Learn to Program with Small Basic

located at (100, 100). By default, the size of this box is about 200×80. Let’s
make this box wider by calling the SetSize() method. Add this line of code
just after creating the multiline text box:
Controls.SetSize(msgText, 280, 80) ' Makes width = 280 and height = 80
The first argument is the identifier of the control you want to resize,
in this case msgText. The second argument (280) is the width, and the third
(80) is the height. If you run the code now, you’ll see an interface similar to
the one shown earlier in Figure 12-2. Note that the upper-left corner of the
message text box didn’t change when you called SetSize().
Step 2: Program Interactivity
You’ve created all the controls you need and positioned them where you
wanted them. Next, you’ll make these controls interactive. You need to
write some code that responds to the button’s click. When a user clicks the
button, the program needs to read the contents of the first name and the
last name text boxes and then display the greeting in the multiline text box.
Add lines 13–21, as shown in Listing 12-1, to complete the program (you’ve
already written lines 2–11 to create the GUI elements).
1 ' FirstGUIApp.sb
2 GraphicsWindow.DrawText(20, 20, "First name:") ' Label
3 fnText = Controls.AddTextBox(100, 20) ' First name text box
4
5 GraphicsWindow.DrawText(20, 60, "Last name:") ' Label
6 lnText = Controls.AddTextBox(100, 60) ' Last name text box
7
8 showBtn = Controls.AddButton("Show Message", 280, 20) ' Button
9
10 msgText = Controls.AddMultiLineTextBox(100, 100) ' Message text box
11 Controls.SetSize(msgText, 280, 80) ' Makes width = 280 and height = 80
12
13 Controls.ButtonClicked = OnButtonClicked ' Handler for button click
14
15 Sub OnButtonClicked
16 firstName = Controls.GetTextBoxText(fnText) ' First name text box
17 lastName = Controls.GetTextBoxText(lnText) ' Last name text box
18 fullName = firstName + " " + lastName ' Constructs full name
19 message = "Hello there, " + fullName + "!" ' Greeting message
20 Controls.SetTextBoxText(msgText, message)
21 EndSub
Listing 12-1: Creating a simple GUI program
Line 13 registers a handler for the ButtonClicked event. This line tells
the Controls object to call the OnButtonClicked() subroutine whenever the
user clicks the Show Message button.
In the OnButtonClicked() subroutine, GetTextBoxText() is called first to
get the text that’s entered into the first-name text box and save it into the
168 Chapter 12