servo: Merge #14141 - Implement home end key scrolling (from samuknet:home-end-key-scroll2); r=glennw

<!-- Please describe your changes on the following line: -->
* Refactor all scroll related code to use a new `ScrollLocation` struct which can either be a `delta` (as before) or a `Start` or `End` request, to represent the desire to scroll to the start and end of the page.
Effectively, everywhere a delta was used, there is now a `ScrollLocation` struct instead.

* Add key press listeners for HOME and END keys so as to cause a scroll to be queued with `ScrollLocation::Start` (in HOME case) or `ScrollLocation::End` (in END case).

* These changes depend on added support for the new `ScrollLocation` in webrender and webrender_traits. See servo/webrender#540.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ x] These changes fix #13082 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because scrolling I/O

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Source-Repo: https://github.com/servo/servo
Source-Revision: 1706ffd6e5a02f26f69970b3b41536a8a85ef6fe

Author: Sam

servo/Cargo.lock

@@ -39,7 +39,7 @@ use style_traits::viewport::ViewportConstraints;
 use time::{precise_time_ns, precise_time_s};
 use touch::{TouchHandler, TouchAction};
 use webrender;
-use webrender_traits::{self, ScrollEventPhase, ServoScrollRootId, LayoutPoint};
+use webrender_traits::{self, ScrollEventPhase, ServoScrollRootId, LayoutPoint, ScrollLocation};
 use windowing::{self, MouseWindowEvent, WindowEvent, WindowMethods, WindowNavigateMsg};
 
 #[derive(Debug, PartialEq)]
@@ -227,8 +227,8 @@ pub struct IOCompositor<Window: WindowMethods> {
 struct ScrollZoomEvent {
     /// Change the pinch zoom level by this factor
     magnification: f32,
-    /// Scroll by this offset
-    delta: TypedPoint2D<f32, DevicePixel>,
+    /// Scroll by this offset, or to Start or End
+    scroll_location: ScrollLocation,
     /// Apply changes to the frame at this location
     cursor: TypedPoint2D<i32, DevicePixel>,
     /// The scroll event phase.
@@ -1027,15 +1027,19 @@ impl<Window: WindowMethods> IOCompositor<Window> {
         match self.touch_handler.on_touch_move(identifier, point) {
             TouchAction::Scroll(delta) => {
                 match point.cast() {
-                    Some(point) => self.on_scroll_window_event(delta, point),
+                    Some(point) => self.on_scroll_window_event(ScrollLocation::Delta(
+                                                               webrender_traits::LayerPoint::from_untyped(
+                                                               &delta.to_untyped())),
+                                                               point),
                     None => error!("Point cast failed."),
                 }
             }
             TouchAction::Zoom(magnification, scroll_delta) => {
                 let cursor = TypedPoint2D::new(-1, -1);  // Make sure this hits the base layer.
                 self.pending_scroll_zoom_events.push(ScrollZoomEvent {
                     magnification: magnification,
-                    delta: scroll_delta,
+                    scroll_location: ScrollLocation::Delta(webrender_traits::LayerPoint::from_untyped(
+                                                           &scroll_delta.to_untyped())),
                     cursor: cursor,
                     phase: ScrollEventPhase::Move(true),
                     event_count: 1,
@@ -1096,7 +1100,7 @@ impl<Window: WindowMethods> IOCompositor<Window> {
     }
 
     fn on_scroll_window_event(&mut self,
-                              delta: TypedPoint2D<f32, DevicePixel>,
+                              scroll_location: ScrollLocation,
                               cursor: TypedPoint2D<i32, DevicePixel>) {
         let event_phase = match (self.scroll_in_progress, self.in_scroll_transaction) {
             (false, None) => ScrollEventPhase::Start,
@@ -1107,33 +1111,33 @@ impl<Window: WindowMethods> IOCompositor<Window> {
         self.in_scroll_transaction = Some(Instant::now());
         self.pending_scroll_zoom_events.push(ScrollZoomEvent {
             magnification: 1.0,
-            delta: delta,
+            scroll_location: scroll_location,
             cursor: cursor,
             phase: event_phase,
             event_count: 1,
         });
     }
 
