[Code] Add solid reactive gradient mode (#17228)

docs/feature_rgb_matrix.md

@@ -688,6 +688,16 @@ Remove the spread effect entirely.
 #define RGB_MATRIX_TYPING_HEATMAP_SLIM
 ```
 
+### RGB Matrix Effect Solid Reactive :id=rgb-matrix-effect-solid-reactive
+
+Solid reactive effects will pulse RGB light on key presses with user configurable hues. To enable gradient mode that will automatically change reactive color, add the following define:
+
+```c
+#define RGB_MATRIX_SOLID_REACTIVE_GRADIENT_MODE
+```
+
+Gradient mode will loop through the color wheel hues over time and its duration can be controlled with the effect speed keycodes (`RGB_SPI`/`RGB_SPD`).
+
 ## Custom RGB Matrix Effects :id=custom-rgb-matrix-effects
 
 By setting `RGB_MATRIX_CUSTOM_USER = yes` in `rules.mk`, new effects can be defined directly from your keymap or userspace, without having to edit any QMK core files. To declare new effects, create a `rgb_matrix_user.inc` file in the user keymap directory or userspace folder.

quantum/rgb_matrix/animations/solid_reactive_anim.h

@@ -4,6 +4,9 @@ RGB_MATRIX_EFFECT(SOLID_REACTIVE)
 #        ifdef RGB_MATRIX_CUSTOM_EFFECT_IMPLS
 
 static HSV SOLID_REACTIVE_math(HSV hsv, uint16_t offset) {
+#            ifdef RGB_MATRIX_SOLID_REACTIVE_GRADIENT_MODE
+    hsv.h = scale16by8(g_rgb_timer, add8(rgb_matrix_config.speed, 1) >> 6);
+#            endif
     hsv.h += qsub8(130, offset);
     return hsv;
 }

quantum/rgb_matrix/animations/solid_reactive_cross.h

@@ -19,6 +19,9 @@ static HSV SOLID_REACTIVE_CROSS_math(HSV hsv, int16_t dx, int16_t dy, uint8_t di
     dy              = dy * 16 > 255 ? 255 : dy * 16;
     effect += dx > dy ? dy : dx;
     if (effect > 255) effect = 255;
+#            ifdef RGB_MATRIX_SOLID_REACTIVE_GRADIENT_MODE
+    hsv.h = scale16by8(g_rgb_timer, add8(rgb_matrix_config.speed, 1) >> 6);
+#            endif
     hsv.v = qadd8(hsv.v, 255 - effect);
     return hsv;
 }

quantum/rgb_matrix/animations/solid_reactive_nexus.h

@@ -16,6 +16,9 @@ static HSV SOLID_REACTIVE_NEXUS_math(HSV hsv, int16_t dx, int16_t dy, uint8_t di
     if (effect > 255) effect = 255;
     if (dist > 72) effect = 255;
     if ((dx > 8 || dx < -8) && (dy > 8 || dy < -8)) effect = 255;
+#            ifdef RGB_MATRIX_SOLID_REACTIVE_GRADIENT_MODE
+    hsv.h = scale16by8(g_rgb_timer, add8(rgb_matrix_config.speed, 1) >> 6);
+#            endif
     hsv.v = qadd8(hsv.v, 255 - effect);
     hsv.h = rgb_matrix_config.hsv.h + dy / 4;
     return hsv;

quantum/rgb_matrix/animations/solid_reactive_simple_anim.h

@@ -4,6 +4,9 @@ RGB_MATRIX_EFFECT(SOLID_REACTIVE_SIMPLE)
 #        ifdef RGB_MATRIX_CUSTOM_EFFECT_IMPLS
 
 static HSV SOLID_REACTIVE_SIMPLE_math(HSV hsv, uint16_t offset) {
+#            ifdef RGB_MATRIX_SOLID_REACTIVE_GRADIENT_MODE
+    hsv.h = scale16by8(g_rgb_timer, add8(rgb_matrix_config.speed, 1) >> 6);
+#            endif
     hsv.v = scale8(255 - offset, hsv.v);
     return hsv;
 }

quantum/rgb_matrix/animations/solid_reactive_wide.h

@@ -14,6 +14,9 @@ RGB_MATRIX_EFFECT(SOLID_REACTIVE_MULTIWIDE)
 static HSV SOLID_REACTIVE_WIDE_math(HSV hsv, int16_t dx, int16_t dy, uint8_t dist, uint16_t tick) {
     uint16_t effect = tick + dist * 5;
     if (effect > 255) effect = 255;
+#            ifdef RGB_MATRIX_SOLID_REACTIVE_GRADIENT_MODE
+    hsv.h = scale16by8(g_rgb_timer, add8(rgb_matrix_config.speed, 1) >> 6);
+#            endif
     hsv.v = qadd8(hsv.v, 255 - effect);
     return hsv;
 }