利用VC开发屏幕抓图程序实列

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1、利用VC+开发屏幕抓图程序实列作者：未知 文章来源：网络在Windows操作系统中，当用户按下PrintScreen按钮后，Windows自动将当前屏幕的图像 拷贝到系统剪贴板中，这时可以通过”画笔这个小程序将剪贴板中的内容保存成图像文件，可以看出，如果需要将当前屏幕保存下来还是比较麻烦的，能否可以自己编写一个应用程序，自动将当前屏幕的内容保存到一个图像文件中去呢？这个答案是肯定的，本实例应用程序就是利用通用的热键管理 DLL库实现的热键功能，在收到热键通知后截取屏幕的内容并保存 到bmp文件中。例如我们设置图片保存路径为c：，热键为F9 + Control，然后按Change按钮设置好热键，

2、那么当我们按下CTRL+F9后，当前界面将以 BMP图像文件的格式被保存在C:目录下。、实现方法热键管理DLL实际上是一个键盘钩子，由它来监视系统的键盘事件。如果有和程序登记符合的按键组合就通知该程序的窗口。为了应用方便，本实例把它做成了一个标准的管理库来为其它的程序通过热键服务，它有两个输出函数：AddHotkey ()和DeleteHotkey()，程序只需要调用这两个函数就可以了，如果编译之后不用改变热键，则只需要AddHotkey就可以了。DLL中的所有的全局变量都放在一个共享段中，定义如下：#pragma data_seg(shareddata)HHOOK hHook =NULL;

3、/ 钩子句柄UINT nHookCount =0; /挂接的程序数目static UCHAR HotKeyMAX_KEY = 0; / 热键虚拟键码static UCHAR HotKeyMaskMAX_KEY = 0; /组合掩码，control=4,alt=2,shift=1static HWND hCallWndMAX_KEY = 0; /win dow han dle associated with hotkeystatic int KeyCo unt =0;static UCHAR MaskBits =0; /00000 Ctrl=4 & Alt=2 & Shift=1#pragma

4、data_seg()关于共享段，有几点重要的说明：一是必须在链接选项里指定该段为共享：一种方法是在 project-settings-link-object/library 中加上 /section:shareddata,rws ;第二种方法是在 def 文件的sections里加上一句 shareddata read write shared;第三种指定共享段的方法在程序里 加上一句 #pragma comment(linker,section:shareddata,rws)。二是所有的变量必须初始化，否 则链接程序会把它放到普通数据段。三是如果不初始化变量，需要在段外用_declspec(

5、allocate(shareddata)变量类型变量名”的方式定义。DLL中的两个输出函数分别用来添加/删除热键，函数代码如下：BOOL _declspec(dllexport) _stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)BOOL bAdded=FALSE; for(int index=0;indexMAX_KEY;index+) if(hCallWndindex=0) hCallWndindex=hWnd; HotKeyindex=cKey; HotKeyMaskindex=cMask; bAdded=TRUE; KeyCount

6、+; break;return bAdded;/删除热键BOOL _declspec(dllexport) _stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)BOOL bRemoved=FALSE;for(int index=0;indexMAX_KEY;index+) if(hCallWndindex=hWnd) if(HotKeyindex=cKey&HotKeyMaskindex=cMask) hCallWndindex=NULL; HotKeyindex=0;HotKeyMaskindex=0; bRemoved=TRUE;K

7、eyCount-;break;return bRemoved;DLL 中的钩子函数如下：LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam) BOOL bProcessed=FALSE; if(HC_ACTION=nCode) if(lParam&0xc0000000)=0xc0000000)/ 有键松开 switch(wParam)case VK_MENU:MaskBits&=ALTBIT;break;case VK_CONTROL:MaskBits&=CTRLBIT;break;case VK_SHIFT:

8、MaskBits&=SHIFTBIT;break;default: /judge the key and send messagebreak;for(int index=0;indexMAX_KEY;index+) if(hCallWndindex=NULL) continue;if(IsWindow(hCallWndindex)&(HotKeyindex=wParam)&(HotKeyMaskindex=Mask Bits) SendMessage(hCallWndindex,WM_HOTKEY,wParam,WM_KEYUP); bProcessed=TRUE;else if(lParam

9、&0xc000ffff)=1) / 有键按下 switch(wParam)case VK_MENU:MaskBits|=ALTBIT;break;case VK_CONTROL:MaskBits|=CTRLBIT;break;case VK_SHIFT:MaskBits|=SHIFTBIT;break;default: /judge the key and send messagebreak;for(int index=0;indexMAX_KEY;index+) if(hCallWndindex=NULL) continue;if(IsWindow(hCallWndindex)&(HotKe

