Cargoify servo

components/compositing/platform/common/glfw_windowing.rs

@@ -0,0 +1,380 @@
+/* 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/. */
+
+//! A windowing implementation using GLFW.
+
+use windowing::{ApplicationMethods, WindowEvent, WindowMethods};
+use windowing::{IdleWindowEvent, ResizeWindowEvent, LoadUrlWindowEvent, MouseWindowEventClass,  MouseWindowMoveEventClass};
+use windowing::{ScrollWindowEvent, ZoomWindowEvent, PinchZoomWindowEvent, NavigationWindowEvent, FinishedWindowEvent};
+use windowing::{QuitWindowEvent, MouseWindowClickEvent, MouseWindowMouseDownEvent, MouseWindowMouseUpEvent};
+use windowing::RefreshWindowEvent;
+use windowing::{Forward, Back};
+
+use alert::{Alert, AlertMethods};
+use libc::{exit, c_int};
+use time;
+use time::Timespec;
+use std::cell::{Cell, RefCell};
+use std::comm::Receiver;
+use std::rc::Rc;
+
+use geom::point::{Point2D, TypedPoint2D};
+use geom::scale_factor::ScaleFactor;
+use geom::size::TypedSize2D;
+use layers::geometry::DevicePixel;
+use servo_msg::compositor_msg::{IdleRenderState, RenderState, RenderingRenderState};
+use servo_msg::compositor_msg::{FinishedLoading, Blank, Loading, PerformingLayout, ReadyState};
+use servo_util::geometry::ScreenPx;
+
+use glfw;
+use glfw::Context;
+
+/// A structure responsible for setting up and tearing down the entire windowing system.
+pub struct Application {
+    pub glfw: glfw::Glfw,
+}
+
+impl ApplicationMethods for Application {
+    fn new() -> Application {
+        let app = glfw::init(glfw::LOG_ERRORS);
+        match app {
+            Err(_) => {
+                // handles things like inability to connect to X
+                // cannot simply fail, since the runtime isn't up yet (causes a nasty abort)
+                println!("GLFW initialization failed");
+                unsafe { exit(1); }
+            }
+            Ok(app) => {
+                Application { glfw: app }
+            }
+        }
+    }
+}
+
+macro_rules! glfw_callback(
+    (
+        $callback:path ($($arg:ident: $arg_ty:ty),*) $block:expr
+    ) => ({
+        struct GlfwCallback;
+        impl $callback for GlfwCallback {
+            fn call(&self $(, $arg: $arg_ty)*) {
+                $block
+            }
+        }
+        ~GlfwCallback
+    });
+
+    (
+        [$($state:ident: $state_ty:ty),*],
+        $callback:path ($($arg:ident: $arg_ty:ty),*) $block:expr
+    ) => ({
+        struct GlfwCallback {
+            $($state: $state_ty,)*
+        }
+        impl $callback for GlfwCallback {
+            fn call(&self $(, $arg: $arg_ty)*) {
+                $block
+            }
+        }
+        ~GlfwCallback {
+            $($state: $state,)*
+        }
+    });
+)
+
+
+/// The type of a window.
+pub struct Window {
+    glfw: glfw::Glfw,
+
+    glfw_window: glfw::Window,
+    events: Receiver<(f64, glfw::WindowEvent)>,
+
+    event_queue: RefCell<Vec<WindowEvent>>,
+
+    mouse_down_button: Cell<Option<glfw::MouseButton>>,
+    mouse_down_point: Cell<Point2D<c_int>>,
+
+    ready_state: Cell<ReadyState>,
+    render_state: Cell<RenderState>,
+
+    last_title_set_time: Cell<Timespec>,
+}
+
+impl WindowMethods<Application> for Window {
+    /// Creates a new window.
+    fn new(app: &Application, is_foreground: bool) -> Rc<Window> {
+        // Create the GLFW window.
