tutorial-and-examples.md

Tutorial and Examples

Main concepts

Basic tgui backend code consists of the following vars and procs:

ui_interact(mob/user, ui_key, datum/tgui/ui, force_open,
  datum/tgui/master_ui, datum/ui_state/state)
ui_data(mob/user)
ui_act(action, params)

• src_object - The atom, which UI corresponds to in the game world.
• ui_interact - The proc where you will handle a request to open an interface. Typically, you would update an existing UI (if it exists), or set up a new instance of UI by calling the SStgui subsystem.
• ui_data - In this proc you munges whatever complex data your src_object has into an associative list, which will then be sent to UI as a JSON string.
• ui_act - This proc receives user actions and reacts to them by changing the state of the game.
• ui_state (set in ui_interact) - This var dictates under what conditions a UI may be interacted with. This may be the standard checks that check if you are in range and conscious, or more.

Once backend is complete, you create an new interface component on the frontend, which will receive this JSON data and render it on screen.

States are easy to write and extend, and what make tgui interactions so powerful. Because states can be overridden from other procs, you can build powerful interactions for embedded objects or remote access.

Using It

Backend

Let's start with a very basic hello world.

/obj/machinery/my_machine/ui_interact(mob/user, ui_key = "main", datum/tgui/ui = null, force_open = 0, datum/tgui/master_ui = null, datum/ui_state/state = default_state)
  ui = SStgui.try_update_ui(user, src, ui_key, ui, force_open)
  if(!ui)
    ui = new(user, src, ui_key, "my_machine", name, 300, 300, master_ui, state)
    ui.open()

This is the proc that defines our interface. There's a bit going on here, so let's break it down. First, we override the ui_interact proc on our object. This will be called by interact for you, which is in turn called by attack_hand (or attack_self for items). ui_interact is also called to update a UI (hence the try_update_ui), so we accept an existing UI to update. The state is a default argument so that a caller can overload it with named arguments (ui_interact(state = overloaded_state)) if needed.

Inside the if(!ui) block (which means we are creating a new UI), we choose our template, title, and size; we can also set various options like style (for themes), or autoupdate. These options will be elaborated on later (as will ui_states).

After ui_interact, we need to define ui_data. This just returns a list of data for our object to use. Let's imagine our object has a few vars:

/obj/machinery/my_machine/ui_data(mob/user)
  var/list/data = list()
  data["health"] = health
  data["color"] = color

  return data

The ui_data proc is what people often find the hardest about tgui, but its really quite simple! You just need to represent your object as numbers, strings, and lists, instead of atoms and datums.

Finally, the ui_act proc is called by the interface whenever the user used an input. The input's action and params are passed to the proc.

/obj/machinery/my_machine/ui_act(action, params)
  if(..())
    return
  if(action == "change_color")
    var/new_color = params["color"]
    if(!(color in allowed_coors))
      return FALSE
    color = new_color
    return TRUE
  update_icon()

The ..() (parent call) is very important here, as it is how we check that the user is allowed to use this interface (to avoid so-called href exploits). It is also very important to clamp and sanitize all input here. Always assume the user is attempting to exploit the game.

Also note the use of . = TRUE (or FALSE), which is used to notify the UI that this input caused an update. This is especially important for UIs that do not auto-update, as otherwise the user will never see their change.

Frontend

Finally, you have to make a UI component. This is also a source of confusion for many new users. If you got some basic javascript and HTML knowledge, that should ease the learning process, although we recommend getting yourself introduced to React and JSX.

A component is not a regular HTML. A component is a pure function, which accepts a props object (it contains properties passed to a component), and outputs an HTML-like structure consisting of regular HTML elements and other UI components.

Interface component will always receive 1 prop which is called state. This object contains a few special values:

• config is always the same and is part of core tgui (it will be explained later),
• data is the data returned from ui_data

import { useBackend } from '../backend';
import { Section, LabeledList } from '../components';

export const SampleInterface = props => {
  const { act, data } = useBackend(props);
  return (
    <Section title="Health status">
      <LabeledList>
        <LabeledList.Item label="Health">
          {data.health}
        </LabeledList.Item>
        <LabeledList.Item label="Color">
          {data.color}
        </LabeledList.Item>
      </LabeledList>
    </Section>
  );
};

This syntax can be very confusing at first, but it is very important to realize that this is just a natural extension of javascript. Here's a few examples of this syntax:

Return a different element based on a condition:

if (condition) {
  return <Foo />;
}
return <Bar />;

Conditionally render a element inside of another element:

<Box>
  {showProgress && (
    <ProgressBar value={progress} />
  )}
</Box>

Looping over the array to make an element for each item:

<LabeledList>
  {items.map(item => (
    <LabeledList.Item key={item.id} label={item.label}>
      {item.content}
    </LabeledList.Item>
  ))}
</LabeledList>

Routing table

Once you finished creating your interface, you must add a route entry to the large ROUTES object, otherwise tgui won't know when and how to render your interface. Key of this ROUTES object corresponds to the interface name you use in DM code.

import { SampleInterface } from './interfaces/SampleInterface';

const ROUTES = {
  sample_interface: {
    component: () => SampleInterface,
    scrollable: true,
  },
};

Copypasta

We all do it, even the best of us. If you just want to make a tgui fast, here's what you need (note that you'll probably be forced to clean your shit up upon code review):

/obj/copypasta/ui_interact(mob/user, ui_key = "main", datum/tgui/ui = null, force_open = 0, datum/tgui/master_ui = null, datum/ui_state/state = default_state) // Remember to use the appropriate state.
  ui = SStgui.try_update_ui(user, src, ui_key, ui, force_open)
  if(!ui)
    ui = new(user, src, ui_key, "copypasta", name, 300, 300, master_ui, state)
    ui.open()

/obj/copypasta/ui_data(mob/user)
  var/list/data = list()
  data["var"] = var
  return data

/obj/copypasta/ui_act(action, params)
  if(..())
    return
  if(action == "copypasta")
    var/newvar = params["var"]
    // A demo of proper input sanitation.
    var = CLAMP(newvar, min_val, max_val)
    return TRUE
  update_icon() // Not applicable to all objects.

And the template:

import { useBackend } from '../backend';
import { Section, LabeledList } from '../components';

export const SampleInterface = props => {
  const { act, data } = useBackend(props);
  return (
    <Section title="Section name">
      <LabeledList>
        <LabeledList.Item label="Variable">
          {data.var}
        </LabeledList.Item>
      </LabeledList>
    </Section>
  );
};