Enable scrolling of UI elements.

chrome/browser/android/vr_shell/vr_shell_gl.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/android/vr_shell/vr_shell_gl.h"
 
 #include <limits>
 #include <utility>
 
 #include "base/android/jni_android.h"
@@ skipping 491 matching lines @@
   for (const auto& plane : scene_->GetUiElements()) {
     if (!plane->IsHitTestable())
       continue;
 
     float distance_to_plane = plane->GetRayDistance(kOrigin, eye_to_target);
     gvr::Vec3f plane_intersection_point =
         GetRayPoint(kOrigin, eye_to_target, distance_to_plane);
 
     gvr::Vec3f rect_2d_point =
         MatrixVectorMul(plane->transform.from_world, plane_intersection_point);
     if (distance_to_plane > 0 && distance_to_plane < closest_element_distance) {

[cjgrant, 2017/02/14 14:08:25]

Unrelated rework: Can you invert this logic, do a continue if it fires, and
bring the remainder of the block out of the condition?

[tiborg, 2017/02/14 21:44:23]

Done.

       float x = rect_2d_point.x + 0.5f;
       float y = 0.5f - rect_2d_point.y;
       bool is_inside = x >= 0.0f && x < 1.0f && y >= 0.0f && y < 1.0f;
       if (!is_inside)
         continue;
 
       closest_element_distance = distance_to_plane;
       Rectf pixel_rect;
       if (plane->fill == Fill::CONTENT) {
         pixel_rect = {0, 0, content_tex_css_width_, content_tex_css_height_};
       } else {
         pixel_rect = {plane->copy_rect.x, plane->copy_rect.y,
                       plane->copy_rect.width, plane->copy_rect.height};
       }
       pixel_x = pixel_rect.width * x + pixel_rect.x;
       pixel_y = pixel_rect.height * y + pixel_rect.y;
 
       target_point_ = plane_intersection_point;
       target_element_ = plane.get();
-      input_target = (plane->fill == Fill::CONTENT) ? InputTarget::CONTENT
-                                                    : InputTarget::UI;
+      // For now treat UI elements, which do not show web content, as NONE input

[cjgrant, 2017/02/14 14:08:25]

General comment on comments: It's usually best to leave out "For now",
"temporarily", etc, as we have no idea how long this code might live.

[tiborg, 2017/02/14 21:44:23]

Done.

+      // targets since they cannot make use of the input anyway.
+      switch (plane->fill) {

[cjgrant, 2017/02/14 14:08:25]

The loop is responsible for finding target_element_, so this switch should live
after the loop and use target_element_.

[tiborg, 2017/02/14 21:44:23]

Done.

+        case Fill::CONTENT:
+          input_target = InputTarget::CONTENT;
+          break;
+        case Fill::SPRITE:
+          input_target = InputTarget::UI;
+          break;
+        default:
+          input_target = InputTarget::NONE;
+          break;
+      }
     }
   }
   SendEventsToTarget(input_target, pixel_x, pixel_y);
 }
 
 void VrShellGl::SendEventsToTarget(InputTarget input_target,
                                    int pixel_x,
                                    int pixel_y) {
   std::vector<std::unique_ptr<WebGestureEvent>> gesture_list =
       controller_->DetectGestures();
   double timestamp = gesture_list.front()->timeStampSeconds();

[cjgrant, 2017/02/14 14:08:25]

Unrelated to this CL, but I'm curious: Do all gestures in the list have the same
timestamp?

[tiborg, 2017/02/14 21:44:23]

I'm not sure but there is a function (
https://cs.corp.google.com/clankium/src/chrome/browser/android/vr_shell/vr_co...),
which sets the time stamp. So, I don't think so.

 
   if (touch_pending_) {
     touch_pending_ = false;
     std::unique_ptr<WebGestureEvent> event(new WebGestureEvent(
         WebInputEvent::GestureTapDown, WebInputEvent::NoModifiers, timestamp));
     event->sourceDevice = blink::WebGestureDeviceTouchpad;
     event->x = pixel_x;
     event->y = pixel_y;
     gesture_list.push_back(std::move(event));
   }
 
   for (const auto& gesture : gesture_list) {
+    gesture->x = pixel_x;

[cjgrant, 2017/02/14 14:08:25]

So here we change gesture, but a line above, gesture is a const reference. Is
the const-ness broken through unique_ptr?

[tiborg, 2017/02/14 21:44:23]

I think the const is referring to the unique_ptr and not the referenced type,
i.e. const std::unique_ptr<...>. So, you cannot let the unique_ptr point to some
other object but you can modify the pointed to object. To make the pointed to
object const you would need std::unique_ptr<const ...>.

[cjgrant, 2017/02/14 22:37:41]

Michael, thoughts on this?  The const is misleading here IMO - I'd ditch it.

[tiborg, 2017/02/14 23:13:52]

Ditched const.

+    gesture->y = pixel_y;
+    auto movableGesture = base::WrapUnique(new WebGestureEvent(*gesture));

[cjgrant, 2017/02/14 14:08:24]

This should use MakeUnique() (ie. the new preferred style).

[tiborg, 2017/02/14 21:44:23]

Done.

+
     switch (gesture->type()) {
+      // Once the user starts scrolling sed all the scroll events to this

[cjgrant, 2017/02/14 14:08:24]

/sed/send/

[tiborg, 2017/02/14 21:44:23]

Done.

+      // element until the scrolling stops.
       case WebInputEvent::GestureScrollBegin:
+        current_scroll_target = input_target;
+        if (current_scroll_target != InputTarget::NONE) {
+          SendGesture(current_scroll_target, std::move(movableGesture));
+        }
+        break;
+      case WebInputEvent::GestureScrollEnd:
+        if (current_scroll_target != InputTarget::NONE) {
+          SendGesture(current_scroll_target, std::move(movableGesture));
+        }
+        current_scroll_target = InputTarget::NONE;
+        break;
       case WebInputEvent::GestureScrollUpdate:
-      case WebInputEvent::GestureScrollEnd:
       case WebInputEvent::GestureFlingCancel:
       case WebInputEvent::GestureFlingStart:
-        SendGesture(InputTarget::CONTENT,
-                    base::WrapUnique(new WebGestureEvent(*gesture)));
+        if (current_scroll_target != InputTarget::NONE) {
+          SendGesture(current_scroll_target, std::move(movableGesture));
+        }
         break;
       case WebInputEvent::GestureTapDown:
-        gesture->x = pixel_x;
-        gesture->y = pixel_y;
-        if (input_target != InputTarget::NONE)
-          SendGesture(input_target,
-                      base::WrapUnique(new WebGestureEvent(*gesture)));
+        if (input_target != InputTarget::NONE) {
+          SendGesture(input_target, std::move(movableGesture));
+        }
         break;
       case WebInputEvent::Undefined:
         break;
       default:
         NOTREACHED();
     }
   }
 
   // Hover support
   bool new_target = input_target != current_input_target_;
@@ skipping 502 matching lines @@
     const base::Callback<void(device::mojom::VRDisplayInfoPtr)>& callback,
     uint32_t device_id) {
   device::mojom::VRDisplayInfoPtr info = VrShell::CreateVRDisplayInfo(
       gvr_api_.get(), content_tex_physical_size_, device_id);
   main_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&RunVRDisplayInfoCallback, callback, base::Passed(&info)));
 }
 
 }  // namespace vr_shell