+        app.glfw.window_hint(glfw::Visible(is_foreground));
+        let (glfw_window, events) = app.glfw.create_window(800, 600, "Servo", glfw::Windowed)
+            .expect("Failed to create GLFW window");
+        glfw_window.make_current();
+
+        // Create our window object.
+        let window = Window {
+            glfw: app.glfw,
+
+            glfw_window: glfw_window,
+            events: events,
+
+            event_queue: RefCell::new(vec!()),
+
+            mouse_down_button: Cell::new(None),
+            mouse_down_point: Cell::new(Point2D(0 as c_int, 0)),
+
+            ready_state: Cell::new(Blank),
+            render_state: Cell::new(IdleRenderState),
+
+            last_title_set_time: Cell::new(Timespec::new(0, 0)),
+        };
+
+        // Register event handlers.
+        window.glfw_window.set_framebuffer_size_polling(true);
+        window.glfw_window.set_refresh_polling(true);
+        window.glfw_window.set_key_polling(true);
+        window.glfw_window.set_mouse_button_polling(true);
+        window.glfw_window.set_cursor_pos_polling(true);
+        window.glfw_window.set_scroll_polling(true);
+
+        let wrapped_window = Rc::new(window);
+
+        wrapped_window
+    }
+
+    /// Returns the size of the window in hardware pixels.
+    fn framebuffer_size(&self) -> TypedSize2D<DevicePixel, uint> {
+        let (width, height) = self.glfw_window.get_framebuffer_size();
+        TypedSize2D(width as uint, height as uint)
+    }
+
+    /// Returns the size of the window in density-independent "px" units.
+    fn size(&self) -> TypedSize2D<ScreenPx, f32> {
+        let (width, height) = self.glfw_window.get_size();
+        TypedSize2D(width as f32, height as f32)
+    }
+
+    /// Presents the window to the screen (perhaps by page flipping).
+    fn present(&self) {
+        self.glfw_window.swap_buffers();
+    }
+
+    fn recv(&self) -> WindowEvent {
+        {
+            let mut event_queue = self.event_queue.borrow_mut();
+            if !event_queue.is_empty() {
+                return event_queue.remove(0).unwrap();
+            }
+        }
+
+        self.glfw.poll_events();
+        for (_, event) in glfw::flush_messages(&self.events) {
+            self.handle_window_event(&self.glfw_window, event);
+        }
+
+        if self.glfw_window.should_close() {
+            QuitWindowEvent
+        } else {
+            self.event_queue.borrow_mut().remove(0).unwrap_or(IdleWindowEvent)
+        }
+    }
+
+    /// Sets the ready state.
+    fn set_ready_state(&self, ready_state: ReadyState) {
+        self.ready_state.set(ready_state);
+        self.update_window_title()
+    }
+
+    /// Sets the render state.
+    fn set_render_state(&self, render_state: RenderState) {
+        if self.ready_state.get() == FinishedLoading &&
+            self.render_state.get() == RenderingRenderState &&
+            render_state == IdleRenderState {
+            // page loaded
+            self.event_queue.borrow_mut().push(FinishedWindowEvent);
+        }
+
+        self.render_state.set(render_state);
+        self.update_window_title()
+    }
+
+    fn hidpi_factor(&self) -> ScaleFactor<ScreenPx, DevicePixel, f32> {
+        let backing_size = self.framebuffer_size().width.get();
+        let window_size = self.size().width.get();
+        ScaleFactor((backing_size as f32) / window_size)
+    }
+}
+
+impl Window {
+    fn handle_window_event(&self, window: &glfw::Window, event: glfw::WindowEvent) {
+        match event {
+            glfw::KeyEvent(key, _, action, mods) => {
+                if action == glfw::Press {
+                    self.handle_key(key, mods)
+                }
+            },
+            glfw::FramebufferSizeEvent(width, height) => {
+                self.event_queue.borrow_mut().push(
+                    ResizeWindowEvent(TypedSize2D(width as uint, height as uint)));
+            },
+            glfw::RefreshEvent => {
+                self.event_queue.borrow_mut().push(RefreshWindowEvent);
+            },
+            glfw::MouseButtonEvent(button, action, _mods) => {
+                let (x, y) = window.get_cursor_pos();
+                //handle hidpi displays, since GLFW returns non-hi-def coordinates.
