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VCL Components
The File Open and File Save Dialog Boxes
The File Open and File Save dialog boxes have several properties in common. File Open is
used when you want to allow the user to open a file in your application (see Figure 8.8). It
is encapsulated in the OpenDialog component. You use the File Save dialog box when getting
a filename from the user in order to save a file. It is also used as the Save As dialog box. The
File Save dialog box is encapsulated by the SaveDialog component.
Figure 8.8.
A typical File Open
dialog box.
NOTE
The File dialog boxes are fairly easy to use in their most basic form. They do have a few
features, however, that need to be explained in order for you to get the full benefit of using
them. The following sections examine the properties that are specific to the File dialog boxes.
The OpenDialog and SaveDialog components merely retrieve a filename
from the user. It is up to the programmer to write code that actually
does something with the filename.
The DefaultExt Property
Use the DefaultExt property to set the default extension that the dialog box will use. The
default extension is the extension that will automatically be appended to the filename if the
user does not supply an extension.
The FileName Property
The FileName property is the most obvious of the File dialog box properties; it holds the text
of the file that the user chooses. Set this property before calling the dialog box if you want
a filename to show in the edit portion of the File dialog box when it is initially displayed. After
the user clicks OK to close the dialog box, this property will contain the full path and filename
of the file chosen.
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