1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112

use crate::pixelcolor::{
    raw::{RawData, RawU2, RawU4, RawU8},
    PixelColor,
};

/// Grayscale color.
pub trait GrayColor: PixelColor {
    /// Returns the luma channel value.
    fn luma(&self) -> u8;

    /// Black color (0% luma)
    const BLACK: Self;

    /// White color (100% luma)
    const WHITE: Self;
}

macro_rules! gray_color {
    ($type:ident, $raw_type:ident, $bpp_str:expr) => {
        #[doc = $bpp_str]
        #[doc = "grayscale color."]
        #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Default)]
        pub struct $type($raw_type);

        impl $type {
            /// Creates a new grayscale color.
            ///
            /// Too large luma values are masked to the valid range by setting
            /// the upper bits to `0`.
            pub const fn new(luma: u8) -> Self {
                Self($raw_type::new(luma))
            }
        }

        impl PixelColor for $type {
            type Raw = $raw_type;
        }

        impl GrayColor for $type {
            fn luma(&self) -> u8 {
                self.0.into_inner()
            }

            /// Black color (0% luma)
            const BLACK: Self = Self::new(0);

            /// White color (100% luma)
            const WHITE: Self = Self::new(255);
        }

        impl From<$raw_type> for $type {
            fn from(data: $raw_type) -> Self {
                Self(data)
            }
        }

        impl From<$type> for $raw_type {
            fn from(color: $type) -> Self {
                color.0
            }
        }
    };
}

gray_color!(Gray2, RawU2, "2 bit");
gray_color!(Gray4, RawU4, "4 bit");
gray_color!(Gray8, RawU8, "8 bit");

#[cfg(test)]
mod tests {
    use super::*;
    use crate::pixelcolor::IntoStorage;

    #[test]
    pub fn new_masks_luma() {
        assert_eq!(Gray2::new(255).luma(), 0x3);
        assert_eq!(Gray4::new(255).luma(), 0xF);
        assert_eq!(Gray8::new(255).luma(), 0xFF);
    }

    #[test]
    pub fn color_constants() {
        assert_eq!(Gray2::BLACK.luma(), 0);
        assert_eq!(Gray4::BLACK.luma(), 0);
        assert_eq!(Gray8::BLACK.luma(), 0);

        assert_eq!(Gray2::WHITE.luma(), 0x3);
        assert_eq!(Gray4::WHITE.luma(), 0xF);
        assert_eq!(Gray8::WHITE.luma(), 0xFF);
    }

    #[test]
    pub fn from_data() {
        assert_eq!(Gray2::from(RawU2::new(0x2)), Gray2::new(0x2));
        assert_eq!(Gray4::from(RawU4::new(0x9)), Gray4::new(0x9));
        assert_eq!(Gray8::from(RawU8::new(0x81)), Gray8::new(0x81));
    }

    #[test]
    pub fn into_data() {
        assert_eq!(RawU2::from(Gray2::new(0x1)), RawU2::new(0x1));
        assert_eq!(RawU4::from(Gray4::new(0x6)), RawU4::new(0x6));
        assert_eq!(RawU8::from(Gray8::new(0x7E)), RawU8::new(0x7E));
    }

    #[test]
    fn convert_to_raw() {
        let color = Gray8::new(0xAA);

        assert_eq!(color.into_storage(), 0xAAu8);
    }
}