窗口封装类与Windows窗口实例的关系－2、亲自动手创建窗口封装类
为了更通俗地阐释CWnd类的封装机制，下面自己动手，模拟CWnd编写一个简单的窗口封装类，名为CBaseWnd，并使用这个类重新实现示例6.1的功能。
6.2.1 实例代码
示例6.2是实现代码，其中定义了3个类，说明如下：
q CBaseWnd相当于CWnd的窗口基类，封装了窗口创建与销毁、窗口状态和风格操作、窗口消息处理等功能，其中的消息处理函数定义为虚拟函数。
q CMainWnd类派生于CBaseWnd，用于创建应用程序主窗口，其中重载了几个消息处理虚函数，实现特定的消息处理。
q CMapHWD类被CBaseWnd类合成，用于管理窗口句柄与窗口封装类的映射关系。CBaseWnd实例与Windows窗口句柄是一一对应的，实例对象只能操作与其建立映射关系的Windows窗口。在CBaseWnd类中定义了一个静态成员：
static CMapHWD MapHWND;
所以，所有的CBaseWnd实例都使用这个公共成员管理窗口句柄的映射关系。在创建窗口时建立映射，在销毁窗口时删除映射。
示例清单6.2（模拟MFC的CWnd窗口封装类）
///////////////////////////////////////////////////BaseWnd.h: interface for the CBaseWnd and CMapHWD class.
#if !defined(AFX_BASEWND_H__7496A1A1_2C75_448D_93C7_FFA39F780483__INCLUDED_)
#define AFX_BASEWND_H__7496A1A1_2C75_448D_93C7_FFA39F780483__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#ifndef proc_msg
#define proc_msg virtual LRESULT
#endif
class CBaseWnd;
//定义映射链表的结点，存储封装类实例和其对应的窗口句柄
typedef struct _HWNDMAPCWND
{
_HWNDMAPCWND()
{
Next=NULL;
Top=NULL;
pWnd=NULL;
WndHandle=NULL;
}
_HWNDMAPCWND(HWND hWnd,CBaseWnd* WndPtr)
{
Next=NULL;
Top=NULL;
pWnd=WndPtr;
WndHandle=hWnd;
}
CBaseWnd* pWnd;//存储封装类指针
HWND WndHandle;//存储窗口句柄指针
_HWNDMAPCWND * Next;//指向下一个结点
_HWNDMAPCWND * Top;//指向上一个结点
}HWNDMAPCWND;
// CMapHWD使用HWNDMAPCWND构造映射链表，并对其进行插入、删除等管理
class CMapHWD
{
public:
CMapHWD()
{
pMapList=&m_Tail;
}
bool Remove(HWND hWnd);
bool insert(HWND hWnd,CBaseWnd* pWnd);
CBaseWnd* GetWndPtr(HWND hWnd)const;
HWND GetHWnd(CBaseWnd* pWnd)const;
private:
HWNDMAPCWND* pMapList;
HWNDMAPCWND m_Tail;
};
class CBaseWnd
{
public:
CBaseWnd();
virtual ~CBaseWnd();
//创建与销毁窗口
virtual BOOL Create(LPCTSTR lpszClassName,
LPCTSTR lpszWindowName, DWORD dwStyle,
const RECT& rect,
HWND pParentWnd, UINT nID,HINSTANCE hInst,
LPVOID lpParam = NULL);
BOOL DestroyWindow();
//操作窗口状态和风格
DWORD GetStyle() const;
DWORD GetExStyle() const;
BOOL ModifyStyle(DWORD dwRemove,DWORD StyleType, DWORD dwAdd, UINT nFlags = 0);
void MoveWindow(int x, int y, int nWidth, int nHeight,
BOOL bRepaint = TRUE);
BOOL ShowWindow(int nCmdShow);
void UpdateWindow();
BOOL SetWindowPos(const HWND pWndInsertAfter, int x, int y,
int cx, int cy, UINT nFlags);
//菜单操作
HMENU GetMenu() const;
BOOL SetMenu(HMENU Menu);
//操作窗口句柄
BOOL Attach(HWND hWndNew);//与窗口句柄建立映射关系
HWND Detach();//删除映射关系
static HWND GetSafeHwnd(CBaseWnd* pWnd);
static CBaseWnd* FromHandle(HWND hWnd);
//窗口消息相关函数
LRESULT SendMessage(UINT message, WPARAM wParam = 0, LPARAM lParam = 0);
BOOL PostMessage(UINT message, WPARAM wParam = 0, LPARAM lParam = 0);
//消息处理，相当于窗口函数
virtual LRESULT WindowProc( UINT message, WPARAM wParam, LPARAM lParam );
