alacritty/src/cursor.rs

//! Helpers for creating different cursor glyphs from font metrics.

use std::cmp;

use crossfont::{BitmapBuffer, Metrics, RasterizedGlyph};

use alacritty_terminal::ansi::CursorStyle;

pub fn get_cursor_glyph(
    cursor: CursorStyle,
    metrics: Metrics,
    offset_x: i8,
    offset_y: i8,
    is_wide: bool,
    cursor_thickness: f64,
) -> RasterizedGlyph {
    // Calculate the cell metrics.
    let height = metrics.line_height as i32 + i32::from(offset_y);
    let mut width = metrics.average_advance as i32 + i32::from(offset_x);

    let line_width = cmp::max((cursor_thickness * f64::from(width)).round() as i32, 1);

    // Double the cursor width if it's above a double-width glyph.
    if is_wide {
        width *= 2;
    }

    match cursor {
        CursorStyle::HollowBlock => get_box_cursor_glyph(height, width, line_width),
        CursorStyle::Underline => get_underline_cursor_glyph(width, line_width),
        CursorStyle::Beam => get_beam_cursor_glyph(height, line_width),
        CursorStyle::Block => get_block_cursor_glyph(height, width),
        CursorStyle::Hidden => RasterizedGlyph::default(),
    }
}

/// Return a custom underline cursor character.
pub fn get_underline_cursor_glyph(width: i32, line_width: i32) -> RasterizedGlyph {
    // Create a new rectangle, the height is relative to the font width.
    let buf = vec![255u8; (width * line_width * 3) as usize];

    // Create a custom glyph with the rectangle data attached to it.
    RasterizedGlyph {
        c: ' ',
        top: line_width,
        left: 0,
        height: line_width,
        width,
        buf: BitmapBuffer::RGB(buf),
    }
}

/// Return a custom beam cursor character.
pub fn get_beam_cursor_glyph(height: i32, line_width: i32) -> RasterizedGlyph {
    // Create a new rectangle that is at least one pixel wide
    let buf = vec![255u8; (line_width * height * 3) as usize];

    // Create a custom glyph with the rectangle data attached to it
    RasterizedGlyph {
        c: ' ',
        top: height,
        left: 0,
        height,
        width: line_width,
        buf: BitmapBuffer::RGB(buf),
    }
}

/// Returns a custom box cursor character.
pub fn get_box_cursor_glyph(height: i32, width: i32, line_width: i32) -> RasterizedGlyph {
    // Create a new box outline rectangle.
    let mut buf = Vec::with_capacity((width * height * 3) as usize);
    for y in 0..height {
        for x in 0..width {
            if y < line_width
                || y >= height - line_width
                || x < line_width
                || x >= width - line_width
            {
                buf.append(&mut vec![255u8; 3]);
            } else {
                buf.append(&mut vec![0u8; 3]);
            }
        }
    }

    // Create a custom glyph with the rectangle data attached to it.
    RasterizedGlyph { c: ' ', top: height, left: 0, height, width, buf: BitmapBuffer::RGB(buf) }
}

/// Return a custom block cursor character.
pub fn get_block_cursor_glyph(height: i32, width: i32) -> RasterizedGlyph {
    // Create a completely filled glyph.
    let buf = vec![255u8; (width * height * 3) as usize];

    // Create a custom glyph with the rectangle data attached to it.
    RasterizedGlyph { c: ' ', top: height, left: 0, height, width, buf: BitmapBuffer::RGB(buf) }
}