ascii-ui/EventManager.js

Graphic terminal emulator for HTML canvas elements

export class EventManager {
    constructor(terminal) {
        this.listeners = new Map();
        this.terminal = terminal;
    }
    addListener(type, listener, widget) {
        const target = widget || this.terminal;
        let targets = this.listeners.get(type);
        if (!targets) {
            targets = new Map();
            this.listeners.set(type, targets);
        }
        let listeners = targets.get(target);
        if (!listeners) {
            listeners = [];
            targets.set(target, listeners);
        }
        listeners.push(listener);
    }
    removeListener(type, listener, widget) {
        const target = widget || this.terminal;
        const targets = this.listeners.get(type);
        if (!targets) {
            return;
        }
        const listeners = targets.get(target);
        if (!listeners) {
            return;
        }
        const index = listeners.indexOf(listener);
        if (index !== -1) {
            listeners.splice(index, 1);
        }
    }
    trigger(event, widget) {
        const path = widget ? [...this.terminal.getWidgetPath(widget), this.terminal] : [this.terminal];
        const targets = this.listeners.get(event.type);
        if (!targets) {
            return;
        }
        for (const target of path) {
            const listeners = targets.get(target);
            if (listeners) {
                for (const listener of listeners) {
                    listener(event, target);
                    if (event.isCancelled()) {
                        return;
                    }
                }
            }
        }
    }
}
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