MFC模型树控件TreeCtrl实现按下Ctrl键多选，按下Shift键连选

MFC模型树控件TreeCtrl实现按下Ctrl键多选，按下Shift键连选

　　MFC的List Box只需要将控件属性中的Selection项设置为Extended，即可实现Ctrl键多选和Shift键连选；然而MFC的Tree Contrl（TreeCtrl）没有像List Box那样设置某个属性就实现Ctrl键多选和Shift键连选的功能，网上大多数MFC的TreeCtrl多选功能是用复选框实现的，也有前辈想通过继承类CTreeCtrl来重写多选功能，其中实现该功能较好的示例为以下链接：http://www.pudn.com/Download/item/id/640887.html，经过试验，发现该示例按住Ctrl只能选中两个项目。于是在此示例的基础上，我重新写了按下Ctrl键的代码，实现了真正的多选。
　　上述链接中包含一个基于对话框的MFC应用程序示例，该示例演示了CTreeCtrEx的用法，要将CTreeCtrlEx合并到自己的项目中，请按照以下步骤操作：
　　（1）将TreeCtrlEx.cpp和TreeCtrlEx.h两个文件复制到项目目录；
　　（2）将它们添加到项目中；
　　（3）在需要的地方包含TreeCtrlEx.h（包含在StdAfx.h中非常方便）；
　　（4）在需要多选的地方，将对象的类型由CTreeCtrl更改为CTreeCtrlEx。
　　TreeCtrlEx.cpp和TreeCtrlEx.h中只有以下6个函数是多选所需要的，其他的可根据自己的需要保留：

afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
afx_msg void OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags);
BOOL SelectItems(HTREEITEM hFromItem, HTREEITEM hToItem);
void ClearSelection(BOOL bMultiOnly = FALSE);
void SelectMultiple(HTREEITEM hClickedItem, UINT nFlags, CPoint point);

　　下面直接上我修改后TreeCtrlEx.cpp和TreeCtrlEx.h中的代码，有什么不对的地方，还请读者留言，大家一起学习。代码仅供参考，转载请标明出处。
　　
TreeCtrlEx.h

#pragma once
#include "afxcmn.h"
#include "vector"
using namespace std;
class CTreeCtrlEx :
	public CTreeCtrl
{
public:
	CTreeCtrlEx();
	~CTreeCtrlEx();
	DECLARE_MESSAGE_MAP()
	afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
	afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
	afx_msg void OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags);
	BOOL SelectItems(HTREEITEM hFromItem, HTREEITEM hToItem);
	void ClearSelection(BOOL bMultiOnly = FALSE);
protected:
	void SelectMultiple(HTREEITEM hClickedItem, UINT nFlags, CPoint point);
public:
	BOOL		m_bEditLabelPending;
	UINT		m_idTimer;
	HTREEITEM	m_hClickedItem;
	BOOL		m_bSelectPending;
	CPoint		m_ptClick;
	HTREEITEM	m_hFirstSelectedItem;
	BOOL		m_bSelectionComplete;
	bool		bIsSelectedItem[100];//存放每一个选项的状态
};

TreeCtrlEx.cpp

#include "stdafx.h"
#include "TreeCtrlEx.h"

#define TCEX_EDITLABEL 1		// Edit label timer event

CTreeCtrlEx::CTreeCtrlEx()
{
	m_bSelectPending = FALSE;
	m_hClickedItem = NULL;
	m_hFirstSelectedItem = NULL;
	m_bSelectionComplete = TRUE;
	m_bEditLabelPending = FALSE;
	for (int i = 0; i < 100; i++)
	{
		bIsSelectedItem[i] = false;//初始化
	}
}


CTreeCtrlEx::~CTreeCtrlEx()
{
}
BEGIN_MESSAGE_MAP(CTreeCtrlEx, CTreeCtrl)
	ON_WM_LBUTTONDOWN()
	ON_WM_LBUTTONUP()
	ON_WM_KEYDOWN()
END_MESSAGE_MAP()


void CTreeCtrlEx::OnLButtonDown(UINT nFlags, CPoint point)
{
	// TODO:  在此添加消息处理程序代码和/或调用默认值
	UINT nHitFlags = 0;
	HTREEITEM hClickedItem = HitTest(point, &nHitFlags);

