用Visual C++设计屏幕抓图程序

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  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,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。

  一、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; //钩子句柄
UINT nHookCount =0; //挂接的程序数目
static UCHAR HotKey[MAX_KEY] = {0}; //热键虚拟键码

http://www.gaodaima.com/?p=65522用Visual C++设计屏幕抓图程序

static UCHAR HotKeyMask[MAX_KEY] = {0}; //组合掩码, control=4,alt=2,shift=1
static HWND hCallWnd[MAX_KEY] = {0}; //window handle associated with hotkey
static int KeyCount =0;
static UCHAR MaskBits =0; //00000 Ctrl=4 & Alt=2 & Shift=1
#pragma 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(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;index<MAX_KEY;index++){
  if(hCallWnd[index]==0){
   hCallWnd[index]=hWnd;
   HotKey[index]=cKey;
   HotKeyMask[index]=cMask;
   bAdded=TRUE;
   KeyCount++;
   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;index<MAX_KEY;index++){
  if(hCallWnd[index]==hWnd){
   if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
    hCallWnd[index]=NULL;
    HotKey[index]=0;
    HotKeyMask[index]=0;
    bRemoved=TRUE;
    KeyCount--;
    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:
     MaskBits&=~SHIFTBIT;
     break;
    default: //judge the key and send message
     break;
   }
   for(int index=0;index<MAX_KEY;index++){
    if(hCallWnd[index]==NULL)
     continue;
    if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
    {
     SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYUP);
     bProcessed=TRUE;
    }
   }
  }
  else if((lParam&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 message
     break;
   }
   for(int index=0;index<MAX_KEY;index++){
    if(hCallWnd[index]==NULL)
     continue;
    if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
    {
     SendMessage(hCallWnd[index],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<MAX_KEY;index++){
    if(hCallWnd[index]==NULL)
     continue;
    if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
     SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
     //lParam的意义可看MSDN中WM_KEYDOWN部分
   }
  }
 }
 return CallNextHookEx( hHook, nCode, wParam, lParam );
}

  抓图程序是一个基于对话框的程序,它在建立对话框的时候调用前面的DLL,登记热键,因此需要将hook.lib添加到工程里,在程序里给出两个DLL函数的定义,也可以写个头文件,再包含进来以下代码:
BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);

  为了添加应用程序对热键通知事件的响应,程序中用的办法是重载WindowProc()函数,该函数代码如下:

LRESULT CCaptureDlg::WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
{
 if(message==WM_HOTKEY&&lParam==WM_KEYDOWN)
 { //lParam表示是按下还是松开,如果有多个热键,由wParam来区分
  SaveBmp();
  return FALSE;
 }
 …… //其它处理及默认处理
}

  将屏幕图像保存到BMP文件中的任务是由函数SaveBmp()来完成的,具体实现参见代码部分。另外为了顺利实现屏幕抓图,程序中还实现了"托盘"功能,由于这一部分本书在实例中已经专门介绍过了,所以不再赘述,读者朋友可以参考相关实例。

  最后需要提醒读者朋友们注意的是,源程序的编译与使用时要先编译hook.dll并将其放在系统目录(win2000/NT是system32,98/ME是system),然后编译对话框程序运行即可。

  二、编程步骤

  1、 启动Visual C++,生成一个DLL项目和一个基于对话框的应用程序项目,并将两个项目分别命名为"Hook"和"Capture";

  2、 在"Hook"项目中导出AddHotkey()、DeleteHotkey()函数;

  3、 在"Capture"项目中按照图一所示设置对话框的界面,具体设置参见代码部分;

  4、 使用Class Wizard在"Capture"项目中添加按钮的鼠标单击消息响应函数,并重载对话框的WindowProc()函数;

  5、 添加代码,编译运行程序。

  三、程序代码

/////////////////////////////////////////////////////////// Hook.h : main header file for the HOOK DLL
#if !defined(AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_)
#define AFX_HOOK_H__AEBFF705_C93A_11D5_B7D6_0080C82BE86B__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
#ifndef __AFXWIN_H__
#error include ''stdafx.h'' before including this file for PCH
#endif
#include "resource.h" // main symbols
class CHookApp : public CWinApp
{
 public:
  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 member functions here.
  // DO NOT EDIT what you see in these blocks of generated code !
  //}}AFX_MSG
 DECLARE_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(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 <windowsx.h>
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
#define MAX_KEY 100
#define CTRLBIT 0x04
#define ALTBIT 0x02
#define SHIFTBIT 0x01
#pragma data_seg("shareddata")
HHOOK hHook =NULL;
UINT nHookCount =0;
static UCHAR HotKey[MAX_KEY] = {0}; //hotkey
static UCHAR HotKeyMask[MAX_KEY] = {0}; //flag for hotkey, value is VK_CONTRL or VK_NEMU or VK_SHIFT
static HWND hCallWnd[MAX_KEY] = {0}; //window associated with hotkey
static 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 code!
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