static LRESULT CALLBACK MyBaseWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
////////////////////////////////////////以下为每个窗口消息定义一个虚拟函数进行处理//////////////////////////////
protected:
// proc_msg OnCreate(LPCREATESTRUCT lpCreateStruct);
proc_msg OnDestroy();
proc_msg OnCommand(WPARAM wParam, LPARAM lParam);
proc_msg OnPaint();
proc_msg OnLButtonDown(UINT nFlags,POINT point);
proc_msg OnRButtonDown(UINT nFlags, POINT point);
proc_msg OnMouseMove(UINT nFlags, POINT point);
proc_msg OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags);
proc_msg OnKeyUp(UINT nChar, UINT nRepCnt, UINT nFlags);
//......
public:
LRESULT Default(UINT message,WPARAM wParam,LPARAM lParam);
HWND m_hWnd;
protected:
void SubWindowClass();
WNDPROC m_SuperWndProc;
private:
static CMapHWD MapHWND;
};
#endif
////////////////////////////////// BaseWnd.cpp: implementation of the CBaseWnd and CMapHWD class.
#include "stdafx.h"
#include "BaseWnd.h"
CMapHWD CBaseWnd::MapHWND;
extern CBaseWnd* pMainWnd;//指向应用程序主窗口
bool CMapHWD::Remove(HWND hWnd)
{
HWNDMAPCWND*pList=pMapList;
if(NULL==pList)
return false;
while(pList!=NULL&&pList->pWnd!=NULL)
{
if(pList->WndHandle==hWnd)
{
HWNDMAPCWND* temp;
temp=pList;
if(pList->Next!=NULL)
{
if(pList->Top!=NULL)
{
pList->Top->Next=pList->Next;
pList->Next->Top=pList->Top;
delete temp;
} else {
pList->Next->Top=NULL;
pMapList=pList->Next;
delete temp;
}
} else if(pList->Top!=NULL){
pList->Top->Next=NULL;
delete temp;
}
else{
delete temp;
pMapList=NULL;
}
return true;
}
pList=pList->Next;
}
return false;
}
bool CMapHWD::insert(HWND hWnd,CBaseWnd* pWnd)
{
if(NULL==pMapList){
pMapList=&m_Tail;
}
HWNDMAPCWND*pList=new HWNDMAPCWND(hWnd,pWnd);
if(NULL==pList)
return false;
pList->Next=pMapList;
pMapList->Top=pList;
pMapList=pList;
return true;
}
CBaseWnd* CMapHWD::GetWndPtr(HWND hWnd)const
{
HWNDMAPCWND*pList=pMapList;
if(NULL==pList)
return false;
while(pList->pWnd!=NULL)
{
if(pList->WndHandle==hWnd)
{ return pList->pWnd;}
pList=pList->Next;;
}
return NULL;
}
HWND CMapHWD::GetHWnd(CBaseWnd* pWnd)const
{
HWNDMAPCWND*pList=pMapList;
if(NULL==pList)
return false;
while(pList->pWnd!=NULL)
{
if(pList->pWnd==pWnd)
{ return pList->WndHandle;}
pList=pList->Next;;
}
return NULL;
}
CBaseWnd::CBaseWnd()
{ m_hWnd=NULL;}
CBaseWnd::~CBaseWnd()
{
if(::IsWindow(m_hWnd))
DestroyWindow();
}
BOOL CBaseWnd::Create(LPCTSTR lpszClassName,
LPCTSTR lpszWindowName, DWORD dwStyle,
const RECT& rect,
HWND ParentWnd, UINT nID,HINSTANCE hInst,
LPVOID lpParam)
{
if(dwStyle&WS_CHILD){
if(!::IsWindow(ParentWnd))
return false;
}
HWND hwnd=::CreateWindow(lpszClassName, lpszWindowName,
dwStyle,