	//必须显式调用标签编辑，OnLButtonDown通常会这样做，但我们不能在这里调用它，因为有多个选择...
	if (!(nFlags&(MK_CONTROL | MK_SHIFT)) && (GetStyle() & TVS_EDITLABELS) && (nHitFlags & TVHT_ONITEMLABEL))
	if (hClickedItem == GetSelectedItem())
	{
		//在编辑标签之前清除多重选择
		ClearSelection();
		SelectItem(hClickedItem);
		//调用标签编辑
		m_bEditLabelPending = TRUE;
		m_idTimer = SetTimer(TCEX_EDITLABEL, GetDoubleClickTime(), NULL);
		return;
	}

	m_bEditLabelPending = FALSE;

	if (nHitFlags & TVHT_ONITEM)
	{
		SetFocus();
		m_hClickedItem = hClickedItem;
		//点击的项目是否已被选中
		BOOL bIsClickedItemSelected = GetItemState(hClickedItem, TVIS_SELECTED) & TVIS_SELECTED;
		if (bIsClickedItemSelected)
		{
			//可能用户想拖放多个项目！所以，等到OnLButtonUp()才进行选择。
			m_bSelectPending = TRUE;
		}
		else
		{
			SelectMultiple(hClickedItem, nFlags, point);
			m_bSelectPending = FALSE;
		}
		m_ptClick = point;
	}
	else
		CTreeCtrl::OnLButtonDown(nFlags, point);
}


void CTreeCtrlEx::OnLButtonUp(UINT nFlags, CPoint point)
{
	// TODO:  在此添加消息处理程序代码和/或调用默认值
	if (m_bSelectPending)
	{
		//一个项目一直在等待执行
		SelectMultiple(m_hClickedItem, nFlags, point);
		m_bSelectPending = FALSE;
	}

	m_hClickedItem = NULL;

	CTreeCtrl::OnLButtonUp(nFlags, point);
}


void CTreeCtrlEx::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
	// TODO:  在此添加消息处理程序代码和/或调用默认值
	CWnd* pWnd = GetParent();

	if (nChar == VK_NEXT || nChar == VK_PRIOR)
	{
		if (!(GetKeyState(VK_SHIFT) & 0x8000))
		{
			//用户在没有按住Shift键的情况下按PG键：清除多选(如果有多选)，让基类做正常的选择工作！
			if (GetSelectedCount()>1)
				ClearSelection(TRUE);

			CTreeCtrl::OnKeyDown(nChar, nRepCnt, nFlags);
			m_hFirstSelectedItem = GetSelectedItem();
			return;
		}

		//表示选择过程未完成的标志(将禁止TVN_SELCHANGED发送给父类)
		m_bSelectionComplete = FALSE;

		//让基类选择项
		CTreeCtrl::OnKeyDown(nChar, nRepCnt, nFlags);
		HTREEITEM hSelectedItem = GetSelectedItem();

		//然后选择介于两者之间的项目
		SelectItems(m_hFirstSelectedItem, hSelectedItem);

		//选择过程现已完成。由于我们已经销毁了Windows的treectrl提供的TVN_SELCHANGED通知，
		//现在我们必须自己生成一个通知，这样我们的父类才能知道选择的更改。
		m_bSelectionComplete = TRUE;

		if (pWnd)
		{
			NM_TREEVIEW tv;
			memset(&tv.itemOld, 0, sizeof(tv.itemOld));

			tv.hdr.hwndFrom = GetSafeHwnd();
			tv.hdr.idFrom = GetWindowLong(GetSafeHwnd(), GWL_ID);
			tv.hdr.code = TVN_SELCHANGED;

			tv.itemNew.hItem = hSelectedItem;
			tv.itemNew.state = GetItemState(hSelectedItem, 0xffffffff);
			tv.itemNew.lParam = GetItemData(hSelectedItem);
			tv.itemNew.mask = TVIF_HANDLE | TVIF_STATE | TVIF_PARAM;

			tv.action = TVC_UNKNOWN;

			pWnd->SendMessage(WM_NOTIFY, tv.hdr.idFrom, (LPARAM)&tv);
		}
	}
	else if (nChar == VK_UP || nChar == VK_DOWN)
	{
		//获取当前选择的项目
		HTREEITEM hSelectedItem = GetSelectedItem();

		HTREEITEM hNextItem;
		if (nChar == VK_UP)
			hNextItem = GetPrevVisibleItem(hSelectedItem);
		else
			hNextItem = GetNextVisibleItem(hSelectedItem);

		if (!(GetKeyState(VK_SHIFT) & 0x8000))
		{
			//用户在没有按住Shift键的情况下按下箭头键：清除多项选择(如果多项选择)，
			//并让基类执行正常的选择工作！
			if (GetSelectedCount()>1)
				ClearSelection(TRUE);

			if (hNextItem)
				CTreeCtrl::OnKeyDown(nChar, nRepCnt, nFlags);
			m_hFirstSelectedItem = GetSelectedItem();
			return;
		}

		if (hNextItem)
		{
			//表示选择过程未完成的标志。
			//(将禁止TVN_SELCHANGED发送给父类)
			m_bSelectionComplete = FALSE;

