Open and Save As Dialog Boxes

The Open dialog box lets the user specify the drive, directory, and the name of a file or set of files to open. You create and display an Open dialog box by initializing an OPENFILENAME structure and passing the structure to the GetOpenFileName function.

The Save As dialog box lets the user specify the drive, directory, and name of a file to save. You create and display a Save As dialog box by initializing an OPENFILENAME structure and passing the structure to the GetSaveFileName function.

Beginning with Windows 95 and Windows NT version 4.0, there is a new version of the Open and Save As dialog boxes that provides user-interface features that are similar to the Windows Explorer. However, Win32 continues to support the old-style Open and Save As dialog boxes for applications that must maintain a user interface consistent with earlier versions of Windows.

In addition to the difference in appearance, the Explorer-style and old-style dialog boxes differ in their use of custom templates and hook procedures for customizing the dialog boxes. However, the Explorer-style and old-style dialog boxes have the same behavior for most basic operations, such as specifying a filename filter, validating the user's input, and getting the filename specified by the user. For more information about the Explorer-style and old-style dialog boxes, see Open and Save As Customization.The following illustration shows a typical Explorer-style Open dialog box.

pics/WIN3200000011.gif

The following illustration shows a typical Explorer-style Save As dialog box.

pics/WIN3200000012.gif

If the user specifies a filename and clicks the OK button, GetOpenFileName or GetSaveFileName returns TRUE. The buffer pointed to by the lpstrFile member of the OPENFILENAME structure contains the full path and filename specified by the user.

If the user cancels the Open or Save As dialog box or an error occurs, the function returns FALSE. To determine the cause of the error, call the CommDlgExtendedError function to retrieve the extended error value. If the lpstrFile buffer is too small to receive the full name, CommDlgExtendedError returns FNERR_BUFFERTOOSMALL and the first 2 bytes of the buffer pointed to by the lpstrFile member are set to an integer value specifying the size required to receive the full name.

Explorer style dialog boxes are only available to 32-bit applications. 16-bit applications cannot use thunking to display an Explorer-style dialog box.

Windows 95: 32-bit applications that use the old-style dialog boxes do so using a thunk. This means that any pointer passed to your hook procedure is a non-persistent copy of the data. For example, the OPENFILENAME pointer passed in the WM_INITDIALOG message is not a pointer to the buffer that you originally specified. If you need to pass private data to your hook procedure, bundle it in a structure and store a pointer to the structure in the lCustData member of the OPENFILENAME structure.

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