Next stage of refactoring font system. This commit introduces

the font cache task, and adapts client code to use it. It also
cleans up some existing code paths.

- Fonts are only read once from disk while in use (they
  are discarded if the reference count reaches zero, however).
  This saves memory and prevents unnecessary reading from disk.
- It will be easier to add web font support, as all fonts
  are created and managed in a single place and the entire
  pipeline ensures that only one in-memory copy of font data
  is required.

An overview of how the pieces fit together:

FontTemplate - A structure containing everything that
is required to create (and select) font handles. This
structure is shared among all matching font handles
(via Arc).

FontTemplateData - A platform specific structure that
contains the actual font data inside a template (this is
a byte array on Linux/Android, CTFont on Mac).

FontHandle - An opaque, platform specific handle to
a font instance. Each FontHandle contains an Arc<>
reference to the FontTemplate it was created from.

FontCache - This is a separate task, that is responsible
for loading and caching FontTemplate structures. There
is one FontCache per constellation. It is only ever accessed
via the FontContext described below.

FontContext - This is the public interface to the FontCache
and is used by the layout and render code to create font
handles. These must *not* be shared between threads. There
is typically one FontContext per thread/task.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/components/main/servo.rs b/src/components/main/servo.rs
index 49f68a2bf1b..f845846280e 100644
--- a/src/components/main/servo.rs
+++ b/src/components/main/servo.rs
@@ -20,6 +20,7 @@ extern crate servo_msg = "msg";
 #[phase(plugin, link)]
 extern crate servo_util = "util";
 extern crate green;
+extern crate gfx;
 extern crate libc;
 extern crate native;
 extern crate rustrt;
@@ -35,6 +36,8 @@ use servo_net::image_cache_task::{ImageCacheTask, SyncImageCacheTask};
 #[cfg(not(test))]
 use servo_net::resource_task::ResourceTask;
 #[cfg(not(test))]
+use gfx::font_cache_task::FontCacheTask;
+#[cfg(not(test))]
 use servo_util::time::TimeProfiler;
 #[cfg(not(test))]
 use servo_util::memory::MemoryProfiler;
@@ -115,10 +118,12 @@ pub fn run(opts: opts::Opts) {
             } else {
                 ImageCacheTask(resource_task.clone())
             };
+        let font_cache_task = FontCacheTask::new();
         let constellation_chan = Constellation::start(compositor_chan,
                                                       opts,
                                                       resource_task,
                                                       image_cache_task,
+                                                      font_cache_task,
                                                       time_profiler_chan_clone);
 
         // Send the URL command to the constellation.