fonts: Use `IpcSharedMemory` to send font data (#33530)

This changes modifes the way that font data is sent over IPC channels.
Instead of serializing the data or sending it via IPC byte senders, font
data is copied into shared memory and a copy of the handle is sent over
the channel.

There is also the idea of sending the file handle of the on disk data of
system fonts. This could be implemented as a further followup once there
is an abstraction in `ipc-channel` over file handles.

To accomplish this, a `FontData` abstraction is added, which also allows
caching an in-memory shared `Arc<Vec<u8>>` version of the data (neeeded
by some APIs). This could also be a place for caching font tables in the
future.

Finally, the `FontCacheThread` is renamed to the `SystemFontService`
while the proxy for this is now named `SystemFontServiceProxy`.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Co-authored-by: Mukilan Thiyagarajan <mukilan@igalia.com>

1 files changed, 33 insertions, 16 deletions

diff --git a/components/fonts/font.rs b/components/fonts/font.rs
index e423c546dae..3af077b4e06 100644
--- a/components/fonts/font.rs
+++ b/components/fonts/font.rs
@@ -27,14 +27,14 @@ use style::values::computed::{FontStretch, FontStyle, FontWeight};
 use unicode_script::Script;
 use webrender_api::{FontInstanceFlags, FontInstanceKey};
 
-use crate::font_cache_thread::{FontIdentifier, FontSource};
 use crate::font_context::FontContext;
 use crate::font_template::{FontTemplateDescriptor, FontTemplateRef, FontTemplateRefMethods};
 use crate::platform::font::{FontTable, PlatformFont};
 pub use crate::platform::font_list::fallback_font_families;
+use crate::system_font_service::{FontIdentifier, SystemFontServiceProxyTrait};
 use crate::{
-    ByteIndex, EmojiPresentationPreference, FallbackFontSelectionOptions, GlyphData, GlyphId,
-    GlyphStore, Shaper,
+    ByteIndex, EmojiPresentationPreference, FallbackFontSelectionOptions, FontData, GlyphData,
+    GlyphId, GlyphStore, Shaper,
 };
 
 #[macro_export]
@@ -66,11 +66,13 @@ pub trait PlatformFontMethods: Sized {
     fn new_from_template(
         template: FontTemplateRef,
         pt_size: Option<Au>,
+        data: &Arc<Vec<u8>>,
     ) -> Result<PlatformFont, &'static str> {
-        let data = template.data();
+        let template = template.borrow();
+
         let face_index = template.identifier().index();
-        let font_identifier = template.borrow().identifier.clone();
-        Self::new_from_data(font_identifier, data, face_index, pt_size)
+        let font_identifier = template.identifier.clone();
+        Self::new_from_data(font_identifier, data.clone(), face_index, pt_size)
     }
 
     fn new_from_data(
@@ -218,6 +220,7 @@ impl malloc_size_of::MallocSizeOf for CachedShapeData {
 #[derive(Debug)]
 pub struct Font {
     pub handle: PlatformFont,
+    pub data: Arc<FontData>,
     pub template: FontTemplateRef,
     pub metrics: FontMetrics,
     pub descriptor: FontDescriptor,
@@ -251,13 +254,19 @@ impl Font {
     pub fn new(
         template: FontTemplateRef,
         descriptor: FontDescriptor,
+        data: Arc<FontData>,
         synthesized_small_caps: Option<FontRef>,
     ) -> Result<Font, &'static str> {
-        let handle = PlatformFont::new_from_template(template.clone(), Some(descriptor.pt_size))?;
+        let handle = PlatformFont::new_from_template(
+            template.clone(),
+            Some(descriptor.pt_size),
+            data.as_arc(),
+        )?;
         let metrics = handle.metrics();
 
