Screens

---

Screens are used to display instructions to the subject.

Here is an example of a screen definition:

screen Intro {
    Parity classification
    ---------------------

    This is a practice block.

    You will be presented with a digit.
    Press LEFT for odd and RIGHT for even digit.

    Press ENTER key for the start.
}

Each screen starts with a keyword screen after which we give a unique name for the screen which is used in show statements in the flow definition. The screen content is enclosed in curly braces.

Most of the time screen content is just a plain static text but sometimes we need to show screen multiple times to the subject which contains almost the same content but with a slight changes.

To support dynamic parts of the screen content it is piped through Jinja template engine and thus can contain variable parts which are filled when the screen is displayed.

For example:

As you can see we have used two variables in the screen definition: myparam and upper_bound. These variable can be defined globally at the beginning of the experiment or can be passed as arguments when the screen is displayed like:

show AnExampleScreen(myparam hello, upper_bound 10)

The screen will be rendered as:

This is just a demonstration of parameter rendering inside screen.
Here is a param that renders as "hello".

And here is some looping from 1 to 9
1. Hello world!
2. Hello world!
3. Hello world!
4. Hello world!
5. Hello world!
6. Hello world!
7. Hello world!
8. Hello world!
9. Hello world!

Special syntax used to interpolate variable part ({{}}, {% for ... %} etc.) is defined by Jinja template engine end the full documentation is available on the project site.