10、yindex=wParam)&(HotKeyMaskindex=Mask Bits)SendMessage(hCallWndindex,WM_HOTKEY,wParam,WM_KEYDOWN); bProcessed=TRUE;if(!bProcessed) / 一般按键事件，为监视键盘的程序留出余地 for(int index=0;index 1000#pragma once#endif / _MSC_VER 1000#ifndef _AFXWIN_H_#error include stdafx.h before including this file for PCH#endif#inclu

11、de resource.h / main symbolsclass CHookApp : public CWinApppublic:CHookApp();/ Overrides/ ClassWizard generated virtual function overrides/AFX_VIRTUAL(CHookApp)public:virtual BOOL InitInstance();virtual int ExitInstance();/AFX_VIRTUAL /AFX_MSG(CHookApp)/ NOTE - the ClassWizard will add and remove me

12、mber functions here./ DO NOT EDIT what you see in these blocks of generated code !/AFX_MSGDECLARE_MESSAGE_MAP();LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam, LPARAM lParam);BOOL _declspec(dllexport)_stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);BOOL _declspec(dllexport)_stdcall DeleteHotkey(

13、HWND,UCHAR key,UCHAR mask); BOOL InitHotkey();BOOL UnInit();#endif/ Hook.cpp : Defines the initialization routines for the DLL.#include stdafx.h#include hook.h#include #ifdef _DEBUG#define new DEBUG_NEW#undef THIS_FILE static char THIS_FILE = _FILE_;#endif#define MAX_KEY 100#define CTRLBIT 0x04#defi

14、ne ALTBIT 0x02#define SHIFTBIT 0x01#pragma data_seg(shareddata) HHOOK hHook =NULL;UINT nHookCount =0;static UCHAR HotKeyMAX_KEY = 0; /hotkeystatic UCHAR HotKeyMaskMAX_KEY = 0; /flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFTstatic HWND hCallWndMAX_KEY = 0; /window associated with hotkeyst

15、atic int KeyCount =0;static UCHAR MaskBits =0; /00000 Ctrl Alt Shift#pragma data_seg()HINSTANCE hins;void VerifyWindow();BEGIN_MESSAGE_MAP(CHookApp, CWinApp) /AFX_MSG_MAP(CHookApp)/ NOTE - the ClassWizard will add and remove mapping macros here./ DO NOT EDIT what you see in these blocks of generated

16、 code! /AFX_MSG_MAPEND_MESSAGE_MAP()CHookApp:CHookApp()/ TODO: add construction code here,/ Place all significant initialization in InitInstanceCHookApp theApp;LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam) BOOL bProcessed=FALSE; if(HC_ACTION=nCode) if(lParam&0xc0000000)=0xc000

17、0000)/ Key up switch(wParam)case VK_MENU:MaskBits&=ALTBIT;break;case VK_CONTROL:MaskBits&=CTRLBIT;break;case VK_SHIFT:MaskBits&=SHIFTBIT;break;default: /judge the key and send messagebreak;for(int index=0;indexMAX_KEY;index+) if(hCallWndindex=NULL)continue;if(IsWindow(hCallWndindex)&(HotKeyindex=wPa

18、ram)&(HotKeyMaskindex=Mask Bits) SendMessage(hCallWndindex,WM_HOTKEY,wParam,WM_KEYUP); bProcessed=TRUE;else if(lParam&0xc000ffff)=1) /Key down switch(wParam)case VK_MENU: MaskBits|=ALTBIT;break;case VK_CONTROL:MaskBits|=CTRLBIT;break;case VK_SHIFT:MaskBits|=SHIFTBIT;break;default: /judge the key and

19、 send message break;for(int index=0;indexMAX_KEY;index+) if(hCallWndindex=NULL) continue;if(IsWindow(hCallWndindex)&(HotKeyindex=wParam)&(HotKeyMaskindex=Mask Bits) SendMessage(hCallWndindex,WM_HOTKEY,wParam,WM_KEYDOWN); bProcessed=TRUE; if(!bProcessed) for(int index=0;index1)nHookCount-;return TRUE

