gpui-cn 0.7.0

//! Immutable frames the engine publishes to the UI.
//!
//! A frame is everything a renderer needs to draw one viewport: the rows as
//! text with cell spans and style runs, the cursor, the colors, the scroll
//! metrics and the input modes. Rows are `Arc`s so a frame that changes one
//! row shares the rest with the previous frame.
//!
//! Derived from Herdr (Apache-2.0).

use std::ops::Range;
use std::sync::Arc;

use ghostty_vt::render::RowId;
use ghostty_vt::style::Palette;

/// An 8-bit RGB color.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
pub struct Rgb(pub u8, pub u8, pub u8);

/// A cell color as the program set it.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub enum Color {
    /// The terminal default for that slot.
    #[default]
    Default,
    /// A 256-color palette index.
    Indexed(u8),
    /// A direct color.
    Rgb(Rgb),
}

/// Underline styles, in SGR 4:n order.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub enum Underline {
    /// No underline.
    #[default]
    None,
    /// A single line.
    Single,
    /// Two lines.
    Double,
    /// A wavy line.
    Curly,
    /// A dotted line.
    Dotted,
    /// A dashed line.
    Dashed,
}

/// The visual attributes of a run of cells.
#[derive(Clone, Debug, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct Style {
    /// Foreground color.
    pub foreground: Color,
    /// Background color.
    pub background: Color,
    /// Underline color; `Default` means the foreground.
    pub underline_color: Color,
    /// Bold.
    pub bold: bool,
    /// Italic.
    pub italic: bool,
    /// Faint, drawn at half opacity.
    pub faint: bool,
    /// Blink.
    pub blink: bool,
    /// Inverse video: foreground and background swapped.
    pub inverse: bool,
    /// Invisible: the text is drawn in the background color.
    pub invisible: bool,
    /// Underline style.
    pub underline: Underline,
    /// Strikethrough.
    pub strikethrough: bool,
    /// Overline.
    pub overline: bool,
}

/// One grid cell of a row: its bytes in the row text and its width.
#[derive(Clone, Debug, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct CellSpan {
    /// The cell's bytes in [`TerminalRow::text`]. Empty for a spacer.
    pub text: Range<usize>,
    /// The column of the cell.
    pub column: u16,
    /// Width in columns: 1, or 2 for a wide character. 0 for a spacer.
    pub width: u8,
    /// Whether this is the tail of a wide character or a wrap spacer, which
    /// is never drawn.
    pub spacer: bool,
    /// The OSC 8 hyperlink on the cell.
    pub hyperlink: Option<Arc<str>>,
}

/// A run of consecutive cells with one style.
#[derive(Clone, Debug, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct StyleRun {
    /// The run's bytes in [`TerminalRow::text`].
    pub text: Range<usize>,
    /// The run's columns.
    pub columns: Range<u16>,
    /// The style of every cell in the run.
    pub style: Style,
}

/// One row of the viewport.
#[derive(Clone, Debug, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct TerminalRow {
    /// The engine's identity for the row. It stays with the row as it
    /// scrolls, so a renderer can key a cache on it.
    pub id: RowId,
    /// The frame revision the row was last rebuilt in.
    pub revision: u64,
    /// The row's text, one grapheme cluster per non-spacer cell, with a
    /// space for an empty cell.
    pub text: Arc<str>,
    /// One span per column.
    pub cells: Arc<[CellSpan]>,
    /// The style runs covering the row.
    pub runs: Arc<[StyleRun]>,
    /// Whether the row continues on the next row.
    pub soft_wrapped: bool,
}

/// Cursor shapes.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub enum CursorShape {
    /// A filled block.
    #[default]
    Block,
    /// A vertical bar.
    Bar,
    /// An underline.
    Underline,
    /// An outlined block, drawn when the terminal is not focused.
    Hollow,
}

/// The cursor as the program left it.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct Cursor {
    /// Column in the viewport.
    pub column: u16,
    /// Row in the viewport.
    pub row: u16,
    /// Whether the cursor is visible and inside the viewport.
    pub visible: bool,
    /// Whether the program asked for a blinking cursor.
    pub blinking: bool,
    /// The shape the program asked for.
    pub shape: CursorShape,
}

