river_bsp_layout/

lib.rs

pub mod user_cmd;

use clap::Parser;
use river_layout_toolkit::{GeneratedLayout, Layout, Rectangle};
use std::fmt::Display;

/// Wrapper for errors relating to the creation or operation of a `BSPLayout`
#[non_exhaustive]
#[derive(Debug)]
pub enum BSPLayoutError {
    /// Encountered when a failure occurs in `user_cmd`
    CmdError(String),

    /// Encountered when there a failure occurs when generating a layout
    LayoutError(String),
}

impl Display for BSPLayoutError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{:?}", self)
    }
}

impl std::error::Error for BSPLayoutError {}

/// Create a Binary Space Partitioned layout. Specifically, this layout recursively
/// divides the screen in half. The split will alternate between vertical and horizontal
/// based on which side of the container is longer. This will result in a grid like
/// layout with more-or-less equal sized windows evenly distributed across the screen
pub struct BSPLayout {
    /// Number of pixels to put between the left inside edge of adjacent windows
    pub ig_left: u32,

    /// Number of pixels to put between the right inside edge of adjacent windows
    pub ig_right: u32,

    /// Number of pixels to put between the bottom inside edge of adjacent windows
    pub ig_bottom: u32,

    /// Number of pixels to put between the top inside edge of adjacent windows
    pub ig_top: u32,

    /// Number of pixels to put between the left screen edge and the adjacent windows
    pub og_left: u32,

    /// Number of pixels to put between the right screen edge and the adjacent windows
    pub og_right: u32,

    /// Number of pixels to put between the bottom screen edge and the adjacent windows
    pub og_bottom: u32,

    /// Number of pixels to put between the top screen edge and the adjacent windows
    pub og_top: u32,

    /// The percentage (between 0.0 and 1.0) of space that should be occupied by the primary window
    /// when a horizontal split takes place
    pub hsplit_perc: f32,

    /// The percentage (between 0.0 and 1.0) of space that should be occupied by the primary window
    /// when a vertical split takes place
    pub vsplit_perc: f32,

    /// Whether the first split should be horizontal or not. If true, then start by dividing the
    /// screen in half from right to left. If false, then start by dividing the screen in half from
    /// top to bottom
    pub start_hsplit: bool,

    /// If `true`, new views will be prepended to the list. Otherwise, new views will be appended.
    pub reversed: bool,
}

impl BSPLayout {
    /// Initialize a new instance of BSPLayout with inner gaps of 5 pixels and outer gaps of 10
    /// pixels on each side, a split percent of 50%, and starting on a vertical split
    ///
    /// # Returns
    ///
    /// A new `BSPLayout`
    pub fn new() -> BSPLayout {
        BSPLayout {
            ig_left: 5,
            ig_right: 5,
            ig_bottom: 5,
            ig_top: 5,
            og_left: 10,
            og_right: 10,
            og_top: 10,
            og_bottom: 10,
            hsplit_perc: 0.5,
            vsplit_perc: 0.5,
            reversed: false,
            start_hsplit: false,
        }
    }

    /// Sets all sides of outer gap to `new_gap`
    ///
    /// # Arguments
    ///
    /// * `new_gap` - The value to assign for the gap on all outer edges
    pub fn set_all_outer_gaps(&mut self, new_gap: u32) {
        self.og_top = new_gap;
        self.og_bottom = new_gap;
        self.og_left = new_gap;
        self.og_right = new_gap;
    }

    /// Sets all inner gaps to `new_gap`
    ///
    /// # Arguments
    ///
    /// * `new_gap` - The value to assign for the gap on all inner edges between windows
    pub fn set_all_inner_gaps(&mut self, new_gap: u32) {
        self.ig_top = new_gap;
        self.ig_left = new_gap;
        self.ig_right = new_gap;
        self.ig_bottom = new_gap;
    }

    /// Shared setup between vsplit and hsplit functions. First checks that vsplit_perc and
    /// hsplit_perc are in range, then creates the layout variable, and finally calculates how many
    /// views are in each half of the split
    ///
    /// # Arguments
    ///
    /// * `view_count` - The total number of views accross both splits
    ///
    /// # Returns
    ///
    /// Tuple containing - in order - `half_view_count`, `views_remaining`, and the initial layout
    /// variable
    ///
    /// # Errors
    ///
    /// If either split percentage is not > 0.0 and < 1.0, return `BSPLayoutError`
    fn setup_split(&self, view_count: u32) -> Result<(u32, u32, GeneratedLayout), BSPLayoutError> {
        if self.vsplit_perc <= 0.0
            || self.vsplit_perc >= 1.0
            || self.hsplit_perc <= 0.0
            || self.hsplit_perc >= 1.0
        {
            return Err(BSPLayoutError::LayoutError(
                "Split percents must be > 0.0 and less than 1.0".to_string(),
            ));
        }
        let layout = GeneratedLayout {
            layout_name: "bsp-layout".to_string(),
            views: Vec::with_capacity(view_count as usize),
        };

        let half_view_count = view_count / 2;
        let views_remaining = view_count % 2; // In case there are odd number of views

