如何在vc ++中将BITMAP转换为HBITMAP [英] how to convert BITMAP to HBITMAP in vc++

问题描述

我在mfc中创建一个基于对话框的应用程序。

我有两个按钮和一个图片控件。

我想保存并检索bmp到（来自）ms访问2007.

在数据库中，我有字段（图片，OLE对象）

在保存按钮中单击

I am creating a dialog based application in mfc.
I have two button and one picture control.
I want to save and retrieve bmp into(from) ms access 2007.
In database, I have field(picture,OLE Object)
In save button click

CDaoDatabase* m_database= new CDaoDatabase();
m_database->Open(L"C:\\Users\\ABC\\ABC.mdb",TRUE,FALSE,L"");
if(m_database->IsOpen())
{
    CString strSQL =_T("SELECT picture FROM Table2");
    CDaoRecordset m_reordset(m_database);
    m_reordset.Open(AFX_DAO_USE_DEFAULT_TYPE,strSQL,0);
    int iRecords =m_reordset.GetRecordCount();
    //CLongBinary bin1;
    if (!iRecords)
    {
        m_reordset.AddNew();
        CPictureHolder pic;
        CBitmap bmp;
        bmp. LoadBitmap (IDB_BITMAP1);

        if (pic.CreateFromBitmap (&bmp))
        {
            IStream* pStream;
            CreateStreamOnHGlobal (NULL, TRUE, &pStream);
            if (pStream)
            {
                LONG sz;
                pic.m_pPict-> SaveAsFile (pStream, TRUE, &sz);

                HGLOBAL hGlobal;
                GetHGlobalFromStream (pStream, &hGlobal);

                CByteArray barray;
                CLongBinary bin;
                bin.m_dwDataLength = GlobalSize (hGlobal);
                bin.m_hData = hGlobal;
                m_reordset.SetFieldValue (_T("picture"), COleVariant (bin));//Register "long binary data"
            }
            m_reordset.Update();
        }
    }
    m_database->Close();

图片字段显示长二进制数据。

在检索按钮中单击

picture field is showing "Long binary data".
In retrieve button click

    CDaoDatabase* m_database= new CDaoDatabase();
COleVariant valuer;
m_database->Open(L"C:\\Users\\ABC\\ABC.mdb",TRUE,FALSE,L"");
if(m_database->IsOpen())
{
    CString strSQL =_T("SELECT picture FROM Table2");
    CBitmap ABitmap;
    BITMAP bm;
    CDaoRecordset m_reordset(m_database);
    m_reordset.Open(AFX_DAO_USE_DEFAULT_TYPE,strSQL,0);
    int iRecords =m_reordset.GetRecordCount();
    valuer=m_reordset.GetFieldValue(0);
    //Retrieve size of array
    u_long pcBufLen =valuer.parray->rgsabound[0].cElements;
    BYTE    *ppBuf = new BYTE[pcBufLen]; //Allocate a buffer to store the data
    BYTE *tmp= NULL;
    if( valuer.vt!=VT_NULL)
    {
        void* pArrayData;
        CByteArray Photo;
        const void* lpbits;
        Photo.SetSize(pcBufLen);

        SafeArrayAccessData(valuer.parray,&pArrayData);

        memcpy(Photo.GetData(),pArrayData,Photo.GetSize());

        memcpy(&bm,pArrayData,sizeof(BITMAP));


        HDC hdc,hdcMem;
        HWND hh=::GetDlgItem(GetSafeHwnd(),IDC_pic);
        hdc = ::GetWindowDC(hh);
        HBITMAP hBitmap=NULL;
        hdcMem  = ::CreateCompatibleDC(hdc);


        SelectObject(hdcMem,::CreateBitmap(bm.bmWidth,bm.bmHeight,bm.bmPlanes,bm.bmBitsPixel,bm.bmBits));
        int res=BitBlt(hdc, 0,0, bm.bmWidth, bm.bmHeight,hdcMem,0,0,SRCCOPY);


        hBitmap=CreateCompatibleBitmap(hdc,100,100);

        HBITMAP t=m_nHeight.SetBitmap(hBitmap);
        DeleteDC(hdcMem );

        SafeArrayUnaccessData(valuer.parray);
    }
    m_database->Close();

m_nHeight是用于IDC_pic控制的CStatic类

m_nHeight is CStatic class for IDC_pic control

value of t is 0x00000000 {unused=??? }

and

bm.bmType=137776450

bm.bmWidth=7

bm.bmHeight=3538944

bm.bmWidthBytes=2621440

bm.bmPlanes=0

bm.bmBitsPixel=320

bm.bmBits=0x01e00000

I am not getting image on picture control, its getting black screen.
 I think problem is in bm.bmPlanes.

帮助我！

Help me!

推荐答案

请注意:) ：

Please observe :) :

void GetImage(VARIANT& val)
{
  CImage img;
  img.LoadFromResource(::AfxGetInstanceHandle(), IDB_BITMAP1);
  COleStreamFile file;
  if (file.CreateMemoryStream()) {
    IStream* pStream(file.GetStream());
    if (pStream &&
        S_OK == cViewImage.Save(pStream, ImageFormatPNG)) {
      file.SeekToBegin();
      UINT uiLen(static_cast<UINT>(file.GetLength()));

      CByteArray arRowData;
      arRowData.SetSize(static_cast<INT_PTR>(uiLen));
      file.Read(arRowData.GetData(), uiLen);

      CD_CSafeArray arPngDump; // just an incapsulation of the SAFEARRAY
      arPngDump.CreateOneDim(VT_UI1, uiLen, arRowData.GetData());
      val = arPngDump.Detach();
    }
  }
  file.Close();
}

void TestBackDbDump(CD_CSafeArray& arPngDump)
{
  COleStreamFile file;
  if (file.CreateMemoryStream()) {
    IStream* pStream(file.GetStream());
    if (pStream) {
      UINT uiLen(static_cast<UINT>(arPngDump.GetLength()));

      CByteArray arRowData;
      arRowData.SetSize(static_cast<INT_PTR>(uiLen));
      arPngDump.Read(arRowData.GetData(), uiLen); // Access/Unaccess inside...
      file.Write(arRowData.GetData(), uiLen); // The data is now in the stream...
      file.SeekToBegin();

      CImage img;
      im.Load(pStream);
      img.Save(_T("d:\\last_test.png"), ImageFormatPNG); // yes, we hope :)
    }
  }
  file.Close();
}

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