Engine

Engine names the ten things the client announces that are not values: a chat message arrived, a sub-interface opened or closed, the clan settings moved. Each is an occasion a useWatch can wait for, or a useRerenderOn can redraw on.

Engine.SUB_CHANGE: EngineEvent
Engine.DIALOG_ABORT: EngineEvent
Engine.CONTENT_CHANGE: EngineEvent
Engine.CHAT: EngineEvent
Engine.FRIENDS: EngineEvent
Engine.CLAN: EngineEvent
Engine.CLAN_SETTINGS: EngineEvent
Engine.CLAN_CHANNEL: EngineEvent
Engine.MISC: EngineEvent
Engine.STOCK: EngineEvent

Reference

The ten occasions

	fires when
Engine.SUB_CHANGE	any sub-interface opens or closes, anywhere in the tree
Engine.DIALOG_ABORT	the server aborts the current dialogue
Engine.CONTENT_CHANGE	the client’s content changes
Engine.CHAT	a chat message arrives
Engine.FRIENDS	the friend list moves
Engine.CLAN	the friends-chat channel moves
Engine.CLAN_SETTINGS	clan settings move
Engine.CLAN_CHANNEL	the clan channel moves
Engine.MISC	the client’s miscellaneous update runs
Engine.STOCK	the Grand Exchange offers move

src/reference-engine.ts2

  useWatch(Engine.SUB_CHANGE, (event) => { writeDivider(event.component); }, label);

Caveats

• The handler receives only event.component.
• Only SUB_CHANGE and DIALOG_ABORT fire on a host in a box 0 wide or 0 tall.

Usage

Rewriting a label when a panel opens or closes

src/reference-engine.ts2

export const SubChangeDivider = (): Component => {
  const label = useRef();
  useWatch(Engine.SUB_CHANGE, (event) => { writeDivider(event.component); }, label);

  return (
    <text ref={label} x={0} y={0} w="fill" h={14} text="No panel has opened yet" font={Fonts.SMALL}
          align="center" valign="middle" shadow color={Colors.DIM} />
  );
};

Redrawing when a message arrives

src/reference-engine.ts2

  useRerenderOn(Engine.CHAT);

Troubleshooting

Which do I want, a watch or a re-render?

A watch when a handler can say the change — a text, a colour, a hide. A re-render when the tree’s shape changes — a component appears or goes.