        Ok((half_view_count, views_remaining, layout))
    }

    /// Divide the screen in two by splitting from right to left first, then subsequently from
    /// top to bottom
    ///
    /// # Arguments
    ///
    /// * `origin_x` - The x position of the top left of the space to be divided
    /// relative to the entire display. For example, if you are dividing the entire
    /// display, then the top left corner is 0, 0. If you are dividing the right
    /// half of a 1920x1080 monitor, then the top left corner would be at 960, 0
    ///
    /// * `origin_y` - The y position of the top left of the space to be divided
    /// relative to the entire display. For example, if you are dividing the entire
    /// display, then the top left corner is 0, 0. If you are dividing the bottom
    /// half of a 1920x1080 monitor, then the top left corner would be at 0, 540
    ///
    /// * `canvas_width` - The width in pixels of the area being divided. If you
    /// are dividing all of a 1920x1080 monitor, then the `canvas_width` would be 1920.
    /// If you are dividing the right half of the monitor, then the width is 960.
    ///
    /// * `canvas_height` - The height in pixels of the area being divided. If you
    /// are dividing all of a 1920x1080 monitor, then the height would be 1080.
    /// If you are dividing the bottom half of the monitor, then the height is 540.
    ///
    /// * `view_count` - How many windows / containers / apps / division the function
    /// needs to make in total.
    ///
    /// # Returns
    ///
    /// A `GeneratedLayout` with `view_count` cells evenly distributed across the screen
    /// in a grid
    fn hsplit(
        &self,
        origin_x: i32,
        origin_y: i32,
        canvas_width: u32,
        canvas_height: u32,
        view_count: u32,
    ) -> Result<GeneratedLayout, BSPLayoutError> {
        let (half_view_count, views_remaining, mut layout) = self.setup_split(view_count)?;

        // Exit condition. When there is only one window left, it should take up the
        // entire available canvas
        if view_count == 1 {
            layout.views.push(Rectangle {
                x: origin_x,
                y: origin_y,
                width: canvas_width,
                height: canvas_height,
            });

            return Ok(layout);
        }

        let mut prime_split = (canvas_height as f32 * self.hsplit_perc) as u32;
        if prime_split == 0 {
            prime_split = 1;
        }
        if prime_split >= canvas_height {
            prime_split = canvas_height - 1;
        }
        let sec_split = canvas_height - prime_split;

        let (prime_sub, sec_sub) = if !self.reversed {
            (self.ig_bottom, self.ig_top)
        } else {
            (self.ig_top, self.ig_bottom)
        };

        let (prime_y, sec_y) = if !self.reversed {
            (origin_y, prime_split as i32 + origin_y + sec_sub as i32)
        } else {
            (sec_split as i32 + origin_y + prime_sub as i32, origin_y)
        };

        let mut prime_layout = self.vsplit(
            origin_x,
            prime_y,
            canvas_width,
            if prime_sub < prime_split {
                prime_split - prime_sub
            } else {
                1
            },
            half_view_count,
        )?;

        let mut sec_layout = self.vsplit(
            origin_x,
            sec_y,
            canvas_width,
            if sec_sub < sec_split {
                sec_split - sec_sub
            } else {
                1
            },
            half_view_count + views_remaining,
        )?;

        layout.views.append(&mut prime_layout.views);
        layout.views.append(&mut sec_layout.views);

        Ok(layout)
    }

    /// Divide the screen in two by splitting from top to bottom first, then subsequently from
    /// right to left
    ///
    /// # Arguments
    ///
    /// * `origin_x` - The x position of the top left of the space to be divided
    /// relative to the entire display. For example, if you are dividing the entire
    /// display, then the top left corner is 0, 0. If you are dividing the right
    /// half of a 1920x1080 monitor, then the top left corner would be at 960, 0
    ///
    /// * `origin_y` - The y position of the top left of the space to be divided
    /// relative to the entire display. For example, if you are dividing the entire
    /// display, then the top left corner is 0, 0. If you are dividing the bottom
    /// half of a 1920x1080 monitor, then the top left corner would be at 0, 540
    ///
    /// * `canvas_width` - The width in pixels of the area being divided. If you
    /// are dividing all of a 1920x1080 monitor, then the `canvas_width` would be 1920.
    /// If you are dividing the right half of the monitor, then the width is 960.
    ///
    /// * `canvas_height` - The height in pixels of the area being divided. If you
    /// are dividing all of a 1920x1080 monitor, then the height would be 1080.
    /// If you are dividing the bottom half of the monitor, then the height is 540.
    ///
    /// * `view_count` - How many windows / containers / apps / division the function
    /// needs to make in total.
    ///
    /// # Returns
    ///
    /// A `GeneratedLayout` with `view_count` cells evenly distributed across the screen
    /// in a grid
    fn vsplit(
        &self,
        origin_x: i32,
        origin_y: i32,
        canvas_width: u32,
        canvas_height: u32,
        view_count: u32,
    ) -> Result<GeneratedLayout, BSPLayoutError> {
        let (half_view_count, views_remaining, mut layout) = self.setup_split(view_count)?;

