Use embedded SVG instead of fonts for icons

The [downsides of icon fonts] are well-documented, and also, why ship all of
the icons when it only uses 14?

[downsides of icon fonts]: https://speakerdeck.com/ninjanails/death-to-icon-fonts

Author: notriddle

Cargo.lock

@@ -33,6 +33,7 @@ serde_json = "1.0"
 shlex = "0.1"
 tempfile = "3.0"
 toml = "0.5.1"
+font-awesome-as-a-crate = "0.1.2"
 
 # Watch feature
 notify = { version = "4.0", optional = true }

Cargo.toml

@@ -207,41 +207,6 @@ impl HtmlHandlebars {
         write_file(destination, "ayu-highlight.css", &theme.ayu_highlight_css)?;
         write_file(destination, "highlight.js", &theme.highlight_js)?;
         write_file(destination, "clipboard.min.js", &theme.clipboard_js)?;
-        write_file(
-            destination,
-            "FontAwesome/css/font-awesome.css",
-            theme::FONT_AWESOME,
-        )?;
-        write_file(
-            destination,
-            "FontAwesome/fonts/fontawesome-webfont.eot",
-            theme::FONT_AWESOME_EOT,
-        )?;
-        write_file(
-            destination,
-            "FontAwesome/fonts/fontawesome-webfont.svg",
-            theme::FONT_AWESOME_SVG,
-        )?;
-        write_file(
-            destination,
-            "FontAwesome/fonts/fontawesome-webfont.ttf",
-            theme::FONT_AWESOME_TTF,
-        )?;
-        write_file(
-            destination,
-            "FontAwesome/fonts/fontawesome-webfont.woff",
-            theme::FONT_AWESOME_WOFF,
-        )?;
-        write_file(
-            destination,
-            "FontAwesome/fonts/fontawesome-webfont.woff2",
-            theme::FONT_AWESOME_WOFF2,
-        )?;
-        write_file(
-            destination,
-            "FontAwesome/fonts/FontAwesome.ttf",
-            theme::FONT_AWESOME_TTF,
-        )?;
         if html_config.copy_fonts {
             write_file(destination, "fonts/fonts.css", theme::fonts::CSS)?;
             for (file_name, contents) in theme::fonts::LICENSES.iter() {
@@ -308,6 +273,7 @@ impl HtmlHandlebars {
         handlebars.register_helper("previous", Box::new(helpers::navigation::previous));
         handlebars.register_helper("next", Box::new(helpers::navigation::next));
         handlebars.register_helper("theme_option", Box::new(helpers::theme::theme_option));
+        handlebars.register_helper("fa", Box::new(helpers::fontawesome::fa_helper));
     }
 
     /// Copy across any additional CSS and JavaScript files which the book

src/renderer/html_handlebars/hbs_renderer.rs

@@ -0,0 +1,38 @@
+use handlebars::{Context, Handlebars, Helper, Output, RenderContext, RenderError};
+use font_awesome_as_a_crate as fa;
+
+pub fn fa_helper(
+    h: &Helper<'_, '_>,
+    _r: &Handlebars<'_>,
+    _ctx: &Context,
+    _rc: &mut RenderContext<'_, '_>,
+    out: &mut dyn Output,
+) -> Result<(), RenderError> {
+    trace!("fa_helper (handlebars helper)");
+
+    let type_ = h.param(0).and_then(|v| v.value().as_str()).and_then(|v| fa::Type::from_str(v).ok()).ok_or_else(|| {
+        RenderError::new("Param 0 with String type is required for fontawesome helper.")
+    })?;
+
+    let name = h.param(1).and_then(|v| v.value().as_str()).ok_or_else(|| {
+        RenderError::new("Param 1 with String type is required for fontawesome helper.")
+    })?;
+
+    trace!("fa_helper: {} {}", type_, name);
+
+    let name = if name.starts_with("fa-") {
+        &name[3..]
+    } else {
+        &name[..]
+    };
+
+    if let Some(id) = h.param(2).and_then(|v| v.value().as_str()) {
+        out.write(&format!("<span class=fa-svg id=\"{}\">", id))?;
+    } else {
+        out.write("<span class=fa-svg>")?;
+    }
+    out.write(fa::svg(type_, name).map_err(|_| RenderError::new(format!("Missing font {}", name)))?)?;
+    out.write("</span>")?;
+
+    Ok(())
+}

src/renderer/html_handlebars/helpers/fontawesome.rs

@@ -1,3 +1,4 @@
 pub mod navigation;
 pub mod theme;
 pub mod toc;
+pub mod fontawesome;