// GDI_CapturingAnImage.cpp : Defines the entry point for the application.//#include "stdafx.h"#include "GDI_CapturingAnImage.h"#define MAX_LOADSTRING 100// Global Variables:HINSTANCE hInst; // current instanceTCHAR szTitle[MAX_LOADSTRING]; // The title bar textTCHAR szWindowClass[MAX_LOADSTRING]; // the main window class name// Forward declarations of functions included in this code module:ATOM MyRegisterClass(HINSTANCE hInstance);BOOL InitInstance(HINSTANCE, int);LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);int APIENTRY _tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow){ UNREFERENCED_PARAMETER(hPrevInstance); UNREFERENCED_PARAMETER(lpCmdLine); MSG msg; HACCEL hAccelTable; // Initialize global strings LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING); LoadString(hInstance, IDC_GDI_CAPTURINGANIMAGE, szWindowClass, MAX_LOADSTRING); MyRegisterClass(hInstance); // Perform application initialization: if (!InitInstance (hInstance, nCmdShow)) { return FALSE; } hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_GDI_CAPTURINGANIMAGE)); // Main message loop: while (GetMessage(&msg, NULL, 0, 0)) { if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)) { TranslateMessage(&msg); DispatchMessage(&msg); } } return (int) msg.wParam;}//// FUNCTION: MyRegisterClass()//// PURPOSE: Registers the window class.//// COMMENTS://// This function and its usage are only necessary if you want this code// to be compatible with Win32 systems prior to the 'RegisterClassEx'// function that was added to Windows 95. It is important to call this function// so that the application will get 'well formed' small icons associated// with it.//ATOM MyRegisterClass(HINSTANCE hInstance){ WNDCLASSEX wcex; wcex.cbSize = sizeof(WNDCLASSEX); wcex.style = CS_HREDRAW | CS_VREDRAW; wcex.lpfnWndProc = WndProc; wcex.cbClsExtra = 0; wcex.cbWndExtra = 0; wcex.hInstance = hInstance; wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_GDI_CAPTURINGANIMAGE)); wcex.hCursor = LoadCursor(NULL, IDC_ARROW); wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1); wcex.lpszMenuName = MAKEINTRESOURCE(IDC_GDI_CAPTURINGANIMAGE); wcex.lpszClassName = szWindowClass; wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL)); return RegisterClassEx(&wcex);}//// FUNCTION: InitInstance(HINSTANCE, int)//// PURPOSE: Saves instance handle and creates main window//// COMMENTS://// In this function, we save the instance handle in a global variable and// create and display the main program window.//BOOL InitInstance(HINSTANCE hInstance, int nCmdShow){ HWND hWnd; hInst = hInstance; // Store instance handle in our global variable hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL); if (!hWnd) { return FALSE; } ShowWindow(hWnd, nCmdShow); UpdateWindow(hWnd); return TRUE;}// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF// ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A// PARTICULAR PURPOSE.//// Copyright (c) Microsoft Corporation. All rights reserved//// FUNCTION: CaptureAnImage(HWND hWnd)//// PURPOSE: Captures a screenshot into a window and then saves it in a .bmp file.//// COMMENTS: //// Note: This sample will attempt to create a file called captureqwsx.bmp // int CaptureAnImage(HWND hWnd){ HDC hdcScreen; HDC hdcWindow; HDC hdcMemDC = NULL; HBITMAP hbmScreen = NULL; BITMAP bmpScreen; // Retrieve the handle to a display device context for the client // area of the window. hdcScreen = GetDC(NULL); hdcWindow = GetDC(hWnd); // Create a compatible DC which is used in a BitBlt from the window DC hdcMemDC = CreateCompatibleDC(hdcWindow); if(!hdcMemDC) { MessageBox(hWnd, L"CreateCompatibleDC has failed",L"Failed", MB_OK); goto done; } // Get the client area for size calculation RECT rcClient; GetClientRect(hWnd, &rcClient); //This is the best stretch mode SetStretchBltMode(hdcWindow,HALFTONE); //The source DC is the entire screen and the destination DC is the current window (HWND) if(!StretchBlt(hdcWindow, 0,0, rcClient.right, rcClient.bottom, hdcScreen, 0,0, GetSystemMetrics (SM_CXSCREEN), GetSystemMetrics (SM_CYSCREEN), SRCCOPY)) { MessageBox(hWnd, L"StretchBlt