+                let (backing_size, _) = window.get_framebuffer_size();
+                let (window_size, _) = window.get_size();
+                let hidpi = (backing_size as f32) / (window_size as f32);
+                let x = x as f32 * hidpi;
+                let y = y as f32 * hidpi;
+                if button == glfw::MouseButtonLeft || button == glfw::MouseButtonRight {
+                    self.handle_mouse(button, action, x as i32, y as i32);
+                }
+            },
+            glfw::CursorPosEvent(xpos, ypos) => {
+                self.event_queue.borrow_mut().push(
+                    MouseWindowMoveEventClass(TypedPoint2D(xpos as f32, ypos as f32)));
+            },
+            glfw::ScrollEvent(xpos, ypos) => {
+                match (window.get_key(glfw::KeyLeftControl),
+                       window.get_key(glfw::KeyRightControl)) {
+                    (glfw::Press, _) | (_, glfw::Press) => {
+                        // Ctrl-Scrollwheel simulates a "pinch zoom" gesture.
+                        if ypos < 0.0 {
+                            self.event_queue.borrow_mut().push(PinchZoomWindowEvent(1.0/1.1));
+                        } else if ypos > 0.0 {
+                            self.event_queue.borrow_mut().push(PinchZoomWindowEvent(1.1));
+                        }
+                    },
+                    _ => {
+                        let dx = (xpos as f32) * 30.0;
+                        let dy = (ypos as f32) * 30.0;
+                        self.scroll_window(dx, dy);
+                    }
+                }
+
+            },
+            _ => {}
+        }
+    }
+
+    /// Helper function to send a scroll event.
+    fn scroll_window(&self, dx: f32, dy: f32) {
+        let (x, y) = self.glfw_window.get_cursor_pos();
+        //handle hidpi displays, since GLFW returns non-hi-def coordinates.
+        let (backing_size, _) = self.glfw_window.get_framebuffer_size();
+        let (window_size, _) = self.glfw_window.get_size();
+        let hidpi = (backing_size as f32) / (window_size as f32);
+        let x = x as f32 * hidpi;
+        let y = y as f32 * hidpi;
+
+        self.event_queue.borrow_mut().push(ScrollWindowEvent(TypedPoint2D(dx, dy),
+        TypedPoint2D(x as i32, y as i32)));
+    }
+
+    /// Helper function to set the window title in accordance with the ready state.
+    fn update_window_title(&self) {
+        let now = time::get_time();
+        if now.sec == self.last_title_set_time.get().sec {
+            return
+        }
+        self.last_title_set_time.set(now);
+
+        match self.ready_state.get() {
+            Blank => {
+                self.glfw_window.set_title("blank — Servo")
+            }
+            Loading => {
+                self.glfw_window.set_title("Loading — Servo")
+            }
+            PerformingLayout => {
+                self.glfw_window.set_title("Performing Layout — Servo")
+            }
+            FinishedLoading => {
+                match self.render_state.get() {
+                    RenderingRenderState => {
+                        self.glfw_window.set_title("Rendering — Servo")
+                    }
+                    IdleRenderState => {
+                        self.glfw_window.set_title("Servo")
+                    }
+                }
+            }
+        }
+    }
+
+    /// Helper function to handle keyboard events.