         Ok(Font {
             handle,
+            data,
             template,
             shaper: OnceLock::new(),
             descriptor,
@@ -526,7 +535,7 @@ impl FontGroup {
     /// `codepoint`. If no such font is found, returns the first available font or fallback font
     /// (which will cause a "glyph not found" character to be rendered). If no font at all can be
     /// found, returns None.
-    pub fn find_by_codepoint<S: FontSource>(
+    pub fn find_by_codepoint<S: SystemFontServiceProxyTrait>(
         &mut self,
         font_context: &FontContext<S>,
         codepoint: char,
@@ -598,7 +607,10 @@ impl FontGroup {
     }
 
     /// Find the first available font in the group, or the first available fallback font.
-    pub fn first<S: FontSource>(&mut self, font_context: &FontContext<S>) -> Option<FontRef> {
+    pub fn first<S: SystemFontServiceProxyTrait>(
+        &mut self,
+        font_context: &FontContext<S>,
+    ) -> Option<FontRef> {
         // From https://drafts.csswg.org/css-fonts/#first-available-font:
         // > The first available font, used for example in the definition of font-relative lengths
         // > such as ex or in the definition of the line-height property, is defined to be the first
@@ -629,7 +641,7 @@ impl FontGroup {
         font_predicate: FontPredicate,
     ) -> Option<FontRef>
     where
-        S: FontSource,
+        S: SystemFontServiceProxyTrait,
         TemplatePredicate: Fn(FontTemplateRef) -> bool,
         FontPredicate: Fn(&FontRef) -> bool,
     {
@@ -659,7 +671,7 @@ impl FontGroup {
         font_predicate: FontPredicate,
     ) -> Option<FontRef>
     where
-        S: FontSource,
+        S: SystemFontServiceProxyTrait,
         TemplatePredicate: Fn(FontTemplateRef) -> bool,
         FontPredicate: Fn(&FontRef) -> bool,
     {
@@ -731,7 +743,7 @@ impl FontGroupFamily {
         font_predicate: &FontPredicate,
     ) -> Option<FontRef>
     where
-        S: FontSource,
+        S: SystemFontServiceProxyTrait,
         TemplatePredicate: Fn(FontTemplateRef) -> bool,
         FontPredicate: Fn(&FontRef) -> bool,
     {
@@ -754,7 +766,7 @@ impl FontGroupFamily {
             .next()
     }
 
-    fn members<S: FontSource>(
+    fn members<S: SystemFontServiceProxyTrait>(
         &mut self,
         font_descriptor: &FontDescriptor,
         font_context: &FontContext<S>,
@@ -883,6 +895,8 @@ pub(crate) fn map_platform_values_to_style_values(mapping: &[(f64, f64)], value:
 
 #[cfg(test)]
 mod test {
+    use crate::FontData;
+
     #[cfg(target_os = "windows")]
     #[test]
     fn test_shape_text_fast() {
@@ -917,14 +931,16 @@ mod test {
 
         let identifier = FontIdentifier::Web(ServoUrl::from_file_path(path.clone()).unwrap());
         let file = File::open(path).unwrap();
-        let data: Arc<Vec<u8>> = Arc::new(file.bytes().map(|b| b.unwrap()).collect());
+        let data = Arc::new(FontData::from_bytes(
+            file.bytes().map(|b| b.unwrap()).collect(),
+        ));
         let platform_font =
-            PlatformFont::new_from_data(identifier.clone(), data.clone(), 0, None).unwrap();
+            PlatformFont::new_from_data(identifier.clone(), data.as_arc().clone(), 0, None)
+                .unwrap();
 
         let template = FontTemplate {
             identifier,
             descriptor: platform_font.descriptor(),
-            data: Some(data),
             stylesheet: None,
         };
         let descriptor = FontDescriptor {
@@ -937,6 +953,7 @@ mod test {
         let font = Font::new(
             Arc::new(atomic_refcell::AtomicRefCell::new(template)),
             descriptor,
+            data,
             None,
         )
         .unwrap();