Colormap: Migrate to using `onLayerChange`

Instead of tracking layer changes ourselves, use the new `onLayerChange` event
to do that for us. This makes the code a tiny bit easier to follow.

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

src/kaleidoscope/plugin/Colormap.cpp

@@ -28,7 +28,7 @@ namespace plugin {
 
 uint16_t ColormapEffect::map_base_;
 uint8_t ColormapEffect::max_layers_;
-uint8_t ColormapEffect::last_highest_layer_;
+uint8_t ColormapEffect::top_layer_;
 
 void ColormapEffect::max_layers(uint8_t max_) {
   if (map_base_ != 0)
@@ -42,21 +42,20 @@ void ColormapEffect::onActivate(void) {
   if (!Kaleidoscope.has_leds)
     return;
 
-  last_highest_layer_ = Layer.top();
-  if (last_highest_layer_ <= max_layers_)
-    ::LEDPaletteTheme.updateHandler(map_base_, last_highest_layer_);
+  top_layer_ = Layer.top();
+  if (top_layer_ <= max_layers_)
+    ::LEDPaletteTheme.updateHandler(map_base_, top_layer_);
 }
 
-void ColormapEffect::update(void) {
-  if (!Kaleidoscope.has_leds || Layer.top() == last_highest_layer_)
-    return;
-
-  onActivate();
+void ColormapEffect::refreshAt(byte row, byte col) {
+  if (top_layer_ <= max_layers_)
+    ::LEDPaletteTheme.refreshAt(map_base_, top_layer_, row, col);
 }
 
-void ColormapEffect::refreshAt(byte row, byte col) {
-  if (last_highest_layer_ <= max_layers_)
-    ::LEDPaletteTheme.refreshAt(map_base_, last_highest_layer_, row, col);
+EventHandlerResult ColormapEffect::onLayerChange() {
+  if (::LEDControl.get_mode() == this)
+    onActivate();
+  return EventHandlerResult::OK;
 }
 
 EventHandlerResult ColormapEffect::onFocusEvent(const char *command) {

src/kaleidoscope/plugin/Colormap.h

@@ -28,15 +28,15 @@ class ColormapEffect : public LEDMode {
 
   void max_layers(uint8_t max_);
 
+  EventHandlerResult onLayerChange();
   EventHandlerResult onFocusEvent(const char *command);
 
  protected:
   void onActivate(void) final;
-  void update(void) final;
   void refreshAt(byte row, byte col) final;
 
  private:
-  static uint8_t last_highest_layer_;
+  static uint8_t top_layer_;
   static uint8_t max_layers_;
   static uint16_t map_base_;
 };