Advanced MFC Programming

Chapter 7. Common Dialog Boxes
“Help” button.
OFN_HIDEREADONLY Set this bit to 0 to enable a Read only check box on the dialog box so that the
user can specify if the file should be opened only for read.
OFN_ALLOWMULTISELECT Set to allow multiple files to be selected at the same time.
Dialog Box Title
The default titles of file dialog boxes are “File Open” and “Save As”. We can change these titles by
preparing text string in a buffer and assign its address to lpstrTitle member of structure OPENFILENAME.
Retrieving Multiple Path Names and File Names
If we allow the user to select more than one file, we need to call function CFileDialog::
GetStartPosition() and CFileDialog::GetNextPathName(…) to retrieve path name for each selected file.
Here, the first function will return a POSITION type value, which could be used to call the second function.
The returned value of the second function is a CString type value, which contains a valid file path name.
Also, when calling the second function, the POSITION value will also be updated, which again can be used
to get the next selected file path name. If all the selected files have been enumerated, a NULL value will be
stored in the variable that holds the POSITION value.
However, there is no similar functions for retrieving all file names. To obtain all the selected file
names, we need to access member lpstrFile of structure OPENFILENAME. After the user has made
selections, the selected folder and file names will be stored in a buffer pointed by member lpstrFile. For
Explorer-style dialog box, folder and file names are separated by ‘\0’ characters; for old style dialog box,
they are separated by SPACE character. In either case, folder name is always the first item contained in the
buffer, which is followed by separator (‘\0’ or SPACE), file name, separator, and file name.... The position
of the first file name is specified by member nFileOffset.
Sample
Sample 7.2\CDB demonstrates these styles. It is based on sample 7.1\CDB, with two new commands
File Dialog Box | Customized File Open and File Dialog Box | Customize File Open Old added to the
application. The IDs of the two commands are ID_FILEDIALOGBOX_CUSTOMIZEDFILEOPEN and
ID_FILEDIALOGBOX_CUSTOMIZEFILEOPENOLD respectively. Message handlers are added for them through
using Class Wizard, the corresponding member functions are CCDBDoc::
OnFiledialogboxCustomizedfileopen() and CCDBDoc::OnFiledialogboxCustomizefileopenold().
For dialog box invoked by command File Dialog Box | Customized File Open, multiple file selection
is enabled. Also, the dialog box has a “Help” button and a “Read only” check box. The following is the
implementation of this command:
void CCDBDoc::OnFiledialogboxCustomizedfileopen()
{
CFileDialog dlg(TRUE);
CString szStr;
POSITION posi;
LPSTR lpstr;
dlg.m_ofn.lpstrFilter="Source
Files(*.C;*.CPP;*.H;*.HPP)\0*.C;*.CPP;*.H;*.HPP\0Document(*.DOC;*.HTML)\0*.DOC;*.HTML\0Al
l(*.*)\0*.*\0";
dlg.m_ofn.nFilterIndex=1;
dlg.m_ofn.lpstrCustomFilter="DIB Files(*.BMP)\0*.BMP\0";
dlg.m_ofn.nMaxCustFilter=26;
dlg.m_ofn.Flags|=OFN_ALLOWMULTISELECT | OFN_SHOWHELP;
dlg.m_ofn.Flags&=~OFN_HIDEREADONLY;
dlg.m_ofn.lpstrTitle="Explorer Style Open";
if(dlg.DoModal() == IDOK)
{
szStr="File Name: ";
lpstr=dlg.m_ofn.lpstrFile+dlg.m_ofn.nFileOffset;
while(*lpstr != '\0')
{
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