			//如果已经选择了下一项，我们假设用户在选择中“向后移动”，因此我们应该清除对上一项的选择
			BOOL bSelect = !(GetItemState(hNextItem, TVIS_SELECTED) & TVIS_SELECTED);

			//选择下一项(这也会取消选择前一项！)
			SelectItem(hNextItem);

			//现在，重新选择之前选择的项目
			if (bSelect || (!(GetItemState(hSelectedItem, TVIS_SELECTED) & TVIS_SELECTED)))
				SelectItems(m_hFirstSelectedItem, hNextItem);

			//选择过程现已完成。由于我们已经销毁了Windows的treectrl提供的TVN_SELCHANGED通知，
			//现在我们必须自己生成一个通知，这样我们的父类才能知道选择的更改。
			m_bSelectionComplete = TRUE;

			if (pWnd)
			{
				NM_TREEVIEW tv;
				memset(&tv.itemOld, 0, sizeof(tv.itemOld));

				tv.hdr.hwndFrom = GetSafeHwnd();
				tv.hdr.idFrom = GetWindowLong(GetSafeHwnd(), GWL_ID);
				tv.hdr.code = TVN_SELCHANGED;

				tv.itemNew.hItem = hNextItem;
				tv.itemNew.state = GetItemState(hNextItem, 0xffffffff);
				tv.itemNew.lParam = GetItemData(hNextItem);
				tv.itemNew.mask = TVIF_HANDLE | TVIF_STATE | TVIF_PARAM;

				tv.action = TVC_UNKNOWN;

				pWnd->SendMessage(WM_NOTIFY, tv.hdr.idFrom, (LPARAM)&tv);
			}
		}

		//由于本例中未调用基类的OnKeyDown()，
		//我们必须向父类提供我们自己的TVN_KEYDOWN通知
		CWnd* pWnd = GetParent();
		if (pWnd)
		{
			NMTVKEYDOWN tvk;

			tvk.hdr.hwndFrom = GetSafeHwnd();
			tvk.hdr.idFrom = GetWindowLong(GetSafeHwnd(), GWL_ID);
			tvk.hdr.code = TVN_KEYDOWN;

			tvk.wVKey = nChar;
			tvk.flags = 0;

			pWnd->SendMessage(WM_NOTIFY, tvk.hdr.idFrom, (LPARAM)&tvk);
		}
	}
	else
		//行为正常
		CTreeCtrl::OnKeyDown(nChar, nRepCnt, nFlags);
}


void CTreeCtrlEx::SelectMultiple(HTREEITEM hClickedItem, UINT nFlags, CPoint point)
{
	//开始准备NM_TreeView结构，以便在选择完成后发送通知
	NM_TREEVIEW tv;
	memset(&tv.itemOld, 0, sizeof(tv.itemOld));

	CWnd* pWnd = GetParent();

	HTREEITEM hOldItem = GetSelectedItem();

	if (hOldItem)
	{
		tv.itemOld.hItem = hOldItem;
		tv.itemOld.state = GetItemState(hOldItem, 0xffffffff);
		tv.itemOld.lParam = GetItemData(hOldItem);
		tv.itemOld.mask = TVIF_HANDLE | TVIF_STATE | TVIF_PARAM;
	}

	//表示选择过程未完成的标志。
	//(将禁止TVN_SELCHANGED发送给父类)
	m_bSelectionComplete = FALSE;

	//操作取决于用户是按住Shift键还是Ctrl键
	if (nFlags & MK_SHIFT)
	{
		//从第一个选定项目选择到单击的项目
		if (!m_hFirstSelectedItem)
			m_hFirstSelectedItem = GetSelectedItem();

		SelectItems(m_hFirstSelectedItem, hClickedItem);
	}
	else if (nFlags & MK_CONTROL)
	{
		//只有一个根节点时，存储该根节点下的所有子节点；
		//当有多个根节点时，还需其他方法存储所有节点，
		//可以参考《MFC之TreeCtrl遍历所有节点》https://www.cnblogs.com/HelloQLQ/p/12678753.html
		vector<HTREEITEM>vecItem;
		HTREEITEM root = GetRootItem();//若存在多个根节点，获取的是第一个根节点
		HTREEITEM child = GetChildItem(root);
		while (child != NULL)
		{
			vecItem.push_back(child);
			child = GetNextItem(child, TVGN_NEXT);
		}

		for (int i = 0; i < vecItem.size(); i++)
		{
			bIsSelectedItem[i] = GetItemState(vecItem[i], TVIS_SELECTED) & TVIS_SELECTED;
		}
		//CString cStr;//查看根节点下的子节点个数
		//cStr.Format(_T("%d"), vecItem.size());
		//MessageBox(cStr);

		BOOL bIsClickedItemSelected = GetItemState(hClickedItem, TVIS_SELECTED) & TVIS_SELECTED;

