如何抓取屏幕中选中区域并存取为bmp位图的类？
/******************************************************************************
* FILE NAME: CopyScreenToBitmap.h * * * * DESCRIPTION: * * 截屏位图文件 * * * * COPYRIGHT: * * (C) Copyright LiuYong * * All Rights Reserved * * * * AUTHOR: * * liu yong * * DATE : 2006-11-29 * * * *******************************************************************************/ class CCopyScreenToBitmap { public: CCopyScreenToBitmap(); ~CCopyScreenToBitmap(); //截取指定区域的屏幕到位图文件，文件目录默认让用户自己选择 BOOL SaveRectToBitmap( LPRECT lpRect, LPSTR lpFileName = NULL ); //截取全屏幕到位图文件，文件目录默认让用户自己选择 BOOL SaveScreenToBitmap( LPSTR lpFileName = NULL ); private: HBITMAP SaveBitmapCopyScreenToBitmap( LPRECT lpRect ); BOOL SaveBitmapToFile( HBITMAP hBitmap , LPSTR lpFileName ) ; void SaveBitmapToClipboard( HBITMAP hBitmap, HWND hWnd );};
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// CopyScreenToBitmap.cpp: implementation of the CCopyScreenToBitmap class.
// //////////////////////////////////////////////////////////////////////#include "stdafx.h"
#include "CopyScreenToBitmap.h"
#include <afxdlgs.h>#ifdef _DEBUG
#undef THIS_FILE static char THIS_FILE[]=__FILE__; #define new DEBUG_NEW #endif//////////////////////////////////////////////////////////////////////
// Construction/Destruction //////////////////////////////////////////////////////////////////////CCopyScreenToBitmap::CCopyScreenToBitmap()
{}
CCopyScreenToBitmap::~CCopyScreenToBitmap()
{}
BOOL CCopyScreenToBitmap::SaveRectToBitmap(LPRECT lpRect, LPSTR lpFileName)
{ if(!lpRect) { ::MessageBox( NULL,"请指定要截图的区域！","提示",MB_ICONINFORMATION ); return FALSE; } HBITMAP hBitmap = SaveBitmapCopyScreenToBitmap(lpRect); if( !lpFileName ) { CString Path;CFileDialog dlg(FALSE,"*.*","新图形",NULL,
"位图文件(*.bmp)|*.bmp|所有文件(*.*)|*.*||",NULL);//not change the default dir
dlg.m_ofn.Flags |= OFN_EXPLORER|OFN_OVERWRITEPROMPT|OFN_HIDEREADONLY|OFN_NOCHANGEDIR; dlg.m_ofn.lpstrTitle = "保存图形";if (dlg.DoModal() == IDCANCEL)
{ ::DeleteObject(hBitmap); return FALSE; }Path = dlg.GetPathName();
//save the bitmap
return SaveBitmapToFile(hBitmap,Path.GetBuffer( Path.GetLength() ) ); } else { return SaveBitmapToFile( hBitmap, lpFileName ); } }BOOL CCopyScreenToBitmap::SaveScreenToBitmap( LPSTR lpFileName )
{ int cxSrc = GetSystemMetrics (SM_CXSCREEN) ; //源设备宽--屏幕宽 int cySrc = GetSystemMetrics (SM_CYSCREEN) ; //源设备高--屏幕高 CRect rect(0,0,cxSrc,cySrc);HBITMAP hBitmap = SaveBitmapCopyScreenToBitmap( &rect );
if( !lpFileName ) { CString Path;CFileDialog dlg(FALSE,"*.*","新图形",NULL,
"位图文件(*.bmp)|*.bmp|所有文件(*.*)|*.*||",NULL);//not change the default dir
dlg.m_ofn.Flags |= OFN_EXPLORER|OFN_OVERWRITEPROMPT|OFN_HIDEREADONLY|OFN_NOCHANGEDIR; dlg.m_ofn.lpstrTitle = "保存图形";if (dlg.DoModal() == IDCANCEL)
{ ::DeleteObject(hBitmap); return FALSE; }Path = dlg.GetPathName();
//save the bitmap
return SaveBitmapToFile(hBitmap,Path.GetBuffer( Path.GetLength() ) ); } else { return SaveBitmapToFile( hBitmap, lpFileName ); } }//lpRect 代表选定区域
HBITMAP CCopyScreenToBitmap::SaveBitmapCopyScreenToBitmap(LPRECT lpRect) { // 屏幕和内存设备描述表 HDC hScrDC, hMemDC;// 位图句柄
HBITMAP hBitmap, hOldBitmap;// 选定区域坐标
int nX, nY, nX2, nY2;// 位图宽度和高度
int nWidth, nHeight;// 屏幕分辨率
int xScrn, yScrn;// 确保选定区域不为空矩形
if (IsRectEmpty(lpRect)) return NULL;//为屏幕创建设备描述表
hScrDC = CreateDC("DISPLAY", NULL, NULL, NULL);//为屏幕设备描述表创建兼容的内存设备描述表
hMemDC = CreateCompatibleDC(hScrDC);// 获得选定区域坐标
nX = lpRect->left; nY = lpRect->top; nX2 = lpRect->right; nY2 = lpRect->bottom;// 获得屏幕分辨率
xScrn = GetDeviceCaps(hScrDC, HORZRES); yScrn = GetDeviceCaps(hScrDC, VERTRES);//确保选定区域是可见的
if (nX < 0) nX = 0; if (nY < 0) nY = 0; if (nX2 > xScrn) nX2 = xScrn; if (nY2 > yScrn) nY2 = yScrn;nWidth = nX2 - nX;
nHeight = nY2 - nY;// 创建一个与屏幕设备描述表兼容的位图
hBitmap = CreateCompatibleBitmap(hScrDC, nWidth, nHeight); // 把新位图选到内存设备描述表中 hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap); // 把屏幕设备描述表拷贝到内存设备描述表中 BitBlt(hMemDC, 0, 0, nWidth, nHeight,hScrDC, nX, nY, SRCCOPY);//得到屏幕位图的句柄
hBitmap = (HBITMAP)SelectObject(hMemDC, hOldBitmap); //清除 DeleteDC(hScrDC); DeleteDC(hMemDC);// 返回位图句柄
return hBitmap; } /////得到屏幕位图句柄以后,我们 /////可以把屏幕内容粘贴到剪贴板上. void CCopyScreenToBitmap::SaveBitmapToClipboard(HBITMAP hBitmap,HWND hWnd) { //hWnd为程序窗口句柄 if (OpenClipboard(hWnd)) { //清空剪贴板 EmptyClipboard();SetClipboardData(CF_BITMAP, hBitmap);
//关闭剪贴板
CloseClipboard(); } }//我们也可以把屏幕内容以位图格式存到磁盘文件上.
