CSCI 220 Computer Programming Visual Basic
Lecture 7: Menu design and the common dialog box

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Menus:
  How they act
  Should follow Windows standards
     Along top of screen
     Alt + underlined letter for quick access
     Shortcut keys
     Can be accessed through arrow keys as well
  How they are seen by VB
     Attached to the form
     Each menu item is a mini control with only a few
     properties
     Each menu item has only a CLICKED event it recognizes.
  The menu design window
     Reached through Window menu when appropriate form is
     selected
     Allows you to create outline of menu structure
     Allows you to change properties of menu items
       Caption:  What the user will see in the menu
          &Denotes NEXT letter will be underlined for quick
          access
       Name: like a control name, often begins with Mnu
          Each menu item MUST have a name!!!!
       Shortcut
          Allows you to assign a Control combination or
          function key to the menu item
       Checked:  Tells whether there is a check mark. TRUE
       or FALSE
       Enabled:  Shows whether user can access the item
       TRUE or FALSE
       Visible:  Shows whether item is visible. TRUE or
       FALSE
       Other properties rarely used
       
     Accessing the code window for a menu item
       Open up any code window in the current form, and
       choose the menu item's NAME from the object list box
       Access the window in DESIGN mode (program not
       running) You will see the code window.
       
     Common Menu guidelines
       Usually 2-3 items deep, can be deeper
       Should be less than 7-10 choices per menu
       If possible, first letter should be underlined, be
       related to shortcut key
       
Common Dialogs
  Concept:
     Dialog boxes already existing in Windows
       Many commands are used in various types of programs
          Save, Open, Choose Font, Choose Color, Font Size.
       Dialog boxes related to these commands are available
       as common dialogs.
     Common Dialog Box Control works very differently from
     most controls.
       Control is NOT visible on the form.
       Control Called by use of action statement
       Example:
          CmDialog1.Action = 3
          
       Same control can "call" any of the dialogs depending
       on the value of the action property.
          Action         Type of box
          1         Open
          2         Save
          3         Color
          4         Font
  Properties
     Filter
       Used in file dialogs to determine how dialog will
       isolate files
       Format
          *.TXT (Text Files)|*.TXT
          No space on either side of    |
     InitDir
       Used to set initial directory in file dialogs.
     Color
       Used to report back a color chosen from the color
       dialog

File Handling
     Purpose:
          Method of handling external data.
          Data is kept in FILES on the disk
          Program can read,write information
          Programmer responsible for controlling flow
     Sequential Access files:
          Work like cassette tape
          Read from beginning to end
          Can be slow with large number of records
          Records can have variable lengths.
          Useful when flexible structure is more important
          than quick access.
     The OPEN statement
          Syntax:
               OPEN filename FOR method AS # filenumber
          Filename
               Any valid DOS filename.
               Be careful allowing the user to create file
               names
          Method
               INPUT:  reads information from an existing
               file
               APPEND: Adds information to end of existing
               file
               OUTPUT: Creates new file, adds info to it.
          Use warnings
               Usually output is used only when creating a
               new file
               It will destroy existing files of the same
               name
               APPEND is generally used for output
          FileNumber
               Must be an integer.  Usually 1 or 2.
               Keep it simple.
     The Write # Statement
          Used to write to a file
          File must have been opened via OPEN
          (Output/Append)
          Syntax:
               WRITE # FileNumber,Value(s)
          FileNumber:  a valid, open file
          Value(s): Direct value, variables, separated by
          commas
     The INPUT # Statement
          Used to get data from a file
          File must have been opened via OPEN (Input)
          Syntax:
               INPUT # FileNumber,Value(s)
          FileNumber:  a valid, open file
          Value(s):  values, variables, separated by
          commas
     The CLOSE statement
          Used to close a file, release its filenumber
          Syntax:
               CLOSE # FileNumber
     The EOF function
          Boolean (True/False) function
          is True if the program has reached the end of the
          file
          Usually used in DO LOOPS with file handling.
          Syntax:
               EOF(FileNumber)
          Example:
               DO
               ...(program code)
               LOOP UNTIL EOF(1)
Other new concepts:
  NOT operator
     Sets a boolean to its opposite value.  Commonly used
     for check boxes and boolean properties
     Example:
       Text1.FontUnderlined = NOT Text1.FontUnderlined
       If FontUnderlined is true, it will become false, if
       false it will become true
  
  SETFOCUS method
     Used in conjunction with an object.  That object
     receives the focus.
     Example:
       Text1.SetFocus
       The Insertion cursor will appear in the text box,
       any subsequent keypresses will be processed by text
       box.
  On Error Resume Next
     Used when you anticipate an error in a procedure (esp.
     file handling)
     When an error occurs, program skips to next line
     Good only in procedure defined

Your project: The text editor

                              
You will create a simple text editor that will demonstrate
the use of menus and the common dialog box.  Your menus
should work in the standard windows fashion, with underlined
characters and shortcut keys.
You will need a File menu with New, Open, save As, and Exit.
You will also need a Change menu containing Bold and Color
options.  The Color option should call a submenu allowing
the user to choose foreground or background color.  The main
part of the form should be taken up with a text box.

Create the Text box.
  Make sure the multiline property is true
  Set the scrollbars property to Vertical.
Add a common dialog box.
  Set its Filter property to *.TXT (Text Files)|*.TXT
  Set the InitDir property to A:\
Create a menu structure as described above.  Give each menu
a meaningful name.
Pseudocode for menu items:
  New
     Set the Text property of the text box to ""
     Use the SetFocus method on the text box
  Open
     Create a temporary string variable NextLine
     Set the Txt property of the text box to ""
     Call the OPEN common dialog
     Open the FileName retrieved by the common dialog for
     input (sequential access)
     Do
       Input from the file NextLine
       Add NextLine to the text property of the text box
     Until the end of the file
     NOTE: Does the condition belong at the top or bottom of this loop?
     Close the file
     Use the SetFocus method on the text box
  Save As
     Call the SAVE AS common dialog
     Open the file name retrieved by the common dialog for
     output
     Write the text property of the text box to the file
     Close the file
     Use the SetFocus method on the text box
  Exit
     End the program
  Bold
     Set the value of the menu's Checked property to the NOT
     value of the property
     (Reverse the property)
     Set the value of the FontBold property of the text box
     to be equal to the Checked property of the menu
  Fore Color
     Call the COLOR common dialog
     Set the foreground color of the text box equal to the
     color returned by the dialog.
  Back Color
     Call the COLOR common dialog
     Set the background color of the text box equal to the
     color returned by the dialog.
Test and save as VB7                    HAVE FUN!!!