Add a "no-delay" mode to SpaceCadet

SpaceCadet now has three "modes": on, off, and on with no delay. In "no-delay"
mode, when a SpaceCadet key is pressed, its primary (modifier) key value is sent
immediately to the host, and if it is released before timing out, that value is
then replaced by the configured "tap" value of the key.

Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>

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

@@ -117,7 +117,7 @@ EventHandlerResult SpaceCadet::onKeyswitchEvent(KeyEvent &event) {
   }
 
   // Do nothing if disabled, but keep the event tracker current.
-  if (mode_ != Mode::ON)
+  if (mode_ == Mode::OFF)
     return EventHandlerResult::OK;
 
   if (!event_queue_.isEmpty()) {
@@ -145,7 +145,13 @@ EventHandlerResult SpaceCadet::onKeyswitchEvent(KeyEvent &event) {
     // Check for a SpaceCadet key
     pending_map_index_ = getSpaceCadetKeyIndex(event.key);
     if (pending_map_index_ >= 0) {
-      // A SpaceCadet key was pressed
+      // A SpaceCadet key has just toggled on. First, if we're in no-delay mode,
+      // we need to send the event unchanged (with the primary `Key` value),
+      // bypassing other `onKeyswitchEvent()` handlers.
+      if (mode_ == Mode::NO_DELAY)
+        Runtime.handleKeyEvent(event);
+      // Queue the press event and abort; this press event will be resolved
+      // later.
       event_queue_.append(event);
       return EventHandlerResult::ABORT;
     }
@@ -194,6 +200,11 @@ void SpaceCadet::flushQueue() {
 void SpaceCadet::flushEvent(bool is_tap) {
   KeyEvent event = event_queue_.event(0);
   if (is_tap && pending_map_index_ >= 0) {
+    // If we're in no-delay mode, we should first send the release of the
+    // modifier key as a courtesy before sending the tap event.
+    if (mode_ == Mode::NO_DELAY) {
+      Runtime.handleKeyEvent(KeyEvent(event.addr, WAS_PRESSED));
+    }
     event.key = map[pending_map_index_].output;
   }
   event_queue_.shift();

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

@@ -66,8 +66,11 @@ class SpaceCadet : public kaleidoscope::Plugin {
   static void disable() {
     mode_ = Mode::OFF;
   }
+  static void enableWithoutDelay() {
+    mode_ = Mode::NO_DELAY;
+  }
   static bool active() {
-    return (mode_ == Mode::ON);
+    return (mode_ == Mode::ON || mode_ == Mode::NO_DELAY);
   }
 
   // Publically accessible variables