Allow handles to store native fonts and return those from 'Handle::lo…

…ad' if possible.

This fixes another chokepoint in Iosevka loading, as we were needlessly reading fonts from disk and stuff with load, whereas we've already had a font at our disposal before creating a handle. That seemed wasteful.
Note that I did cargo check --all-features this code, but I am only sure of coretext part compiling. If we pursue cross-platform support, we'll need to revisit this (probably). The idea from this commit is not specific to this commit though.

src/handle.rs

@@ -14,11 +14,13 @@
 //!
 //! To open the font referenced by a handle, use a loader.
 
+use std::any::Any;
 use std::path::PathBuf;
 use std::sync::Arc;
 
 use crate::error::FontLoadingError;
 use crate::font::Font;
+use crate::loader::Loader;
 
 /// Encapsulates the information needed to locate and open a font.
 ///
@@ -45,6 +47,11 @@ pub enum Handle {
         /// If the memory consists of a single font, this value will be 0.
         font_index: u32,
     },
+    /// An already-loaded font.
+    Native {
+        /// Type-erased font storage. Use [`Self::from_native`] to retrieve the font object.
+        inner: Arc<dyn Any + Send + Sync>,
+    },
 }
 
 impl Handle {
@@ -66,6 +73,22 @@ impl Handle {
         Handle::Memory { bytes, font_index }
     }
 
+    /// Creates a new handle from a system handle.
+    pub fn from_native<T: Loader>(inner: &T) -> Self {
+        Self::Native {
+            inner: Arc::new(inner.native_font()),
+        }
+    }
+    /// Retrieves a handle to the font object.
+    ///
+    /// May return None if inner object is not of type `T` or if this handle does not contain a native font object.
+    pub fn native_as<T: 'static + Send + Sync>(&self) -> Option<&T> {
+        if let Self::Native { inner } = self {
+            inner.downcast_ref()
+        } else {
+            None
+        }
+    }
     /// A convenience method to load this handle with the default loader, producing a Font.
     #[inline]
     pub fn load(&self) -> Result<Font, FontLoadingError> {

src/loader.rs

@@ -15,6 +15,7 @@ use log::warn;
 use pathfinder_geometry::rect::{RectF, RectI};
 use pathfinder_geometry::transform2d::Transform2F;
 use pathfinder_geometry::vector::Vector2F;
+use std::convert::TryFrom;
 use std::sync::Arc;
 
 use crate::canvas::{Canvas, RasterizationOptions};
@@ -35,7 +36,7 @@ use std::path::Path;
 /// fonts.
 pub trait Loader: Clone + Sized {
     /// The handle that the API natively uses to represent a font.
-    type NativeFont;
+    type NativeFont: 'static + Send + Sync;
 
     /// Loads a font from raw font data (the contents of a `.ttf`/`.otf`/etc. file).
     ///
@@ -63,22 +64,23 @@ pub trait Loader: Clone + Sized {
     }
 
     /// Creates a font from a native API handle.
-    unsafe fn from_native_font(native_font: Self::NativeFont) -> Self;
+    unsafe fn from_native_font(native_font: &Self::NativeFont) -> Self;
 
     /// Loads the font pointed to by a handle.
     fn from_handle(handle: &Handle) -> Result<Self, FontLoadingError> {
-        match *handle {
-            Handle::Memory {
-                ref bytes,
-                font_index,
-            } => Self::from_bytes((*bytes).clone(), font_index),
+        match handle {
+            Handle::Memory { bytes, font_index } => Self::from_bytes((*bytes).clone(), *font_index),
             #[cfg(not(target_arch = "wasm32"))]
-            Handle::Path {
-                ref path,
-                font_index,
-            } => Self::from_path(path, font_index),
+            Handle::Path { path, font_index } => Self::from_path(path, *font_index),
             #[cfg(target_arch = "wasm32")]
             Handle::Path { .. } => Err(FontLoadingError::NoFilesystem),
+            Handle::Native { .. } => {
+                if let Some(native) = handle.native_as::<Self::NativeFont>() {
+                    unsafe { Ok(Self::from_native_font(native)) }
+                } else {
+                    Err(FontLoadingError::UnknownFormat)
+                }
+            }
         }
     }
 

