每次程序模拟按这个键
然后将图片存到剪切板
然后程序访问剪切板，
存到文件中。
或者直接调用winapi将界面复制到剪切板
API定时＋截屏！
Windows GDI
（1）截屏
Capturing an Image
You can use a bitmap to capture an image, Ａnd you can store the captured image in memory, display it at a different location in your application///'s window, Ｏr display it in another window.
In some cases, you may want your application to capture images Ａnd store them only temporarily. For example, when you scale Ｏr zoom a picture created in a drawing application, the application must temporarily save the normal view of the image Ａnd display the zoomed view. Later, when the user selects the normal view, the application must replace the zoomed image with a copy of the normal view that it temporarily saved.
To store an image temporarily, your application must call CreateCompatibleDC to create a DC that is compatible with the current window DC. After you create a compatible DC, you create a bitmap with the appropriate dimensions by calling the CreateCompatibleBitmap function Ａnd then select it into this device context by calling the SelectObject function.
After the compatible device context is created Ａnd the appropriate bitmap has been selected into it, you can capture the image. The BitBlt function captures images. This function performs a bit block transfer that is, it copies data from a source bitmap into a destination bitmap. However, the two arguments to this function are not bitmap handles. Instead, BitBlt receives handles that identify two device contexts Ａnd copies the bitmap data from a bitmap selected into the source DC into a bitmap selected into the target DC. In this case, the target DC is the compatible DC, so when BitBlt completes the transfer, the image has been stored in memory. To redisplay the image, call BitBlt a second time, specifying the compatible DC as the source DC Ａnd a window (or printer) DC as the target DC.
The following example code, from an application that captures an image of the entire desktop, creates a compatible device context Ａnd a bitmap with the appropriate dimensions, selects the bitmap into the compatible DC, Ａnd then copies the image using the BitBlt function.
// Create a normal DC Ａnd a memory DC for the entire screen. The
// normal DC provides a //"snapshot//" of the screen contents. The
// memory DC keeps a copy of this //"snapshot//" in the associated
// bitmap.
hdcScreen = CreateDC(//"DISPLAY//", NULL, NULL, NULL);
hdcCompatible = CreateCompatibleDC(hdcScreen);
// Create a compatible bitmap for hdcScreen.
hbmScreen = CreateCompatibleBitmap(hdcScreen,
GetDeviceCaps(hdcScreen, HORZRES),
GetDeviceCaps(hdcScreen, VERTRES));
if (hbmScreen == 0)
errhandler(//"hbmScreen//", hwnd);
// Select the bitmaps into the compatible DC.
if (!SelectObject(hdcCompatible, hbmScreen))
errhandler(//"Compatible Bitmap Selection//", hwnd);
// Hide the application window.
ShowWindow(hwnd, SW_HIDE);
//Copy color data for the entire display into a
//bitmap that is selected into a compatible DC.
if (!BitBlt(hdcCompatible,
0,0,
bmp.bmWidth, bmp.bmHeight,
hdcScreen,
0,0,
SRCCOPY))
errhandler(//"Screen to Compat Blt Failed//", hwnd);
// Redraw the application window.
ShowWindow(hwnd, SW_SHOW);
（2）保存
Storing an Image
Many applications store images permanently as files. For example, drawing applications store pictures, spreadsheet applications store charts, CAD applications store drawings, Ａnd so on.
If you are writing an application that stores a bitmap image in a file, you should use the bitmap file format described in Bitmap Storage. To store a bitmap in this format, you must use a BITMAPINFOHEADER, a BITMAPV4HEADER, Ｏr a BITMAPV5HEADER structure Ａnd an array of RGBQUAD structures, as well as an array of palette indexes.
The following example code defines a function that uses a BITMAPINFO structure Ａnd allocates memory for Ａnd initializes members within a BITMAPINFOHEADER structure. Note that the BITMAPINFO structure cannot be used with either a BITMAPV4HEADER Ｏr a BITMAPV5HEADER structure.
PBITMAPINFO CreateBitmapInfoStruct(HWND hwnd, HBITMAP hBmp)
{
BITMAP bmp;
PBITMAPINFO pbmi;
WORD cClrBits;
// Retrieve the bitmap color format, width, Ａnd height.
if (!GetObject(hBmp, sizeof(BITMAP), (LPSTR)&bmp))
errhandler(/"GetObject/", hwnd);
// Convert the color format to a count of bits.
cClrBits = (WORD)(bmp.bmPlanes * bmp.bmBitsPixel);
if (cClrBits == 1)
cClrBits = 1;
else if (cClrBits <= 4)
cClrBits = 4;
else if (cClrBits <= 8)
cClrBits = 8;
else if (cClrBits <= 16)
cClrBits = 16;
else if (cClrBits <= 24)
cClrBits = 24;
else cClrBits = 32;
// Allocate memory for the BITMAPINFO structure. (This structure
// contains a BITMAPINFOHEADER structure Ａnd an array of RGBQUAD
// data structures.)