+    fn handle_key(&self, key: glfw::Key, mods: glfw::Modifiers) {
+        match key {
+            glfw::KeyEscape => self.glfw_window.set_should_close(true),
+            glfw::KeyL if mods.contains(glfw::Control) => self.load_url(), // Ctrl+L
+            glfw::KeyEqual if mods.contains(glfw::Control) => { // Ctrl-+
+                self.event_queue.borrow_mut().push(ZoomWindowEvent(1.1));
+            }
+            glfw::KeyMinus if mods.contains(glfw::Control) => { // Ctrl--
+                self.event_queue.borrow_mut().push(ZoomWindowEvent(1.0/1.1));
+            }
+            glfw::KeyBackspace if mods.contains(glfw::Shift) => { // Shift-Backspace
+                self.event_queue.borrow_mut().push(NavigationWindowEvent(Forward));
+            }
+            glfw::KeyBackspace => { // Backspace
+                self.event_queue.borrow_mut().push(NavigationWindowEvent(Back));
+            }
+            glfw::KeyPageDown => {
+                let (_, height) = self.glfw_window.get_size();
+                self.scroll_window(0.0, -height as f32);
+            }
+            glfw::KeyPageUp => {
+                let (_, height) = self.glfw_window.get_size();
+                self.scroll_window(0.0, height as f32);
+            }
+            _ => {}
+        }
+    }
+
+    /// Helper function to handle a click
+    fn handle_mouse(&self, button: glfw::MouseButton, action: glfw::Action, x: c_int, y: c_int) {
+        // FIXME(tkuehn): max pixel dist should be based on pixel density
+        let max_pixel_dist = 10f64;
+        let event = match action {
+            glfw::Press => {
+                self.mouse_down_point.set(Point2D(x, y));
+                self.mouse_down_button.set(Some(button));
+                MouseWindowMouseDownEvent(button as uint, TypedPoint2D(x as f32, y as f32))
+            }
+            glfw::Release => {
+                match self.mouse_down_button.get() {
+                    None => (),
+                    Some(but) if button == but => {
+                        let pixel_dist = self.mouse_down_point.get() - Point2D(x, y);
+                        let pixel_dist = ((pixel_dist.x * pixel_dist.x +
+                                           pixel_dist.y * pixel_dist.y) as f64).sqrt();
+                        if pixel_dist < max_pixel_dist {
+                            let click_event = MouseWindowClickEvent(button as uint,
+                                                                    TypedPoint2D(x as f32, y as f32));
+                            self.event_queue.borrow_mut().push(MouseWindowEventClass(click_event));
+                        }
+                    }
+                    Some(_) => (),
+                }
+                MouseWindowMouseUpEvent(button as uint, TypedPoint2D(x as f32, y as f32))
+            }
+            _ => fail!("I cannot recognize the type of mouse action that occured. :-(")
+        };
+        self.event_queue.borrow_mut().push(MouseWindowEventClass(event));
+    }
+
+    /// Helper function to pop up an alert box prompting the user to load a URL.
+    fn load_url(&self) {
+        let mut alert: Alert = AlertMethods::new("Navigate to:");
+        alert.add_prompt();
+        alert.run();
+        let value = alert.prompt_value();
+        if "" == value.as_slice() {    // To avoid crashing on Linux.
+            self.event_queue.borrow_mut().push(LoadUrlWindowEvent("http://purple.com/".to_string()))
+        } else {
+            self.event_queue.borrow_mut().push(LoadUrlWindowEvent(value.clone()))
+        }
+    }
+}

components/compositing/platform/common/glut_windowing.rs

@@ -0,0 +1,303 @@
+/* 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/. */
+
+//! A windowing implementation using GLUT.
+
+use windowing::{ApplicationMethods, WindowEvent, WindowMethods};
+use windowing::{IdleWindowEvent, ResizeWindowEvent, LoadUrlWindowEvent, MouseWindowEventClass};
+use windowing::{ScrollWindowEvent, ZoomWindowEvent, NavigationWindowEvent, FinishedWindowEvent};
+use windowing::{MouseWindowClickEvent, MouseWindowMouseDownEvent, MouseWindowMouseUpEvent};
+use windowing::{Forward, Back};
+
+use alert::{Alert, AlertMethods};
+use libc::{c_int, c_uchar};
+use std::cell::{Cell, RefCell};
+use std::rc::Rc;
+use geom::point::{Point2D, TypedPoint2D};
+use geom::scale_factor::ScaleFactor;
+use geom::size::TypedSize2D;
+use layers::geometry::DevicePixel;
+use servo_msg::compositor_msg::{IdleRenderState, RenderState, RenderingRenderState};
+use servo_msg::compositor_msg::{FinishedLoading, Blank, ReadyState};
+use servo_util::geometry::ScreenPx;
+
+use glut::glut::{ACTIVE_SHIFT, DOUBLE, WindowHeight};
+use glut::glut::WindowWidth;
+use glut::glut;
+
+// static THROBBER: [char, ..8] = [ '⣾', '⣽', '⣻', '⢿', '⡿', '⣟', '⣯', '⣷' ];
+
+/// A structure responsible for setting up and tearing down the entire windowing system.
