问C++如何在内存中获取16色(4位)位图的屏幕截图输出

EN

#include "stdafx.h"
#include <windows.h>
#include <stdio.h>

LPBITMAPINFO ConstructBitmapInfo(int nBits, int nX, int nY);
VOID RocketBuffer(LPVOID lpData);

int _tmain(int argc, _TCHAR* argv[])
{
    HWND hDesktop = NULL;
    HDC hCurrenDC = NULL;
    INT nX, nY;
    LPBITMAPINFO lpBmpInfo;
    HBITMAP hBmpScreen;
    LPVOID lpBmpBuffer = NULL;

    if(NULL == (hDesktop = GetDesktopWindow()))
        return GetLastError();

    if (NULL == (hCurrenDC = GetDC(hDesktop)))
        return GetLastError();

    nX = GetSystemMetrics(SM_CXSCREEN);
    nY = GetSystemMetrics(SM_CYSCREEN);

    HDC hOrgMemDC = NULL;
    hOrgMemDC = CreateCompatibleDC(hCurrenDC);
    lpBmpInfo = ConstructBitmapInfo(4, nX, nY);
    hBmpScreen = CreateDIBSection(hCurrenDC, lpBmpInfo, DIB_RGB_COLORS, &lpBmpBuffer, NULL, 0);

    SelectObject(hOrgMemDC, hBmpScreen);

    if(!BitBlt(hOrgMemDC, 0, 0, nX, nY, hCurrenDC, 0, 0, SRCCOPY))
    {
        return GetLastError();
    }

    LPBYTE lpWriteData = new BYTE[lpBmpInfo->bmiHeader.biSizeImage * 2];

    memcpy(lpWriteData, lpBmpBuffer, lpBmpInfo->bmiHeader.biSizeImage);
    RocketBuffer(lpBmpBuffer);

    delete[] lpWriteData;

    return 0;
}

LPBITMAPINFO ConstructBitmapInfo(int nBits, int nX, int nY)
{   
    int color_num = nBits <= 8 ? 1 << nBits : 0;

    int nBISize = sizeof(BITMAPINFOHEADER) + (color_num * sizeof(RGBQUAD));
    BITMAPINFO  *lpbmi = (BITMAPINFO *) new BYTE[nBISize];

    BITMAPINFOHEADER    *lpbmih = &(lpbmi->bmiHeader);
    lpbmih->biSize = sizeof(BITMAPINFOHEADER);
    lpbmih->biWidth = nX;
    lpbmih->biHeight = nY;
    lpbmih->biPlanes = 1;
    lpbmih->biBitCount = nBits;
    lpbmih->biCompression = BI_RGB;
    lpbmih->biXPelsPerMeter = 0;
    lpbmih->biYPelsPerMeter = 0;
    lpbmih->biClrUsed = 0;
    lpbmih->biClrImportant = 0;
    lpbmih->biSizeImage = (((lpbmih->biWidth * lpbmih->biBitCount + 31) & ~31) >> 3) * lpbmih->biHeight;

    if (nBits >= 16)
        return lpbmi;

    HDC hDC = GetDC(NULL);
    HBITMAP hBmp = CreateCompatibleBitmap(hDC, 1, 1); 
    GetDIBits(hDC, hBmp, 0, 0, NULL, lpbmi, DIB_RGB_COLORS);
    ReleaseDC(NULL, hDC);
    DeleteObject(hBmp);

    return lpbmi;
}

VOID RocketBuffer(LPVOID lpData)
{
    // ...
}