if (cClrBits != 24)
pbmi = (PBITMAPINFO) LocalAlloc(LPTR,
sizeof(BITMAPINFOHEADER) +
sizeof(RGBQUAD) * (1<< cClrBits));
// There is no RGBQUAD array for the 24-bit-per-pixel format.
else
pbmi = (PBITMAPINFO) LocalAlloc(LPTR,
sizeof(BITMAPINFOHEADER));
// Initialize the fields in the BITMAPINFO structure.
pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pbmi->bmiHeader.biWidth = bmp.bmWidth;
pbmi->bmiHeader.biHeight = bmp.bmHeight;
pbmi->bmiHeader.biPlanes = bmp.bmPlanes;
pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel;
if (cClrBits < 24)
pbmi->bmiHeader.biClrUsed = (1<<cClrBits);
// If the bitmap is not compressed, set the BI_RGB flag.
pbmi->bmiHeader.biCompression = BI_RGB;
// Compute the number of bytes in the array of color
// indices Ａnd store the result in biSizeImage.
// For Windows NT, the width must be DWORD aligned unless
// the bitmap is RLE compressed. This example shows this.
// For Windows 95/98/Me, the width must be WORD aligned unless the
// bitmap is RLE compressed.
pbmi->bmiHeader.biSizeImage = ((pbmi->bmiHeader.biWidth * cClrBits +31) & ~31) /8
* pbmi->bmiHeader.biHeight;
// Set biClrImportant to 0, indicating that all of the
// device colors are important.
pbmi->bmiHeader.biClrImportant = 0;
return pbmi;
}
The following example code defines a function that initializes the remaining structures, retrieves the array of palette indices, opens the file, copies the data, Ａnd closes the file.
void CreateBMPFile(HWND hwnd, LPTSTR pszFile, PBITMAPINFO pbi,
HBITMAP hBMP, HDC hDC)
{
HANDLE hf; // file handle
BITMAPFILEHEADER hdr; // bitmap file-header
PBITMAPINFOHEADER pbih; // bitmap info-header
LPBYTE lpBits; // memory pointer
DWORD dwTotal; // total count of bytes
DWORD cb; // incremental count of bytes
BYTE *hp; // byte pointer
DWORD dwTmp;
pbih = (PBITMAPINFOHEADER) pbi;
lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED, pbih->biSizeImage);
if (!lpBits)
errhandler(/"GlobalAlloc/", hwnd);
// Retrieve the color table (RGBQUAD array) Ａnd the bits
// (array of palette indices) from the DIB.
if (!GetDIBits(hDC, hBMP, 0, (WORD) pbih->biHeight, lpBits, pbi,
DIB_RGB_COLORS))
{
errhandler(/"GetDIBits/", hwnd);
}
// Create the .BMP file.
hf = CreateFile(pszFile,
GENERIC_READ | GENERIC_WRITE,
(DWORD) 0,
NULL,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
(HANDLE) NULL);
if (hf == INVALID_HANDLE_VALUE)
errhandler(/"CreateFile/", hwnd);
hdr.bfType = 0x4d42; // 0x42 = /"B/" 0x4d = /"M/"
// Compute the size of the entire file.
hdr.bfSize = (DWORD) (sizeof(BITMAPFILEHEADER) +
pbih->biSize + pbih->biClrUsed
* sizeof(RGBQUAD) + pbih->biSizeImage);
hdr.bfReserved1 = 0;
hdr.bfReserved2 = 0;
// Compute the offset to the array of color indices.
hdr.bfOffBits = (DWORD) sizeof(BITMAPFILEHEADER) +
pbih->biSize + pbih->biClrUsed
* sizeof (RGBQUAD);
// Copy the BITMAPFILEHEADER into the .BMP file.
if (!WriteFile(hf, (LPVOID) &hdr, sizeof(BITMAPFILEHEADER),
(LPDWORD) &dwTmp, NULL)))
{
errhandler(/"WriteFile/", hwnd);
}
// Copy the BITMAPINFOHEADER Ａnd RGBQUAD array into the file.
if (!WriteFile(hf, (LPVOID) pbih, sizeof(BITMAPINFOHEADER)
+ pbih->biClrUsed * sizeof (RGBQUAD),
(LPDWORD) &dwTmp, ( NULL))
errhandler(/"WriteFile/", hwnd);
// Copy the array of color indices into the .BMP file.
dwTotal = cb = pbih->biSizeImage;
hp = lpBits;
if (!WriteFile(hf, (LPSTR) hp, (int) cb, (LPDWORD) &dwTmp,NULL))
errhandler(/"WriteFile/", hwnd);
// Close the .BMP file.
if (!CloseHandle(hf))
errhandler(/"CloseHandle/", hwnd);
// Free memory.
GlobalFree((HGLOBAL)lpBits);
}