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//! Draw text

use crate::{
    character::CharacterCache,
    color,
    math::Matrix2d,
    math::Vec2d,
    types::{Color, FontSize},
    DrawState, Graphics, Image, Transformed,
};

/// Renders text
#[derive(Copy, Clone)]
pub struct Text {
    /// The color
    pub color: Color,
    /// The font size
    pub font_size: FontSize,
    /// Whether or not the text's position should be rounded (to a signed distance field).
    pub round: bool,
}

impl Text {
    /// Creates a new text with black color
    pub fn new(font_size: FontSize) -> Text {
        Text {
            color: color::BLACK,
            font_size,
            round: false,
        }
    }

    /// Creates a new colored text
    pub fn new_color(color: Color, font_size: FontSize) -> Text {
        Text {
            color,
            font_size,
            round: false,
        }
    }

    /// A builder method indicating that the Text's position should be rounded upon drawing.
    pub fn round(mut self) -> Text {
        self.round = true;
        self
    }

    /// Draws text at position with a character cache
    pub fn draw_pos<C, G>(
        &self,
        text: &str,
        pos: Vec2d,
        cache: &mut C,
        draw_state: &DrawState,
        transform: Matrix2d,
        g: &mut G,
    ) -> Result<(), C::Error>
    where
        C: CharacterCache,
        G: Graphics<Texture = <C as CharacterCache>::Texture>,
    {
        self.draw(text, cache, draw_state, transform.trans_pos(pos), g)
    }

    /// Draws text with a character cache
    pub fn draw<C, G>(
        &self,
        text: &str,
        cache: &mut C,
        draw_state: &DrawState,
        transform: Matrix2d,
        g: &mut G,
    ) -> Result<(), C::Error>
    where
        C: CharacterCache,
        G: Graphics<Texture = <C as CharacterCache>::Texture>,
    {
        let mut image = Image::new_color(self.color);

        let mut x = 0.0;
        let mut y = 0.0;
        for ch in text.chars() {
            let character = cache.character(self.font_size, ch)?;
            let mut ch_x = x + character.left();
            let mut ch_y = y - character.top();
            if self.round {
                ch_x = ch_x.round();
                ch_y = ch_y.round();
            }
            image = image.src_rect([
                character.atlas_offset[0],
                character.atlas_offset[1],
                character.atlas_size[0],
                character.atlas_size[1],
            ]);
            image.draw(
                character.texture,
                draw_state,
                transform.trans(ch_x, ch_y),
                g,
            );
            x += character.advance_width();
            y += character.advance_height();
        }

        Ok(())
    }
}