Dialog Boxes

1. Dialog Boxes

2. The OpenFileDialog and SaveFileDialog Controls • All dialog boxes derive from the CommonDialog class and share similar features • The OpenFileDialog and SaveFileDialog controls are derived from the CommonDialog class • These classes allow the end user to select a file to open or save • The FolderBrowserDialog control also derives from the CommonDialog class • This control allows the end user to select a folder

3. Members of the OpenFileDialog and SaveFileDialog Classes • The CheckFileExists and CheckPathExists properties control whether the end user can select a file or folder that does not exist • The FileName property contains the filename selected by the end user • The Filter property defines the type of files that will be displayed for selection • The FilterIndex property contains the index of the current filter • The Filter and FilterIndex properties work together

4. Members of the OpenFileDialog and SaveFileDialog Classes (continued) • The InitialDirectory property contains the initial folder where the search for files begins • The OverwritePrompt property applies only to the SaveFileDialog. If True, the end user will be prompted before a file is overwritten • The RestoreDirectory property defines whether the current directory will be restored after the end user selects a file • The ShowDialog method displays the respective dialog box

5. The Filter Property (introduction) • The Filter property restricts the files displayed based on a file extension • A filter consists of • A description • Followed by a vertical bar • Followed by the actual filter • Multiple filters can be connected together • Do not put spaces between the vertical bars

6. The Filter Property (Example) • Set the Filter to three possible filters (*.txt), (*.rtf), and (*.*) • Set the FilterIndex to select the second filter by default ofdMain.Filter = "Text files (*.txt)|*.txt|" _ "Rich text files (*.rtf)|*.rtf|All files" _ "(*.*)|*.*" ofdMain.FilterIndex = 2

7. Using the SaveFileDialog Control • The SaveFileDialog control works the same way as the OpenFileDialog control • Set the OverwritePrompt property to Trueto prevent the end user from accidentally overwriting files

8. The FolderBrowserDialog(Introduction) • Use the FolderBrowserDialog to browse for folders instead of files • Members • The Description property contains the text appearing in the title bar • The RootFolder property contains the topmost folder appearing in the dialog box • The SelectedPath property contains the folder selected by the end user • The ShowDialog method displays the dialog box

9. Using Windows-Defined Directories • Members of the System.Environmentclass are used to get system directories • The SystemDirectory property gets the Windows system directory • The directory is typically C:\Windows\System32 • The CurrentDirectory property contains the directory from which the application was run • The GetFolderPath method gets a system special folder

10. Color (About) • Color is made up of RGB values and an “alpha” value that controls opacity • Values range between 0 and 255 • 255,255,255 is white • 0,0,0 is black

11. The ColorDialog (Introduction) • It works the same way as the other dialog boxes • Call ShowDialog to display the dialog box • The Color property contains the selected color • Properties • AllowFullOpen allows the user to select custom colors • FullOpen displays the full color palette

12. The FontDialog (Introduction) • It works the same way as the other dialog boxes • Call ShowDialog to display the dialog box • There are many more properties to work with • ShowApply, ShowColor, ShowEffects control how the dialog box appears • Font gets or sets the desired font • MaxSize and MinSize control the selectable font sizes