+pub struct Application;
+
+impl ApplicationMethods for Application {
+    fn new() -> Application {
+        glut::init();
+        glut::init_display_mode(DOUBLE);
+        Application
+    }
+}
+
+impl Drop for Application {
+    fn drop(&mut self) {
+        drop_local_window();
+    }
+}
+
+/// The type of a window.
+pub struct Window {
+    pub glut_window: glut::Window,
+
+    pub event_queue: RefCell<Vec<WindowEvent>>,
+
+    pub drag_origin: Point2D<c_int>,
+
+    pub mouse_down_button: Cell<c_int>,
+    pub mouse_down_point: Cell<Point2D<c_int>>,
+
+    pub ready_state: Cell<ReadyState>,
+    pub render_state: Cell<RenderState>,
+    pub throbber_frame: Cell<u8>,
+}
+
+impl WindowMethods<Application> for Window {
+    /// Creates a new window.
+    fn new(_: &Application, _: bool) -> Rc<Window> {
+        // Create the GLUT window.
+        glut::init_window_size(800, 600);
+        let glut_window = glut::create_window("Servo".to_string());
+
+        // Create our window object.
+        let window = Window {
+            glut_window: glut_window,
+
+            event_queue: RefCell::new(vec!()),
+
+            drag_origin: Point2D(0 as c_int, 0),
+
+            mouse_down_button: Cell::new(0),
+            mouse_down_point: Cell::new(Point2D(0 as c_int, 0)),
+
+            ready_state: Cell::new(Blank),
+            render_state: Cell::new(IdleRenderState),
+            throbber_frame: Cell::new(0),
+        };
+
+        // Register event handlers.
+
+        //Added dummy display callback to freeglut. According to freeglut ref, we should register some kind of display callback after freeglut 3.0.
+
+        struct DisplayCallbackState;
+        impl glut::DisplayCallback for DisplayCallbackState {
+            fn call(&self) {
+                debug!("GLUT display func registgered");
+            }
+        }
+        glut::display_func(box DisplayCallbackState);
+        struct ReshapeCallbackState;
+        impl glut::ReshapeCallback for ReshapeCallbackState {
+            fn call(&self, width: c_int, height: c_int) {
+                let tmp = local_window();
+                tmp.event_queue.borrow_mut().push(ResizeWindowEvent(TypedSize2D(width as uint, height as uint)))
+            }
+        }
+        glut::reshape_func(glut_window, box ReshapeCallbackState);
+        struct KeyboardCallbackState;
+        impl glut::KeyboardCallback for KeyboardCallbackState {
+            fn call(&self, key: c_uchar, _x: c_int, _y: c_int) {
+                let tmp = local_window();
+                tmp.handle_key(key)
+            }
+        }
+        glut::keyboard_func(box KeyboardCallbackState);
+        struct MouseCallbackState;
+        impl glut::MouseCallback for MouseCallbackState {
+            fn call(&self, button: c_int, state: c_int, x: c_int, y: c_int) {
+                if button < 3 {
+                    let tmp = local_window();
+                    tmp.handle_mouse(button, state, x, y);
+                } else {
+                    match button {
+                        3 => {
+                            let tmp = local_window();
+                            tmp.event_queue.borrow_mut().push(ScrollWindowEvent(
+                                    TypedPoint2D(0.0f32, 5.0f32),
+                                    TypedPoint2D(0i32, 5i32)));
+                        },
+                        4 => {
+                            let tmp = local_window();
+                            tmp.event_queue.borrow_mut().push(ScrollWindowEvent(
+                                    TypedPoint2D(0.0f32, -5.0f32),
+                                    TypedPoint2D(0i32, -5i32)));
+                        },
+                        _ => {}
+                    }
+                }
+            }
+        }
+        glut::mouse_func(box MouseCallbackState);
+
+        let wrapped_window = Rc::new(window);
+
+        install_local_window(wrapped_window.clone());
+
+        wrapped_window
+    }
+
+    /// Returns the size of the window in hardware pixels.
