Refactor font loading from per-document to the portfolio (#659)

* Cleanup default font loading

* Refactor fonts

* Fix menulist mouse navigation

* Format

* Formatting

* Move default font into consts.rs

Co-authored-by: Keavon Chambers <keavon@keavon.com>

graphene/src/layers/text_layer/font_cache.rs

@@ -0,0 +1,64 @@
+use serde::{Deserialize, Serialize};
+use std::collections::HashMap;
+
+/// A font type (storing font family and font style and an optional preview URL)
+#[derive(Debug, Clone, Serialize, Deserialize, Hash, PartialEq, Eq)]
+pub struct Font {
+	pub font_family: String,
+	pub font_style: String,
+}
+impl Font {
+	pub fn new(font_family: String, font_style: String) -> Self {
+		Self { font_family, font_style }
+	}
+}
+
+/// A cache of all loaded font data and preview urls along with the default font (send from `init_app` in `editor_api.rs`)
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct FontCache {
+	/// Actual font file data used for rendering a font with ttf_parser and rustybuzz
+	font_file_data: HashMap<Font, Vec<u8>>,
+	/// Web font preview URLs used for showing fonts when live editing
+	preview_urls: HashMap<Font, String>,
+	/// The default font (used as a fallback)
+	default_font: Option<Font>,
+}
+impl FontCache {
+	/// Returns the font family name if the font is cached, otherwise returns the default font family name if that is cached
+	pub fn resolve_font<'a>(&'a self, font: &'a Font) -> Option<&'a Font> {
+		if self.loaded_font(font) {
+			Some(font)
+		} else {
+			self.default_font.as_ref().filter(|font| self.loaded_font(font))
+		}
+	}
+
+	/// Try to get the bytes for a font
+	pub fn get<'a>(&'a self, font: &Font) -> Option<&'a Vec<u8>> {
+		self.resolve_font(font).and_then(|font| self.font_file_data.get(font))
+	}
+
+	/// Check if the font is already loaded
+	pub fn loaded_font(&self, font: &Font) -> bool {
+		self.font_file_data.contains_key(font)
+	}
+
+	/// Insert a new font into the cache
+	pub fn insert(&mut self, font: Font, perview_url: String, data: Vec<u8>, is_default: bool) {
+		if is_default {
+			self.default_font = Some(font.clone());
+		}
+		self.font_file_data.insert(font.clone(), data);
+		self.preview_urls.insert(font, perview_url);
+	}
+
+	/// Checks if the font cache has a default font
+	pub fn has_default(&self) -> bool {
+		self.default_font.is_some()
+	}
+
+	/// Gets the preview URL for showing in text field when live editing
+	pub fn get_preview_url(&self, font: &Font) -> Option<&String> {
+		self.preview_urls.get(font)
+	}
+}