LEDs: add rainbow effects

Setting the headlights to Solid with white, and then setting the
taillights to Rainbow Cycle allows users to replicate the "Mullet"
effect from the Float package.

Using Rainbow Cycle on the front and the back replicates the "Rave"
effect from the Float package.

Rainbow Fade has also been added, which was inspired by the Float
package's "RGB Fade" effect.

Feature: Add the Rainbow Cycle and Rainbow Fade LED effects.

src/conf/datatypes.h

@@ -86,6 +86,8 @@ typedef enum {
     LED_MODE_STROBE,
     LED_MODE_KNIGHT_RIDER,
     LED_MODE_FELONY,
+    LED_MODE_RAINBOW_CYCLE,
+    LED_MODE_RAINBOW_FADE,
 } LedMode;
 
 typedef enum {

src/conf/settings.xml

@@ -2255,6 +2255,8 @@ p, li { white-space: pre-wrap; }
             <enumNames>Strobe</enumNames>
             <enumNames>Knight Rider</enumNames>
             <enumNames>Felony</enumNames>
+            <enumNames>Rainbow Cycle</enumNames>
+            <enumNames>Rainbow Fade</enumNames>
         </leds.front.mode>
         <leds.front.brightness>
             <longName>Front Brightness</longName>
@@ -2417,6 +2419,8 @@ p, li { white-space: pre-wrap; }
             <enumNames>Strobe</enumNames>
             <enumNames>Knight Rider</enumNames>
             <enumNames>Felony</enumNames>
+            <enumNames>Rainbow Cycle</enumNames>
+            <enumNames>Rainbow Fade</enumNames>
         </leds.rear.mode>
         <leds.rear.brightness>
             <longName>Rear Brightness</longName>
@@ -2579,6 +2583,8 @@ p, li { white-space: pre-wrap; }
             <enumNames>Strobe</enumNames>
             <enumNames>Knight Rider</enumNames>
             <enumNames>Felony</enumNames>
+            <enumNames>Rainbow Cycle</enumNames>
+            <enumNames>Rainbow Fade</enumNames>
         </leds.headlights.mode>
         <leds.headlights.brightness>
             <longName>Headlights Brightness</longName>
@@ -2743,6 +2749,8 @@ p, li { white-space: pre-wrap; }
             <enumNames>Strobe</enumNames>
             <enumNames>Knight Rider</enumNames>
             <enumNames>Felony</enumNames>
+            <enumNames>Rainbow Cycle</enumNames>
+            <enumNames>Rainbow Fade</enumNames>
         </leds.taillights.mode>
         <leds.taillights.brightness>
             <longName>Taillights Brightness</longName>
@@ -3035,6 +3043,8 @@ p, li { white-space: pre-wrap; }
             <enumNames>Strobe</enumNames>
             <enumNames>Knight Rider</enumNames>
             <enumNames>Felony</enumNames>
+            <enumNames>Rainbow Cycle</enumNames>
+            <enumNames>Rainbow Fade</enumNames>
         </leds.status_idle.mode>
         <leds.status_idle.brightness>
             <longName>Status Idle Brightness</longName>

src/leds.c

@@ -308,6 +308,62 @@ static void anim_felony(Leds *leds, const LedStrip *strip, const LedBar *bar, fl
     }
 }
 
+static const uint32_t rainbow_cycle_colors[] = {
+    0x00FFFF00,
+    0x0000FF00,
+    0x0000FFFF,
+    0x000000FF,
+    0x00FF00FF,
+    0x00FF0000,
+};
+static const uint8_t rainbow_cycle_colors_len =
+    sizeof(rainbow_cycle_colors) / sizeof(rainbow_cycle_colors[0]);
+
+static void anim_rainbow_cycle(Leds *leds, const LedStrip *strip, float time) {
+    uint8_t color_idx = (uint8_t) (time / 0.1f) % rainbow_cycle_colors_len;
+    strip_set_color(leds, strip, rainbow_cycle_colors[color_idx], strip->brightness, 1.0f);
+}
+
+static const uint32_t rainbow_fade_colors[] = {
+    0x00FF5000,  // FLAME
+    0x00FF7800,  // ORANGE
+    0x00FFA000,  // YELLOW
+    0x0000FF00,  // GREEN
+    0x0000FFFF,  // CYAN
+    0x008000FF,  // VIOLET
+    0x00FF70A0,  // LAVENDER
+};
+static const uint8_t rainbow_fade_colors_len =
+    sizeof(rainbow_fade_colors) / sizeof(rainbow_fade_colors[0]);
+
+static void anim_rainbow_fade(Leds *leds, const LedStrip *strip, float time) {
+    float phase = fmodf(time, (float) rainbow_fade_colors_len);
+    uint8_t curr_color_idx = (uint8_t) floorf(phase);
+    uint8_t next_color_idx = (curr_color_idx + 1) % rainbow_fade_colors_len;
+
+    // extract rbg components from current color
+    uint32_t curr_color = rainbow_fade_colors[curr_color_idx];
+    uint8_t r_curr = (curr_color >> 16) & 0xFF;
+    uint8_t g_curr = (curr_color >> 8) & 0xFF;
+    uint8_t b_curr = curr_color & 0xFF;
+
+    // extract rbg components from next color
+    uint32_t next_color = rainbow_fade_colors[next_color_idx];
+    uint8_t r_next = (next_color >> 16) & 0xFF;
+    uint8_t g_next = (next_color >> 8) & 0xFF;
+    uint8_t b_next = next_color & 0xFF;
+
+    // smoothly interpolate between the current and next color
+    float ratio = phase - curr_color_idx;
+    float smooth_ratio = (1.0f - cosf(ratio * M_PI)) / 2.0f;
+    uint8_t r = (uint8_t) ((1.0f - smooth_ratio) * r_curr + smooth_ratio * r_next);
+    uint8_t g = (uint8_t) ((1.0f - smooth_ratio) * g_curr + smooth_ratio * g_next);
+    uint8_t b = (uint8_t) ((1.0f - smooth_ratio) * b_curr + smooth_ratio * b_next);
+    uint32_t color = (r << 16) | (g << 8) | b;
+
+    strip_set_color(leds, strip, color, strip->brightness, 1.0f);
+}
+
 static void led_strip_animate(Leds *leds, const LedStrip *strip, const LedBar *bar, float time) {
     time *= bar->speed;
 
@@ -330,6 +386,12 @@ static void led_strip_animate(Leds *leds, const LedStrip *strip, const LedBar *b
     case LED_MODE_FELONY:
         anim_felony(leds, strip, bar, time);
         break;
+    case LED_MODE_RAINBOW_CYCLE:
+        anim_rainbow_cycle(leds, strip, time);
+        break;
+    case LED_MODE_RAINBOW_FADE:
+        anim_rainbow_fade(leds, strip, time);
+        break;
     }
 }