我们在进行Windows编程的时候，经常需要进行屏幕截取，我们来实现截取屏幕，不依赖MFC来实现屏幕截取。请见代码实现与注释讲解
源自：
- /* 头文件 */
- #include <windows.h>
- /* 常量定义 */
- #define PALVERSION 0x300
- #define CAP_SHOW_MODE_STRTCH 1
- #define CAP_SHOW_MODE_NOSTRTCH 0
- /* 全局变量 */
- HBITMAP ghBitmap = NULL;
- RECT rectShow;
- // 修改这里截取不同的窗口，如果为NULL，则截取屏幕
- LPSTR szCaptureWindowName = "Windows 任务管理器";
- /* 函数申明 */
- LRESULT CALLBACK MainWndProc(HWND, UINT, WPARAM, LPARAM);
- HBITMAP ScreenCapture(LPSTR filename ,WORD BitCount,LPRECT lpRect);
- VOID DoPaint(HWND hWnd, DWORD dwMode);
- /*************************************
- * DWORD WINAPI WinMain(HINSTANCE hinstance,
- HINSTANCE hPrevInstance,
- LPSTR lpCmdLine,
- int nCmdShow)
- * 功能 截屏，保存为文件，并显示在窗口上
- *
- **************************************/
- INT WINAPI WinMain(HINSTANCE hinstance,
- HINSTANCE hPrevInstance,
- LPSTR lpCmdLine,
- int nCmdShow)
- {
- WNDCLASSEX wcx;
- HWND hwnd;
- MSG msg;
- WORD wport = 80;
- BOOL fGotMessage;
- HWND hwndCap = NULL;
- // 截取全屏幕还是窗口
- if(szCaptureWindowName != NULL)
- {
- hwndCap = FindWindow(NULL,"Windows 任务管理器");
- // 获取窗口的RECT，可自行修改，获取屏幕中的任意区域
- if(!GetWindowRect(hwndCap,&rectShow))
- {
- MessageBox(NULL,"Can not find window to capture", "erroe",MB_OK);
- return 0;
- }
- }
- // 注册窗口类，并创建窗口，用于显示截取的位图
- wcx.cbSize = sizeof(wcx);
- wcx.style = CS_HREDRAW | CS_VREDRAW;
- wcx.lpfnWndProc = MainWndProc;
- wcx.cbClsExtra = 0;
- wcx.cbWndExtra = 0;
- wcx.hInstance = hinstance;
- wcx.hIcon = LoadIcon(NULL, MAKEINTRESOURCE(IDI_APPLICATION));
- wcx.hCursor = LoadCursor(NULL, IDC_ARROW);
- wcx.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
- wcx.lpszMenuName = NULL;
- wcx.lpszClassName = "MainWClass";
- wcx.hIconSm = NULL;
- if( !RegisterClassEx(&wcx))
- return 1;
- // 创建窗口
- hwnd = CreateWindow(
- "MainWClass",
- "CAP",
- WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN | WS_CLIPSIBLINGS |
- WS_MAXIMIZE | WS_POPUPWINDOW,
- CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
- (HWND) NULL, (HMENU) NULL, hinstance, (LPVOID) NULL);
- if (!hwnd)
- return 1;
- // 截取屏幕，可根据需要设置不同的参数，这里只演示截取特定窗口。
- ghBitmap = ScreenCapture("taskmgr.bmp" ,32, &rectShow);
- // 显示
- ShowWindow(hwnd, nCmdShow);
- UpdateWindow(hwnd);
- while ((fGotMessage = GetMessage(&msg, (HWND) NULL, 0, 0)) != 0 && fGotMessage != -1)
- {
- TranslateMessage(&msg);
- DispatchMessage(&msg);
- }
- return msg.wParam;
- UNREFERENCED_PARAMETER(lpCmdLine);
- }
- LRESULT CALLBACK MainWndProc(
- HWND hwnd,
- UINT uMsg,
- WPARAM wParam,
- LPARAM lParam)
- {
- switch (uMsg)
- {
- case WM_PAINT:
