fonts: Clean up WebRender web fonts when they are no longer used (#32545)

This is the first part of cleaning up unused WebRender resources.
Currently this only cleans up web font resources, but a more
full-featured implementation in the future could also clean up unused
system fonts.

Fixes #32345.

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

1 files changed, 21 insertions, 5 deletions

diff --git a/components/shared/webrender/lib.rs b/components/shared/webrender/lib.rs
index e5a794fccf0..718d53e44a1 100644
--- a/components/shared/webrender/lib.rs
+++ b/components/shared/webrender/lib.rs
@@ -191,16 +191,18 @@ pub trait WebRenderFontApi {
         flags: FontInstanceFlags,
     ) -> FontInstanceKey;
     fn add_font(&self, data: Arc<Vec<u8>>, index: u32) -> FontKey;
-    /// Forward an already prepared `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 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,
         font_index: u32,
         result_sender: IpcSender<FontKey>,
     );
-    /// Forward an already prepared `AddFontInstance` message, sending it on to the compositor. This
-    /// is used to get WebRender [`FontInstanceKey`]s for web fonts in the per-layout `FontContext`.
+    /// Forward a `AddFontInstance` message, sending it on to the compositor. This is used to get
+    /// WebRender [`FontInstanceKey`]s for web fonts in the per-layout `FontContext`.
     fn forward_add_font_instance_message(
         &self,
         font_key: FontKey,
@@ -208,7 +210,6 @@ pub trait WebRenderFontApi {
         flags: FontInstanceFlags,
         result_receiver: IpcSender<FontInstanceKey>,
     );
-    fn add_system_font(&self, handle: NativeFontHandle) -> FontKey;
 }
 
 pub enum CanvasToCompositorMsg {
@@ -257,6 +258,8 @@ pub enum ScriptToCompositorMsg {
     GenerateImageKey(IpcSender<ImageKey>),
     /// Perform a resource update operation.
     UpdateImages(Vec<SerializedImageUpdate>),
+    /// Remove the given font resources from our WebRender instance.
+    RemoveFonts(Vec<FontKey>, Vec<FontInstanceKey>),
 }
 
 /// A mechanism to send messages from networking to the WebRender instance.
@@ -420,6 +423,19 @@ impl WebRenderScriptApi {
             }
         });
     }
+
+    pub fn remove_unused_font_resources(
+        &self,
+        keys: Vec<FontKey>,
+        instance_keys: Vec<FontInstanceKey>,
+    ) {
+        if keys.is_empty() && instance_keys.is_empty() {
+            return;
+        }
+        let _ = self
+            .0
+            .send(ScriptToCompositorMsg::RemoveFonts(keys, instance_keys));
+    }
 }
 
 #[derive(Deserialize, Serialize)]