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>

2 files changed, 7 insertions, 7 deletions

diff --git a/components/shared/script_layout/lib.rs b/components/shared/script_layout/lib.rs
index 1faff34b767..1ad180411d3 100644
--- a/components/shared/script_layout/lib.rs
+++ b/components/shared/script_layout/lib.rs
@@ -24,7 +24,7 @@ use canvas_traits::canvas::{CanvasId, CanvasMsg};
 use crossbeam_channel::Sender;
 use euclid::default::{Point2D, Rect};
 use euclid::Size2D;
-use fonts::FontCacheThread;
+use fonts::SystemFontServiceProxy;
 use ipc_channel::ipc::IpcSender;
 use libc::c_void;
 use malloc_size_of_derive::MallocSizeOf;
@@ -175,7 +175,7 @@ pub struct LayoutConfig {
     pub script_chan: IpcSender<ConstellationControlMsg>,
     pub image_cache: Arc<dyn ImageCache>,
     pub resource_threads: ResourceThreads,
-    pub font_cache_thread: FontCacheThread,
+    pub system_font_service: Arc<SystemFontServiceProxy>,
     pub time_profiler_chan: time::ProfilerChan,
     pub webrender_api_sender: WebRenderScriptApi,
     pub paint_time_metrics: PaintTimeMetrics,
@@ -281,7 +281,7 @@ pub trait ScriptThreadFactory {
     fn create(
         state: InitialScriptState,
         layout_factory: Arc<dyn LayoutFactory>,
-        font_cache_thread: FontCacheThread,
+        system_font_service: Arc<SystemFontServiceProxy>,
         load_data: LoadData,
         user_agent: Cow<'static, str>,
     );
diff --git a/components/shared/webrender/lib.rs b/components/shared/webrender/lib.rs
index 718d53e44a1..14f3d3d338a 100644
--- a/components/shared/webrender/lib.rs
+++ b/components/shared/webrender/lib.rs
@@ -15,7 +15,7 @@ use crossbeam_channel::Sender;
 use display_list::{CompositorDisplayListInfo, ScrollTreeNodeId};
 use embedder_traits::Cursor;
 use euclid::default::Size2D;
-use ipc_channel::ipc::{self, IpcBytesReceiver, IpcSender};
+use ipc_channel::ipc::{self, IpcSender, IpcSharedMemory};
 use libc::c_void;
 use log::warn;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
@@ -190,14 +190,14 @@ pub trait WebRenderFontApi {
         size: f32,
         flags: FontInstanceFlags,
     ) -> FontInstanceKey;
-    fn add_font(&self, data: Arc<Vec<u8>>, index: u32) -> FontKey;
+    fn add_font(&self, data: Arc<IpcSharedMemory>, index: u32) -> FontKey;
     fn add_system_font(&self, handle: NativeFontHandle) -> FontKey;
 
     /// Forward a `AddFont` message, sending it on to the compositor. This is used to get WebRender
     /// [`FontKey`]s for web fonts in the per-layout `FontContext`.
     fn forward_add_font_message(
         &self,
-        bytes_receiver: IpcBytesReceiver,
+        data: Arc<IpcSharedMemory>,
         font_index: u32,
         result_sender: IpcSender<FontKey>,
     );
@@ -219,7 +219,7 @@ pub enum CanvasToCompositorMsg {
 
 pub enum FontToCompositorMsg {
     AddFontInstance(FontKey, f32, FontInstanceFlags, Sender<FontInstanceKey>),
-    AddFont(Sender<FontKey>, u32, IpcBytesReceiver),
+    AddFont(Sender<FontKey>, u32, Arc<IpcSharedMemory>),
     AddSystemFont(Sender<FontKey>, NativeFontHandle),
 }