libnotcurses_sys/
alpha.rs

1//! NcAlpha
2
3#[allow(unused_imports)] // for doc comments
4use crate::NcCell;
5
6/// Alpha information, part of an [`NcChannel`][crate::NcChannel],
7/// applies to [`NcCell`]'s foreground or background color.
8///
9/// # Default:
10/// *[`NcAlpha::Opaque`]*
11///
12/// ## Diagram
13///
14/// Internally it's 2 bits of alpha, surrounded by context dependent bits:
15///
16/// ```txt
17/// ~~AA~~~~ -------- -------- --------
18/// ```
19///
20/// See also: [`NcChannels`][crate::NcChannels] for more context information.
21#[repr(u32)]
22#[derive(Debug, Clone, Copy, PartialEq, Eq)]
23pub enum NcAlpha {
24    /// Indicates [`NcCell`]'s foreground or background color will be a
25    /// composite between its color and the `NcCell`s' corresponding colors
26    /// underneath it.
27    Blend = c_api::NCALPHA_BLEND,
28
29    /// Indicates the foreground color will be high-contrast,
30    /// relative to the computed background.
31    ///
32    /// Background cannot be high-contrast.
33    HighContrast = c_api::NCALPHA_HIGHCONTRAST,
34
35    /// Indicates [`NcCell`]'s foreground or background color is used unchanged.
36    Opaque = c_api::NCALPHA_OPAQUE,
37
38    /// Indicates [`NcCell`]'s foreground or background color is derived
39    /// entirely from the `NcCell`s underneath it.
40    Transparent = c_api::NCALPHA_TRANSPARENT,
41}
42
43mod core_impls {
44    use super::{c_api, NcAlpha};
45    use core::fmt;
46
47    impl Default for NcAlpha {
48        fn default() -> Self {
49            Self::Opaque
50        }
51    }
52
53    impl fmt::Display for NcAlpha {
54        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
55            use NcAlpha::*;
56            write!(
57                f,
58                "{}",
59                match self {
60                    Blend => "Blend",
61                    HighContrast => "HighContrast",
62                    Opaque => "Opaque",
63                    Transparent => "Transparent",
64                }
65            )
66        }
67    }
68
69    impl From<c_api::NcAlpha_u32> for NcAlpha {
70        fn from(alpha: c_api::NcAlpha_u32) -> Self {
71            use {c_api::*, NcAlpha::*};
72            match alpha {
73                NCALPHA_BLEND => Blend,
74                NCALPHA_HIGHCONTRAST => HighContrast,
75                NCALPHA_OPAQUE => Opaque,
76                NCALPHA_TRANSPARENT => Transparent,
77                _ => Self::default(),
78            }
79        }
80    }
81
82    impl From<NcAlpha> for c_api::NcAlpha_u32 {
83        fn from(alpha: NcAlpha) -> Self {
84            use {c_api::*, NcAlpha::*};
85            match alpha {
86                Blend => NCALPHA_BLEND,
87                HighContrast => NCALPHA_HIGHCONTRAST,
88                Opaque => NCALPHA_OPAQUE,
89                Transparent => NCALPHA_TRANSPARENT,
90            }
91        }
92    }
93}
94
95impl NcAlpha {
96    /// Displays the short name identifier of the alpha value.
97    pub fn display_short(&self) -> &str {
98        use NcAlpha::*;
99        match self {
100            Blend => "B",
101            HighContrast => "H",
102            Opaque => "O",
103            Transparent => "T",
104        }
105    }
106}
107
108pub(crate) mod c_api {
109    use crate::c_api::ffi;
110
111    #[allow(unused_imports)] // for doc comments
112    use crate::NcCell;
113
114    /// 2 bits of alpha (surrounded by context dependent bits)
115    /// part of an [`NcChannel`][crate::NcChannel].
116    ///
117    /// It's recommended to use [`NcAlpha`][crate::NcAlpha] instead.
118    ///
119    /// # Associated `c_api` constants
120    ///
121    /// - [`NCALPHA_BLEND`]
122    /// - [`NCALPHA_HIGHCONTRAST`]
123    /// - [`NCALPHA_OPAQUE`]
124    /// - [`NCALPHA_TRANSPARENT`]
125    ///
126    /// ## Diagram
127    ///
128    /// ```txt
129    /// ~~AA~~~~ -------- -------- --------
130    /// ```
131    /// `type in C: no data type`
132    pub type NcAlpha_u32 = u32;
133
134    /// [`NcAlpha_u32`] bits indicating [`NcCell`]'s foreground or background color
135    /// will be a composite between its color and the `NcCell`s' corresponding
136    /// colors underneath it.
137    pub const NCALPHA_BLEND: NcAlpha_u32 = ffi::NCALPHA_BLEND;
138
139    /// [`NcAlpha_u32`] bits indicating [`NcCell`]'s foreground color will be
140    /// high-contrast (relative to the computed background).
141    /// Background cannot be high-contrast.
142    pub const NCALPHA_HIGHCONTRAST: NcAlpha_u32 = ffi::NCALPHA_HIGHCONTRAST;
143
144    /// [`NcAlpha_u32`] bits indicating [`NcCell`]'s foreground or background color
145    /// is used unchanged.
146    pub const NCALPHA_OPAQUE: NcAlpha_u32 = ffi::NCALPHA_OPAQUE;
147
148    /// [`NcAlpha_u32`] bits indicating [`NcCell`]'s foreground or background color
149    /// is derived entirely from the `NcCell`s underneath it.
150    pub const NCALPHA_TRANSPARENT: NcAlpha_u32 = ffi::NCALPHA_TRANSPARENT;
151}
libnotcurses_sys/alpha.rs

libnotcurses_sys/
alpha.rs