rect.left, rect.top,
rect.right-rect.left, rect.bottom-rect.top,
ParentWnd,
(HMENU)nID, hInst,lpParam);
if(hwnd!=NULL)
{//与创建的窗口建立映射关系
Attach(hwnd);
SubWindowClass();
return true;
}
else return false;
}
HMENU CBaseWnd::GetMenu() const
{
if(::IsWindow(m_hWnd))
return ::GetMenu(m_hWnd);
else return NULL;
}
BOOL CBaseWnd::SetMenu(HMENU Menu)
{
if(::IsWindow(m_hWnd))
return ::SetMenu(m_hWnd, Menu);
else return false;
}
BOOL CBaseWnd::DestroyWindow()
{
if (m_hWnd == NULL)
return FALSE;
BOOL bResult = ::DestroyWindow(m_hWnd);
//删除映射关系
Detach();
return bResult;
}
BOOL CBaseWnd::Attach(HWND hWndNew)
{
if(!::IsWindow(hWndNew))
return false;
if(m_hWnd != NULL)
return false;
if(FromHandle(hWndNew) != NULL)
return false;
if(MapHWND.insert(hWndNew,this))
{
m_hWnd=hWndNew;
return TRUE;
}
return false;
}
HWND CBaseWnd::Detach()
{
HWND hWnd = m_hWnd;
if (hWnd != NULL)
{
MapHWND.Remove(m_hWnd);
m_hWnd = NULL;
}
return hWnd;
}
HWND CBaseWnd::GetSafeHwnd(CBaseWnd*pWnd)
{
if(NULL!=pWnd)
{ return MapHWND.GetHWnd(pWnd);
}
return NULL;
}
CBaseWnd* CBaseWnd::FromHandle(HWND hWnd)
{
if(NULL!=hWnd)
{ return MapHWND.GetWndPtr(hWnd);
}
return NULL;
}
void CBaseWnd::GetWindowRect(RECT &rcWindow) const
{
if(::IsWindow(m_hWnd))
::GetWindowRect(m_hWnd, &rcWindow);
}
void CBaseWnd::GetClientRect(RECT &rcClient) const
{
if(::IsWindow(m_hWnd))
::GetClientRect(m_hWnd, &rcClient);
}
BOOL CBaseWnd::ShowWindow(int nCmdShow)
{
if(::IsWindow(m_hWnd))
{ return ::ShowWindow(m_hWnd,nCmdShow);
}
return false;
}
void CBaseWnd::UpdateWindow()
{
if(::IsWindow(m_hWnd))
{ ::UpdateWindow(m_hWnd);
}
}
BOOL CBaseWnd::SetWindowPos(const HWND pWndInsertAfter, int x, int y,
int cx, int cy, UINT nFlags)
{
if(!::IsWindow(m_hWnd))
return false;
return ::SetWindowPos(m_hWnd, pWndInsertAfter,
x, y, cx, cy, nFlags);
}
DWORD CBaseWnd::GetStyle() const
{
if(::IsWindow(m_hWnd))
{ return ::GetWindowLong(m_hWnd,GWL_STYLE);
}
return 0;
}
DWORD CBaseWnd::GetExStyle() const
{
if(::IsWindow(m_hWnd))
{ return ::GetWindowLong(m_hWnd,GWL_EXSTYLE);
}
return 0;
}
BOOL CBaseWnd::ModifyStyle(DWORD dwRemove, DWORD StyleType,DWORD dwAdd, UINT nFlags)
{
if(!::IsWindow(m_hWnd))
return false;
if(StyleType!=GWL_STYLE&&StyleType!=GWL_EXSTYLE)
return false;
DWORD dwStyle = ::GetWindowLong(m_hWnd, StyleType);
DWORD dwNewStyle = (dwStyle & ~dwRemove) | dwAdd;
if (dwStyle == dwNewStyle)
return FALSE;
::SetWindowLong(m_hWnd, StyleType, dwNewStyle);
if (nFlags != 0)
{ ::SetWindowPos(m_hWnd, NULL, 0, 0, 0, 0,
SWP_NOSIZE | SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE | nFlags);
}
return TRUE;
}