20、;BOOL unhooked = UnhookWindowsHookEx(hHook); if(unhooked=TRUE)nHookCount=0;hHook=NULL;return unhooked;BOOL _declspec(dllexport) _stdcall AddHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask) BOOL bAdded=FALSE;for(int index=0;indexMAX_KEY;index+)if(hCallWndindex=0) hCallWndindex=hWnd; HotKeyindex=cKey;HotKeyMa

21、skindex=cMask;bAdded=TRUE;KeyCount+;break;return bAdded;BOOL _declspec(dllexport) _stdcall DeleteHotkey(HWND hWnd,UCHAR cKey,UCHAR cMask)BOOL bRemoved=FALSE;for(int index=0;indexMAX_KEY;index+) if(hCallWndindex=hWnd) if(HotKeyindex=cKey&HotKeyMaskindex=cMask) hCallWndindex=NULL;HotKeyindex=0;HotKeyM

22、askindex=0; bRemoved=TRUE;KeyCount-;break;return bRemoved;void VerifyWindow()for(int i=0;i 1000#pragma once#endif / _MSC_VER 1000class CCaptureDlg : public CDialog/ Constructionpublic:BOOL bTray;BOOL bRegistered;BOOL RegisterHotkey();UCHAR cKey;UCHAR cMask;void DeleteIcon();void AddIcon();UINT nCoun

23、t;void SaveBmp();CCaptureDlg(CWnd* pParent = NULL); / standard constructor/ Dialog Data/AFX_DATA(CCaptureDlg)enum IDD = IDD_CAPTURE_DIALOG ;CComboBox m_Key;BOOL m_bControl;BOOL m_bAlt;BOOL m_bShift;CString m_Path;CString m_Number;/AFX_DATA/ ClassWizard generated virtual function overrides/AFX_VIRTUA

24、L(CCaptureDlg)public:virtual BOOL PreTranslateMessage(MSG* pMsg); protected:virtual void DoDataExchange(CDataExchange* pDX); / DDX/DDV supportvirtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam); /AFX_VIRTUAL/ Implementation protected:HICON m_hIcon;/ Generated message map functions

25、/AFX_MSG(CCaptureDlg)virtual BOOL OnInitDialog();afx_msg void OnSysCommand(UINT nID, LPARAM lParam);afx_msg void OnPaint();afx_msg HCURSOR OnQueryDragIcon();virtual void OnCancel();afx_msg void OnAbout();afx_msg void OnBrowse();afx_msg void OnChange();/AFX_MSGDECLARE_MESSAGE_MAP() ;#endif / CaptureD

26、lg.cpp : implementation file#include stdafx.h#include Capture.h#include CaptureDlg.h#include #pragma comment(lib,hook.lib)#ifdef _DEBUG#define new DEBUG_NEW#undef THIS_FILE static char THIS_FILE = _FILE_;#endif#define IDM_SHELL WM_USER+1BOOL _declspec(dllexport)_stdcall AddHotkey(HWND,UCHAR key,UCHA

27、R mask);BOOL _declspec(dllexport)_stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask); UCHARKey_Table=0x78,0x79,0x7a,0x7b,0x6a,0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39 ;class CAboutDlg : public CDialogpublic: CAboutDlg();/ Dialog Data/AFX_DATA(CAboutDlg)enum IDD = IDD_ABOUTBOX ;/AFX_DATA/ Class

28、Wizard generated virtual function overrides/AFX_VIRTUAL(CAboutDlg)protected:virtual void DoDataExchange(CDataExchange* pDX); / DDX/DDV support /AFX_VIRTUAL/ Implementationprotected:/AFX_MSG(CAboutDlg)/AFX_MSGDECLARE_MESSAGE_MAP();CAboutDlg:CAboutDlg() : CDialog(CAboutDlg:IDD)/AFX_DATA_INIT(CAboutDlg

29、)/AFX_DATA_INITvoid CAboutDlg:DoDataExchange(CDataExchange* pDX)CDialog:DoDataExchange(pDX);/AFX_DATA_MAP(CAboutDlg) /AFX_DATA_MAPBEGIN_MESSAGE_MAP(CAboutDlg, CDialog)/AFX_MSG_MAP(CAboutDlg)/ No message handlers/AFX_MSG_MAPEND_MESSAGE_MAP()CCaptureDlg:CCaptureDlg(CWnd* pParent /*=NULL*/): CDialog(CC

30、aptureDlg:IDD, pParent)/AFX_DATA_INIT(CCaptureDlg)m_bControl = FALSE;m_bAlt = FALSE;m_bShift = FALSE;m_Path = _T(c:);m_Number = _T(0 picture captured.);nCount=0;bRegistered=FALSE;bTray=FALSE;/AFX_DATA_INIT/ Note that LoadIcon does not require a subsequent DestroyIcon in Win32 m_hIcon = AfxGetApp()-L

