从浏览按钮显示图像

问题描述

I am new to C++ and I'm using MFC by Visual Studio 2012 How can I display an Image in a picture control from browse button? On browse button click, I set the path to an edit control like that

void CSimilarityOfImagesDlg::OnBnClickedButton1()
{
    CFileDialog dlg(TRUE);
    int iRet = dlg.DoModal();
    CString path = dlg.GetPathName();

    SetWindowText (path);
    CEdit* cedit;
    cedit = reinterpret_cast<CEdit *>(GetDlgItem(IDC_EDIT1));
    cedit->SetWindowTextW(path);
    cedit->GetWindowTextW(path);

}

MFC/ATL framework comes with CImage class that allows you to load images (PNG, JPEG, BMP, GIF and other formats are supported). In order to display the target image in your picture control you need to use the CStatic::SetBitmap() method. The CImage class implements Detach() method that allows you to get direct access to HBITMAP object. Here is an example:

The m_PictureCtrl is defined in your dialog window header file like this:

CStatic m_PictureCtrl;

It is mapped to IDC_PIC_STATIC control ID using standard MFC Data Exchange mechanism.

void CTestPicDlg::DoDataExchange(CDataExchange* pDX)
{
    CDialogEx::DoDataExchange(pDX);
    DDX_Control(pDX, IDC_PIC_STATIC, m_PictureCtrl);
}

The Browse Button handler looks like this:

CFileDialog dlg(TRUE);
if (dlg.DoModal() == IDOK)
{    
    CString sPath = dlg.GetPathName();

    CImage img;
    HRESULT hr = img.Load(sPath);
    if (FAILED(hr))
    {
        CString sErrorMsg;
        sErrorMsg.Format(_T("Failed to load %s"), sPath );    
        AfxMessageBox(sErrorMsg);
        return;
    }

    CRect rect;
    m_PictureCtrl.GetClientRect(rect);
    int nWidth = rect.Width();
    int nHeight = rect.Height();

    CDC* pScreenDC = GetDC();
    CDC MemDC;
    MemDC.CreateCompatibleDC(pScreenDC);
    CBitmap bmp;
    bmp.CreateCompatibleBitmap(pScreenDC, nWidth, nHeight);

    CBitmap *pOldObj = MemDC.SelectObject(&bmp);
    img.StretchBlt(MemDC.m_hDC, 0, 0, nWidth, nHeight, 0, 0, img.GetWidth(), img.GetHeight(), SRCCOPY);
    MemDC.SelectObject(pOldObj);

    m_PictureCtrl.SetBitmap((HBITMAP)bmp.Detach());
    ReleaseDC(pScreenDC);
}

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