1 files changed, 123 insertions, 0 deletions
diff --git a/components/layout/context.rs b/components/layout/context.rs
new file mode 100644
index 00000000000..936314dcb63
--- /dev/null
+++ b/components/layout/context.rs
@@ -0,0 +1,123 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Data needed by the layout task.
+
+use css::matching::{ApplicableDeclarationsCache, StyleSharingCandidateCache};
+
+use geom::{Rect, Size2D};
+use gfx::display_list::OpaqueNode;
+use gfx::font_context::FontContext;
+use gfx::font_cache_task::FontCacheTask;
+use script::layout_interface::LayoutChan;
+use servo_msg::constellation_msg::ConstellationChan;
+use servo_net::local_image_cache::LocalImageCache;
+use servo_util::geometry::Au;
+use servo_util::opts::Opts;
+use sync::{Arc, Mutex};
+use std::mem;
+use style::Stylist;
+use url::Url;
+
+struct LocalLayoutContext {
+    font_context: FontContext,
+    applicable_declarations_cache: ApplicableDeclarationsCache,
+    style_sharing_candidate_cache: StyleSharingCandidateCache,
+}
+
+local_data_key!(local_context_key: *mut LocalLayoutContext)
+
+fn create_or_get_local_context(shared_layout_context: &SharedLayoutContext) -> *mut LocalLayoutContext {
+    let maybe_context = local_context_key.get();
+
+    let context = match maybe_context {
+        None => {
+            let context = box LocalLayoutContext {
+                font_context: FontContext::new(shared_layout_context.font_cache_task.clone()),
+                applicable_declarations_cache: ApplicableDeclarationsCache::new(),
+                style_sharing_candidate_cache: StyleSharingCandidateCache::new(),
+            };
+            local_context_key.replace(Some(unsafe { mem::transmute(context) }));
+            local_context_key.get().unwrap()
+        },
+        Some(context) => context
+    };
+
+    *context
+}
+
+pub struct SharedLayoutContext {
+    /// The local image cache.
+    pub image_cache: Arc<Mutex<LocalImageCache>>,
+
+    /// The current screen size.
+    pub screen_size: Size2D<Au>,
+
+    /// A channel up to the constellation.
+    pub constellation_chan: ConstellationChan,
+
+    /// A channel up to the layout task.
+    pub layout_chan: LayoutChan,
+
+    /// Interface to the font cache task.
+    pub font_cache_task: FontCacheTask,
+
+    /// The CSS selector stylist.
+    ///
+    /// FIXME(#2604): Make this no longer an unsafe pointer once we have fast `RWArc`s.
+    pub stylist: *const Stylist,
+
+    /// The root node at which we're starting the layout.
+    pub reflow_root: OpaqueNode,
+
+    /// The URL.
+    pub url: Url,
+
+    /// The command line options.
+    pub opts: Opts,
+
+    /// The dirty rectangle, used during display list building.
+    pub dirty: Rect<Au>,
+}
+
+pub struct LayoutContext<'a> {
+    pub shared: &'a SharedLayoutContext,
+    cached_local_layout_context: *mut LocalLayoutContext,
+}
+
+impl<'a> LayoutContext<'a> {
+    pub fn new(shared_layout_context: &'a SharedLayoutContext) -> LayoutContext<'a> {
+
+        let local_context = create_or_get_local_context(shared_layout_context);
+
+        LayoutContext {
+            shared: shared_layout_context,
+            cached_local_layout_context: local_context,
+        }
+    }
+
+    #[inline(always)]
+    pub fn font_context<'a>(&'a self) -> &'a mut FontContext {
+        unsafe {
+            let cached_context = &*self.cached_local_layout_context;
+            mem::transmute(&cached_context.font_context)
+        }
+    }
+
+    #[inline(always)]
+    pub fn applicable_declarations_cache<'a>(&'a self) -> &'a mut ApplicableDeclarationsCache {
+        unsafe {
+            let cached_context = &*self.cached_local_layout_context;
+            mem::transmute(&cached_context.applicable_declarations_cache)
+        }
+    }
+
+    #[inline(always)]
+    pub fn style_sharing_candidate_cache<'a>(&'a self) -> &'a mut StyleSharingCandidateCache {
+        unsafe {
+            let cached_context = &*self.cached_local_layout_context;
+            mem::transmute(&cached_context.style_sharing_candidate_cache)
+        }
+    }
+}