src/loaders/core_text.rs

@@ -122,8 +122,8 @@ impl Font {
     }
 
     /// Creates a font from a native API handle.
-    pub unsafe fn from_native_font(core_text_font: NativeFont) -> Font {
-        Font::from_core_text_font_no_path(core_text_font)
+    pub unsafe fn from_native_font(core_text_font: &NativeFont) -> Font {
+        Font::from_core_text_font_no_path(core_text_font.clone())
     }
     /// Creates a font from a native API handle, without performing a lookup on the disk.
     pub unsafe fn from_core_text_font_no_path(core_text_font: NativeFont) -> Font {
@@ -132,27 +132,6 @@ impl Font {
             font_data: FontData::Unavailable,
         }
     }
-    unsafe fn from_core_text_font(core_text_font: NativeFont) -> Font {
-        let mut font_data = FontData::Unavailable;
-        match core_text_font.url() {
-            None => warn!("No URL found for Core Text font!"),
-            Some(url) => match url.to_path() {
-                Some(path) => match File::open(path) {
-                    Ok(ref mut file) => match utils::slurp_file(file) {
-                        Ok(data) => font_data = FontData::Memory(Arc::new(data)),
-                        Err(_) => warn!("Couldn't read file data for Core Text font!"),
-                    },
-                    Err(_) => warn!("Could not open file for Core Text font!"),
-                },
-                None => warn!("Could not convert URL from Core Text font to path!"),
-            },
-        }
-
-        Font {
-            core_text_font,
-            font_data,
-        }
-    }
 
     /// Creates a font from a Core Graphics font handle.
     ///
@@ -637,7 +616,7 @@ impl Loader for Font {
     }
 
     #[inline]
-    unsafe fn from_native_font(native_font: Self::NativeFont) -> Self {
+    unsafe fn from_native_font(native_font: &Self::NativeFont) -> Self {
         Font::from_native_font(native_font)
     }
 

src/loaders/directwrite.rs

@@ -160,7 +160,8 @@ impl Font {
 
     /// Creates a font from a native API handle.
     #[inline]
-    pub unsafe fn from_native_font(native_font: NativeFont) -> Font {
+    pub unsafe fn from_native_font(native_font: &NativeFont) -> Font {
+        let native_font = native_font.clone();
         Font {
             dwrite_font: native_font.dwrite_font,
             dwrite_font_face: native_font.dwrite_font_face,
@@ -747,7 +748,7 @@ impl Loader for Font {
     }
 
     #[inline]
-    unsafe fn from_native_font(native_font: Self::NativeFont) -> Self {
+    unsafe fn from_native_font(native_font: &Self::NativeFont) -> Self {
         Font::from_native_font(native_font)
     }
 

src/loaders/freetype.rs

@@ -182,9 +182,10 @@ impl Font {
     }
 
     /// Creates a font from a native API handle.
-    pub unsafe fn from_native_font(freetype_face: NativeFont) -> Font {
+    pub unsafe fn from_native_font(freetype_face: &NativeFont) -> Font {
         // We make an in-memory copy of the underlying font data. This is because the native font
         // does not necessarily hold a strong reference to the memory backing it.
+        let freetype_face = *freetype_face;
         const CHUNK_SIZE: usize = 4096;
         let mut font_data = vec![];
         loop {
@@ -1013,7 +1014,7 @@ impl Loader for Font {
     }
 
     #[inline]
-    unsafe fn from_native_font(native_font: Self::NativeFont) -> Self {
+    unsafe fn from_native_font(native_font: &Self::NativeFont) -> Self {
         Font::from_native_font(native_font)
     }
 

src/sources/core_text.rs

@@ -154,12 +154,6 @@ fn css_stretchiness_to_core_text_width(css_stretchiness: Stretch) -> f32 {
     0.25 * core_text_loader::piecewise_linear_find_index(css_stretchiness, &Stretch::MAPPING) - 1.0
 }
 
-#[derive(Clone)]
-struct FontDataInfo {
-    data: Arc<Vec<u8>>,
-    file_type: FileType,
-}
-
 fn create_handles_from_core_text_collection(
     collection: CTFontCollection,
 ) -> Result<Vec<Handle>, SelectionError> {
@@ -169,8 +163,8 @@ fn create_handles_from_core_text_collection(
             let descriptor = descriptors.get(index).unwrap();
             let native = new_from_descriptor(&descriptor, 16.);
             let font = unsafe { Font::from_core_text_font_no_path(native.clone()) };
-            todo!();
-            //fonts.push(Handle::from(font));
+
+            fonts.push(Handle::from_native(&font));
         }
     }
     if fonts.is_empty() {