CHookApp::CHookApp()
{
 // TODO: add construction code here,
 // Place all significant initialization in InitInstance
}

CHookApp theApp;
LRESULT CALLBACK KeyboardProc(int nCode,WPARAM wParam,LPARAM lParam)
{
 BOOL bProcessed=FALSE;
 if(HC_ACTION==nCode)
 {
  if((lParam&0xc0000000)==0xc0000000){// 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 message
     break;
   }
   for(int index=0;index<MAX_KEY;index++){
    if(hCallWnd[index]==NULL)
     continue;
    if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
    {
     SendMessage(hCallWnd[index],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 send message
     break;
   }
   for(int index=0;index<MAX_KEY;index++)
   {
    if(hCallWnd[index]==NULL)
     continue;
    if(IsWindow(hCallWnd[index])&&(HotKey[index]==wParam)&&(HotKeyMask[index]==MaskBits))
    {
     SendMessage(hCallWnd[index],WM_HOTKEY,wParam,WM_KEYDOWN);
     bProcessed=TRUE;
    }
   }
  }
  if(!bProcessed){
   for(int index=0;index<MAX_KEY;index++){
    if(hCallWnd[index]==NULL)
     continue;
    if(IsWindow(hCallWnd[index])&&(HotKey[index]==0)&&(HotKeyMask[index]==0))
     SendMessage(hCallWnd[index],WM_HOTKEY,WM_HOTKEY,lParam);
   }
  }
 }
 return CallNextHookEx( hHook, nCode, wParam, lParam );
}

BOOL InitHotkey()
{
 if(hHook!=NULL){
  nHookCount++;
  return TRUE;
 }
 else
  hHook=SetWindowsHookEx(WH_KEYBOARD,(HOOKPROC)KeyboardProc,hins,0);
  if(hHook!=NULL)
   nHookCount++;
  return (hHook!=NULL);
}
BOOL UnInit()
{
 if(nHookCount>1){
  nHookCount--;
  return TRUE;
}
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;index<MAX_KEY;index++){
  if(hCallWnd[index]==0){
   hCallWnd[index]=hWnd;
   HotKey[index]=cKey;
   HotKeyMask[index]=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;index<MAX_KEY;index++){
  if(hCallWnd[index]==hWnd){
   if(HotKey[index]==cKey&&HotKeyMask[index]==cMask){
    hCallWnd[index]=NULL;
    HotKey[index]=0;
    HotKeyMask[index]=0;
    bRemoved=TRUE;
    KeyCount--;
    break;
   }
  }
 }
 return bRemoved;
}

void VerifyWindow()
{
 for(int i=0;i<MAX_KEY;i++){
  if(hCallWnd[i]!=NULL){
   if(!IsWindow(hCallWnd[i])){
    hCallWnd[i]=NULL;
    HotKey[i]=0;
    HotKeyMask[i]=0;
    KeyCount--;
   }
  }
 }
}

BOOL CHookApp::InitInstance()
{
 AFX_MANAGE_STATE(AfxGetStaticModuleState());
 hins=AfxGetInstanceHandle();
 InitHotkey();
 return CWinApp::InitInstance();
}

int CHookApp::ExitInstance()
{
 VerifyWindow();
 UnInit();
 return CWinApp::ExitInstance();
}

////////////////////////////////////////////////////////////////////// CaptureDlg.h : header file
#if !defined(AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_)
#define AFX_CAPTUREDLG_H__97B51708_C928_11D5_B7D6_0080C82BE86B__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

class CCaptureDlg : public CDialog
{
 // Construction
 public:
  BOOL bTray;
  BOOL bRegistered;
  BOOL RegisterHotkey();
  UCHAR cKey;
  UCHAR cMask;
  void DeleteIcon();
  void AddIcon();
  UINT nCount;
  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_VIRTUAL(CCaptureDlg)
 public:
  virtual BOOL PreTranslateMessage(MSG* pMsg);
 protected:
  virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
  virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam);
  //}}AFX_VIRTUAL
  // Implementation
 protected:
  HICON m_hIcon;
  // Generated message map functions
  //{{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_MSG
  DECLARE_MESSAGE_MAP()
};
#endif

