IdleLEDs: Implement a .suspend() and a .resume() method

Sometimes we want to control LEDs outside of `IdleLEDs`, like through
`HostPowerManagement`, and in these cases, we would like `IdleLEDs` to have an
up-to-date idea about what's going on. That is, if the host enters sleep,
`IdleLEDs` should be aware of that, and enter idle state. Once the host wakes
up, either via the keyboard or otherwise, `IdleLEDs` should resume its tasks.

With the new `.suspend()` and `.resume()` method, this becomes possible.

This addresses a big part of #1287.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

plugins/Kaleidoscope-IdleLEDs/README.md

@@ -91,6 +91,16 @@ the following properties and methods.
 > Setting the timeout to 0 will disable the plugin until it is set to a higher
 > value.
 
+### `.suspend()`, `.resume()`
+
+> Suspends or resumes `IdleLEDs`. When suspended, `IdleLEDs` will immediately
+> enter idle state, and turn LEDs off. When resuming, it will turn the LEDs back
+> on, and start checking idleness again.
+>
+> The intended use of these functions is when LEDs are turned on or off by other
+> means, such as part of host power management, and syncing that state with
+> `IdleLEDs` is desired.
+
 ## Focus commands
 
 The plugin provides a single [Focus][FocusSerial] command, but only when using

plugins/Kaleidoscope-IdleLEDs/src/kaleidoscope/plugin/IdleLEDs.cpp

@@ -1,6 +1,6 @@
 /* -*- mode: c++ -*-
  * Kaleidoscope-Idle-LEDs -- Turn off the LEDs when the keyboard's idle
- * Copyright (C) 2018, 2019, 2020, 2021  Keyboard.io, Inc
+ * Copyright (C) 2018, 2019, 2020, 2021, 2022  Keyboard.io, Inc
  * Copyright (C) 2019  Dygma, Inc
  *
  * This program is free software: you can redistribute it and/or modify it under
@@ -44,26 +44,38 @@ void IdleLEDs::setIdleTimeoutSeconds(uint32_t new_limit) {
   idle_time_limit = new_limit * 1000;
 }
 
+void IdleLEDs::resume() {
+  // Enabling LEDs is fairly expensive, so we only do it if we have to.
+  if (!::LEDControl.isEnabled()) {
+    ::LEDControl.enable();
+  }
+  idle_       = false;
+  start_time_ = Runtime.millisAtCycleStart();
+}
+
+void IdleLEDs::suspend() {
+  // Disabling LEDs is fairly expensive, so we only do it if we have to.
+  if (::LEDControl.isEnabled()) {
+    ::LEDControl.disable();
+  }
+
+  idle_ = true;
+}
+
 EventHandlerResult IdleLEDs::beforeEachCycle() {
   if (idle_time_limit == 0)
     return EventHandlerResult::OK;
 
-  if (::LEDControl.isEnabled() &&
+  if (!idle_ &&
       Runtime.hasTimeExpired(start_time_, idle_time_limit)) {
-    ::LEDControl.disable();
-    idle_ = true;
+    suspend();
   }
 
   return EventHandlerResult::OK;
 }
 
 EventHandlerResult IdleLEDs::onKeyEvent(KeyEvent &event) {
-  if (idle_) {
-    ::LEDControl.enable();
-    idle_ = false;
-  }
-
-  start_time_ = Runtime.millisAtCycleStart();
+  resume();
 
   return EventHandlerResult::OK;
 }

plugins/Kaleidoscope-IdleLEDs/src/kaleidoscope/plugin/IdleLEDs.h

@@ -1,6 +1,6 @@
 /* -*- mode: c++ -*-
  * Kaleidoscope-Idle-LEDs -- Turn off the LEDs when the keyboard's idle
- * Copyright (C) 2018, 2019, 2021  Keyboard.io, Inc
+ * Copyright (C) 2018, 2019, 2021, 2022  Keyboard.io, Inc
  * Copyright (C) 2019  Dygma, Inc
  *
  * This program is free software: you can redistribute it and/or modify it under
@@ -33,6 +33,8 @@ class IdleLEDs : public kaleidoscope::Plugin {
 
   static uint32_t idleTimeoutSeconds();
   static void setIdleTimeoutSeconds(uint32_t new_limit);
+  static void suspend();
+  static void resume();
 
   EventHandlerResult beforeEachCycle();
   EventHandlerResult onKeyEvent(KeyEvent &event);