Function set

static/mobile/app.js:777–785

(cx)

      const knob = el.querySelector(".fader-knob");
      const rect = el.getBoundingClientRect();
      const set = (cx) => {
        let v = (cx - rect.left) / rect.width;
        v = Math.max(0, Math.min(1, v));
        state.vols[id] = v;
        const pct = Math.round(v * 100) + "%";
        fill.style.width = pct;
        knob.style.left = pct;
        if (engine && laneActive(id)) engine.setGain(id, v);
      };
      set(e.clientX);
      el.setPointerCapture(e.pointerId);
      const mv = (ev) => set(ev.clientX);