6. Menu-Driven and Calculator Projects

In this lesson we will consider two projects, one a menu driven drawing project and the other a calculator project.   Menus are one of the most important and most characteristic elements of the Windows User Interface.   Menu Commands are similar to Controls.   They recognize only the click events.   When you group controls as arrays, give them the same name property, but give their index property as 0, 1, 2, 3 etc. to distinguish them.

1.      Menu Driven Project:

A view of the Menu bar and some Menu Items:

Suppose we want to build a program with a menu bar with two titles and one or more menu items for each of the menu titles somewhat as shown in the figure 1.   In this example the menu items denote different pixel values for drawing lines.   The different menu items are connected to appropriate codes which will enable you to select the pixel thickness from the menu and draw figures of of different thickness.

 
                                    Figure 1

 Menu Editor Window:

 Start VB from the Standard EXE mode.   Select the item “Menu Editor” from the Tools Menu.   The Menu Editor Window appears as shown in the figure 2.   This window lets you create a menu bar that contains all the menu items you want.

                                     Figure 2

Creating the Menu Bar:

In this project we will have only two menu titles in the menu bar.   Of course one can have as many as required for the concerned problem.   The first title is ‘Draw’.   Type ‘&Draw’ in the Caption field.   The & symbol before D tells that D is a hot key and users can use alt+D key combination to pull down the menu.   Next press the Tab key.   This moves the insertion point to the next text box ‘Name’, which is the name of the control.   Enter ‘menDraw’ in the Name field and click the right arrow key at the bottom of the menu editor window.   This is how the computer recognizes the item as menu title.  The prefix ‘men’ is used to indicate to the users that the item ‘Draw’ is the name of the menu title.   The Caption field is cleared to enable the next menu title to be entered.   Now enter ‘&Quit’ in the Caption field and ‘menQuit’ in the Name field and click OK.   Now the design window will show a menu bar with two items ‘Draw’ and ‘Quit’.   At the bottom you will see the two items entered as shown in the figure 2a.

&Draw

&Quit

Figure 2a

Creating Menu Items:

Now we have to enter the menu items under the menu titles Draw and Quit. B  Open the Menu Editor Window.   Select &Quit.  Select Insert.   This action will insert a line between the two items.   Type &Erase in the Caption field and miErase in the Name field.   The prefix ‘mi’ indicates that the item ‘Erase’ is a  menu item and not a menu title.  Now the bottom window will appear as shown in the figure 2b.

 &Draw

 …&Erase

 &Quit

  Figure 2b

In a similar manner add the menu item Exit for the menu title Quit.   Use the Caption name as E&xit and the control name as miExit.