/// The colors a frame is drawn with.
#[derive(Clone, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub struct TerminalColors {
    /// Default foreground.
    pub(crate) foreground: Rgb,
    /// Default background.
    pub(crate) background: Rgb,
    /// Cursor color; `None` means the foreground.
    pub(crate) cursor: Option<Rgb>,
    /// Selection background; `None` means the default foreground.
    pub(crate) selection_background: Option<Rgb>,
    /// Selection foreground; `None` means the default background.
    pub(crate) selection_foreground: Option<Rgb>,
    /// The 256-color palette.
    pub(crate) palette: [Rgb; 256],
}

impl Default for TerminalColors {
    /// Ghostty's default palette with a light foreground on a dark
    /// background.
    fn default() -> Self {
        Self {
            foreground: Rgb(0xff, 0xff, 0xff),
            background: Rgb(0x28, 0x2c, 0x34),
            cursor: None,
            selection_background: None,
            selection_foreground: None,
            palette: Palette::default().0.map(|c| Rgb(c.r, c.g, c.b)),
        }
    }
}

impl TerminalColors {
    /// The default palette with the given foreground and background.
    #[must_use]
    pub fn new(foreground: Rgb, background: Rgb) -> Self {
        Self {
            foreground,
            background,
            ..Self::default()
        }
    }

    /// Set the cursor color.
    #[must_use]
    pub fn with_cursor(mut self, cursor: Rgb) -> Self {
        self.cursor = Some(cursor);
        self
    }

    /// Set the selection colors.
    #[must_use]
    pub fn with_selection(mut self, background: Rgb, foreground: Rgb) -> Self {
        self.selection_background = Some(background);
        self.selection_foreground = Some(foreground);
        self
    }

    /// Set one palette entry.
    #[must_use]
    pub fn with_palette_entry(mut self, index: u8, color: Rgb) -> Self {
        self.palette[usize::from(index)] = color;
        self
    }

    /// The default foreground.
    pub fn foreground(&self) -> Rgb {
        self.foreground
    }

    /// The default background.
    pub fn background(&self) -> Rgb {
        self.background
    }

    /// The cursor color; `None` means the foreground.
    pub fn cursor(&self) -> Option<Rgb> {
        self.cursor
    }

    /// The selection background; `None` means the default foreground, as
    /// in Ghostty.
    pub fn selection_background(&self) -> Option<Rgb> {
        self.selection_background
    }

    /// The selection foreground; `None` means the default background, as
    /// in Ghostty.
    pub fn selection_foreground(&self) -> Option<Rgb> {
        self.selection_foreground
    }

    /// The 256-color palette.
    pub fn palette(&self) -> &[Rgb; 256] {
        &self.palette
    }

    /// A gpui-cn theme config on these colors, for a [`ThemeScope`] that
    /// draws the chrome around a terminal, such as its tab strip, in the
    /// terminal's colors: the background is the surface and the
    /// foreground the ink. The accent, contrast, fonts, and semantic colors
    /// come from `theme`'s dark config on a dark background and its light
    /// config otherwise.
    ///
    /// [`ThemeScope`]: crate::ThemeScope
    pub fn theme_config(&self, theme: &crate::Theme) -> crate::ThemeConfig {
        let surface = crate::terminal::colors::hsla(self.background);
        let mut config = if crate::theme::lightness(surface) < 0.5 {
            theme.dark.clone()
        } else {
            theme.light.clone()
        };
        config.surface = surface;
        config.ink = crate::terminal::colors::hsla(self.foreground);
        config
    }
}

/// A linear or rectangular selection in viewport cells.
///
/// `start` and `end` are `(column, row)`, both inclusive.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub struct CellSelection {
    /// The first cell.
    pub start: (u16, u16),
    /// The last cell.
    pub end: (u16, u16),
    /// Whether the selection is a rectangle instead of a run of lines.
    pub rectangle: bool,
}

impl CellSelection {
    /// A selection from `start` to `end`.
    #[must_use]
    pub fn new(start: (u16, u16), end: (u16, u16), rectangle: bool) -> Self {
        Self {
            start,
            end,
            rectangle,
        }
    }
}

/// Where the viewport sits in the scrollable area.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct ScrollMetrics {
    /// Rows in scrollback plus the active area.
    pub total_rows: usize,
    /// The viewport's first row within `total_rows`.
    pub offset: usize,
    /// Rows in the viewport.
    pub viewport_rows: usize,
}

impl ScrollMetrics {
    /// Whether the viewport shows the bottom of the scrollback.
    #[must_use]
    pub fn at_bottom(self) -> bool {
        self.offset + self.viewport_rows >= self.total_rows
    }
}