     fn on_scroll_start_window_event(&mut self,
-                                    delta: TypedPoint2D<f32, DevicePixel>,
+                                    scroll_location: ScrollLocation,
                                     cursor: TypedPoint2D<i32, DevicePixel>) {
         self.scroll_in_progress = true;
         self.pending_scroll_zoom_events.push(ScrollZoomEvent {
             magnification: 1.0,
-            delta: delta,
+            scroll_location: scroll_location,
             cursor: cursor,
             phase: ScrollEventPhase::Start,
             event_count: 1,
         });
     }
 
     fn on_scroll_end_window_event(&mut self,
-                                  delta: TypedPoint2D<f32, DevicePixel>,
+                                  scroll_location: ScrollLocation,
                                   cursor: TypedPoint2D<i32, DevicePixel>) {
         self.scroll_in_progress = false;
         self.pending_scroll_zoom_events.push(ScrollZoomEvent {
             magnification: 1.0,
-            delta: delta,
+            scroll_location: scroll_location,
             cursor: cursor,
             phase: ScrollEventPhase::End,
             event_count: 1,
@@ -1146,14 +1150,34 @@ impl<Window: WindowMethods> IOCompositor<Window> {
         // Batch up all scroll events into one, or else we'll do way too much painting.
         let mut last_combined_event: Option<ScrollZoomEvent> = None;
         for scroll_event in self.pending_scroll_zoom_events.drain(..) {
-            let this_delta = scroll_event.delta;
             let this_cursor = scroll_event.cursor;
+
+            let this_delta = match scroll_event.scroll_location {
+                ScrollLocation::Delta(delta) => delta,
+                ScrollLocation::Start | ScrollLocation::End => {
+                    // If this is an event which is scrolling to the start or end of the page,
+                    // disregard other pending events and exit the loop.
+                    last_combined_event = Some(scroll_event);
+                    break;
+                }
+            };
+
             if let Some(combined_event) = last_combined_event {
                 if combined_event.phase != scroll_event.phase {
-                    let delta = (combined_event.delta / self.scale).to_untyped();
+                    let combined_delta = match combined_event.scroll_location {
+                        ScrollLocation::Delta(delta) => delta,
+                        ScrollLocation::Start | ScrollLocation::End => {
+                            // If this is an event which is scrolling to the start or end of the page,
+                            // disregard other pending events and exit the loop.
+                            last_combined_event = Some(scroll_event);
+                            break;
+                        }
+                    };
+                    let delta = (TypedPoint2D::from_untyped(&combined_delta.to_untyped()) / self.scale)
+                                 .to_untyped();
+                    let delta = webrender_traits::LayerPoint::from_untyped(&delta);
                     let cursor =
                         (combined_event.cursor.to_f32() / self.scale).to_untyped();
-                    let delta = webrender_traits::LayerPoint::from_untyped(&delta);
                     let location = webrender_traits::ScrollLocation::Delta(delta);
                     let cursor = webrender_traits::WorldPoint::from_untyped(&cursor);
                     self.webrender_api.scroll(location, cursor, combined_event.phase);
@@ -1165,7 +1189,8 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                 (last_combined_event @ &mut None, _) => {
                     *last_combined_event = Some(ScrollZoomEvent {
                         magnification: scroll_event.magnification,
-                        delta: this_delta,
+                        scroll_location: ScrollLocation::Delta(webrender_traits::LayerPoint::from_untyped(
+                                                               &this_delta.to_untyped())),
                         cursor: this_cursor,
                         phase: scroll_event.phase,
                         event_count: 1,
@@ -1177,30 +1202,41 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                     // fling. This causes events to get bunched up occasionally, causing
                     // nasty-looking "pops". To mitigate this, during a fling we average
                     // deltas instead of summing them.
-                    let old_event_count =
-                        ScaleFactor::new(last_combined_event.event_count as f32);
-                    last_combined_event.event_count += 1;
-                    let new_event_count =
-                        ScaleFactor::new(last_combined_event.event_count as f32);
-                    last_combined_event.delta =
-                        (last_combined_event.delta * old_event_count + this_delta) /
-                        new_event_count;
+                    if let ScrollLocation::Delta(delta) = last_combined_event.scroll_location {
+                        let old_event_count =
+                            ScaleFactor::new(last_combined_event.event_count as f32);
+                        last_combined_event.event_count += 1;
+                        let new_event_count =
+                            ScaleFactor::new(last_combined_event.event_count as f32);
+                        last_combined_event.scroll_location = ScrollLocation::Delta(
+                            (delta * old_event_count + this_delta) /
+                            new_event_count);
+                    }
                 }
                 (&mut Some(ref mut last_combined_event), _) => {
-                    last_combined_event.delta = last_combined_event.delta + this_delta;
-                    last_combined_event.event_count += 1
+                    if let ScrollLocation::Delta(delta) = last_combined_event.scroll_location {
+                        last_combined_event.scroll_location = ScrollLocation::Delta(delta + this_delta);
+                        last_combined_event.event_count += 1
+                    }
                 }
             }
         }
 
