rust_animation/
font.rs

1// Adapted from the file below:
2// https://github.com/alexheretic/ab-glyph/blob/main/dev/examples/image.rs
3
4use ab_glyph::{point, Font, FontVec, Glyph, Point, PxScale, ScaleFont};
5use image::{DynamicImage, ImageBuffer, Rgba};
6
7pub struct FontRenderer {
8  font_path: String,
9  font: Option<FontVec>,
10}
11
12impl FontRenderer {
13  pub fn new(font_path: String) -> Self {
14    let mut font_renderer = FontRenderer {
15      font_path: "".to_string(),
16      font: None,
17    };
18    font_renderer.load_font(font_path);
19
20    font_renderer
21  }
22
23  pub fn load_font(&mut self, font_path: String) {
24    println!("load_font: {}", font_path);
25    let font_path = std::env::current_dir().unwrap().join(font_path);
26    let data = std::fs::read(&font_path).unwrap();
27
28    match &mut self.font {
29      Some(_font) => {
30        println!("font already loaded");
31      }
32      None => {
33        println!("loading font...");
34        self.font = Some(FontVec::try_from_vec(data).unwrap_or_else(|_| {
35          panic!("error constructing a Font from data at {:?}", font_path);
36        }));
37        if let Some(name) = font_path.file_name().and_then(|n| n.to_str()) {
38          eprintln!("Using font: {name}");
39        }
40
41        self.font_path = font_path.to_str().unwrap().to_string();
42      }
43    }
44  }
45
46  pub fn render(&mut self, text: &str) -> ImageBuffer<Rgba<u8>, Vec<u8>> {
47    // The font size to use
48    let scale = PxScale::from(45.0);
49
50    let font = self.font.as_ref().unwrap();
51    let scaled_font = font.as_scaled(scale);
52
53    let mut glyphs = Vec::new();
54    self.layout_paragraph(scaled_font, point(20.0, 20.0), 9999.0, text, &mut glyphs);
55
56    // Use a dark red colour
57    let colour = (255, 0, 0);
58
59    // work out the layout size
60    let glyphs_height = scaled_font.height().ceil() as u32;
61    let glyphs_width = {
62      let min_x = glyphs.first().unwrap().position.x;
63      let last_glyph = glyphs.last().unwrap();
64      let max_x = last_glyph.position.x + scaled_font.h_advance(last_glyph.id);
65      (max_x - min_x).ceil() as u32
66    };
67
68    println!(
69      "glyphs_width: {}, glyphs_height: {}",
70      glyphs_width, glyphs_height
71    );
72
73    // Create a new rgba image with some padding
74    let mut image = DynamicImage::new_rgba8(glyphs_width + 40, glyphs_height + 40).to_rgba8();
75
76    // Loop through the glyphs in the text, positing each one on a line
77    for glyph in glyphs {
78      if let Some(outlined) = scaled_font.outline_glyph(glyph) {
79        let bounds = outlined.px_bounds();
80        // Draw the glyph into the image per-pixel by using the draw closure
81        outlined.draw(|x, y, v| {
82          // Offset the position by the glyph bounding box
83          let px = image.get_pixel_mut(x + bounds.min.x as u32, y + bounds.min.y as u32);
84          // Turn the coverage into an alpha value (blended with any previous)
85          *px = Rgba([
86            colour.0,
87            colour.1,
88            colour.2,
89            px.0[3].saturating_add((v * 255.0) as u8),
90          ]);
91        });
92      }
93    }
94
95    // Return the image buffer
96    image
97  }
98
99  pub fn layout_paragraph<F, SF>(
100    &self,
101    font: SF,
102    position: Point,
103    max_width: f32,
104    text: &str,
105    target: &mut Vec<Glyph>,
106  ) where
107    F: Font,
108    SF: ScaleFont<F>,
109  {
110    let v_advance = font.height() + font.line_gap();
111    let mut caret = position + point(0.0, font.ascent());
112    let mut last_glyph: Option<Glyph> = None;
113    for c in text.chars() {
114      if c.is_control() {
115        if c == '\n' {
116          caret = point(position.x, caret.y + v_advance);
117          last_glyph = None;
118        }
119        continue;
120      }
121      let mut glyph = font.scaled_glyph(c);
122      if let Some(previous) = last_glyph.take() {
123        caret.x += font.kern(previous.id, glyph.id);
124      }
125      glyph.position = caret;
126
127      last_glyph = Some(glyph.clone());
128      caret.x += font.h_advance(glyph.id);
129
130      if !c.is_whitespace() && caret.x > position.x + max_width {
131        caret = Point {
132          x: position.x,
133          y: caret.y + v_advance,
134        };
135        glyph.position = caret;
136        last_glyph = None;
137      }
138
139      target.push(glyph);
140    }
141  }
142}
rust_animation/font.rs

rust_animation/
font.rs