/// Terminal modes the UI has to know about.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct InputModes {
    /// A program is receiving mouse reports.
    pub mouse_reporting: bool,
    /// The alternate screen is active.
    pub alternate_screen: bool,
    /// Bracketed paste is on.
    pub bracketed_paste: bool,
    /// Focus reporting (mode 1004) is on.
    pub focus_reporting: bool,
    /// Alternate scroll (mode 1007): wheel events become arrow keys on the
    /// alternate screen.
    pub alternate_scroll: bool,
}

/// The grid size and the cell size in device pixels.
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub struct Viewport {
    columns: u16,
    rows: u16,
    cell_width: u32,
    cell_height: u32,
}

impl Default for Viewport {
    fn default() -> Self {
        Self {
            columns: 80,
            rows: 24,
            cell_width: 8,
            cell_height: 16,
        }
    }
}

/// The largest grid the engine accepts on either axis.
pub const MAX_GRID: u16 = 1000;

impl Viewport {
    /// A viewport, rejecting empty grids, grids over [`MAX_GRID`] and cells
    /// over 4096 pixels.
    pub fn new(columns: u16, rows: u16, cell_width: u32, cell_height: u32) -> Option<Self> {
        if columns == 0
            || rows == 0
            || columns > MAX_GRID
            || rows > MAX_GRID
            || cell_width == 0
            || cell_height == 0
            || cell_width > 4096
            || cell_height > 4096
        {
            return None;
        }
        Some(Self {
            columns,
            rows,
            cell_width,
            cell_height,
        })
    }
    /// Columns.
    #[must_use]
    pub fn columns(self) -> u16 {
        self.columns
    }
    /// Rows.
    #[must_use]
    pub fn rows(self) -> u16 {
        self.rows
    }
    /// Cell width in device pixels.
    #[must_use]
    pub fn cell_width(self) -> u32 {
        self.cell_width
    }
    /// Cell height in device pixels.
    #[must_use]
    pub fn cell_height(self) -> u32 {
        self.cell_height
    }
}

/// One rendered viewport.
#[derive(Clone, Debug, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct TerminalFrame {
    /// Increments on every published frame.
    pub revision: u64,
    /// Increments when the rows, the viewport or the scroll position change,
    /// so a selection anchored to content knows when it moved.
    pub content_revision: u64,
    /// The grid this frame was built for.
    pub viewport: Viewport,
    /// The viewport rows, top to bottom.
    pub rows: Arc<[Arc<TerminalRow>]>,
    /// The cursor.
    pub cursor: Cursor,
    /// The colors.
    pub colors: TerminalColors,
    /// The scroll position.
    pub scroll: ScrollMetrics,
    /// The input modes.
    pub modes: InputModes,
}

impl TerminalFrame {
    /// The rows as text, trailing spaces trimmed, joined with newlines.
    #[must_use]
    pub fn text(&self) -> String {
        self.rows
            .iter()
            .map(|row| row.text.trim_end())
            .collect::<Vec<_>>()
            .join("\n")
    }
}

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

    #[test]
    fn the_default_colors_are_ghosttys_built_in_ones() {
        // Ghostty's src/config/Config.zig at the pinned commit: `background`
        // #282c34, `foreground` #ffffff, and no cursor or selection color.
        let colors = TerminalColors::default();
        assert_eq!(colors.background(), Rgb(0x28, 0x2c, 0x34));
        assert_eq!(colors.foreground(), Rgb(0xff, 0xff, 0xff));
        assert_eq!(colors.cursor(), None);
        assert_eq!(colors.selection_background(), None);
        assert_eq!(colors.selection_foreground(), None);
        assert_eq!(colors.palette()[1], Rgb(0xcc, 0x66, 0x66));
    }

    #[test]
    fn viewport_rejects_bad_sizes() {
        assert!(Viewport::new(0, 1, 8, 16).is_none());
        assert!(Viewport::new(1, 0, 8, 16).is_none());
        assert!(Viewport::new(1001, 1, 8, 16).is_none());
        assert!(Viewport::new(1, 1, 0, 16).is_none());
        assert!(Viewport::new(80, 24, 8, 16).is_some());
    }

    #[test]
    fn scroll_metrics_know_the_bottom() {
        assert!(
            ScrollMetrics {
                total_rows: 30,
                offset: 6,
                viewport_rows: 24
            }
            .at_bottom()
        );
        assert!(
            !ScrollMetrics {
                total_rows: 30,
                offset: 0,
                viewport_rows: 24
            }
            .at_bottom()
        );
    }
}