- // 显示截取的屏幕
- DoPaint(hwnd,CAP_SHOW_MODE_STRTCH);
- break;
- case WM_DESTROY:
- // 创建的BITMAP对象需要删除，以释放资源
- DeleteObject(ghBitmap);
- ExitProcess(0);
- break;
- default:
- break;
- }
- return DefWindowProc(hwnd, uMsg, wParam, lParam);
- }
- /*************************************
- * VOID DoPaint(HWND hWnd, DWORD dwMode)
- * 功能 将位图（全局变量ghBitmap）显示在界面上
- *
- * 参数 HWND hWnd，用于显示位图的窗口
- * DWORD dwMode，模式，是否拉申
- *
- * 无返回值
- **************************************/
- VOID DoPaint(HWND hWnd, DWORD dwMode)
- {
- PAINTSTRUCT ps;
- RECT rect;
- HDC hdcMem;
- BITMAP bm;
- // BeginPaint
- HDC hDC = BeginPaint(hWnd, &ps);
- // 获取窗口的Client区域，用于显示位图
- GetClientRect(hWnd, &rect);
- // 设置拉申模式
- SetStretchBltMode(hDC, HALFTONE);
- // 将BITMAP对象选择入内存DC
- hdcMem = CreateCompatibleDC(hDC);
- SelectObject(hdcMem, ghBitmap);
- if (ghBitmap)
- {
- // 获取DIB属性
- if (GetObject(ghBitmap, sizeof(BITMAP), &bm))
- {
- // 判断参数示：是否根据显示窗口大小拉申位图
- // 采用不同的方面将内存DC StretchBl t至窗口Client区域DC
- if(dwMode == CAP_SHOW_MODE_STRTCH)
- {
- StretchBlt(hDC, 0, 0, rect.right, rect.bottom,
- hdcMem, 0, 0, bm.bmWidth, bm.bmHeight, SRCCOPY);
- }
- else
- {
- // 不拉伸，计算显示的位置，将其显示在Client的中央
- INT ixStart = (rect.right - rect.left - bm.bmWidth)/2;
- INT iyStart = (rect.bottom - rect.top - bm.bmHeight)/2;
- ixStart = ixStart < 0 ? 0 : ixStart;
- iyStart = iyStart < 0 ? 0 : iyStart;
- BitBlt(hDC, 0, 0, rect.right, rect.bottom,
- hdcMem,-ixStart,-iyStart, SRCCOPY);
- }
- DeleteDC(hdcMem);
- }
- }
- // 如果没有位图，则使用Brush填充
- else
- {
- PatBlt(hDC, 0, 0, rect.right, rect.bottom, BLACKNESS);
- }
- // EndPaint
- EndPaint(hWnd, &ps);
- }
- /*************************************
- * BITMAP ScreenCapture(LPSTR filename ,WORD BitCount,LPRECT lpRect);
- * 功能 截取指定区域的屏幕，并保存为文件
- *
- * 参数 LPSTR filename 保存位图文件的文件路径，如果为NULL，则不保存
- * WORD BitCount Bit深度，用于表示一个像素点所使用的数据长度
- * LPRECT lpRect 所需截取的屏幕区域，如果为NULL，则获取全屏幕
- *
- * 返回 HBITMAP 所截取的位图对象
- **************************************/
- HBITMAP ScreenCapture(LPSTR filename ,WORD BitCount,LPRECT lpRect)
- {
- HBITMAP hBitmap;
- // 显示器屏幕DC
- HDC hScreenDC = CreateDC("DISPLAY", NULL, NULL, NULL);
- HDC hmemDC = CreateCompatibleDC(hScreenDC);
- // 显示器屏幕的宽和高
- int ScreenWidth = GetDeviceCaps(hScreenDC, HORZRES);
- int ScreenHeight = GetDeviceCaps(hScreenDC, VERTRES);
- // 旧的BITMAP，用于与所需截取的位置交换
- HBITMAP hOldBM;
- // 保存位图数据
- PVOID lpvpxldata;
- // 截屏获取的长宽及起点
- INT ixStart;
- INT iyStart;
- INT iX;
- INT iY;
- // 位图数据大小
- DWORD dwBitmapArraySize;
- // 几个大小
- DWORD nBitsOffset;
- DWORD lImageSize ;
