retroglyph-ui 0.5.0

//! [`Text`]: a single line of plain text in one [`Style`].
use retroglyph_core::color::Style;

use super::Widget;
use crate::Surface;
use crate::align::Align;
use crate::text::draw_clipped;

/// A single line of text in one [`Style`], clipped (not wrapped) to
/// `area.width()` columns. Only the first row of `area` is used.
///
/// The plain-content cousin of [`PrintLine`](super::PrintLine) (which
/// prints a multi-span [`Line`](retroglyph_core::text::Line), for mixed
/// styling within one line) and [`Paragraph`](super::Paragraph) (which
/// word-wraps across multiple lines): reach
/// for `Text` for a single already-one-line label or readout in a single
/// style, with no wrapping and no per-span styling. `style` defaults to
/// [`Style::new()`] and `align` to [`Align::Left`]; set them with
/// [`Text::style`]/[`Text::align`].
///
/// Unlike [`super::BoxBorder`], [`super::Gauge`], [`super::StatBar`],
/// [`super::Table`], and [`super::Button`], `Text` has no `theme()`/
/// `theme_on()` pair: a line of plain text has no single semantic
/// [`Theme`](crate::theme::Theme) role to map onto, so callers set `style` directly.
///
/// # Examples
///
/// ```
/// use retroglyph_core::grid::{Grid, Rect};
/// use retroglyph_ui::align::Align;
/// use retroglyph_ui::widget::{Text, Widget};
/// use retroglyph_ui::Surface;
///
/// let area = Rect::new(0, 0, 10, 1);
/// let mut grid = Grid::new(10, 1);
/// Text::new("OK")
///     .align(Align::Right)
///     .render(&mut Surface::new(&mut grid, area, 0));
/// ```
#[derive(Clone, Copy, Debug)]
pub struct Text<'a> {
    content: &'a str,
    style: Style,
    align: Align,
}

impl<'a> Text<'a> {
    /// A line of `content` in the default style, left-aligned.
    #[must_use]
    pub fn new(content: &'a str) -> Self {
        Self {
            content,
            style: Style::new(),
            align: Align::Left,
        }
    }

    /// Set the text's style.
    #[must_use]
    pub const fn style(mut self, style: Style) -> Self {
        self.style = style;
        self
    }

    /// Set how the line is aligned within `area.width()` columns.
    #[must_use]
    pub const fn align(mut self, align: Align) -> Self {
        self.align = align;
        self
    }
}

impl Widget for Text<'_> {
    fn render(&self, surface: &mut Surface<'_>) {
        let width = surface.width();
        if width == 0 {
            return;
        }
        let _ = draw_clipped(surface, (0, 0), width, self.content, self.align, self.style);
    }
}

#[cfg(test)]
mod tests {
    use retroglyph_core::color::Color;
    use retroglyph_core::grid::{Grid, Pos, Rect};

    use super::*;

    #[test]
    fn prints_the_content_in_the_given_style() {
        let area = Rect::new(0, 0, 10, 1);
        let mut grid = Grid::new(10, 1);
        Text::new("hi")
            .style(Style::new().fg(Color::WHITE))
            .render(&mut Surface::new(&mut grid, area, 0));

        assert_eq!(grid[Pos::new(0, 0)].glyph(), 'h');
        assert_eq!(grid[Pos::new(1, 0)].glyph(), 'i');
        assert_eq!(grid[Pos::new(0, 0)].style().foreground(), Color::WHITE);
    }

    #[test]
    fn clips_to_area_width() {
        let area = Rect::new(0, 0, 5, 1);
        let mut grid = Grid::new(5, 1);
        Text::new("a much longer message than fits").render(&mut Surface::new(&mut grid, area, 0));

        assert_eq!(grid[Pos::new(4, 0)].glyph(), 'c'); // "a muc"
    }

    #[test]
    fn right_align_places_text_against_the_right_edge() {
        let area = Rect::new(0, 0, 10, 1);
        let mut grid = Grid::new(10, 1);
        Text::new("hi")
            .align(Align::Right)
            .render(&mut Surface::new(&mut grid, area, 0));

        // "hi" (2 cols) in 10 cols, right-aligned: starts at column 8.
        assert_eq!(grid[Pos::new(8, 0)].glyph(), 'h');
        assert_eq!(grid[Pos::new(9, 0)].glyph(), 'i');
        assert_eq!(grid[Pos::new(7, 0)].glyph(), ' ');
    }

    #[test]
    fn center_align_centers_text() {
        let area = Rect::new(0, 0, 10, 1);
        let mut grid = Grid::new(10, 1);
        Text::new("hi")
            .align(Align::Center)
            .render(&mut Surface::new(&mut grid, area, 0));

        // 8 cols slack, 4 on the left: "hi" starts at column 4.
        assert_eq!(grid[Pos::new(4, 0)].glyph(), 'h');
        assert_eq!(grid[Pos::new(5, 0)].glyph(), 'i');
    }

    #[test]
    fn zero_width_is_a_no_op() {
        let area = Rect::new(0, 0, 0, 1);
        let mut grid = Grid::new(1, 1);
        Text::new("hi").render(&mut Surface::new(&mut grid, area, 0));
        assert_eq!(grid[Pos::new(0, 0)].glyph(), ' ');
    }
}