Advanced MFC Programming

Chapter 7. Common Dialog Boxes
To decide if this notification is CDN_SELCHANGE or not, first we need to cast lParam parameter to an
OFNOTIFY type pointer. The following is the format of structure OFNOTIFY:
typedef struct _OFNOTIFY {
NMHDR hdr;
LPOPENFILENAME lpOFN;
LPTSTR pszFile;
} OFNOTIFY, FAR *LPOFNOTIFY;
The first member of OFNOTIFY is an NMHDR structure:
typedef struct tagNMHDR {
HWND hwndFrom;
UINT idFrom;
UINT code;
} NMHDR;
From its member code, we can judge if the current notification is CDN_SELCHANGE or not.
Sample
Sample 7.4\CDB demonstrates how to add a file preview window to Explorer-style file dialog box. If
the user selects a file with “*.cpp” extension after the file dialog is activated, the contents of the file will be
displayed in the preview window before it is opened.
In the sample, a new command File Dialog Box | Custom File Dlg is added to the application, whose
command ID is ID_FILEDIALOGBOX_CUSTOMFILEDLG. Also, a WM_COMMAND message handler is added for this
command through using Class Wizard, whose correspondung member function is CCDBDoc::
OnFiledialogboxCustomfiledlg().
A new dialog template IDD_COMDLG32 is also added, it contains a static text control stc32, and an edit
box control IDC_EDIT (Figure 7-4). This edit box has “Disabled” and “Multiline” styles. This will
implement a read only edit box that can display multiple lines of text. A new class MCCusFileDialog is
derived from FileDialog. In this class, function OnNotity(…) is overridden.
The following is the definition of class MCCusFileDialog:
class MCCusFileDialog : public CFileDialog
{
DECLARE_DYNAMIC(MCCusFileDialog)
public:
MCCusFileDialog(BOOL bOpenFileDialog,
LPCTSTR lpszDefExt = NULL,
LPCTSTR lpszFileName = NULL,
DWORD dwFlags = OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT,
LPCTSTR lpszFilter = NULL,
CWnd* pParentWnd = NULL);
protected:
//{{AFX_MSG(MCCusFileDialog)
//}}AFX_MSG
virtual BOOL OnNotify(WPARAM wParam, LPARAM lParam, LRESULT* pResult);
DECLARE_MESSAGE_MAP()
};
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