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//! Direction-related structures. //! //! This module defines two main concepts: [`Orientation`] and [`Direction`]. //! //! [`Orientation`]: enum.Orientation.html //! [`Direction`]: enum.Direction.html //! //! ### Orientation //! //! `Orientation` is a simple enum that can take two values: //! `Horizontal` or `Vertical`. //! //! ### Direction //! //! `Direction` is a bit more complex, and can be of two kinds: //! //! * Absolute direction: left, up, right, or down //! * Relative direction: front or back. Its actual direction depends on the //! orientation. //! //! Usually, "front" refers to the "forward" direction, or the "next" //! element. For example, for a vertical `LinearLayout`, "front" would refer //! to the "down" direction. //! //! This is mostly relevant when referring to change of focus. Hitting the //! `Tab` key would usually cycle focus in the "front" direction, while //! using the arrow keys would use absolute directions instead. use crate::Vec2; use crate::XY; /// Describes a vertical or horizontal orientation for a view. #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)] pub enum Orientation { /// Horizontal orientation Horizontal, /// Vertical orientation Vertical, } impl Orientation { /// Returns a `XY(Horizontal, Vertical)`. pub fn pair() -> XY<Orientation> { XY::new(Orientation::Horizontal, Orientation::Vertical) } /// Returns the component of `v` corresponding to this orientation. /// /// (`Horizontal` will return the x value, /// and `Vertical` will return the y value.) pub fn get<T: Clone>(self, v: &XY<T>) -> T { v.get(self).clone() } /// Returns the other orientation. pub fn swap(self) -> Self { match self { Orientation::Horizontal => Orientation::Vertical, Orientation::Vertical => Orientation::Horizontal, } } /// Returns a mutable reference to the component of the given vector /// corresponding to this orientation. /// /// # Examples /// ```rust /// # use cursive_core::XY; /// # use cursive_core::direction::Orientation; /// let o = Orientation::Horizontal; /// let mut xy = XY::new(1, 2); /// *o.get_ref(&mut xy) = 42; /// /// assert_eq!(xy, XY::new(42, 2)); /// ``` pub fn get_ref<T>(self, v: &mut XY<T>) -> &mut T { match self { Orientation::Horizontal => &mut v.x, Orientation::Vertical => &mut v.y, } } /// Takes an iterator on sizes, and stack them in the current orientation, /// returning the size of the required bounding box. /// /// * For an horizontal view, returns `(Sum(x), Max(y))`. /// * For a vertical view, returns `(Max(x), Sum(y))`. pub fn stack<T: Iterator<Item = Vec2>>(self, iter: T) -> Vec2 { match self { Orientation::Horizontal => { iter.fold(Vec2::zero(), |a, b| a.stack_horizontal(&b)) } Orientation::Vertical => { iter.fold(Vec2::zero(), |a, b| a.stack_vertical(&b)) } } } /// Creates a new `Vec2` with `main_axis` in `self`'s axis, and /// `second_axis` for the other axis. /// /// # Examples /// /// ```rust /// # use cursive_core::direction::Orientation; /// # use cursive_core::Vec2; /// let o = Orientation::Horizontal; /// let vec = o.make_vec(1, 2); /// /// assert_eq!(vec, Vec2::new(1, 2)); /// /// let o = Orientation::Vertical; /// let vec = o.make_vec(1, 2); /// /// assert_eq!(vec, Vec2::new(2, 1)); /// ``` pub fn make_vec(self, main_axis: usize, second_axis: usize) -> Vec2 { let mut result = Vec2::zero(); *self.get_ref(&mut result) = main_axis; *self.swap().get_ref(&mut result) = second_axis; result } } /// Represents a direction, either absolute or orientation-dependent. /// /// * Absolute directions are Up, Down, Left, and Right. /// * Relative directions are Front and Back. #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] pub enum Direction { /// An absolute direction. Abs(Absolute), /// A direction relative to the current orientation. Rel(Relative), } impl Direction { /// Returns the relative direction for the given orientation. /// /// Some combination have no corresponding relative position. For example, /// `Direction::Abs(Up)` means nothing for `Orientation::Horizontal`. pub fn relative(self, orientation: Orientation) -> Option<Relative> { match self { Direction::Abs(abs) => abs.relative(orientation), Direction::Rel(rel) => Some(rel), } } /// Returns the absolute direction in the given `orientation`. pub fn