ColorFromPalette() [6/8]

CRGB fl::ColorFromPalette	(	const CRGBPalette32 &	pal,
		fl::u8	index,
		fl::u8	brightness,
		TBlendType	blendType )

Definition at line 815 of file colorutils.cpp.hpp.

                                                                          {
    if (blendType == LINEARBLEND_NOWRAP) {
        index = map8(index, 0, 247); // Blend range is affected by lo3 blend of
                                     // values, remap to avoid wrapping
    }
 
    fl::u8 hi5 = index;
#if defined(FL_IS_AVR)
    hi5 /= 2;
    hi5 /= 2;
    hi5 /= 2;
#else
    hi5 >>= 3;
#endif
    fl::u8 lo3 = index & 0x07;
 
    // const CRGB* entry = &(pal[0]) + hi5;
    // since hi5 is always 0..31, hi4 * sizeof(CRGB) can be a single-byte value,
    // instead of the two byte 'int' that avr-gcc defaults to.
    // So, we multiply hi5 X sizeof(CRGB), giving hi5XsizeofCRGB;
    fl::u8 hi5XsizeofCRGB = hi5 * sizeof(CRGB);
    // We then add that to a base array pointer.
    const CRGB *entry = (CRGB *)((fl::u8 *)(&(pal[0])) + hi5XsizeofCRGB);
 
    fl::u8 red1 = entry->red;
    fl::u8 green1 = entry->green;
    fl::u8 blue1 = entry->blue;
 
    fl::u8 blend = lo3 && (blendType != NOBLEND);
 
    if (blend) {
 
        if (hi5 == 31) {
            entry = &(pal[0]);
        } else {
            ++entry;
        }
 
        fl::u8 f2 = lo3 << 5;
        fl::u8 f1 = 255 - f2;
 
        fl::u8 red2 = entry->red;
        red1 = scale8_LEAVING_R1_DIRTY(red1, f1);
        red2 = scale8_LEAVING_R1_DIRTY(red2, f2);
        red1 += red2;
 
        fl::u8 green2 = entry->green;
        green1 = scale8_LEAVING_R1_DIRTY(green1, f1);
        green2 = scale8_LEAVING_R1_DIRTY(green2, f2);
        green1 += green2;
 
        fl::u8 blue2 = entry->blue;
        blue1 = scale8_LEAVING_R1_DIRTY(blue1, f1);
        blue2 = scale8_LEAVING_R1_DIRTY(blue2, f2);
        blue1 += blue2;
 
        cleanup_R1();
    }
 
    if (brightness != 255) {
        if (brightness) {
            ++brightness; // adjust for rounding
            // Now, since brightness is nonzero, we don't need the full
            // scale8_video logic; we can just to scale8 and then add one
            // (unless scale8 fixed) to all nonzero inputs.
            if (red1) {
                red1 = scale8_LEAVING_R1_DIRTY(red1, brightness);
#if !(FASTLED_SCALE8_FIXED == 1)
                ++red1;
#endif
            }
            if (green1) {
                green1 = scale8_LEAVING_R1_DIRTY(green1, brightness);
#if !(FASTLED_SCALE8_FIXED == 1)
                ++green1;
#endif
            }
            if (blue1) {
                blue1 = scale8_LEAVING_R1_DIRTY(blue1, brightness);
#if !(FASTLED_SCALE8_FIXED == 1)
                ++blue1;
#endif
            }
            cleanup_R1();
        } else {
            red1 = 0;
            green1 = 0;
            blue1 = 0;
        }
    }
 
    return CRGB(red1, green1, blue1);
}

References blend(), brightness, FL_NO_EXCEPT, and map8().

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