---- 屏幕截取是令人比較感興趣的事情.雖然現在有不少應用程序如HYPERSNAP等可以用來截取你所喜歡的屏幕畫面,但是如果能把這個功能加到自己的程序中,就更能利用它強大的作用.
---- 下面用VC來逐步介紹在Windows95下的實現過程.首先我們要確定屏幕截取的區域,用LPRECT結構來定義.可以截取一個窗口,或整個屏幕.以下代碼把選定的屏幕區域拷貝到位圖中.
HBITMAP CopyScreenToBitmap(LPRECT lpRect)
//lpRect 代表選定區域
{
HDC???????hScrDC, hMemDC;??????
// 屏幕和內存設備描述表
HBITMAP????hBitmap, hOldBitmap;???
// 位圖句柄
int???????nX, nY, nX2, nY2;??????
// 選定區域坐標
int???????nWidth, nHeight;??????
// 位圖寬度和高度
int???????xScrn, yScrn;?????????
// 屏幕分辨率
???// 確保選定區域不為空矩形
???if (IsRectEmpty(lpRect))
?????return NULL;
???//為屏幕創建設備描述表
???hScrDC = CreateDC("DISPLAY", NULL, NULL, NULL);
???//為屏幕設備描述表創建兼容的內存設備描述表
???hMemDC = CreateCompatibleDC(hScrDC);
???// 獲得選定區域坐標
???nX = lpRect- >left;
???nY = lpRect- >top;
???nX2 = lpRect- >right;
???nY2 = lpRect- >bottom;
???// 獲得屏幕分辨率
???xScrn = GetDeviceCaps(hScrDC, HORZRES);
???yScrn = GetDeviceCaps(hScrDC, VERTRES);
???//確保選定區域是可見的
???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;
???// 創建一個與屏幕設備描述表兼容的位圖
hBitmap = CreateCompatibleBitmap
(hScrDC, nWidth, nHeight);
???// 把新位圖選到內存設備描述表中
???hOldBitmap = SelectObject(hMemDC, hBitmap);
???// 把屏幕設備描述表拷貝到內存設備描述表中
BitBlt(hMemDC, 0, 0, nWidth, nHeight,
hScrDC, nX, nY, SRCCOPY);
???//得到屏幕位圖的句柄
???hBitmap = SelectObject(hMemDC, hOldBitmap);
???//清除
???DeleteDC(hScrDC);
???DeleteDC(hMemDC);
???// 返回位圖句柄
???return hBitmap;
}
???
得到屏幕位圖句柄以后,我們
可以把屏幕內容粘貼到剪貼板上.
????if (OpenClipboard(hWnd))
?????//hWnd為程序窗口句柄
??????{
????????//清空剪貼板
????????EmptyClipboard();
????????//把屏幕內容粘貼到剪貼板上,
????????hBitmap 為剛才的屏幕位圖句柄
????????SetClipboardData(CF_BITMAP, hBitmap);
????????//關閉剪貼板
????????CloseClipboard();
??????}
???我們也可以把屏幕內容以位圖格式存到磁盤文件上.
??????
int SaveBitmapToFile(HBITMAP hBitmap ,
LPSTR lpFileName) //hBitmap 為剛才的屏幕位圖句柄
{???? ?//lpFileName 為位圖文件名
HDC????????????hDC;?????????
?? ?//設備描述表
??????int????????????iBits;??????
? //當前顯示分辨率下每個像素所占字節數
WORD????????????wBitCount;???
??? //位圖中每個像素所占字節數
??????//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,
?dwDIBSize, dwWritten;
BITMAP??????????Bitmap;????????
//位圖屬性結構
BITMAPFILEHEADER???bmfHdr;????????
//位圖文件頭結構
??????BITMAPINFOHEADER???bi;????????????
//位圖信息頭結構
LPBITMAPINFOHEADER lpbi;??????????
//指向位圖信息頭結構
??????HANDLE??????????fh, hDib, hPal,hOldPal=NULL;
//定義文件，分配內存句柄，調色板句柄
??
???//計算位圖文件每個像素所占字節數
???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;
???//計算調色板大小
???if (wBitCount 〈 = 8)
??????dwPaletteSize = (1 〈 〈???wBitCount) *
??????sizeof(RGBQUAD);
???
???//設置位圖信息頭結構
???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 ;
???//為位圖內容分配內存
???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, 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,
?(BITMAPINFOHEADER *)
????lpbi, DIB_RGB_COLORS);
???//恢復調色板???
???if (hOldPal)
???{
??????SelectPalette(hDC, hOldPal, TRUE);
??????RealizePalette(hDC);
??????ReleaseDC(NULL, hDC);
???}
???//創建位圖文件????
fh = CreateFile(lpFileName, GENERIC_WRITE,
0, NULL, CREATE_ALWAYS,
?????????FILE_ATTRIBUTE_NORMAL | FILE_
?????????FLAG_SEQUENTIAL_SCAN, NULL);
???if (fh == INVALID_HANDLE_VALUE)
??????return FALSE;
???// 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);
???// 寫入位圖文件其余內容
???WriteFile(fh, (LPSTR)lpbi, dwDIBSize,
???&dwWritten, NULL);
???//清除???
???GlobalUnlock(hDib);
???GlobalFree(hDib);
???CloseHandle(fh);
}
from:
http://www.cnsdn.com.cn/inc/show.asp?id=3472