void CBaseWnd::MoveWindow(int x, int y, int nWidth, int nHeight,BOOL bRepaint)
{
if(!::IsWindow(m_hWnd))
return;
::MoveWindow(m_hWnd, x, y, nWidth, nHeight, bRepaint);
}
LRESULT CBaseWnd::WindowProc( UINT message, WPARAM wParam, LPARAM lParam )
{
switch (message)
{
case WM_KEYDOWN:
return OnKeyDown(wParam,lParam&0xFF,(lParam>>16)&0xFF);
case WM_KEYUP:
return OnKeyUp(wParam,lParam&0xFF,(lParam>>16)&0xFF);
case WM_COMMAND:
return OnCommand(wParam,lParam);
case WM_LBUTTONDOWN:
POINT lPoint;
lPoint.x=lParam&0xFF;
lPoint.y=(lParam>>16)&0xFF;
return OnLButtonDown(wParam,lPoint);
case WM_RBUTTONDOWN:
POINT rPoint;
rPoint.x=lParam&0xFF;
rPoint.y=(lParam>>16)&0xFF;
return OnRButtonDown(wParam,rPoint);
case WM_PAINT:
return OnPaint();
case WM_DESTROY:
return OnDestroy();
break;
default:
//调用默认的消息处理过程处理当前消息
return Default(message, wParam, lParam);
}
return 0;
}
LRESULT CALLBACK CBaseWnd::MyBaseWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
//处理窗口消息的窗口函数
if(hWnd!=NULL)
{
CBaseWnd* pWnd=CBaseWnd::FromHandle(hWnd);
if(pWnd!=NULL)
return pWnd->WindowProc(message, wParam, lParam);
}
return 0;
}
LRESULT CBaseWnd::SendMessage(UINT message, WPARAM wParam, LPARAM lParam)
{
if(IsWindow(m_hWnd))
{ return ::SendMessage(m_hWnd,message,wParam,lParam);
}
return -1;
}
BOOL CBaseWnd::PostMessage(UINT message, WPARAM wParam, LPARAM lParam)
{
if(IsWindow(m_hWnd))
{return ::PostMessage(m_hWnd,message,wParam,lParam);
}
return false;
}
/////////////////message process///////////////////
LRESULT CBaseWnd::OnDestroy()
{
LRESULT ret=0;
if(::IsWindow(m_hWnd))
{
ret=Default(WM_DESTROY,0,0);
}
if(NULL!=pMainWnd)
{
if(MapHWND.GetWndPtr(m_hWnd)==pMainWnd)
::PostQuitMessage(0);
}
if(NULL!=m_hWnd)
{Detach();}
return ret;
}
LRESULT CBaseWnd::OnCommand(WPARAM wParam, LPARAM lParam)
{
return Default(WM_COMMAND,wParam,lParam);
}
LRESULT CBaseWnd::OnPaint()
{ return Default(WM_PAINT,0,0);
}
LRESULT CBaseWnd::OnLButtonDown(UINT nFlags, POINT point)
{
return Default(WM_LBUTTONDOWN,(WPARAM)nFlags,(LPARAM)MAKELONG (point.y,point.x));
}
LRESULT CBaseWnd::OnRButtonDown(UINT nFlags, POINT point)
{return Default(WM_RBUTTONDOWN,(WPARAM)nFlags, (LPARAM)MAKELONG(point.y,point.x));
}
LRESULT CBaseWnd::OnMouseMove(UINT nFlags, POINT point)
{ return Default(WM_MOUSEMOVE,(WPARAM)nFlags, (LPARAM)MAKELONG(point.y,point.x));
}
LRESULT CBaseWnd::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{ return Default(WM_KEYDOWN,(WPARAM)nChar, (LPARAM)MAKELONG(nFlags,nRepCnt));
}
LRESULT CBaseWnd::OnKeyUp(UINT nChar, UINT nRepCnt, UINT nFlags)
{ return Default(WM_KEYUP,(WPARAM)nChar, (LPARAM)MAKELONG(nFlags,nRepCnt));
}
void CBaseWnd::SubWindowClass()