        // Exit condition. When there is only one window left, it should take up the
        // entire available canvas
        if view_count == 1 {
            layout.views.push(Rectangle {
                x: origin_x,
                y: origin_y,
                width: canvas_width,
                height: canvas_height,
            });

            return Ok(layout);
        }

        let mut prime_split = (canvas_width as f32 * self.vsplit_perc) as u32;
        if prime_split == 0 {
            prime_split = 1;
        }
        if prime_split >= canvas_width {
            prime_split = canvas_width - 1;
        }

        let sec_split = canvas_width - prime_split;

        let (prime_sub, sec_sub) = if !self.reversed {
            (self.ig_right, self.ig_left)
        } else {
            (self.ig_left, self.ig_right)
        };

        let (prime_x, sec_x) = if !self.reversed {
            (origin_x, prime_split as i32 + origin_x + sec_sub as i32)
        } else {
            (sec_split as i32 + origin_x + prime_sub as i32, origin_x)
        };

        let mut prime_layout = self.hsplit(
            prime_x,
            origin_y,
            if prime_sub < prime_split {
                prime_split - prime_sub
            } else {
                1
            },
            canvas_height,
            half_view_count,
        )?;

        let mut sec_layout = self.hsplit(
            sec_x,
            origin_y,
            if sec_sub < sec_split {
                sec_split - sec_sub
            } else {
                1
            },
            canvas_height,
            half_view_count + views_remaining,
        )?;

        layout.views.append(&mut prime_layout.views);
        layout.views.append(&mut sec_layout.views);

        Ok(layout)
    }
}

impl Layout for BSPLayout {
    type Error = BSPLayoutError;

    const NAMESPACE: &'static str = "bsp-layout";

    /// Handle commands passed to the layout with `send-layout-cmd`. Supports individually setting
    /// the gaps on each side of the screen as well as inner edges. Also supports setting all outer
    /// and inner gaps at the same time
    ///
    /// # Examples
    ///
    /// ```
    /// use river_bsp_layout::BSPLayout;
    /// use river_layout_toolkit::Layout;
    ///
    /// // Initialize layout with 0 gaps
    /// let mut bsp = BSPLayout::new();
    /// bsp.set_all_inner_gaps(0);
    /// bsp.set_all_outer_gaps(0);
    ///
    /// // Set gap between windows and the monitor edge to be 5 pixels
    /// let res = bsp.user_cmd("--outer-gap 5".to_string(), None, "eDP-1").unwrap();
    /// assert_eq!(bsp.og_top, 5);
    /// assert_eq!(bsp.og_bottom, 5);
    /// assert_eq!(bsp.og_right, 5);
    /// assert_eq!(bsp.og_left, 5);
    /// ```
    ///
    /// # Errors
    ///
    /// Will return `BSPLayoutError::CmdError` if an unrecognized command is passed
    /// or if an invalid argument is passed to a valid command.
    fn user_cmd(
        &mut self,
        cmd: String,
        _tags: Option<u32>,
        _output: &str,
    ) -> Result<(), Self::Error> {
        let mut cmd: Vec<&str> = cmd.split(" ").collect();
        cmd.insert(0, "");
        let cmd = match user_cmd::UserCmd::try_parse_from(cmd) {
            Ok(c) => c,
            Err(e) => {
                eprintln!("{}", e);
                return Ok(());
            }
        };

        cmd.handle_outer_gaps(self);
        cmd.handle_inner_gaps(self);
        cmd.handle_start_split(self)?;
        cmd.handle_set_split(self);
        cmd.handle_ch_split(self);
        cmd.handle_reverse(self);

        Ok(())
    }

    /// Create the geometry for the `BSPLayout`
    ///
    /// # Arguments
    ///
    /// * `view_count` - The number of views / windows / containers to divide the screen into
    /// * `usable_width` - How many pixels wide the whole display is
    /// * `usable_height` - How many pixels tall the whole display is
    /// * `_tags` - Int representing which tags are currently active based on which
    /// bit is toggled
    /// * `_output` - The name of the output to generate the layout on
    ///
    /// # Examples
    ///
    /// ```
    /// use river_bsp_layout::BSPLayout;
    /// use river_layout_toolkit::Layout;
    ///
    /// let mut bsp = BSPLayout::new();
    /// bsp.generate_layout(2, 1920, 1080, 0b000000001, "eDP-1").unwrap();
    /// ```
    fn generate_layout(
        &mut self,
        view_count: u32,
        usable_width: u32,
        usable_height: u32,
        _tags: u32,
        _output: &str,
    ) -> Result<GeneratedLayout, Self::Error> {
        if !self.start_hsplit {
            Ok(self.vsplit(
                self.og_left as i32,
                self.og_top as i32,
                usable_width - self.og_left - self.og_right,
                usable_height - self.og_top - self.og_bottom,
                view_count,
            ))?
        } else {
            Ok(self.hsplit(
                self.og_left as i32,
                self.og_top as i32,
                usable_width - self.og_left - self.og_right,
                usable_height - self.og_top - self.og_bottom,
                view_count,
            ))?
        }
    }
}