Rolling 20210913

code/main/Color.h

@@ -0,0 +1,69 @@
+#pragma once
+
+#include <cstdint>
+#include "esp_attr.h"
+union Hsv;
+
+union Rgb {
+    struct __attribute__ ((packed)) {
+        uint8_t r, g, b, a;
+    };
+    uint32_t value;
+
+    Rgb( uint8_t r = 0, uint8_t g = 0, uint8_t b = 0, uint8_t a = 255 ) : r( r ), g( g ), b( b ), a( a ) {}
+    Rgb( Hsv c );
+    Rgb& operator=( Rgb rgb ) { swap( rgb ); return *this; }
+    Rgb& operator=( Hsv hsv );
+    Rgb operator+( Rgb in ) const;
+    Rgb& operator+=( Rgb in );
+    bool operator==( Rgb in ) const { return in.value == value; }
+    Rgb& blend( Rgb in );
+    void swap( Rgb& o ) {  value = o.value; }
+    void linearize() {
+        r = channelGamma(r);
+        g = channelGamma(g);
+        b = channelGamma(b);
+    }
+
+    uint8_t IRAM_ATTR getGrb( int idx );
+
+    void stretchChannels( uint8_t maxR, uint8_t maxG, uint8_t maxB ) {
+        r = stretch( r, maxR );
+        g = stretch( g, maxG );
+        b = stretch( b, maxB );
+    }
+
+    void stretchChannelsEvenly( uint8_t max ) {
+        stretchChannels( max, max, max );
+    }
+
+private:
+    uint8_t stretch( int value, uint8_t max ) {
+        return ( value * max ) >> 8;
+    }
+
+    uint8_t channelGamma( int channel ) {
+        /* The optimal gamma correction is x^2.8. However, this is expensive to
+         * compute. Therefore, we use x^3 for gamma correction. Also, we add a
+         * bias as the WS2812 LEDs do not turn on for values less than 4. */
+        if (channel == 0)
+            return channel;
+        channel = channel * channel * channel * 251;
+        channel >>= 24;
+        return static_cast< uint8_t >( 4 + channel );
+    }
+};
+
+union Hsv {
+    struct __attribute__ ((packed)) {
+        uint8_t h, s, v, a;
+    };
+    uint32_t value;
+
+    Hsv( uint8_t h, uint8_t s = 0, uint8_t v = 0, uint8_t a = 255 ) : h( h ), s( s ), v( v ), a( a ) {}
+    Hsv( Rgb r );
+    Hsv& operator=( Hsv h ) { swap( h ); return *this; }
+    Hsv& operator=( Rgb rgb );
+    bool operator==( Hsv in ) const { return in.value == value; }
+    void swap( Hsv& o ) { value = o.value; }
+};