{/*为方便地处理窗口消息，将关联的窗口子类化，即将静态成员函数MyBaseWndProc()设置为处理窗口消息的窗口过程，并将原始的窗口过程保存在成员m_SuperWndProc中，在消息处理的最后调用*/
if(NULL==m_hWnd)
return;
m_SuperWndProc = (WNDPROC)SetWindowLong(m_hWnd, GWL_WNDPROC,
(DWORD)MyBaseWndProc);
if(m_SuperWndProc==MyBaseWndProc)
m_SuperWndProc=NULL;
}
LRESULT CBaseWnd::Default(UINT message, WPARAM wParam, LPARAM lParam)
{
//默认的消息处理函数。如果窗口已被子类化，则调用原始的窗口过程
if(NULL!=m_SuperWndProc)
return ::CallWindowProc(m_SuperWndProc, m_hWnd,message,wParam, lParam);
return ::DefWindowProc(m_hWnd, message, wParam, lParam);
}
///////////////////////// MainWnd.h: interface for the CMainWnd class.
#if !defined(AFX_MAINWND_H__F3B00F31_F2DD_488F_BA2D_0892A9E8FE6F__INCLUDED_)
#define AFX_MAINWND_H__F3B00F31_F2DD_488F_BA2D_0892A9E8FE6F__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#include "BaseWnd.h"
class CMainWnd : public CBaseWnd
{
public:
CMainWnd();
virtual ~CMainWnd();
protected:
//根据需要，重载消息处理虚函数，处理相应消息
proc_msg OnPaint();
proc_msg OnLButtonDown(UINT nFlags,POINT point);
proc_msg OnRButtonDown(UINT nFlags, POINT point);
};
#endif
//////////////////////////// MainWnd.cpp : implementation of the CMainWnd class
#include "stdafx.h"
#include "MainWnd.h"
CMainWnd::CMainWnd(){}
CMainWnd::~CMainWnd(){}
LRESULT CMainWnd::OnPaint(void)
{
PAINTSTRUCT ps;
HDC dc = BeginPaint(m_hWnd, &ps);
RECT rt;
GetClientRect(rt);
::SetBkColor(dc,::GetSysColor(COLOR_BACKGROUND));
::SetTextColor(dc,RGB(255,255,255));
DrawText(dc, "My window created by class CMainWnd,simulating CWnd of MFC",-1,&rt, DT_CENTER);
EndPaint(m_hWnd, &ps);
return CBaseWnd::OnPaint();
}
LRESULT CMainWnd::OnLButtonDown(UINT nFlags,POINT point)
{ int ScreenWidth;
int ScreenLength;
RECT rcWindow;
GetWindowRect(rcWindow);
ScreenWidth=GetSystemMetrics(SM_CXSCREEN);
ScreenLength=GetSystemMetrics(SM_CYSCREEN);
//单击鼠标，设置窗口位置
SetWindowPos(HWND_TOP,ScreenWidth/4,
ScreenWidth/4,ScreenLength/2,ScreenLength/2,SWP_SHOWWINDOW);
Sleep(300);
SetWindowPos(HWND_TOP,ScreenWidth/3,
ScreenWidth/3,ScreenLength/3,ScreenLength/3,SWP_SHOWWINDOW);
Sleep(100);
SetWindowPos(HWND_TOP,ScreenWidth/4,
ScreenWidth/4,ScreenLength/2,ScreenLength/2,SWP_SHOWWINDOW);
Sleep(100);
SetWindowPos(HWND_TOP,rcWindow.left,rcWindow.top,
rcWindow.right-rcWindow.left,rcWindow.bottom-rcWindow.top,
SWP_SHOWWINDOW);
return CBaseWnd::OnLButtonDown(nFlags,point);
}
LRESULT CMainWnd::OnRButtonDown(UINT nFlags, POINT point)
{ //右击鼠标，隐藏、显示窗口
ShowWindow(SW_HIDE);
Sleep(300);
ShowWindow(SW_SHOW);
return CBaseWnd::OnRButtonDown(nFlags,point);
}
/////////////////////////////////////////////// c222.cpp : Defines the entry point for the application.
