blendAlphaMaxChannel()

CRGB CRGB::blendAlphaMaxChannel ( const CRGB & upper, const CRGB & lower )

static

Definition at line 60 of file crgb.cpp.hpp.

                                                                                 {
    // Use luma of upper pixel as alpha (0..255)
    fl::u8 max_component = 0;
    for (int i = 0; i < 3; ++i) {
        if (upper.raw[i] > max_component) {
            max_component = upper.raw[i];
        }
    }
    // uint8_t alpha = upper.getLuma();
    // blend(lower, upper, alpha) → (lower * (255−alpha) + upper * alpha) / 256
    fl::u8 amountOf2 = 255 - max_component;
    return CRGB::blend(upper, lower, amountOf2);
}

References CRGB(), blend(), and fl::FL_NO_EXCEPT.

Referenced by fl::Frame::draw(), fl::XYDrawComposited::draw(), and fl::Frame::drawXY().

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