- DWORD lFileSize ;
- // 位图信息头
- BITMAPINFO bmInfo;
- // 位图文件头
- BITMAPFILEHEADER bmFileHeader;
- // 写文件用
- HANDLE hbmfile;
- DWORD dwWritten;
- // 如果LPRECT 为NULL 截取整个屏幕
- if(lpRect == NULL)
- {
- ixStart = iyStart = 0;
- iX = ScreenWidth;
- iY =ScreenHeight;
- }
- else
- {
- ixStart = lpRect->left;
- iyStart = lpRect->top;
- iX = lpRect->right - lpRect->left;
- iY = lpRect->bottom - lpRect->top;
- }
- // 创建BTIMAP
- hBitmap = CreateCompatibleBitmap(hScreenDC, iX, iY);
- // 将BITMAP选择入内存DC。
- hOldBM = (HBITMAP)SelectObject(hmemDC, hBitmap);
- // BitBlt屏幕DC到内存DC，根据所需截取的获取设置参数
- BitBlt(hmemDC, 0, 0, iX, iY, hScreenDC, ixStart, iyStart, SRCCOPY);
- // 将旧的BITMAP对象选择回内存DC，返回值为被替换的对象，既所截取的位图
- hBitmap = (HBITMAP)SelectObject(hmemDC, hOldBM);
- if(filename == NULL)
- {
- DeleteDC( hScreenDC);
- DeleteDC(hmemDC);
- return hBitmap;
- }
- // 为位图数据申请内存空间
- dwBitmapArraySize = ((((iX*32) + 31) & ~31)>> 3)* iY;
- lpvpxldata = HeapAlloc(GetProcessHeap(),HEAP_NO_SERIALIZE,dwBitmapArraySize);
- ZeroMemory(lpvpxldata,dwBitmapArraySize);
- // 添充 BITMAPINFO 结构
- ZeroMemory(&bmInfo,sizeof(BITMAPINFO));
- bmInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
- bmInfo.bmiHeader.biWidth = iX;
- bmInfo.bmiHeader.biHeight = iY;
- bmInfo.bmiHeader.biPlanes = 1;
- bmInfo.bmiHeader.biBitCount = BitCount;
- bmInfo.bmiHeader.biCompression = BI_RGB;
- // 添充 BITMAPFILEHEADER 结构
- ZeroMemory(&bmFileHeader,sizeof(BITMAPFILEHEADER));
- nBitsOffset = sizeof(BITMAPFILEHEADER) + bmInfo.bmiHeader.biSize;
- lImageSize =
- ((((bmInfo.bmiHeader.biWidth * bmInfo.bmiHeader.biBitCount) + 31) & ~31)>> 3)
- * bmInfo.bmiHeader.biHeight;
- lFileSize = nBitsOffset + lImageSize;
- bmFileHeader.bfType = 'B'+('M'<<8);
- bmFileHeader.bfSize = lFileSize;
- bmFileHeader.bfOffBits = nBitsOffset;
- // 获取DIB用于写入到文件
- GetDIBits(hmemDC, hBitmap, 0, bmInfo.bmiHeader.biHeight,
- lpvpxldata, &bmInfo, DIB_RGB_COLORS);
- // 写文件
- hbmfile = CreateFile(filename,
- GENERIC_WRITE,
- FILE_SHARE_WRITE,
- NULL,
- CREATE_ALWAYS,
- FILE_ATTRIBUTE_NORMAL,
- NULL);
- if(hbmfile == INVALID_HANDLE_VALUE)
- {
- MessageBox(NULL,"create file error","error",MB_OK);
- }
- WriteFile(hbmfile,&bmFileHeader,sizeof(BITMAPFILEHEADER),&dwWritten,NULL);
- WriteFile(hbmfile,&bmInfo,sizeof(BITMAPINFO),&dwWritten,NULL);
- WriteFile(hbmfile,lpvpxldata,lImageSize,&dwWritten,NULL);
- CloseHandle(hbmfile);
- // 释放内存，清除不同的DC。
- // 这里没有删除BITMAP对象，需在显示完成后删除
- HeapFree(GetProcessHeap(),HEAP_NO_SERIALIZE,lpvpxldata);
- ReleaseDC(0, hScreenDC);
- DeleteDC(hmemDC);
- return hBitmap;
- }