         // TODO(gw): Support zoom (WR issue #28).
         if let Some(combined_event) = last_combined_event {
-            let delta = (combined_event.delta / self.scale).to_untyped();
-            let delta = webrender_traits::LayoutPoint::from_untyped(&delta);
+            let scroll_location = match combined_event.scroll_location {
+                ScrollLocation::Delta(delta) => {
+                    let scaled_delta = (TypedPoint2D::from_untyped(&delta.to_untyped()) / self.scale)
+                                       .to_untyped();
+                    let calculated_delta = webrender_traits::LayoutPoint::from_untyped(&scaled_delta);
+                                           ScrollLocation::Delta(calculated_delta)
+                },
+                // Leave ScrollLocation unchanged if it is Start or End location.
+                sl @ ScrollLocation::Start | sl @ ScrollLocation::End => sl,
+            };
             let cursor = (combined_event.cursor.to_f32() / self.scale).to_untyped();
-            let location = webrender_traits::ScrollLocation::Delta(delta);
             let cursor = webrender_traits::WorldPoint::from_untyped(&cursor);
-            self.webrender_api.scroll(location, cursor, combined_event.phase);
+            self.webrender_api.scroll(scroll_location, cursor, combined_event.phase);
             self.waiting_for_results_of_scroll = true
         }
 
@@ -1295,7 +1331,7 @@ impl<Window: WindowMethods> IOCompositor<Window> {
     fn on_pinch_zoom_window_event(&mut self, magnification: f32) {
         self.pending_scroll_zoom_events.push(ScrollZoomEvent {
             magnification: magnification,
-            delta: TypedPoint2D::zero(), // TODO: Scroll to keep the center in view?
+            scroll_location: ScrollLocation::Delta(TypedPoint2D::zero()), // TODO: Scroll to keep the center in view?
             cursor:  TypedPoint2D::new(-1, -1), // Make sure this hits the base layer.
             phase: ScrollEventPhase::Move(true),
             event_count: 1,
@@ -1693,6 +1729,7 @@ impl<Window: WindowMethods> IOCompositor<Window> {
     }
 }
 
+
 /// Why we performed a composite. This is used for debugging.
 #[derive(Copy, Clone, PartialEq, Debug)]
 pub enum CompositingReason {

servo/components/compositing/compositor.rs

@@ -16,6 +16,7 @@ use servo_geometry::ScreenPx;
 use servo_url::ServoUrl;
 use std::fmt::{Debug, Error, Formatter};
 use style_traits::cursor::Cursor;
+use webrender_traits::ScrollLocation;
 
