropTarget (point);
return;
}
}
else if (point.y >= cy - m_nScrollMargin && point.y <= cy) {
HTREEITEM hFirstVisible = GetFirstVisibleItem ();
m_pImageList->DragShowNolock (FALSE);
SendMessage (WM_VSCROLL, MAKEWPARAM (SB_LINEDOWN, 0), NULL);
m_pImageList->DragShowNolock (TRUE);
//
// Kill the timer if the window did not scroll, or redraw the
// drop target highlight if the window did scroll.
//
if (GetFirstVisibleItem () == hFirstVisible)
KillTimer (1);
else {
HighlightDropTarget (point);
return;
}
}
// If the cursor is hovering over a collapsed item, expand the tree.
UINT nFlags;
HTREEITEM hItem = HitTest (point, &nFlags);
if (hItem != NULL && ItemHasChildren (hItem) && !IsItemExpanded (hItem)) {
m_pImageList->DragShowNolock (FALSE);
Expand (hItem, TVE_EXPAND);
m_pImageList->DragShowNolock (TRUE);
KillTimer (1);
return;
}
}
BOOL CDragDropTreeCtrl::IsChildOf(HTREEITEM hItem1, HTREEITEM hItem2)
{
HTREEITEM hParent = hItem1;
while ((hParent = GetParentItem (hParent)) != NULL) {
if (hParent == hItem2)
return TRUE;
}
return FALSE;
}
void CDragDropTreeCtrl::MoveTree(HTREEITEM hDest, HTREEITEM hSrc)
{
CopyTree (hDest, hSrc);
DeleteItem (hSrc);
}
void CDragDropTreeCtrl::CopyTree(HTREEITEM hDest, HTREEITEM hSrc)
{
// Get the attributes of item to be copied.
int nImage, nSelectedImage;
GetItemImage (hSrc, nImage, nSelectedImage);
CString string = GetItemText (hSrc);
// Create an exact copy of the item at the destination.
HTREEITEM hNewItem = InsertItem (string, nImage, nSelectedImage, hDest);
// If the item has subitems, copy the M, too.
if (ItemHasChildren (hSrc))
CopyChildren (hNewItem, hSrc);
// Select the newly added item.
SelectItem (hNewItem);
}
void CDragDropTreeCtrl::CopyChildren(HTREEITEM hDest, HTREEITEM hSrc)
{
// Get the first subitem.
HTREEITEM hItem = GetChildItem (hSrc);
ASSERT (hItem != NULL);
// Create a copy of it at the destination.
int nImage, nSelectedImage;
GetItemImage (hItem, nImage, nSelectedImage);
CString string = GetItemText (hItem);
HTREEITEM hNewItem = InsertItem (string, nImage, nSelectedImage, hDest);
// If the subitem has subitems, copy the M, too.
if (ItemHasChildren (hItem))
CopyChildren (hNewItem, hItem);
// Do the same for other subitems of hSrc.
while ((hItem = GetNextSiblingItem (hItem)) != NULL) {
GetItemImage (hItem, nImage, nSelectedImage);
string = GetItemText (hItem);
hNewItem = InsertItem (string, nImage, nSelectedImage, hDest);
if (ItemHasChildren (hItem))
CopyChildren (hNewItem, hItem);
}
}
BOOL CDragDropTreeCtrl::IsItemExpanded(HTREEITEM hItem)
{
return GetItemState (hItem, TVIS_EXPANDED) & TVIS_EXPANDED;
}
HTREEITEM CDragDropTreeCtrl::HighlightDropTarget(CPoint point)
{
// Find out which item (if any) the cursor is over.
UINT nFlags;
HTREEITEM hItem = HitTest (point, &nFlags);
// Highlight the item, or unhighlight all items if the cursor isn't
// over an item.
m_pImageList->DragShowNolock (FALSE);
SelectDropTarget (hItem);
m_pImageList->DragShowNolock (TRUE);
// Return the handle of the highlighted item.
return hItem;
}