Chase: Allow setting the distance too

Fixes #546.

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

src/kaleidoscope/plugin/LEDEffect-Chase.cpp

@@ -29,16 +29,16 @@ void LEDChaseEffect::update(void) {
   }
   last_update_ = now;
 
-  // The red LED is at `pos`; the blue one follows behind. `chase_sign` is either +1 or
-  // -1; `chase_pixels` is the gap between them.
-  int8_t pos2 = pos - (chase_sign * chase_pixels);
+  // The red LED is at `pos_`; the blue one follows behind. `direction_` is
+  // either +1 or -1; `distance_` is the gap between them.
+  int8_t pos2 = pos_ - (direction_ * distance_);
 
-  // First, we turn off the LEDs that were turned on in the previous update. `pos` is
-  // always in the valid range (0 <= pos < LED_COUNT), but after it changes direction, for
-  // the first few updates, `pos2` will be out of bounds. Since it's an unsigned integer,
-  // even when it would have a value below zero, it underflows and so one test is good for
-  // both ends of the range.
-  ::LEDControl.setCrgbAt(pos, CRGB(0, 0, 0));
+  // First, we turn off the LEDs that were turned on in the previous update.
+  // `pos_` is always in the valid range (0 <= pos_ < LED_COUNT), but after it
+  // changes direction, for the first few updates, `pos2` will be out of bounds.
+  // Since it's an unsigned integer, even when it would have a value below zero,
+  // it underflows and so one test is good for both ends of the range.
+  ::LEDControl.setCrgbAt(pos_, CRGB(0, 0, 0));
   if (pos2 < LED_COUNT)
     ::LEDControl.setCrgbAt(pos2, CRGB(0, 0, 0));
 
@@ -48,18 +48,18 @@ void LEDChaseEffect::update(void) {
   // it back in bounds. When this happens, the blue light "jumps" behind the red one, and
   // will be out of bounds. The simplest way to do this is to assign it a value that is
   // known to be invalid (LED_COUNT).
-  pos += chase_sign;
-  if (pos < LED_COUNT && pos > 0) {
-    pos2 += chase_sign;
+  pos_ += direction_;
+  if (pos_ < LED_COUNT && pos_ > 0) {
+    pos2 += direction_;
   } else {
-    chase_sign = -chase_sign;
-    pos += chase_sign;
+    direction_ = -direction_;
+    pos_ += direction_;
     pos2 = LED_COUNT;
   }
 
   // Last, we turn on the LEDs at their new positions. As before, the blue light (pos2) is
   // only set if it's in the valid LED range.
-  ::LEDControl.setCrgbAt(pos, CRGB(255, 0, 0));
+  ::LEDControl.setCrgbAt(pos_, CRGB(255, 0, 0));
   if (pos2 < LED_COUNT)
     ::LEDControl.setCrgbAt(pos2, CRGB(0, 0, 255));
 }

src/kaleidoscope/plugin/LEDEffect-Chase.h

@@ -30,14 +30,20 @@ class LEDChaseEffect : public LEDMode {
   void update_delay(uint16_t delay) {
     update_delay_ = delay;
   }
+  uint8_t distance() {
+    return distance_;
+  }
+  void distance(uint8_t value) {
+    distance_ = value;
+  }
 
  protected:
   void update(void) final;
 
  private:
-  int8_t pos = 0;
-  int8_t chase_sign = 1; //negative values when it's going backwar
-  uint8_t chase_pixels = 5;
+  int8_t pos_ = 0;
+  int8_t direction_ = 1;
+  uint8_t distance_ = 5;
   uint16_t update_delay_ = 150;
   uint16_t last_update_ = 0;
 };