has failed",L"Failed", MB_OK); goto done; } // Create a compatible bitmap from the Window DC hbmScreen = CreateCompatibleBitmap(hdcWindow, rcClient.right-rcClient.left, rcClient.bottom-rcClient.top); if(!hbmScreen) { MessageBox(hWnd, L"CreateCompatibleBitmap Failed",L"Failed", MB_OK); goto done; } // Select the compatible bitmap into the compatible memory DC. SelectObject(hdcMemDC,hbmScreen); // Bit block transfer into our compatible memory DC. if(!BitBlt(hdcMemDC, 0,0, rcClient.right-rcClient.left, rcClient.bottom-rcClient.top, hdcWindow, 0,0, SRCCOPY)) { MessageBox(hWnd, L"BitBlt has failed", L"Failed", MB_OK); goto done; } // Get the BITMAP from the HBITMAP GetObject(hbmScreen,sizeof(BITMAP),&bmpScreen); BITMAPFILEHEADER bmfHeader; BITMAPINFOHEADER bi; bi.biSize = sizeof(BITMAPINFOHEADER); bi.biWidth = bmpScreen.bmWidth; bi.biHeight = bmpScreen.bmHeight; bi.biPlanes = 1; bi.biBitCount = 32; bi.biCompression = BI_RGB; bi.biSizeImage = 0; bi.biXPelsPerMeter = 0; bi.biYPelsPerMeter = 0; bi.biClrUsed = 0; bi.biClrImportant = 0; DWORD dwBmpSize = ((bmpScreen.bmWidth * bi.biBitCount + 31) / 32) * 4 * bmpScreen.bmHeight; // Starting with 32-bit Windows, GlobalAlloc and LocalAlloc are implemented as wrapper functions that // call HeapAlloc using a handle to the process's default heap. Therefore, GlobalAlloc and LocalAlloc // have greater overhead than HeapAlloc. HANDLE hDIB = GlobalAlloc(GHND,dwBmpSize); char *lpbitmap = (char *)GlobalLock(hDIB); // Gets the "bits" from the bitmap and copies them into a buffer // which is pointed to by lpbitmap. GetDIBits(hdcWindow, hbmScreen, 0, (UINT)bmpScreen.bmHeight, lpbitmap, (BITMAPINFO *)&bi, DIB_RGB_COLORS); // A file is created, this is where we will save the screen capture. HANDLE hFile = CreateFile(L"captureqwsx.bmp", GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); // Add the size of the headers to the size of the bitmap to get the total file size DWORD dwSizeofDIB = dwBmpSize + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER); //Offset to where the actual bitmap bits start. bmfHeader.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER); //Size of the file bmfHeader.bfSize = dwSizeofDIB; //bfType must always be BM for Bitmaps bmfHeader.bfType = 0x4D42; //BM DWORD dwBytesWritten = 0; WriteFile(hFile, (LPSTR)&bmfHeader, sizeof(BITMAPFILEHEADER), &dwBytesWritten, NULL); WriteFile(hFile, (LPSTR)&bi, sizeof(BITMAPINFOHEADER), &dwBytesWritten, NULL); WriteFile(hFile, (LPSTR)lpbitmap, dwBmpSize, &dwBytesWritten, NULL); //Unlock and Free the DIB from the heap GlobalUnlock(hDIB); GlobalFree(hDIB); //Close the handle for the file that was created CloseHandle(hFile); //Clean updone: DeleteObject(hbmScreen); DeleteObject(hdcMemDC); ReleaseDC(NULL,hdcScreen); ReleaseDC(hWnd,hdcWindow); return 0;}//// FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)//// PURPOSE: Processes messages for the main window.//// WM_COMMAND - process the application menu// WM_PAINT - Paint the main window// WM_DESTROY - post a quit message and return////LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam){ int wmId, wmEvent; PAINTSTRUCT ps; HDC hdc; switch (message) { case WM_CREATE: { break; } case WM_COMMAND: wmId = LOWORD(wParam); wmEvent = HIWORD(wParam); // Parse the menu selections: switch (wmId) { case IDM_ABOUT: DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About); break; case IDM_EXIT: DestroyWindow(hWnd); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } break; case WM_MOVE: case WM_PAINT: hdc = BeginPaint(hWnd, &ps); CaptureAnImage(hWnd); EndPaint(hWnd, &ps); break; case WM_DESTROY: PostQuitMessage(0); break; default: return DefWindowProc(hWnd, message, wParam, lParam); } return 0;}// Message handler for about box.INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam){ UNREFERENCED_PARAMETER(lParam); switch (message) { case WM_INITDIALOG: return (INT_PTR)TRUE; case WM_COMMAND: if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) { EndDialog(hDlg, LOWORD(wParam)); return (INT_PTR)TRUE; } break; } return (INT_PTR)FALSE;}
