lcd-async 0.1.3

Async fork of mipidsi crate
Documentation 
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
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141

use embedded_graphics_core::pixelcolor::RgbColor;

use crate::dcs::BitsPerPixel;

impl BitsPerPixel {
    /// Returns the bits per pixel for a embedded-graphics [`RgbColor`].
    pub const fn from_rgb_color<C: RgbColor>() -> Self {
        let bpp = C::MAX_R.trailing_ones() + C::MAX_G.trailing_ones() + C::MAX_B.trailing_ones();

        match bpp {
            3 => Self::Three,
            8 => Self::Eight,
            12 => Self::Twelve,
            16 => Self::Sixteen,
            18 => Self::Eighteen,
            24 => Self::TwentyFour,
            _ => panic!("invalid RgbColor bits per pixel"),
        }
    }
}

/// An iterator that alternately takes and skips elements of another iterator.
#[allow(dead_code)]
struct TakeSkip<I> {
    iter: I,
    take: u32,
    take_remaining: u32,
    skip: u32,
}

impl<I> TakeSkip<I> {
    #[allow(dead_code)]
    pub fn new(iter: I, take: u32, skip: u32) -> Self {
        Self {
            iter,
            take,
            take_remaining: take,
            skip,
        }
    }
}

impl<I: Iterator> Iterator for TakeSkip<I> {
    type Item = I::Item;

    fn next(&mut self) -> Option<Self::Item> {
        if self.take_remaining > 0 {
            self.take_remaining -= 1;
            self.iter.next()
        } else if self.take > 0 {
            self.take_remaining = self.take - 1;
            nth_u32(&mut self.iter, self.skip)
        } else {
            None
        }
    }
}

#[cfg(not(target_pointer_width = "16"))]
#[allow(dead_code)]
fn take_u32<I: Iterator>(iter: I, max_count: u32) -> impl Iterator<Item = I::Item> {
    iter.take(max_count.try_into().unwrap())
}

#[cfg(target_pointer_width = "16")]
#[allow(dead_code)]
fn take_u32<I: Iterator>(iter: I, max_count: u32) -> impl Iterator<Item = I::Item> {
    let mut count = 0;
    iter.take_while(move |_| {
        count += 1;
        count <= max_count
    })
}

#[cfg(not(target_pointer_width = "16"))]
#[allow(dead_code)]
fn nth_u32<I: Iterator>(mut iter: I, n: u32) -> Option<I::Item> {
    iter.nth(n.try_into().unwrap())
}

#[cfg(target_pointer_width = "16")]
#[allow(dead_code)]
fn nth_u32<I: Iterator>(mut iter: I, n: u32) -> Option<I::Item> {
    for _ in 0..n {
        iter.next();
    }
    iter.next()
}

#[cfg(test)]
mod test {
    use crate::dcs::BitsPerPixel;
    use embedded_graphics_core::pixelcolor::*;

    use super::TakeSkip;

    #[test]
    fn bpp_from_rgb_color_works() {
        assert_eq!(
            BitsPerPixel::from_rgb_color::<Rgb565>(),
            BitsPerPixel::Sixteen
        );
        assert_eq!(
            BitsPerPixel::from_rgb_color::<Rgb666>(),
            BitsPerPixel::Eighteen
        );
        assert_eq!(
            BitsPerPixel::from_rgb_color::<Rgb888>(),
            BitsPerPixel::TwentyFour
        );
    }

    #[test]
    #[should_panic]
    fn bpp_from_rgb_color_invalid_panics() {
        BitsPerPixel::from_rgb_color::<Rgb555>();
    }

    #[test]
    fn take_skip_iter() {
        let mut iter = TakeSkip::new(0..11, 3, 2);
        assert_eq!(iter.next(), Some(0));
        assert_eq!(iter.next(), Some(1));
        assert_eq!(iter.next(), Some(2));
        // Skip 3 and 4
        assert_eq!(iter.next(), Some(5));
        assert_eq!(iter.next(), Some(6));
        assert_eq!(iter.next(), Some(7));
        // Skip 8 and 9
        assert_eq!(iter.next(), Some(10));
        assert_eq!(iter.next(), None);
    }

    #[test]
    fn take_skip_with_take_equals_zero() {
        // take == 0 should not cause an integer overflow or infinite loop and
        // just return None
        let mut iter = TakeSkip::new(0..11, 0, 2);
        assert_eq!(iter.next(), None);
    }
}