+    fn framebuffer_size(&self) -> TypedSize2D<DevicePixel, uint> {
+        TypedSize2D(glut::get(WindowWidth) as uint, glut::get(WindowHeight) as uint)
+    }
+
+    /// Returns the size of the window in density-independent "px" units.
+    fn size(&self) -> TypedSize2D<ScreenPx, f32> {
+        self.framebuffer_size().as_f32() / self.hidpi_factor()
+    }
+
+    /// Presents the window to the screen (perhaps by page flipping).
+    fn present(&self) {
+        glut::swap_buffers();
+    }
+
+    fn recv(&self) -> WindowEvent {
+        if !self.event_queue.borrow_mut().is_empty() {
+            return self.event_queue.borrow_mut().remove(0).unwrap();
+        }
+
+        glut::check_loop();
+
+        self.event_queue.borrow_mut().remove(0).unwrap_or(IdleWindowEvent)
+    }
+
+    /// Sets the ready state.
+    fn set_ready_state(&self, ready_state: ReadyState) {
+        self.ready_state.set(ready_state);
+        //FIXME: set_window_title causes crash with Android version of freeGLUT. Temporarily blocked.
+        //self.update_window_title()
+    }
+
+    /// Sets the render state.
+    fn set_render_state(&self, render_state: RenderState) {
+        if self.ready_state.get() == FinishedLoading &&
+            self.render_state.get() == RenderingRenderState &&
+            render_state == IdleRenderState {
+            // page loaded
+            self.event_queue.borrow_mut().push(FinishedWindowEvent);
+        }
+
+        self.render_state.set(render_state);
+        //FIXME: set_window_title causes crash with Android version of freeGLUT. Temporarily blocked.
+        //self.update_window_title()
+    }
+
+    fn hidpi_factor(&self) -> ScaleFactor<ScreenPx, DevicePixel, f32> {
+        //FIXME: Do nothing in GLUT now.
+        ScaleFactor(1.0)
+    }
+}
+
+impl Window {
+    /// Helper function to set the window title in accordance with the ready state.
+    // fn update_window_title(&self) {
+    //     let throbber = THROBBER[self.throbber_frame];
+    //     match self.ready_state {
+    //         Blank => {
+    //             glut::set_window_title(self.glut_window, "Blank")
+    //         }
+    //         Loading => {
+    //             glut::set_window_title(self.glut_window, format!("{:c} Loading . Servo", throbber))
+    //         }
+    //         PerformingLayout => {
+    //             glut::set_window_title(self.glut_window, format!("{:c} Performing Layout . Servo", throbber))
+    //         }
+    //         FinishedLoading => {
+    //             match self.render_state {
+    //                 RenderingRenderState => {
+    //                     glut::set_window_title(self.glut_window, format!("{:c} Rendering . Servo", throbber))
+    //                 }
+    //                 IdleRenderState => glut::set_window_title(self.glut_window, "Servo"),
+    //             }
+    //         }
+    //     }
+    // }
+
+    /// Helper function to handle keyboard events.
