Code Walkthrough

Today, we’re discussing how to build a simple calculator GUI using SciLab. What components do you think a calculator should have?

It should have buttons for numbers and operations!

And we need text fields for input and output.

Exactly! We need two input fields for the numbers, buttons for addition, subtraction, multiplication, and division, and a static text area to display the result.

How do we connect the buttons to perform actions?

Great question! We assign callback functions to these buttons that define what happens when they are clicked. This will be essential in our walkthrough.

To recap: we need two inputs, four operation buttons, and a result area. Let’s move to how we code the functionality.

Now let's discuss callback functions. When the user clicks a button, a specific callback executes. How do you think this works in code?

I think we write a function for each button that tells it what to do!

That's correct! For example, for an addition button, we can write a function that reads numbers from input fields, sums them up, and displays the result in the static area.

Can we see an example of that function?

Absolutely! Here's a simple example: function onAddClick() {...} This function will read input values, perform the addition, and display the result. Let’s remember: callbacks link user actions to code execution efficiently.

So remember, each operation needs a unique callback! Do we understand how to link functions now?

Let's move on to how we link these callbacks to the buttons. Each button needs a 'callback' property set to the corresponding function. How do you think we do that?

We specify the callback when we create the button with uicontrol!

Exactly! For example, we would write: uicontrol('style', 'pushbutton', 'string', '+', 'callback', 'onAddClick()'). This means when the '+' button is clicked, onAddClick() will execute.

What if I want to modify the button later?

Good point! You can always modify the button properties, including the callback, using the handle returned when the button is created. This gives you flexible control over your UI.

So, we now know how to link GUI components! Let’s summarize what we've covered in this session.