31、oadIcon(IDR_MAINFRAME);void CCaptureDlg:DoDataExchange(CDataExchange* pDX)CDialog:DoDataExchange(pDX);/AFX_DATA_MAP(CCaptureDlg)DDX_Control(pDX, IDC_KEY, m_Key);DDX_Check(pDX, IDC_CONTROL, m_bControl);DDX_Check(pDX, IDC_ALT, m_bAlt);DDX_Check(pDX, IDC_SHIFT, m_bShift);DDX_Text(pDX, IDC_PATH, m_Path)

32、;DDX_Text(pDX, IDC_NUMBER, m_Number);/AFX_DATA_MAPBEGIN_MESSAGE_MAP(CCaptureDlg, CDialog)/AFX_MSG_MAP(CCaptureDlg)ON_WM_SYSCOMMAND()ON_WM_PAINT()ON_WM_QUERYDRAGICON()ON_BN_CLICKED(ID_ABOUT, OnAbout) ON_BN_CLICKED(IDC_BROWSE, OnBrowse) ON_BN_CLICKED(ID_CHANGE, OnChange) /AFX_MSG_MAPEND_MESSAGE_MAP()B

33、OOL CCaptureDlg:OnInitDialog()CDialog:OnInitDialog();ASSERT(IDM_ABOUTBOX & 0xFFF0) = IDM_ABOUTBOX);ASSERT(IDM_ABOUTBOX AppendMenu(MF_SEPARATOR); pSysMenu-AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);SetIcon(m_hIcon, TRUE); / Set big iconSetIcon(m_hIcon, FALSE); / Set small iconm_Key.SetCurSel(0

34、);RegisterHotkey();CMenu* pMenu=GetSystemMenu(FALSE); pMenu-DeleteMenu(SC_MAXIMIZE,MF_BYCOMMAND); pMenu-DeleteMenu(SC_SIZE,MF_BYCOMMAND); pMenu-DeleteMenu(SC_RESTORE,MF_BYCOMMAND); return TRUE; / return TRUE unless you set the focus to a controlvoid CCaptureDlg:OnSysCommand(UINT nID, LPARAM lParam)

35、if (nID & 0xFFF0) = IDM_ABOUTBOX)CAboutDlg dlgAbout;dlgAbout.DoModal();elseCDialog:OnSysCommand(nID, lParam);void CCaptureDlg:OnPaint()if (IsIconic()CPaintDC dc(this); / device context for paintingSendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0); / Center icon in client rectangleint cxIco

36、n = GetSystemMetrics(SM_CXICON);int cyIcon = GetSystemMetrics(SM_CYICON);CRect rect;GetClientRect(&rect);int x = (rect.Width() - cxIcon + 1) / 2;int y = (rect.Height() - cyIcon + 1) / 2;/ Draw the icondc.DrawIcon(x, y, m_hIcon);elseCDialog:OnPaint();HCURSOR CCaptureDlg:OnQueryDragIcon()return (HCURS

37、OR) m_hIcon;void CCaptureDlg:OnCancel()if(bTray)DeleteIcon(); CDialog:OnCancel();void CCaptureDlg:OnAbout()CAboutDlg dlg;dlg.DoModal();void CCaptureDlg:OnBrowse()CString str;BROWSEINFO bi;char nameMAX_PATH;ZeroMemory(&bi,sizeof(BROWSEINFO); bi.hwndOwner=GetSafeHwnd();bi.pszDisplayName=name;bi.lpszTi

38、tle=Select folder; bi.ulFlags=BIF_RETURNONLYFSDIRS;LPITEMIDLIST idl=SHBrowseForFolder(&bi); if(idl=NULL)return;SHGetPathFromIDList(idl,str.GetBuffer(MAX_PATH); str.ReleaseBuffer();m_Path=str;if(str.GetAt(str.GetLength()-1)!=)m_Path+=;UpdateData(FALSE);void CCaptureDlg:SaveBmp()CDC dc; dc.CreateDC(DI

39、SPLAY,NULL,NULL,NULL);CBitmap bm;int Width=GetSystemMetrics(SM_CXSCREEN);int Height=GetSystemMetrics(SM_CYSCREEN); bm.CreateCompatibleBitmap(&dc,Width,Height); CDC tdc;tdc.CreateCompatibleDC(&dc);CBitmap*pOld=tdc.SelectObject(&bm); tdc.BitBlt(0,0,Width,Height,&dc,0,0,SRCCOPY); tdc.SelectObject(pOld)

