Add adaptive progression and item expansion

js/input.js

@@ -0,0 +1,47 @@
+// ---- keyboard + mouse input ----
+const Input = {
+  keys: {},
+  pressed: {},   // edge-triggered, cleared each frame
+  mx: W / 2, my: H / 2,
+  mdown: false,
+  mpressed: false, // edge-triggered mouse
+  mreleased: false,
+  anyKey: false,
+};
+
+function initInput(canvas) {
+  window.addEventListener('keydown', (e) => {
+    const k = e.key.toLowerCase();
+    if (!Input.keys[k]) Input.pressed[k] = true;
+    Input.keys[k] = true;
+    Input.anyKey = true;
+    if (['arrowup', 'arrowdown', 'arrowleft', 'arrowright', ' '].includes(k)) e.preventDefault();
+  });
+  window.addEventListener('keyup', (e) => { Input.keys[e.key.toLowerCase()] = false; });
+  window.addEventListener('blur', () => { Input.keys = {}; Input.mdown = false; });
+
+  function setMouse(e) {
+    const r = canvas.getBoundingClientRect();
+    Input.mx = (e.clientX - r.left) * (W / r.width);
+    Input.my = (e.clientY - r.top) * (H / r.height);
+  }
+  canvas.addEventListener('mousemove', setMouse);
+  canvas.addEventListener('mousedown', (e) => {
+    setMouse(e);
+    if (e.button === 0) { Input.mdown = true; Input.mpressed = true; Input.anyKey = true; }
+  });
+  window.addEventListener('mouseup', (e) => {
+    if (e.button === 0) { Input.mdown = false; Input.mreleased = true; }
+  });
+  canvas.addEventListener('contextmenu', (e) => e.preventDefault());
+}
+
+function clearInputEdges() {
+  Input.pressed = {};
+  Input.mpressed = false;
+  Input.mreleased = false;
+  Input.anyKey = false;
+}
+
+function keyDown(...ks) { return ks.some(k => Input.keys[k]); }
+function keyPressed(...ks) { return ks.some(k => Input.pressed[k]); }