 #[derive(Clone)]
 pub enum MouseWindowEvent {
@@ -62,7 +63,7 @@ pub enum WindowEvent {
     Touch(TouchEventType, TouchId, TypedPoint2D<f32, DevicePixel>),
     /// Sent when the user scrolls. The first point is the delta and the second point is the
     /// origin.
-    Scroll(TypedPoint2D<f32, DevicePixel>, TypedPoint2D<i32, DevicePixel>, TouchEventType),
+    Scroll(ScrollLocation, TypedPoint2D<i32, DevicePixel>, TouchEventType),
     /// Sent when the user zooms.
     Zoom(f32),
     /// Simulated "pinch zoom" gesture for non-touch platforms (e.g. ctrl-scrollwheel).

servo/components/compositing/windowing.rs

@@ -35,6 +35,11 @@ servo_geometry = {path = "../../components/geometry"}
 servo_url = {path = "../../components/url"}
 style_traits = {path = "../../components/style_traits"}
 
+[dependencies.webrender_traits]
+git = "https://github.com/servo/webrender"
+default-features = false
+features = ["serde_derive", "ipc"]
+
 [target.'cfg(target_os="macos")'.dependencies]
 objc = "0.2"
 cocoa = "0.5"

servo/ports/cef/Cargo.toml

@@ -8,6 +8,7 @@ use interfaces::{CefBrowser, CefBrowserHost, CefClient, cef_browser_t, cef_brows
 use types::cef_event_flags_t::{EVENTFLAG_ALT_DOWN, EVENTFLAG_CONTROL_DOWN, EVENTFLAG_SHIFT_DOWN};
 use types::cef_key_event_type_t::{KEYEVENT_CHAR, KEYEVENT_KEYDOWN, KEYEVENT_KEYUP, KEYEVENT_RAWKEYDOWN};
 use types::{cef_mouse_button_type_t, cef_mouse_event, cef_rect_t, cef_key_event, cef_window_handle_t};
+use webrender_traits::ScrollLocation;
 use wrappers::CefWrap;
 
 use compositing::windowing::{WindowEvent, MouseWindowEvent};
@@ -471,7 +472,7 @@ full_cef_class_impl! {
             let delta_y: c_int = delta_y;
             let delta = TypedPoint2D::new(delta_x as f32, delta_y as f32);
             let origin = TypedPoint2D::new((*event).x as i32, (*event).y as i32);
-            this.downcast().send_window_event(WindowEvent::Scroll(delta,
+            this.downcast().send_window_event(WindowEvent::Scroll(ScrollLocation::Delta(delta),
                                                                   origin,
                                                                   TouchEventType::Move))
         }}

servo/ports/cef/browser_host.rs

@@ -28,6 +28,7 @@ extern crate style_traits;
 
 extern crate net_traits;
 extern crate msg;
+extern crate webrender_traits;
 
 extern crate libc;
 

servo/ports/cef/lib.rs

@@ -23,6 +23,10 @@ servo_config = {path = "../../components/config"}
 servo_url = {path = "../../components/url"}
 style_traits = {path = "../../components/style_traits"}
 
+[dependencies.webrender_traits]
+git = "https://github.com/servo/webrender"
+default_features = false
+
 [target.'cfg(any(target_os = "linux", target_os = "macos"))'.dependencies]
 osmesa-sys = "0.1.2"
 

servo/ports/glutin/Cargo.toml

@@ -22,6 +22,8 @@ extern crate servo_config;
 extern crate servo_geometry;
 extern crate servo_url;
 extern crate style_traits;
+extern crate webrender_traits;
+
 #[cfg(target_os = "windows")] extern crate winapi;
 #[cfg(target_os = "windows")] extern crate user32;
 #[cfg(target_os = "windows")] extern crate gdi32;