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, 6 insertions, 6 deletions

diff --git a/src/components/gfx/render_task.rs b/src/components/gfx/render_task.rs
index 8048db3b70d..d6c31bce048 100644
--- a/src/components/gfx/render_task.rs
+++ b/src/components/gfx/render_task.rs
@@ -7,7 +7,7 @@
 use buffer_map::BufferMap;
 use display_list::optimizer::DisplayListOptimizer;
 use display_list::DisplayList;
-use font_context::{FontContext, FontContextInfo};
+use font_context::FontContext;
 use render_context::RenderContext;
 
 use azure::azure_hl::{B8G8R8A8, Color, DrawTarget, StolenGLResources};
@@ -34,6 +34,7 @@ use servo_util::time::{TimeProfilerChan, profile};
 use servo_util::time;
 use std::comm::{Receiver, Sender, channel};
 use sync::Arc;
+use font_cache_task::FontCacheTask;
 
 /// Information about a layer that layout sends to the painting task.
 pub struct RenderLayer {
@@ -144,12 +145,15 @@ impl<C:RenderListener + Send> RenderTask<C> {
                   port: Receiver<Msg>,
                   compositor: C,
                   constellation_chan: ConstellationChan,
+                  font_cache_task: FontCacheTask,
                   failure_msg: Failure,
                   opts: Opts,
                   time_profiler_chan: TimeProfilerChan,
                   shutdown_chan: Sender<()>) {
 
         let ConstellationChan(c) = constellation_chan.clone();
+        let fc = font_cache_task.clone();
+
         let mut task_opts = TaskOpts::new();
         task_opts.name = Some("RenderTask".into_maybe_owned());
         task_opts.on_exit = Some(proc(result: task::Result) {
@@ -172,11 +176,7 @@ impl<C:RenderListener + Send> RenderTask<C> {
                     port: port,
                     compositor: compositor,
                     constellation_chan: constellation_chan,
-                    font_ctx: box FontContext::new(FontContextInfo {
-                        backend: opts.render_backend.clone(),
-                        needs_font_list: false,
-                        time_profiler_chan: time_profiler_chan.clone(),
-                    }),
+                    font_ctx: box FontContext::new(fc.clone()),
                     opts: opts,
                     time_profiler_chan: time_profiler_chan,