Beginning Programming FOR Dummies 3RD EDITION by Wallace Wang

Author:Wallace Wang [Wang, Wallace]
Language: eng
Format: epub
Tags: Team DDU
Published: 0101-01-01T00:00:00+00:00

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198 Part III: Advanced Programming with Liberty BASIC

Each time that you create additional menu commands, you need to create instructions (which a [label] identifies) for the computer to follow whenever the user chooses those commands.

Figure 14-2:

Liberty

BASIC

can create

pull-down

menus.

Making Pop-Up Menus

In addition to pull-down menus, many programs also offer pop-up menus that appear next to the mouse pointer when you right-click the mouse. To create a pop-up menu in Liberty BASIC, you need to use the POPUPMENU command, as follows:

POPUPMENU “command1”, [label1], “command2”, [label2]

To make the POPUPMENU easier to understand, place each command and label on a separate line and use the underscore character (_) at the end of each line.

The underscore character tells Liberty BASIC that additional instructions appear on the following line. You can use the underscore character to divide long lines of commands into shorter, separate lines, such as you see in the following example:

POPUPMENU _

“command1”, [label1], _

“command2”, [label2], _

“command3”, [label3]

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Chapter 14: Creating a User Interface

199

Here’s what the preceding commands do:

1. The POPUPMENU command tells the computer, “Create a pop-up menu next to the current position of the mouse pointer.”

2. The “command1” and “command2“ text are the actual commands that appear on the pop-up menu. You can add additional commands so that your pop-up menus can display 5, 7, or 15 different commands.

3. The [label1] and [label2] labels identify instructions for the computer to follow if the user chooses a particular menu command. So if the user chose “command1”, the computer immediately follows the instructions that the [label1] label identifies.

If you want to add a horizontal line to separate commands on your pop-up menu, just use the vertical line character (|) in place of a command and omit any label following the | character, as shown in the example below.

POPUPMENU _

“command1”, [label1], _

|, _

“command3”, [label3]

To see how pop-up menus work, try the following program, as shown in Figure 14-3. Notice how the vertical line character creates a horizontal line to separate commands on the pop-up menu.

NOMAINWIN

POPUPMENU _

“Destroy the planet”, [one], _

“Poison the environment”, [two], _

| ,_

“Get elected to political office”, [three]

NOTICE “Nothing selected.”

END

[one]

NOTICE “Launching missiles now.”

END

[two]

NOTICE “Spilling oil into the oceans.”

END

[three]

NOTICE “Fooled the public once more.”

END

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