## 1. 實現截圖程序的api接口 ##
HBITMAP CaptureScreen(LPRECT lpRect)//lpRect爲NULL時表示全屏幕截圖
{
HDC hdc, hdcMem ;
HBITMAP hemfCopy ;
HWND hwndScr ;
int dstcx, dstcy ;
if(lpRect)
{
dstcx = lpRect->right - lpRect->left ;
dstcy = lpRect->bottom - lpRect->top ;
}
else
{
dstcx = GetSystemMetrics(SM_CXSCREEN) ;
dstcy = GetSystemMetrics(SM_CYSCREEN) ;
}
if (LockWindowUpdate(hwndScr = GetDesktopWindow ()))
{
hdc = GetDCEx (hwndScr, NULL, DCX_CACHE | DCX_LOCKWINDOWUPDATE) ;
hdcMem = CreateCompatibleDC (hdc) ;
if(NULL==hdcMem)
{
ReleaseDC (hwndScr, hdc) ;
LockWindowUpdate (NULL) ;
return NULL;
}
hemfCopy = CreateCompatibleBitmap (hdc, abs(dstcx), abs(dstcy)) ;
if(NULL==hemfCopy)
{
DeleteDC (hdcMem) ;
ReleaseDC (hwndScr, hdc) ;
LockWindowUpdate (NULL) ;
return NULL;
}
SelectObject (hdcMem, hemfCopy) ;
if(lpRect)
StretchBlt (hdcMem, 0, 0, abs(dstcx), abs(dstcy),
hdc, lpRect->left, lpRect->top, dstcx, dstcy, SRCCOPY|CAPTUREBLT) ;
else
BitBlt (hdcMem, 0, 0, dstcx, dstcy,
hdc, 0, 0, SRCCOPY|CAPTUREBLT) ;
DeleteDC (hdcMem) ;
ReleaseDC (hwndScr, hdc) ;
LockWindowUpdate (NULL) ;
return hemfCopy;
}
return NULL;
}
``
2、保存圖片
BOOL SaveBmp(HBITMAP hBitmap,CString FileName)
{
HDC hDC;
//當前分辨率下每象素所佔字節數
int iBits;
//位圖中每象素所佔字節數
WORD wBitCount;
//定義調色板大小, 位圖中像素字節大小 ,位圖文件大小 , 寫入文件字節數
DWORD dwPaletteSize=0, dwBmBitsSize=0, dwDIBSize=0, dwWritten=0;
//位圖屬性結構
BITMAP Bitmap;
//位圖文件頭結構
BITMAPFILEHEADER bmfHdr;
//位圖信息頭結構
BITMAPINFOHEADER bi;
//指向位圖信息頭結構
LPBITMAPINFOHEADER lpbi;
//定義文件,分配內存句柄,調色板句柄
HANDLE fh, hDib, hPal,hOldPal=NULL;
//計算位圖文件每個像素所佔字節數
hDC = CreateDC(TEXT("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
wBitCount = 24;
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.biClrImportant = 0;
bi.biClrUsed = 0;
dwBmBitsSize = ((Bitmap.bmWidth *wBitCount+31) / 32)*4* Bitmap.bmHeight;
//爲位圖內容分配內存
hDib = GlobalAlloc(GHND,dwBmBitsSize+dwPaletteSize+sizeof(BITMAPINFOHEADER));
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
*lpbi = bi;
// 處理調色板
hPal = GetStockObject(DEFAULT_PALETTE);
if (hPal)
{
hDC = ::GetDC(NULL);
hOldPal = ::SelectPalette(hDC,(HPALETTE)hPal, FALSE);
RealizePalette(hDC);
}
// 獲取該調色板下新的像素值
GetDIBits(hDC,hBitmap, 0,(UINT)Bitmap.bmHeight,
(LPSTR)lpbi+ sizeof(BITMAPINFOHEADER)+dwPaletteSize,
(BITMAPINFO *)lpbi, DIB_RGB_COLORS);
//恢復調色板
if (hOldPal)
{
::SelectPalette(hDC, (HPALETTE)hOldPal, TRUE);
RealizePalette(hDC);
::ReleaseDC(NULL, hDC);
}
//創建位圖文件
fh = CreateFile(FileName, GENERIC_WRITE,0, NULL, CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);
if (fh == INVALID_HANDLE_VALUE) return FALSE;
// 設置位圖文件頭
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;
// 寫入位圖文件頭
WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);
// 寫入位圖文件其餘內容
WriteFile(fh, (LPSTR)lpbi, dwDIBSize, &dwWritten, NULL);
//清除
GlobalUnlock(hDib);
GlobalFree(hDib);
CloseHandle(fh);
return TRUE;
}
3、在dialog中 顯示
在onPaint中顯示 ,其中mfc設計到 BITMAP hbitmap和cbitmap之間的關係
在mfc程序中,使用cbitmap
CPaintDC dc(this);
CDC dcimage;
CBitmap bkg;
bkg.Attach(g_bitmap);
BITMAP bkginfo;
bkg.GetBitmap(&bkginfo);//獲取位圖信息
dcimage.CreateCompatibleDC(&dc);
dcimage.SelectObject(&bkg);
// dc.BitBlt(0,0,nWidth,nHeight,&dcimage,0,0,SRCCOPY);
dc.StretchBlt(0,0,nWidth,nHeight,&dcimage,0,0,bkginfo.bmWidth,bkginfo.bmHeight,SRCCOPY);
`