		//必须合成TVN_SELCHANGING通知
		if (pWnd)
		{
			tv.hdr.hwndFrom = GetSafeHwnd();
			tv.hdr.idFrom = GetWindowLong(GetSafeHwnd(), GWL_ID);
			tv.hdr.code = TVN_SELCHANGING;

			tv.itemNew.hItem = hClickedItem;
			tv.itemNew.state = GetItemState(hClickedItem, 0xffffffff);
			tv.itemNew.lParam = GetItemData(hClickedItem);

			tv.itemOld.hItem = NULL;
			tv.itemOld.mask = 0;

			tv.action = TVC_BYMOUSE;

			tv.ptDrag.x = point.x;
			tv.ptDrag.y = point.y;

			pWnd->SendMessage(WM_NOTIFY, tv.hdr.idFrom, (LPARAM)&tv);
		}

		for (int i = 0; i < vecItem.size(); i++)
		{
			if (bIsSelectedItem[i] && vecItem[i] == hClickedItem)
				SetItemState(vecItem[i], 0, TVIS_SELECTED);
			else if (bIsSelectedItem[i] && vecItem[i] != hClickedItem)
				SetItemState(vecItem[i], TVIS_SELECTED, TVIS_SELECTED);
			else if (!bIsSelectedItem[i] && vecItem[i] == hClickedItem)
				SetItemState(vecItem[i], TVIS_SELECTED, TVIS_SELECTED);
			else if (!bIsSelectedItem[i] && vecItem[i] != hClickedItem)
				SetItemState(vecItem[i], 0, TVIS_SELECTED);
		}
	}
	else
	{
		//首先清除所有“多选”项目的选择
		ClearSelection();

		//然后选择单击的项目
		SelectItem(hClickedItem);
		SetItemState(hClickedItem, TVIS_SELECTED, TVIS_SELECTED);

		//存储为第一个选定项目
		m_hFirstSelectedItem = hClickedItem;
	}

	//选择流程现已完成。由于我们已经销毁了Windows的treectrl提供的TVN_SELCHANGED通知，
	//现在我们必须自己生成一个通知。
	//这样我们的父类就可以知道选择的更改。
	m_bSelectionComplete = TRUE;

	if (pWnd)
	{
		tv.hdr.hwndFrom = GetSafeHwnd();
		tv.hdr.idFrom = GetWindowLong(GetSafeHwnd(), GWL_ID);
		tv.hdr.code = TVN_SELCHANGED;

		tv.itemNew.hItem = m_hClickedItem;
		tv.itemNew.state = GetItemState(m_hClickedItem, 0xffffffff);
		tv.itemNew.lParam = GetItemData(m_hClickedItem);
		tv.itemNew.mask = TVIF_HANDLE | TVIF_STATE | TVIF_PARAM;

		tv.action = TVC_UNKNOWN;

		pWnd->SendMessage(WM_NOTIFY, tv.hdr.idFrom, (LPARAM)&tv);
	}
}


BOOL CTreeCtrlEx::SelectItems(HTREEITEM hFromItem, HTREEITEM hToItem)
{
	//确定选择方向
	//(查看树中排在第一位的项目)
	HTREEITEM hItem = GetRootItem();

	while (hItem && hItem != hFromItem && hItem != hToItem)
		hItem = GetNextVisibleItem(hItem);

	if (!hItem)
		return FALSE;	//树中不可见的项目

	BOOL bReverse = hItem == hToItem;

	// "Really" select the 'to' item 这将取消选择之前选择的项

	SelectItem(hToItem);

	//再次浏览所有可见项目，然后选择/取消选择

	hItem = GetRootItem();
	BOOL bSelect = FALSE;

	while (hItem)
	{
		if (hItem == (bReverse ? hToItem : hFromItem))
			bSelect = TRUE;

		if (bSelect)
		{
			if (!(GetItemState(hItem, TVIS_SELECTED) & TVIS_SELECTED))
				SetItemState(hItem, TVIS_SELECTED, TVIS_SELECTED);
		}
		else
		{
			if (GetItemState(hItem, TVIS_SELECTED) & TVIS_SELECTED)
				SetItemState(hItem, 0, TVIS_SELECTED);
		}

		if (hItem == (bReverse ? hFromItem : hToItem))
			bSelect = FALSE;

		hItem = GetNextVisibleItem(hItem);
	}
	return TRUE;
}


void CTreeCtrlEx::ClearSelection(BOOL bMultiOnly/*=FALSE*/)
{
	for (HTREEITEM hItem = GetRootItem(); hItem != NULL; hItem = GetNextVisibleItem(hItem))
	if (GetItemState(hItem, TVIS_SELECTED) & TVIS_SELECTED)
		SetItemState(hItem, 0, TVIS_SELECTED);
}