+    fn handle_key(&self, key: u8) {
+        debug!("got key: {}", key);
+        let modifiers = glut::get_modifiers();
+        match key {
+            42 => self.load_url(),
+            43 => self.event_queue.borrow_mut().push(ZoomWindowEvent(1.1)),
+            45 => self.event_queue.borrow_mut().push(ZoomWindowEvent(0.909090909)),
+            56 => self.event_queue.borrow_mut().push(ScrollWindowEvent(TypedPoint2D(0.0f32, 5.0f32),
+                                                                       TypedPoint2D(0i32, 5i32))),
+            50 => self.event_queue.borrow_mut().push(ScrollWindowEvent(TypedPoint2D(0.0f32, -5.0f32),
+                                                                       TypedPoint2D(0i32, -5i32))),
+            127 => {
+                if (modifiers & ACTIVE_SHIFT) != 0 {
+                    self.event_queue.borrow_mut().push(NavigationWindowEvent(Forward));
+                }
+                else {
+                    self.event_queue.borrow_mut().push(NavigationWindowEvent(Back));
+                }
+            }
+            _ => {}
+        }
+    }
+
+    /// Helper function to handle a click
+    fn handle_mouse(&self, button: c_int, state: c_int, x: c_int, y: c_int) {
+        // FIXME(tkuehn): max pixel dist should be based on pixel density
+        let max_pixel_dist = 10f32;
+        let event = match state {
+            glut::MOUSE_DOWN => {
+                self.mouse_down_point.set(Point2D(x, y));
+                self.mouse_down_button.set(button);
+                MouseWindowMouseDownEvent(button as uint, TypedPoint2D(x as f32, y as f32))
+            }
+            glut::MOUSE_UP => {
+                if self.mouse_down_button.get() == button {
+                    let pixel_dist = self.mouse_down_point.get() - Point2D(x, y);
+                    let pixel_dist = ((pixel_dist.x * pixel_dist.x +
+                                       pixel_dist.y * pixel_dist.y) as f32).sqrt();
+                    if pixel_dist < max_pixel_dist {
+                        let click_event = MouseWindowClickEvent(button as uint,
+                                                           TypedPoint2D(x as f32, y as f32));
+                        self.event_queue.borrow_mut().push(MouseWindowEventClass(click_event));
+                    }
+                }
+                MouseWindowMouseUpEvent(button as uint, TypedPoint2D(x as f32, y as f32))
+            }
+            _ => fail!("I cannot recognize the type of mouse action that occured. :-(")
+        };
+        self.event_queue.borrow_mut().push(MouseWindowEventClass(event));
+    }
+
+    /// Helper function to pop up an alert box prompting the user to load a URL.
+    fn load_url(&self) {
+        let mut alert: Alert = AlertMethods::new("Navigate to:");
+        alert.add_prompt();
+        alert.run();
+        let value = alert.prompt_value();
+        if "" == value.as_slice() {    // To avoid crashing on Linux.
+            self.event_queue.borrow_mut().push(LoadUrlWindowEvent("http://purple.com/".to_string()))
+        } else {
+            self.event_queue.borrow_mut().push(LoadUrlWindowEvent(value.clone()))
+        }
+    }
+}
+
+local_data_key!(TLS_KEY: Rc<Window>)
+
+fn install_local_window(window: Rc<Window>) {
+    TLS_KEY.replace(Some(window));
+}
+
+fn drop_local_window() {
+    TLS_KEY.replace(None);
+}
+
+fn local_window() -> Rc<Window> {
+    TLS_KEY.get().unwrap().clone()
+}

components/compositing/platform/mod.rs

@@ -0,0 +1,18 @@
+/* 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/. */
+
+//! Platform-specific functionality for Servo.
+
+#[cfg(target_os="android")]
+pub use platform::common::glut_windowing::{Application, Window};
+#[cfg(not(target_os="android"))]
+pub use platform::common::glfw_windowing::{Application, Window};
+
+pub mod common {
+    #[cfg(target_os="android")]
+    pub mod glut_windowing;
+    #[cfg(not(target_os="android"))]
+    pub mod glfw_windowing;
+}
+