Auto merge of #18933 - mrobinson:wr-text-index, r=jdm

Use WebRender to compute text index on click events

This is the second half of switching over to WebRender for hit testing.
Now that WebRender gives us the location of the hit tested point in the
display item, we can use that to calculate text index.

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- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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1 files changed, 64 insertions, 47 deletions

diff --git a/components/script/dom/mouseevent.rs b/components/script/dom/mouseevent.rs
index 7e6fbd52eb8..62ec6f16ed3 100644
--- a/components/script/dom/mouseevent.rs
+++ b/components/script/dom/mouseevent.rs
@@ -15,6 +15,7 @@ use dom::eventtarget::EventTarget;
 use dom::uievent::UIEvent;
 use dom::window::Window;
 use dom_struct::dom_struct;
+use euclid::Point2D;
 use servo_config::prefs::PREFS;
 use std::cell::Cell;
 use std::default::Default;
@@ -32,6 +33,7 @@ pub struct MouseEvent {
     meta_key: Cell<bool>,
     button: Cell<i16>,
     related_target: MutNullableDom<EventTarget>,
+    point_in_target: Cell<Option<Point2D<f32>>>
 }
 
 impl MouseEvent {
@@ -48,6 +50,7 @@ impl MouseEvent {
             meta_key: Cell::new(false),
             button: Cell::new(0),
             related_target: Default::default(),
+            point_in_target: Cell::new(None),
         }
     }
 
@@ -57,28 +60,34 @@ impl MouseEvent {
                            MouseEventBinding::Wrap)
     }
 
-    pub fn new(window: &Window,
-               type_: DOMString,
-               can_bubble: EventBubbles,
-               cancelable: EventCancelable,
-               view: Option<&Window>,
-               detail: i32,
-               screen_x: i32,
-               screen_y: i32,
-               client_x: i32,
-               client_y: i32,
-               ctrl_key: bool,
-               alt_key: bool,
-               shift_key: bool,
-               meta_key: bool,
-               button: i16,
-               related_target: Option<&EventTarget>) -> DomRoot<MouseEvent> {
+    pub fn new(
+        window: &Window,
+        type_: DOMString,
+        can_bubble: EventBubbles,
+        cancelable: EventCancelable,
+        view: Option<&Window>,
+        detail: i32,
+        screen_x: i32,
+        screen_y: i32,
+        client_x: i32,
+        client_y: i32,
+        ctrl_key: bool,
+        alt_key: bool,
+        shift_key: bool,
+        meta_key: bool,
+        button: i16,
+        related_target: Option<&EventTarget>,
+        point_in_target: Option<Point2D<f32>>
+    ) -> DomRoot<MouseEvent> {
         let ev = MouseEvent::new_uninitialized(window);
-        ev.InitMouseEvent(type_, bool::from(can_bubble), bool::from(cancelable),
-                          view, detail,
-                          screen_x, screen_y, client_x, client_y,
-                          ctrl_key, alt_key, shift_key, meta_key,
-                          button, related_target);
+        ev.InitMouseEvent(
+            type_, bool::from(can_bubble), bool::from(cancelable),
+            view, detail,
+            screen_x, screen_y, client_x, client_y,
+            ctrl_key, alt_key, shift_key, meta_key,
+            button, related_target,
+        );
+        ev.point_in_target.set(point_in_target);
         ev
     }
 
@@ -87,18 +96,24 @@ impl MouseEvent {
                        init: &MouseEventBinding::MouseEventInit) -> Fallible<DomRoot<MouseEvent>> {
         let bubbles = EventBubbles::from(init.parent.parent.parent.bubbles);
         let cancelable = EventCancelable::from(init.parent.parent.parent.cancelable);
-        let event = MouseEvent::new(window,
-                                    type_,
-                                    bubbles,
-                                    cancelable,
-                                    init.parent.parent.view.r(),
-                                    init.parent.parent.detail,
-                                    init.screenX, init.screenY,
-                                    init.clientX, init.clientY, init.parent.ctrlKey,
-                                    init.parent.altKey, init.parent.shiftKey, init.parent.metaKey,
-                                    init.button, init.relatedTarget.r());
+        let event = MouseEvent::new(
+            window,
+            type_,
+            bubbles,
+            cancelable,
+            init.parent.parent.view.r(),
+            init.parent.parent.detail,
+            init.screenX, init.screenY,
+            init.clientX, init.clientY, init.parent.ctrlKey,
+            init.parent.altKey, init.parent.shiftKey, init.parent.metaKey,
+            init.button, init.relatedTarget.r(), None
+        );
         Ok(event)
     }
+
+    pub fn point_in_target(&self) -> Option<Point2D<f32>> {
+        self.point_in_target.get()
+    }
 }
 
 impl MouseEventMethods for MouseEvent {
@@ -166,22 +181,24 @@ impl MouseEventMethods for MouseEvent {
     }
 
     // https://w3c.github.io/uievents/#widl-MouseEvent-initMouseEvent
-    fn InitMouseEvent(&self,
-                      type_arg: DOMString,
-                      can_bubble_arg: bool,
-                      cancelable_arg: bool,
-                      view_arg: Option<&Window>,
-                      detail_arg: i32,
-                      screen_x_arg: i32,
-                      screen_y_arg: i32,
-                      client_x_arg: i32,
-                      client_y_arg: i32,
-                      ctrl_key_arg: bool,
-                      alt_key_arg: bool,
-                      shift_key_arg: bool,
-                      meta_key_arg: bool,
-                      button_arg: i16,
-                      related_target_arg: Option<&EventTarget>) {
+    fn InitMouseEvent(
+        &self,
+        type_arg: DOMString,
+        can_bubble_arg: bool,
+        cancelable_arg: bool,
+        view_arg: Option<&Window>,
+        detail_arg: i32,
+        screen_x_arg: i32,
+        screen_y_arg: i32,
+        client_x_arg: i32,
+        client_y_arg: i32,
+        ctrl_key_arg: bool,
+        alt_key_arg: bool,
+        shift_key_arg: bool,
+        meta_key_arg: bool,
+        button_arg: i16,
+        related_target_arg: Option<&EventTarget>,
+    ) {
         if self.upcast::<Event>().dispatching() {
             return;
         }