////////////////////// CaptureDlg.cpp : implementation file
#include "stdafx.h"
#include "Capture.h"
#include "CaptureDlg.h"
#include <windowsx.h>
#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+1
BOOL __declspec(dllexport)__stdcall AddHotkey(HWND,UCHAR key,UCHAR mask);
BOOL __declspec(dllexport)__stdcall DeleteHotkey(HWND,UCHAR key,UCHAR mask);
UCHAR Key_Table[]={0x78,0x79,0x7a,0x7b,0x6a,0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39};
class CAboutDlg : public CDialog
{
 public:
  CAboutDlg();
  // Dialog Data
  //{{AFX_DATA(CAboutDlg)
  enum { IDD = IDD_ABOUTBOX };
  //}}AFX_DATA
  // ClassWizard generated virtual function overrides
  //{{AFX_VIRTUAL(CAboutDlg)
 protected:
  virtual void DoDataExchange(CDataExchange* pDX); // DDX/DDV support
  //}}AFX_VIRTUAL
  // Implementation
 protected:
  //{{AFX_MSG(CAboutDlg)
  //}}AFX_MSG
 DECLARE_MESSAGE_MAP()
};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
 //{{AFX_DATA_INIT(CAboutDlg)
 //}}AFX_DATA_INIT
}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
 CDialog::DoDataExchange(pDX);
 //{{AFX_DATA_MAP(CAboutDlg)
 //}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
 //{{AFX_MSG_MAP(CAboutDlg)
 // No message handlers
 //}}AFX_MSG_MAP
END_MESSAGE_MAP()

CCaptureDlg::CCaptureDlg(CWnd* pParent /*=NULL*/)
: CDialog(CCaptureDlg::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()->LoadIcon(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);
 DDX_Text(pDX, IDC_NUMBER, m_Number);
 //}}AFX_DATA_MAP
}

BEGIN_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_MAP
END_MESSAGE_MAP()

BOOL CCaptureDlg::OnInitDialog()
{
 CDialog::OnInitDialog();
 ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
 ASSERT(IDM_ABOUTBOX < 0xF000);
 CMenu* pSysMenu = GetSystemMenu(FALSE);
 if (pSysMenu != NULL)
 {
  CString strAboutMenu;
  strAboutMenu.LoadString(IDS_ABOUTBOX);
  if (!strAboutMenu.IsEmpty())
  {
   pSysMenu->AppendMenu(MF_SEPARATOR);
   pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
  }
 }
 SetIcon(m_hIcon, TRUE); // Set big icon
 SetIcon(m_hIcon, FALSE); // Set small icon
 m_Key.SetCurSel(0);
 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 control
}

void CCaptureDlg::OnSysCommand(UINT nID, LPARAM lParam)
{
 if ((nID & 0xFFF0) == IDM_ABOUTBOX)
 {
  CAboutDlg dlgAbout;
  dlgAbout.DoModal();
 }
 else
 {
  CDialog::OnSysCommand(nID, lParam);
 }
}

void CCaptureDlg::OnPaint()
{
 if (IsIconic())
 {
  CPaintDC dc(this); // device context for painting
  SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);
  // Center icon in client rectangle
  int cxIcon = 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 icon
  dc.DrawIcon(x, y, m_hIcon);
 }
 else
 {
  CDialog::OnPaint();
 }
}

HCURSOR CCaptureDlg::OnQueryDragIcon()
{
 return (HCURSOR) 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 name[MAX_PATH];
 ZeroMemory(&bi,sizeof(BROWSEINFO));
 bi.hwndOwner=GetSafeHwnd();
 bi.pszDisplayName=name;
 bi.lpszTitle="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("DISPLAY",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);
 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(BITMAPINFOHEADER);
 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.bfReserved2=0;
 bfh.bfType=((WORD)(''M''<< 8)|''B'');
 bfh.bfSize=54+size;
 bfh.bfOffBits=54;
 CFile bf;
 if(bf.Open(name,CFile::modeCreate|CFile::modeWrite)){
  bf.WriteHuge(&bfh,sizeof(BITMAPFILEHEADER));
  bf.WriteHuge(&bih,sizeof(BITMAPINFOHEADER));
  bf.WriteHuge(lpData,size);
  bf.Close();
  nCount++;
 }
 GlobalFreePtr(lpData);
 if(nCount==1)
  m_Number.Format("%d picture captured.",nCount);
 else
  m_Number.Format("%d pictures captured.",nCount);
 UpdateData(FALSE);
}

BOOL CCaptureDlg::PreTranslateMessage(MSG* pMsg)
{
 if(pMsg -> 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();
 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);
 int id=pMenu->TrackPopupMenu(TPM_RIGHTALIGN|TPM_NONOTIFY|TPM_RETURNCMD|TPM_LEFTBUTTON,pt.x,pt.y,this);
 if(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.LoadString(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=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_bControl)
  mask|=4;
 if(m_bAlt)
  mask|=2;
 if(m_bShift)
  mask|=1;
 key=Key_Table[m_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。

欢迎大家阅读《用Visual C++设计屏幕抓图程序》,跪求各位点评,若觉得好的话请收藏本文,by 搞代码

原创文章,转载请注明: 转载自搞代码

本文链接地址: 用Visual C++设计屏幕抓图程序

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