Add onKey function for custom key commands for patterns

CONTRIBUTING.md

@@ -138,6 +138,18 @@ pnpm --filter "./packages/**" publish --access public
 To manually publish a single package, increase the version in the `package.json`, then run `pnpm publish`.
 Important: Always publish with `pnpm`, as `npm` does not support overriding main files in `publishConfig`, which is done in all the packages.
 
+
+## useful commands
+```sh
+#regenerate the test snapshots (ex: when updating or creating new pattern functions)
+pnpm snapshot 
+
+#start the OSC server
+pnpm run osc
+
+#build the standalone version
+pnpm tauri build
+```
 ## Have Fun
 
 Remember to have fun, and that this project is driven by the passion of volunteers!

packages/core/signal.mjs

@@ -7,7 +7,8 @@ This program is free software: you can redistribute it and/or modify it under th
 import { Hap } from './hap.mjs';
 import { Pattern, fastcat, reify, silence, stack, register } from './pattern.mjs';
 import Fraction from './fraction.mjs';
-import { id, _mod } from './util.mjs';
+
+import { id, isKeyDown } from './util.mjs';
 
 export function steady(value) {
   // A continuous value
@@ -639,3 +640,35 @@ export const never = register('never', function (_, pat) {
 export const always = register('always', function (func, pat) {
   return func(pat);
 });
+
+/**
+ *
+ * Do something on a keypress, or array of keypresses
+ * [Key name reference](https://developer.mozilla.org/en-US/docs/Web/API/UI_Events/Keyboard_event_key_values)
+ *
+ * @name whenKey
+ * @memberof Pattern
+ * @returns Pattern
+ * @example
+ * s("bd(5,8)").whenKey("Control:j", x => x.segment(16).color("red")).whenKey("Control:i", x => x.fast(2).color("blue"))
+ */
+
+export const whenKey = register('whenKey', function (input, func, pat) {
+  return pat.when(keyDown(input), func);
+});
+
+/**
+ *
+ * returns true when a key or array of keys is held
+ * [Key name reference](https://developer.mozilla.org/en-US/docs/Web/API/UI_Events/Keyboard_event_key_values)
+ *
+ * @name keyDown
+ * @memberof Pattern
+ * @returns Pattern
+ * @example
+ * keyDown("Control:j").pick([s("bd(5,8)"), s("cp(3,8)")])
+ */
+
+export const keyDown = register('keyDown', function (pat) {
+  return pat.fmap(isKeyDown);
+});

packages/core/util.mjs

@@ -434,6 +434,50 @@ function getUnixTimeSeconds() {
   return Date.now() * 0.001;
 }
 
+export const keyAlias = new Map([
+  ['control', 'Control'],
+  ['ctrl', 'Control'],
+  ['alt', 'Alt'],
+  ['shift', 'Shift'],
+  ['down', 'ArrowDown'],
+  ['up', 'ArrowUp'],
+  ['left', 'ArrowLeft'],
+  ['right', 'ArrowRight'],
+]);
+let keyState;
+
+export function getCurrentKeyboardState() {
+  if (keyState == null) {
+    if (typeof window === 'undefined') {
+      return;
+    }
+    keyState = {};
+    // Listen for the keydown event to mark the key as pressed
+    window.addEventListener('keydown', (event) => {
+      keyState[event.key] = true; // Mark the key as pressed
+    });
+
+    // Listen for the keyup event to mark the key as released
+    window.addEventListener('keyup', (event) => {
+      keyState[event.key] = false; // Mark the key as released
+    });
+  }
+
+  return { ...keyState }; // Return a shallow copy of the key state object
+}
+//keyname: string | Array<string>
+//keyname reference: https://developer.mozilla.org/en-US/docs/Web/API/UI_Events/Keyboard_event_key_values
+export function isKeyDown(keyname) {
+  if (Array.isArray(keyname) === false) {
+    keyname = [keyname];
+  }
+  const keyState = getCurrentKeyboardState();
+  return keyname.every((x) => {
+    const keyName = keyAlias.get(x) ?? x;
+    return keyState[keyName];
+  });
+}
+
 // Floating point versions, see Fraction for rational versions
 // // greatest common divisor
 // export const gcd = function (x, y, ...z) {

test/__snapshots__/examples.test.mjs.snap

@@ -4065,6 +4065,8 @@ exports[`runs examples > example "juxBy" example index 0 1`] = `
 ]
 `;
 
+exports[`runs examples > example "keyDown" example index 0 1`] = `[]`;
+
 exports[`runs examples > example "lastOf" example index 0 1`] = `
 [
   "[ 0/1 → 1/4 | note:c3 ]",
@@ -8832,6 +8834,8 @@ exports[`runs examples > example "when" example index 0 1`] = `
 ]
 `;
 
+exports[`runs examples > example "whenKey" example index 0 1`] = `[]`;
+
 exports[`runs examples > example "withValue" example index 0 1`] = `
 [
   "[ 0/1 → 1/3 | 10 ]",