Layouts are Squib’s Best Feature

Working with tons of options to a method can be tiresome. Ideally everything in a game prototype should be data-driven, easily changed, and your Ruby code should readable without being littered with magic numbers.

For this, most Squib methods have a layout option. Layouts are a way of setting default values for any parameter given to the method. They let you group things logically, manipulate options, and use built-in stylings.

Think of layouts and DSL calls like CSS and HTML: you can always specify style in your logic (e.g. directly in an HTML tag), but a cleaner approach is to group your styles together in a separate sheet and work on them separately.

To use a layout, set the layout: option on Deck.new to point to a YAML file. Any command that allows a layout option can be set with a Ruby symbol or string, and the command will then load the specified options. The individual command can also override these options.

For example, instead of this:

# deck.rb
Squib::Deck.new do
  rect x: 75, y: 75, width: 675, height: 975
end

You can put your logic in the layout file and reference them:

# custom-layout.yml
bleed:
  x: 75
  y: 75
  width: 975
  height: 675

Then your script looks like this:

# deck.rb
Squib::Deck.new(layout: 'custom-layout.yml') do
  rect layout: 'bleed'
end

The goal is to make your Ruby code separate the data decisions from logic. For the above example, you are separating the decision to draw rectangle around the “bleed” area, and then your YAML file is defining specifically what “bleed” actually means. (Who is going to remember that x: 75 means “bleed area”??) This process of separating logic from data makes your code more readable, changeable, and maintainable.

Warning

YAML is very finnicky about not allowing tab characters. Use two spaces for indentation instead. If you get a Psych syntax error, this is likely the culprit. Indendation is also strongly enforced in Yaml too. See the Yaml docs for more info.

Order of Precedence for Options

Layouts will override Squib’s system defaults, but are overriden by anything specified in the command itself. Thus, the order of precedence looks like this:

  1. Use what the DSL method specified, e.g. rect x: 25
  2. If anything was not yet specified, use what was given in a layout (if a layout was specified in the command and the file was given to the Deck). e.g. rect layout: :bleed
  3. If still anything was not yet specified, use what was given in Squib’s defaults as defined in the DSL Reference.

For example, back to our example:

# custom-layout.yml
bleed:
  x: 0.25in
  y: 0.25in
  width: 2.5in
  height: 3.5in

(Note that this example makes use of Unit Conversion)

Combined with this script:

# deck.rb
Squib::Deck.new(layout: 'custom-layout.yml') do
  rect layout: 'bleed', x: 50
end

The options that go into rect will be:

  • x will be 50 because it’s specified in the DSL method and overrides the layout
  • y, width, and height were specified in the layout file, so their values are used
  • The rect’s stroke_color (and others options like it) was never specified anywhere, so the default for rect is used - as discussed in Parameters are Optional.

Note

Defaults are not global for the name of the option - they are specific to the method itself. For example, the default fill_color for rect is '#0000' but for showcase it’s :white.

Note

Layouts work with all options (for DSL methods that support layouts), so you can use options like file or font or whatever is needed.

Warning

If you provide an option in the Yaml file that is not supported by the DSL method, the DSL method will simply ignore it. Same behavior as described in Parameters are Optional.

When Layouts Are Similar, Use extends

Using layouts are a great way of keeping your Ruby code clean and concise. But those layout Yaml files can get pretty long. If you have a bunch of icons along the top of a card, for example, you’re specifying the same y option over and over again. This is annoyingly verbose, and what if you want to move all those icons downward at once?

Squib provides a way of reusing layouts with the special extends` key. When defining an `extends key, we can merge in another key and modify its data coming in if we want to. This allows us to do things like place text next to an icon and be able to move them with each other. Like this:

# If we change attack, we move defend too!
attack:
  x: 100
  y: 100
defend:
  extends: attack
  x: 150
  #defend now is {:x => 150, :y => 100}

Over time, using extends saves you a lot of space in your Yaml files while also giving more structure and readability to the file itself.

You can also modify data as they get passed through extends:

# If we change attack, we move defend too!
attack:
  x: 100
defend:
  extends: attack
  x: += 50
  #defend now is {:x => 150, :y => 100}
The following operators are supported within evaluating extends
  • += will add the giuven number to the inherited number
  • -= will subtract the given number from the inherited number

Both operators also support Unit Conversion

From a design point of view, you can also extract out a base design and have your other layouts extend from them:

top_icons:
  y: 100
  font: Arial 36
attack:
  extends: top_icon
  x: 25
defend:
  extends: top_icon
  x: 50
health:
  extends: top_icon
  x: 75
# ...and so on

Note

Those fluent in Yaml may notice that extends key is similar to Yaml’s merge keys. Technically, you can use these together - but I just recommend sticking with extends since it does what merge keys do and more. If you do choose to use both extends and Yaml merge keys, the Yaml merge keys are processed first (upon Yaml parsing), then extends (after parsing).

Yes, extends is Multi-Generational

As you might expect, extends can be composed multiple times:

socrates:
  x: 100
plato:
  extends: socrates
  x: += 10    # evaluates to 150
aristotle:
  extends: plato
  x: += 20    # evaluates to 150

Yes, extends has Multiple Inheritance

If you want to extend multiple parents, it looks like this:

socrates:
  x: 100
plato:
  y: 200
aristotle:
  extends:
    - socrates
    - plato
  x: += 50    # evaluates to 150

If multiple keys override the same keys in a parent, the later (“younger”) child in the extends list takes precedent. Like this:

socrates:
  x: 100
plato:
  x: 200
aristotle:
  extends:
    - plato    # note the order here
    - socrates
  x: += 50     # evaluates to 150 from socrates

Multiple Layout Files get Merged

Squib also supports the combination of multiple layout files. If you provide an Array of files then Squib will merge them sequentially. Colliding keys will be completely re-defined by the later file. The extends key is processed after each file, but can be used across files. Here’s an example:

# load order: a.yml, b.yml

##############
# file a.yml #
##############
grandparent:
  x: 100
parent_a:
  extends: grandparent
  x: += 10   # evaluates to 110
parent_b:
  extends: grandparent
  x: += 20   # evaluates to 120

##############
# file b.yml #
##############
child_a:
  extends: parent_a  # i.e. extends a layout in a separate file
  x: += 3    # evaluates to 113 (i.e 110 + 3)
parent_b:    # redefined
  extends: grandparent
  x: += 30   # evaluates to 130 (i.e. 100 + 30)
child_b:
  extends: parent_b
  x: += 3    # evaluates to 133 (i.e. 130 + 3)
This can be helpful for:
  • Creating a base layout for structure, and one for full color for easier color/black-and-white switching
  • Sharing base layouts with other designers

Squib Comes with Built-In Layouts

Why mess with x-y coordinates when you’re first prototyping your game? Just use a built-in layout to get your game to the table as quickly as possible.

If your layout file is not found in the current directory, Squib will search for its own set of layout files. The latest the development version of these can be found on GitHub.

Contributions in this area are particularly welcome!!

The following depictions of the layouts are generated with this script

See Layouts in Action

This sample demonstrates many different ways of using and combining layouts.

This sample demonstrates built-in layouts based on popular games (e.g. fantasy.yml and economy.yml)