//lpFileName 为位图文件名 BOOL CCopyScreenToBitmap::SaveBitmapToFile(HBITMAP hBitmap , LPSTR lpFileName) { //设备描述表 HDC hDC; //当前显示分辨率下每个像素所占字节数 int iBits; //位图中每个像素所占字节数 WORD wBitCount=32; //定义调色板大小， 位图中像素字节大小 ， //位图文件大小 ， 写入文件字节数 DWORD dwPaletteSize=0, dwBmBitsSize, dwDIBSize, dwWritten;//位图属性结构
BITMAP Bitmap;//位图文件头结构
BITMAPFILEHEADER bmfHdr;//位图信息头结构
BITMAPINFOHEADER bi;//指向位图信息头结构
LPBITMAPINFOHEADER lpbi;//定义文件，分配内存句柄，调色板句柄
HANDLE fh, hDib; HPALETTE hPal,hOldPal=NULL;//计算位图文件每个像素所占字节数
hDC = CreateDC("DISPLAY",NULL,NULL,NULL); iBits = GetDeviceCaps(hDC, BITSPIXEL) * GetDeviceCaps(hDC, PLANES); DeleteDC(hDC);if (iBits <= 1)
wBitCount = 1; else if (iBits <= 4) wBitCount = 4; else if (iBits <= 8) wBitCount = 8; else if (iBits <= 24) wBitCount = 24;//计算调色板大小
if (wBitCount <= 8) dwPaletteSize = (1 << wBitCount) *sizeof(RGBQUAD);//设置位图信息头结构
GetObject(hBitmap, sizeof(BITMAP), (LPSTR)&Bitmap); bi.biSize = sizeof(BITMAPINFOHEADER); bi.biWidth = Bitmap.bmWidth; bi.biHeight = Bitmap.bmHeight; bi.biPlanes = 1; bi.biBitCount = wBitCount; bi.biCompression = BI_RGB; bi.biSizeImage = 0; bi.biXPelsPerMeter = 0; bi.biYPelsPerMeter = 0; bi.biClrUsed = 0; bi.biClrImportant = 0;dwBmBitsSize = ((Bitmap.bmWidth *wBitCount+31)/32)* 4*Bitmap.bmHeight ;
//为位图内容分配内存
hDib = GlobalAlloc(GHND,dwBmBitsSize+dwPaletteSize+sizeof(BITMAPINFOHEADER)); lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib); *lpbi = bi;// 处理调色板
hPal = (HPALETTE)GetStockObject(DEFAULT_PALETTE); if (hPal) { hDC = GetDC(NULL); hOldPal = SelectPalette(hDC, hPal, FALSE); RealizePalette(hDC); }// 获取该调色板下新的像素值
GetDIBits(hDC, hBitmap, 0, (UINT)Bitmap.bmHeight,(LPSTR)lpbi + sizeof(BITMAPINFOHEADER)+dwPaletteSize,(LPBITMAPINFO)lpbi, DIB_RGB_COLORS);//恢复调色板
if (hOldPal) { SelectPalette(hDC, hOldPal, TRUE); RealizePalette(hDC); ReleaseDC(NULL, hDC); }//创建位图文件
fh = CreateFile(lpFileName, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);if (fh == INVALID_HANDLE_VALUE)
return FALSE;//设置位图文件头
bmfHdr.bfType = 0x4D42; // "BM" dwDIBSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + dwPaletteSize + dwBmBitsSize; bmfHdr.bfSize = dwDIBSize; bmfHdr.bfReserved1 = 0; bmfHdr.bfReserved2 = 0; bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER)+ dwPaletteSize;// 写入位图文件头
WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);// 写入位图文件其余内容
WriteFile(fh, (LPSTR)lpbi, dwDIBSize, &dwWritten, NULL);//清除
GlobalUnlock(hDib); GlobalFree(hDib); CloseHandle(fh);return TRUE;
}