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310 Day 8
The Files Property
Files, a read-only property, is a TStrings instance that contains the list of files selected when
multiple file selection is enabled.
The Filter Property
The Filter property contains a list of the file types from which the user can choose. The file
types are displayed in the File of type: combo box in the file dialog box. You can set Filter
to reflect types of files specific to your application. For instance, a simple text-editing program
could have the filter set to show files of type TXT, INI, and LOG, to name just a few. The filter
can easily be set at design time through the Filter Editor dialog box. To invoke the Filter
Editor, double-click the Value column next to the Filter property in the Object Inspector.
Figure 8.9 shows the Filter Editor for a File Open dialog box, as described previously.
Figure 8.9.
The Filter Editor
dialog box.
The Filter Name column contains a textual description of the file type. The Filter column
is the actual file mask that will be used to display files of that type.
Although you can enter the filter string directly in the Value column of the Object Inspector,
it is easiest to use the Filter Editor. If you are only using a single filter, you can type it directly
into the Value column for the Filter property. Separate the description and filter with a pipe.
For instance, to have a single filter for all file types, you would enter the following:
All Files (*.*)|*.*
The FilterIndex Property
The FilterIndex property is used to set the filter that will be used when the dialog box is
initially displayed. The index is not zero based as you might expect, however. The first filter
in the list is 1, the second is 2, and so on. For example, refer to Figure 8.9. If you wanted the
All Files filter to be the one initially displayed, you would set the FilterIndex property to 4.