Improve documentation for devtools messages a bit more.

components/devtools/actors/inspector.rs

@@ -5,7 +5,7 @@
 //! Liberally derived from the [Firefox JS implementation]
 //! (http://mxr.mozilla.org/mozilla-central/source/toolkit/devtools/server/actors/inspector.js).
 
-use devtools_traits::{DevtoolScriptControlMsg, NodeInfo};
+use devtools_traits::{DevtoolScriptControlMsg, NodeInfo, ComputedNodeLayout};
 use devtools_traits::DevtoolScriptControlMsg::{GetRootNode, GetDocumentElement, GetChildren};
 use devtools_traits::DevtoolScriptControlMsg::{GetLayout, ModifyAttribute};
 
@@ -458,7 +458,7 @@ impl Actor for PageStyleActor {
                                       registry.actor_to_script(target.to_string()),
                                       tx))
                                 .unwrap();
-                let (width, height) = rx.recv().unwrap();
+                let ComputedNodeLayout { width, height } = rx.recv().unwrap();
 
                 let auto_margins = msg.get(&"autoMargins".to_string())
                     .and_then(&Json::as_boolean).unwrap_or(false);

components/devtools_traits/lib.rs

@@ -145,24 +145,31 @@ pub enum TimelineMarkerType {
     DOMEvent,
 }
 
+/// The properties of a DOM node as computed by layout.
+#[derive(Deserialize, Serialize)]
+pub struct ComputedNodeLayout {
+    pub width: f32,
+    pub height: f32,
+}
+
 /// Messages to process in a particular script task, as instructed by a devtools client.
 #[derive(Deserialize, Serialize)]
 pub enum DevtoolScriptControlMsg {
     /// Evaluate a JS snippet in the context of the global for the given pipeline.
     EvaluateJS(PipelineId, String, IpcSender<EvaluateJSReply>),
-    /// Retrieve the details of the root node (ie. document) for the given pipeline.
+    /// Retrieve the details of the root node (ie. the document) for the given pipeline.
     GetRootNode(PipelineId, IpcSender<NodeInfo>),
     /// Retrieve the details of the document element for the given pipeline.
     GetDocumentElement(PipelineId, IpcSender<NodeInfo>),
     /// Retrieve the details of the child nodes of the given node in the given pipeline.
     GetChildren(PipelineId, String, IpcSender<Vec<NodeInfo>>),
     /// Retrieve the computed layout properties of the given node in the given pipeline.
-    GetLayout(PipelineId, String, IpcSender<(f32, f32)>),
+    GetLayout(PipelineId, String, IpcSender<ComputedNodeLayout>),
-    /// Retrieve all stored console messages for a given pipeline.
+    /// Retrieve all stored console messages for the given pipeline.
     GetCachedMessages(PipelineId, CachedConsoleMessageTypes, IpcSender<Vec<CachedConsoleMessage>>),
     /// Update a given node's attributes with a list of modifications.
     ModifyAttribute(PipelineId, String, Vec<Modification>),
-    /// Request live console messages for a given pipeline.
+    /// Request live console messages for a given pipeline (true if desired, false otherwise).
     WantsLiveNotifications(PipelineId, bool),
     /// Request live notifications for a given set of timeline events for a given pipeline.
     SetTimelineMarkers(PipelineId, Vec<TimelineMarkerType>, IpcSender<TimelineMarker>),

components/script/devtools.rs

@@ -4,7 +4,7 @@
 
 use devtools_traits::{CachedConsoleMessage, CachedConsoleMessageTypes, PAGE_ERROR, CONSOLE_API};
 use devtools_traits::{EvaluateJSReply, NodeInfo, Modification, TimelineMarker, TimelineMarkerType};
-use devtools_traits::{ConsoleAPI, PageError, ScriptToDevtoolsControlMsg};
+use devtools_traits::{ConsoleAPI, PageError, ScriptToDevtoolsControlMsg, ComputedNodeLayout};
 use dom::bindings::conversions::jsstring_to_str;
 use dom::bindings::conversions::FromJSValConvertible;
 use dom::bindings::js::Root;
@@ -97,13 +97,16 @@ pub fn handle_get_children(page: &Rc<Page>, pipeline: PipelineId, node_id: Strin
     reply.send(children).unwrap();
 }
 
-pub fn handle_get_layout(page: &Rc<Page>, pipeline: PipelineId, node_id: String, reply: IpcSender<(f32, f32)>) {
+pub fn handle_get_layout(page: &Rc<Page>,
+                         pipeline: PipelineId,
+                         node_id: String,
+                         reply: IpcSender<ComputedNodeLayout>) {
     let node = find_node_by_unique_id(&*page, pipeline, node_id);
     let elem = ElementCast::to_ref(node.r()).expect("should be getting layout of element");
     let rect = elem.GetBoundingClientRect();
     let width = *rect.r().Width();
     let height = *rect.r().Height();
-    reply.send((width, height)).unwrap();
+    reply.send(ComputedNodeLayout { width: width, height: height }).unwrap();
 }
 
 pub fn handle_get_cached_messages(_pipeline_id: PipelineId,