windows api 实现对指定窗口名称进行截图保存

有几个问题

1. 第一是有些窗口的截图是黑色的
2. 第二是截出来的窗口的显示大小有些问题
3. 第三是只能截出现在桌面的窗口（包括被挡住的窗口），但是不包括最小化的窗口
   如果有大佬知道怎么做，一定要教教我啊，谢谢！

#include "stdio.h"

#include "windows.h"

/************************************************************************/

/* hBitmap    为刚才的屏幕位图句柄

/* lpFileName 为需要保存的位图文件名

/************************************************************************/

int SaveBitmapToFile(HBITMAP hBitmap, LPSTR lpFileName)

{

    HDC            hDC; //设备描述表

    int            iBits;//当前显示分辨率下每个像素所占字节数

    WORD           wBitCount;//位图中每个像素所占字节数    

    DWORD          dwPaletteSize = 0;//定义调色板大小

    DWORD          dwBmBitsSize;//位图中像素字节大小

    DWORD          dwDIBSize;// 位图文件大小

    DWORD          dwWritten;//写入文件字节数

    BITMAP         Bitmap;//位图结构

    BITMAPFILEHEADER   bmfHdr;   //位图属性结构   

    BITMAPINFOHEADER   bi;       //位图文件头结构

    LPBITMAPINFOHEADER lpbi;     //位图信息头结构     指向位图信息头结构

    HANDLE          fh;//定义文件句柄

    HANDLE            hDib;//分配内存句柄

    HANDLE            hPal;//分配内存句柄

    HANDLE          hOldPal = NULL;//调色板句柄  



    //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;

    else if (iBits <= 32)

        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);

    if (lpbi == NULL)

    {

        return 0;

    }



    *lpbi = bi;

    // 处理调色板

    hPal = GetStockObject(DEFAULT_PALETTE);

    if (hPal)

    {

        hDC = GetDC(NULL);

        hOldPal = ::SelectPalette(hDC, (HPALETTE)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, (HPALETTE)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 1;

}

HBITMAP   GetCaptureBmp()

{

    HDC     hDC;

    HDC     MemDC;

    BYTE*   Data;

    HBITMAP   hBmp;

    BITMAPINFO   bi;

    HWND hq = FindWindow(NULL, "网易云音乐");
    hDC = GetWindowDC(hq);
    RECT rect;
    GetWindowRect(hq, &rect);
    int w = rect.right - rect.left, h = rect.bottom - rect.top;

    memset(&bi, 0, sizeof(bi));

    bi.bmiHeader.biSize = sizeof(BITMAPINFO);

    bi.bmiHeader.biWidth = w*1.235;

    bi.bmiHeader.biHeight = h*1.225;

    bi.bmiHeader.biPlanes = 1;

    bi.bmiHeader.biBitCount = 24;





    MemDC = CreateCompatibleDC(hDC);

    hBmp = CreateDIBSection(MemDC, &bi, DIB_RGB_COLORS, (void**)&Data, NULL, 0);

    SelectObject(MemDC, hBmp);

    BitBlt(MemDC, 1, 1, w*GetSystemMetrics(SM_CXSCREEN) / GetDeviceCaps(hDC, HORZSIZE), h*GetSystemMetrics(SM_CYSCREEN) / GetDeviceCaps(hDC, VERTSIZE), hDC, 9, 9, SRCCOPY);

    ReleaseDC(NULL, hDC);

    DeleteDC(MemDC);

    return   hBmp;

}


void main()

{

    HBITMAP   hBmp;

    hBmp = GetCaptureBmp();

    SaveBitmapToFile(hBmp, "D:\\11.bmp");

}