40、;BITMAP btm;bm.GetBitmap(&btm);DWORD size=btm.bmWidthBytes*btm.bmHeight;LPSTR lpData=(LPSTR)GlobalAllocPtr(GPTR,size); BITMAPINFOHEADER bih;bih.biBitCount=btm.bmBitsPixel;bih.biClrImportant=0;bih.biClrUsed=0;bih.biCompression=0;bih.biHeight=btm.bmHeight;bih.biPlanes=1;bih.biSize=sizeof(BITMAPINFOHEA

41、DER);bih.biSizeImage=size;bih.biWidth=btm.bmWidth;bih.biXPelsPerMeter=0;bih.biYPelsPerMeter=0;GetDIBits(dc,bm,0,bih.biHeight,lpData,(BITMAPINFO*)&bih,DIB_RGB_COLORS); static int filecount=0;CString name;name.Format(pict%04d.bmp,filecount+);name=m_Path+name;BITMAPFILEHEADER bfh; bfh.bfReserved1=bfh.b

42、fReserved2=0;bfh.bfType=(WORD)(M message = WM_KEYDOWN)if(pMsg - wParam = VK_ESCAPE)return TRUE;if(pMsg - wParam = VK_RETURN)return TRUE;return CDialog:PreTranslateMessage(pMsg);LRESULT CCaptureDlg:WindowProc(UINT message, WPARAM wParam, LPARAM lParam) if(message=WM_HOTKEY&lParam=WM_KEYDOWN)SaveBmp()

43、;return FALSE; if(message=IDM_SHELL&lParam=WM_RBUTTONUP)CMenu pop;pop.LoadMenu(MAKEINTRESOURCE(IDR_MENU1);CMenu*pMenu=pop.GetSubMenu(0);pMenu-SetDefaultItem(ID_EXITICON);CPoint pt;GetCursorPos(&pt);intid=pMenu-TrackPopupMenu(TPM_RIGHTALIGN|TPM_NONOTIFY|TPM_RETURNCMD|T PM_LEFTBUTTON,pt.x,pt.y,this);i

44、f(id=ID_EXITICON)DeleteIcon();else if(id=ID_EXIT)OnCancel();return FALSE;LRESULT res= CDialog:WindowProc(message, wParam, lParam); if(message=WM_SYSCOMMAND&wParam=SC_MINIMIZE) AddIcon();return res;void CCaptureDlg:AddIcon()NOTIFYICONDATA data;data.cbSize=sizeof(NOTIFYICONDATA);CString tip;tip.LoadSt

45、ring(IDS_ICONTIP);data.hIcon=GetIcon(0);data.hWnd=GetSafeHwnd();strcpy(data.szTip,tip);data.uCallbackMessage=IDM_SHELL;data.uFlags=NIF_ICON|NIF_MESSAGE |NIF_TIP ;data.uID=98;Shell_NotifyIcon(NIM_ADD,&data);ShowWindow(SW_HIDE); bTray=TRUE;void CCaptureDlg:DeleteIcon()NOTIFYICONDATA data; data.cbSize=

46、sizeof(NOTIFYICONDATA); data.hWnd=GetSafeHwnd();data.uID=98; Shell_NotifyIcon(NIM_DELETE,&data); ShowWindow(SW_SHOW); SetForegroundWindow(); ShowWindow(SW_SHOWNORMAL); bTray=FALSE;void CCaptureDlg:OnChange()RegisterHotkey();BOOL CCaptureDlg:RegisterHotkey()UpdateData();UCHAR mask=0;UCHAR key=0; if(m

47、_bControl)mask|=4;if(m_bAlt)mask|=2;if(m_bShift)mask|=1; key=Key_Tablem_Key.GetCurSel(); if(bRegistered)DeleteHotkey(GetSafeHwnd(),cKey,cMask); bRegistered=FALSE;cMask=mask; cKey=key; bRegistered=AddHotkey(GetSafeHwnd(),cKey,cMask); return bRegistered;四、小结本实例通过一个钩子 DLL 实现了屏幕抓图的功能，它有一个缺陷，那就是只能保存整 个屏幕图像， 不过读者朋友可以在此基础上， 实现屏幕任意区域的抓图功能， 具体方法不再 赘述，实现起来很容易的了，呵呵。