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, 2 insertions, 7 deletions

diff --git a/src/components/gfx/gfx.rs b/src/components/gfx/gfx.rs
index dd7d58c7616..4a7c4e217b2 100644
--- a/src/components/gfx/gfx.rs
+++ b/src/components/gfx/gfx.rs
@@ -45,12 +45,6 @@ extern crate harfbuzz;
 #[cfg(target_os="macos")] extern crate core_graphics;
 #[cfg(target_os="macos")] extern crate core_text;
 
-pub use gfx_font = font;
-pub use gfx_font_context = font_context;
-pub use gfx_font_list = font_list;
-pub use servo_gfx_font = font;
-pub use servo_gfx_font_list = font_list;
-
 pub use render_context::RenderContext;
 
 // Private rendering modules
@@ -65,7 +59,8 @@ pub mod render_task;
 // Fonts
 pub mod font;
 pub mod font_context;
-pub mod font_list;
+pub mod font_cache_task;
+pub mod font_template;
 
 // Misc.
 mod buffer_map;