Struct FontCache 

pub struct FontCache<T: Texture> { /* private fields */ }

The main structure for maintaing a cache of rendered glyphs

FontCache is specifically an intermediary step. It doesn’t understand how to read font files or how to break up a string into glyphs: that’s handled by the FontProvider. It doesn’t handle sending glyphs to the GPU: if you want to do that, provide a Texture that stores its data on the GPU. What it does do is keep track of which glyphs have already been rendered, where they were stored, and provide a consistent API over a variety of ways of rendering characters.

Implementations

impl<T: Texture> FontCache<T>

pub fn new(font: Box<dyn FontProvider>, texture: T) -> Self

Create a new FontCache that pulls from the given provider and renders to the provided texture

Examples found in repository

examples/render_image.rs (line 13)

fn main() {
    let font_data = include_bytes!("DejaVuSans.ttf");
    let font = Font::from_bytes(font_data as &[u8]).expect("Error constructing Font");
    let font = SizedFont::new(font, 24.0);

    let image = ImageBuffer::new(200, 200);

    let mut cache = FontCache::new(Box::new(font), image);
    cache.render_string("Hello, world!").for_each(|r| {
        r.unwrap();
    });
    cache.render_string("こんにちは世界！").for_each(|r| {
        r.unwrap();
    });
    cache.render_string("Привет, мир!").for_each(|r| {
        r.unwrap();
    });
    cache
        .texture()
        .save("result.png")
        .expect("Failed to save file");
}

pub fn clear(&mut self)

Forget the position of the characters in the texture, and re-set the cursor.

This doesn’t set any data in the Texture! Old glyphs may continue to work, but this is akin to a use-after-free.

pub fn render_glyph( &mut self, key: Glyph, ) -> Result<(Metrics, TextureGlyph), CacheError>

Render a glyph to the texture

pub fn render_string<'a>( &'a mut self, string: &str, ) -> impl 'a + Iterator<Item = Result<(Metrics, TextureGlyph), CacheError>>

Attempt to convert a string into a series of glyphs or errors

Before being converted, the string is normalized if the “unicode-normalilzation” feature is activated, and whitespace characters are removed.

Examples found in repository

examples/render_image.rs (line 14)

fn main() {
    let font_data = include_bytes!("DejaVuSans.ttf");
    let font = Font::from_bytes(font_data as &[u8]).expect("Error constructing Font");
    let font = SizedFont::new(font, 24.0);

    let image = ImageBuffer::new(200, 200);

    let mut cache = FontCache::new(Box::new(font), image);
    cache.render_string("Hello, world!").for_each(|r| {
        r.unwrap();
    });
    cache.render_string("こんにちは世界！").for_each(|r| {
        r.unwrap();
    });
    cache.render_string("Привет, мир!").for_each(|r| {
        r.unwrap();
    });
    cache
        .texture()
        .save("result.png")
        .expect("Failed to save file");
}

pub fn cache_string(&mut self, string: &str) -> Result<(), CacheError>

Cache a string or return an error if one occurred

This can be useful if the entire domain of the possible glyphs is known beforehand (like a bitmap font.) Under the hood, this just calls [render_string] and ignores the returned glyphs.

pub fn replace_texture(&mut self, texture: T) -> T

Swap out the internal texture for another one

This will clear the cache automatically, to avoid holding references to invalid areas of the texture

pub fn texture(&self) -> &T

Examples found in repository

examples/render_image.rs (line 24)

fn main() {
    let font_data = include_bytes!("DejaVuSans.ttf");
    let font = Font::from_bytes(font_data as &[u8]).expect("Error constructing Font");
    let font = SizedFont::new(font, 24.0);

    let image = ImageBuffer::new(200, 200);

    let mut cache = FontCache::new(Box::new(font), image);
    cache.render_string("Hello, world!").for_each(|r| {
        r.unwrap();
    });
    cache.render_string("こんにちは世界！").for_each(|r| {
        r.unwrap();
    });
    cache.render_string("Привет, мир!").for_each(|r| {
        r.unwrap();
    });
    cache
        .texture()
        .save("result.png")
        .expect("Failed to save file");
}

pub fn font(&self) -> &dyn FontProvider