如何创建24位色的Bitmap然后保存到磁盘上面？

[HashCodeWithJava]

保存bitmap的代码都没有什么问题.
问题是我创建的Bitmap,然后用SetPixel在上面写点后，居然只有两种颜色(白与黑)

这是我的代码，大家帮我看看吧.

CDC memDC;
CBitmap *pBitmap = new CBitmap();
memDC.CreateCompatibleDC(NULL);
pBitmap->CreateCompatibleBitmap(&memDC,Width,1);
CBitmap *pOldBitmap = memDC.SelectObject(pBitmap);
for(int i=0;i<Width;i++)
{
memDC.SetPixel(i,0,RGB(g_Buffer[3*i],g_Buffer[3*i+1],g_Buffer[3*i+2]));
}
memDC.SelectObject(pOldBitmap);

谢谢指教？

[_foo]

::GetDC(0)

[bluebohe]

pBitmap->CreateCompatibleBitmap(&memDC,Width,1);
这句话第一个参数改成你实际要显示在上面的dc，比如this->GetDC();

[taianmonkey]

BOOL Tofile(HBITMAP hbitmap, LPSTR lpfilename)
{
HDC hdc; //设备描述表
int ibits;
WORD wbitcount; //当前显示分辨率下每个像素所占字节数

//位图中每个像素所占字节数，定义调色板大小，位图中像素字节大小，位图文件大小 ，写入文件字节数
DWORD dwpalettesize=0, dwbmbitssize, dwdibsize, dwwritten;

BITMAP bitmap; //位图属性结构
BITMAPFILEHEADER bmfhdr; //位图文件头结构
BITMAPINFOHEADER bi; //位图信息头结构
LPBITMAPINFOHEADER lpbi; //指向位图信息头结构

//定义文件，分配内存句柄，调色板句柄
HANDLE fh, hdib, hpal,holdpal=NULL;

//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 <= 16)
wbitcount = 16;
else if (ibits <= 24)
wbitcount = 24;
else
wbitcount = 32;

//计算调色板大小
if (wbitcount <= 8)//小于八位按八位处理
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);
*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,(BITMAPINFO*)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 TRUE;
}

[_foo]

pBitmap->CreateCompatibleBitmap(&memDC,Width,1);//把dc改为屏幕ＤＣ试试

[HashCodeWithJava]

如何得到屏幕的DC?