absolute(self, orientation: Orientation) -> Absolute { match self { Direction::Abs(abs) => abs, Direction::Rel(rel) => rel.absolute(orientation), } } /// Returns the direction opposite `self`. pub fn opposite(self) -> Self { match self { Direction::Abs(abs) => Direction::Abs(abs.opposite()), Direction::Rel(rel) => Direction::Rel(rel.swap()), } } /// Shortcut to create `Direction::Rel(Relative::Back)` pub fn back() -> Self { Direction::Rel(Relative::Back) } /// Shortcut to create `Direction::Rel(Relative::Front)` pub fn front() -> Self { Direction::Rel(Relative::Front) } /// Shortcut to create `Direction::Abs(Absolute::Left)` pub fn left() -> Self { Direction::Abs(Absolute::Left) } /// Shortcut to create `Direction::Abs(Absolute::Right)` pub fn right() -> Self { Direction::Abs(Absolute::Right) } /// Shortcut to create `Direction::Abs(Absolute::Up)` pub fn up() -> Self { Direction::Abs(Absolute::Up) } /// Shortcut to create `Direction::Abs(Absolute::Down)` pub fn down() -> Self { Direction::Abs(Absolute::Down) } /// Shortcut to create `Direction::Abs(Absolute::None)` pub fn none() -> Self { Direction::Abs(Absolute::None) } } /// Direction relative to an orientation. #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] pub enum Relative { // TODO: handle right-to-left? (Arabic, ...) /// Front relative direction. /// /// * Horizontally, this means `Left` /// * Vertically, this means `Up` Front, /// Back relative direction. /// /// * Horizontally, this means `Right` /// * Vertically, this means `Down`. Back, } impl Relative { /// Returns the absolute direction in the given `orientation`. pub fn absolute(self, orientation: Orientation) -> Absolute { match (orientation, self) { (Orientation::Horizontal, Relative::Front) => Absolute::Left, (Orientation::Horizontal, Relative::Back) => Absolute::Right, (Orientation::Vertical, Relative::Front) => Absolute::Up, (Orientation::Vertical, Relative::Back) => Absolute::Down, } } /// Picks one of the two values in a tuple. /// /// First one is `self` is `Front`, second one if `self` is `Back`. pub fn pick<T>(self, (front, back): (T, T)) -> T { match self { Relative::Front => front, Relative::Back => back, } } /// Returns the other relative direction. pub fn swap(self) -> Self { match self { Relative::Front => Relative::Back, Relative::Back => Relative::Front, } } /// Returns the relative position of `a` to `b`. /// /// If `a < b`, it would be `Front`. /// If `a > b`, it would be `Back`. /// If `a == b`, returns `None`. pub fn a_to_b(a: usize, b: usize) -> Option<Self> { use std::cmp::Ordering; match a.cmp(&b) { Ordering::Less => Some(Relative::Front), Ordering::Greater => Some(Relative::Back), Ordering::Equal => None, } } } /// Absolute direction (up, down, left, right). #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] pub enum Absolute { /// Left Left, /// Up Up, /// Right Right, /// Down Down, /// No real direction. /// /// Used when the "direction" is accross layers for instance. None, } impl Absolute { /// Returns the relative direction for the given orientation. /// /// Returns `None` when the direction does not apply to the given /// orientation (ex: `Left` and `Vertical`). pub fn relative(self, orientation: Orientation) -> Option<Relative> { match (orientation, self) { (Orientation::Horizontal, Absolute::Left) | (Orientation::Vertical, Absolute::Up) => Some(Relative::Front), (Orientation::Horizontal, Absolute::Right) | (Orientation::Vertical, Absolute::Down) => Some(Relative::Back), _ => None, } } /// Returns the direction opposite `self`. pub fn opposite(self) -> Self { match self { Absolute::Left => Absolute::Right, Absolute::Right => Absolute::Left, Absolute::Up => Absolute::Down, Absolute::Down => Absolute::Up, Absolute::None => Absolute::None, } } /// Splits this absolute direction into an orientation and relative direction. /// /// For example, `Right` will give `(Horizontal, Back)`. pub fn split(self) -> (Orientation, Relative) { match self { Absolute::Left => (Orientation::Horizontal, Relative::Front), Absolute::Right => (Orientation::Horizontal, Relative::Back), Absolute::Up => (Orientation::Vertical, Relative::Front), Absolute::Down => (Orientation::Vertical, Relative::Back), // TODO: Remove `Absolute::None` Absolute::None => panic!("None direction not supported here"), } } }