#include "stdafx.h"
#include "mainWnd.h"
#define szWindowClass "MyClassName"
#define szTitle "MyWindow"
ATOM MyRegisterClass(HINSTANCE hInstance);
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
CBaseWnd* pMainWnd=NULL;
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
MSG msg;
HWND hWnd=NULL;
//注册窗口类
MyRegisterClass(hInstance);
CMainWnd MyWnd;//指向应用程序主窗口
RECT rt;
rt.left=0,rt.top=0, rt.right=CW_USEDEFAULT,rt.bottom=0;
//使用封装类操作窗口
if(!MyWnd.Create(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW|WS_BORDER,
rt,NULL, NULL, hInstance))
return false;
//显示主窗口
pMainWnd=&MyWnd;
MyWnd.ShowWindow(nCmdShow);
MyWnd.UpdateWindow();
//先创建主窗口，然后进入消息循环
while (GetMessage(&msg, NULL, 0, 0))
{ TranslateMessage(&msg);
DispatchMessage(&msg);
}
//收到WM_QUIT消息，退出
return msg.wParam;
}
ATOM MyRegisterClass(HINSTANCE hInstance)
{……}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
return ::DefWindowProc(hWnd, message, wParam, lParam);
}
6.2.2 原理分析
通过6.2.1小节的代码，建立了一个比较粗糙的窗口封装类，并用它编写了一个简单的应用程序。CBaseWnd类既可以创建主窗口，也可以创建子窗口，该类是模拟CWnd编写的，有些代码是直接从CWnd类中复制的，目的是帮助我们理解CWnd的封装机制。
一个窗口封装类主要包括映射Windows窗口句柄、通过该句柄操作系统窗口、为需要处理的窗口消息提供处理函数等几个方面内容。CBaseWnd较圆满地解决了前两个问题，但在消息处理方面做得不够理想。
CBaseWnd使用虚拟函数处理消息（MFC使用消息映射机制），派生类重载虚拟函数即可实现特定的消息处理。由于窗口是在创建完成后与类对象关联并子类化的，所以WM_ CREATE之前的窗口消息，封装类无法接收，但可以采用系统钩子或全局子类化的方法解决这个问题（关于子类化的详细阐述参见8.6节）。在本例中，为弥补这个缺陷，CBase Wnd::Create()已定义为虚拟函数，如果用户需要在WM_CREATE消息到来之际完成必要的操作，例如创建子窗口，可以通过重载Create()虚函数实现。由于不可能为所有的命令消息定义虚拟函数，所以具体的命令消息如菜单、按钮、加速键，只能通过重载OnCommand()函数进行细分处理。另外，该类没有为子窗口传递系统消息和反射通知消息（见第9章）。
当然，CBaseWnd没有父类，因而缺少如CCmdTarget基类的支撑。
