Add support for getting an element's computed style through WebDriver.

components/msg/webdriver_msg.rs

@@ -16,6 +16,7 @@ pub enum WebDriverScriptCommand {
     FocusElement(String, IpcSender<Result<(), ()>>),
     GetActiveElement(IpcSender<Option<String>>),
     GetElementAttribute(String, String, IpcSender<Result<Option<String>, ()>>),
+    GetElementCSS(String, String, IpcSender<Result<String, ()>>),
     GetElementTagName(String, IpcSender<Result<String, ()>>),
     GetElementText(String, IpcSender<Result<String, ()>>),
     GetFrameId(WebDriverFrameId, IpcSender<Result<Option<PipelineId>, ()>>),

components/script/script_task.rs

@@ -1108,6 +1108,8 @@ impl ScriptTask {
                 webdriver_handlers::handle_get_name(&page, pipeline_id, node_id, reply),
             WebDriverScriptCommand::GetElementAttribute(node_id, name, reply) =>
                 webdriver_handlers::handle_get_attribute(&page, pipeline_id, node_id, name, reply),
+            WebDriverScriptCommand::GetElementCSS(node_id, name, reply) =>
+                webdriver_handlers::handle_get_css(&page, pipeline_id, node_id, name, reply),
             WebDriverScriptCommand::GetElementText(node_id, reply) =>
                 webdriver_handlers::handle_get_text(&page, pipeline_id, node_id, reply),
             WebDriverScriptCommand::GetFrameId(frame_id, reply) =>

components/script/webdriver_handlers.rs

@@ -2,12 +2,14 @@
  * 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/. */
 
+use dom::bindings::codegen::Bindings::CSSStyleDeclarationBinding::CSSStyleDeclarationMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::DocumentMethods;
 use dom::bindings::codegen::Bindings::ElementBinding::ElementMethods;
 use dom::bindings::codegen::Bindings::HTMLElementBinding::HTMLElementMethods;
 use dom::bindings::codegen::Bindings::HTMLIFrameElementBinding::HTMLIFrameElementMethods;
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::codegen::Bindings::NodeListBinding::NodeListMethods;
+use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::conversions::{FromJSValConvertible, StringificationBehavior};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::Root;
@@ -217,6 +219,21 @@ pub fn handle_get_attribute(page: &Rc<Page>,
     }).unwrap();
 }
 
+pub fn handle_get_css(page: &Rc<Page>,
+                      pipeline: PipelineId,
+                      node_id: String,
+                      name: String,
+                      reply: IpcSender<Result<String, ()>>) {
+    reply.send(match find_node_by_unique_id(&*page, pipeline, node_id) {
+        Some(node) => {
+            let window = page.window();
+            let elem = node.downcast::<Element>().unwrap();
+            Ok(String::from(
+                window.GetComputedStyle(&elem, None).GetPropertyValue(DOMString::from(name))))
+        },
+        None => Err(())
+    }).unwrap();
+}
 
 pub fn handle_get_url(page: &Rc<Page>,
                       _pipeline: PipelineId,

components/webdriver_server/lib.rs

@@ -539,6 +539,20 @@ impl Handler {
         }
     }
 
+    fn handle_element_css(&self, element: &WebElement, name: &String) -> WebDriverResult<WebDriverResponse> {
+        let pipeline_id = try!(self.frame_pipeline());
+
+        let (sender, receiver) = ipc::channel().unwrap();
+        let cmd = WebDriverScriptCommand::GetElementCSS(element.id.clone(), name.clone(), sender);
+        let cmd_msg = WebDriverCommandMsg::ScriptCommand(pipeline_id, cmd);
+        self.constellation_chan.send(ConstellationMsg::WebDriverCommand(cmd_msg)).unwrap();
+        match receiver.recv().unwrap() {
+            Ok(value) => Ok(WebDriverResponse::Generic(ValueResponse::new(value.to_json()))),
+            Err(_) => Err(WebDriverError::new(ErrorStatus::StaleElementReference,
+                                              "Unable to find element in document"))
+        }
+    }
+
     fn handle_set_timeouts(&mut self, parameters: &TimeoutsParameters) -> WebDriverResult<WebDriverResponse> {
         //TODO: this conversion is crazy, spec should limit these to u32 and check upstream
         let value = parameters.ms as u32;
@@ -731,6 +745,8 @@ impl WebDriverHandler<ServoExtensionRoute> for Handler {
             WebDriverCommand::GetElementTagName(ref element) => self.handle_element_tag_name(element),
             WebDriverCommand::GetElementAttribute(ref element, ref name) =>
                 self.handle_element_attribute(element, name),
+            WebDriverCommand::GetCSSValue(ref element, ref name) =>
+                self.handle_element_css(element, name),
             WebDriverCommand::ExecuteScript(ref x) => self.handle_execute_script(x),
             WebDriverCommand::ExecuteAsyncScript(ref x) => self.handle_execute_async_script(x),
             WebDriverCommand::ElementSendKeys(ref element, ref keys) =>