使用mfc对话框显示.bmp图像时出错

Question

I am trying to display a bitmap image using MFC application. I am using a browse button to select file which is working properly. But when I try to load an image by double clicking on the file, the application is launched, but the image is not displayed.

Here is my code for browse button and function to open a double clicked image.

void COpenImageDlg::OnBnClickedButton1()
{
    // TODO: Add your control notification handler code here
    CString path;
    CFileDialog dlg(TRUE);
    int result=dlg.DoModal();
    if(result==IDOK)
    {
    path=dlg.GetPathName();
    UpdateData(FALSE);
    }

    HBITMAP hBmp = (HBITMAP)::LoadImage(NULL, path, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE|LR_CREATEDIBSECTION);
    CBitmap bmp;

    bmp.Attach(hBmp); 

    CClientDC dc(this); 
    CDC bmDC; 
    bmDC.CreateCompatibleDC(&dc); 
    CBitmap *pOldbmp = bmDC.SelectObject(&bmp); 

    BITMAP  bi; 
    bmp.GetBitmap(&bi); 

    dc.BitBlt(0,0,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY); 

    bmDC.SelectObject(pOldbmp);
}

void COpenImageDlg::OpenImage1(CString path)
{

    //CString path;
    CFileDialog dlg(TRUE);
    int result=dlg.DoModal();
    if(result==IDOK)
    {
    path=dlg.GetPathName();
    UpdateData(FALSE);
    }

    HBITMAP hBmp = (HBITMAP)::LoadImage(NULL, path, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE|LR_CREATEDIBSECTION);
    CBitmap bmp;

    bmp.Attach(hBmp); 

    CClientDC dc(this); 
    CDC bmDC; 
    bmDC.CreateCompatibleDC(&dc); 
    CBitmap *pOldbmp = bmDC.SelectObject(&bmp); 

    BITMAP  bi; 
    bmp.GetBitmap(&bi); 

    dc.BitBlt(0,0,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY); 
}

Init class :

`BOOL COpenImageApp::InitInstance() { // InitCommonControlsEx() is required on Windows XP if an application // manifest specifies use of ComCtl32.dll version 6 or later to enable // visual styles. Otherwise, any window creation will fail.

INITCOMMONCONTROLSEX InitCtrls;
InitCtrls.dwSize = sizeof(InitCtrls);
// Set this to include all the common control classes you want to use
// in your application.
InitCtrls.dwICC = ICC_WIN95_CLASSES;
InitCommonControlsEx(&InitCtrls);

CWinApp::InitInstance();

AfxEnableControlContainer();

// Create the shell manager, in case the dialog contains
// any shell tree view or shell list view controls.
CShellManager *pShellManager = new CShellManager;


// Standard initialization
// If you are not using these features and wish to reduce the size
// of your final executable, you should remove from the following
// the specific initialization routines you do not need
// Change the registry key under which our settings are stored
// TODO: You should modify this string to be something appropriate
// such as the name of your company or organization
SetRegistryKey(_T("Local AppWizard-Generated Applications"));

COpenImageDlg dlg;
m_pMainWnd = &dlg;
INT_PTR nResponse = dlg.DoModal();

char* buff;
char* command_line = GetCommandLine();

buff = strchr(command_line, ' ');
buff++;
buff = strchr(buff, ' ');
buff++;
buff = strchr(buff, ' ');
buff++;

if (buff != NULL)
{

HBITMAP hBmp = (HBITMAP)::LoadImage(NULL, "C:\Users\Raguvaran\Desktop\tiger.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE|LR_CREATEDIBSECTION);
CBitmap bmp;
bmp.Attach(hBmp); 

dlg.RedrawWindow();
CClientDC dc(m_pMainWnd); 
CDC bmDC; 
bmDC.CreateCompatibleDC(&dc); 
CBitmap *pOldbmp = bmDC.SelectObject(&bmp); 

BITMAP  bi; 
bmp.GetBitmap(&bi); 

dc.BitBlt(0,0,bi.bmWidth,bi.bmHeight,&bmDC,0,0,SRCCOPY); 

}

//RedrawWindow(dlg, NULL, NULL, RDW_INVALIDATE);
//UpdateWindow(dlg);

if (nResponse == IDOK)
{
    // TODO: Place code here to handle when the dialog is
    //  dismissed with OK
}
else if (nResponse == IDCANCEL)
{
    // TODO: Place code here to handle when the dialog is
    //  dismissed with Cancel
}

// Delete the shell manager created above.
if (pShellManager != NULL)
{
    delete pShellManager;
}

// Since the dialog has been closed, return FALSE so that we exit the
//  application, rather than start the application's message pump.
return FALSE;

}`

I used the same code for browse button and it displays the image. But when I double click the file, the image is not displayed. Please tell me what I am doing wrong.

Answer 1

If you have associated your application with a particular file extension, it will be launched automatically when you double-click such a file (as you have said).

When this happens, your application is launched with the file name (actually the full path) supplied as a command line argument to your application.

In SDI MFC applications, this is handled automatically by the framework as long as you haven't overridden the default File/Open handling mechanism, but if you have a dialog-based application you will need to add code for this yourself.

Answer 2

Your dialog COpenImageDlg is created and displayed inside the call to DoModal before the command line has a chance to be processed. When the DoModal returns, the dialog is already destroyed, so there is no dialog for the code to draw upon.

Answer 3

I understand that when you double click the file to choose a image on file dialog, the image doesn't show. I just tried your code of function OnBnClickedButton1 and OpenImage1. And it turns out that the image is displayed when double click to choose a image. I use VS2010 on win7. I hope this will help you though i donot find the error of your code.

Answer 4

I found the answer to my question. It was actually a very stupid mistake. When I read the file address using Commandline, the address has single slash, whereas I need to pass the address using double slash. Such a silly bug. Sorry to waste your time.