Inject vr controller events into Android Native UI.

chrome/browser/android/vr_shell/android_ui_gesture_target.cc

+// Copyright 2017 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/android_ui_gesture_target.h"
+
+#include "jni/MotionEventSynthesizer_jni.h"
+
+namespace vr_shell {
+
+AndroidUiGestureTarget::AndroidUiGestureTarget(jobject event_synthesizer,
+                                               float scroll_ratio)
+    : event_synthesizer_(event_synthesizer), scroll_ratio_(scroll_ratio) {
+  DCHECK(event_synthesizer_);
+}
+
+AndroidUiGestureTarget::~AndroidUiGestureTarget() = default;
+
+void AndroidUiGestureTarget::DispatchWebInputEvent(
+    std::unique_ptr<blink::WebInputEvent> event) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  blink::WebMouseEvent* mouse;
+  blink::WebGestureEvent* gesture;
+  if (blink::WebInputEvent::isMouseEventType(event->type())) {
+    mouse = static_cast<blink::WebMouseEvent*>(event.get());
+  } else {
+    gesture = static_cast<blink::WebGestureEvent*>(event.get());
+  }
+
+  switch (event->type()) {
+    case blink::WebGestureEvent::GestureScrollBegin:
+      DCHECK(gesture->data.scrollBegin.deltaHintUnits ==
+             blink::WebGestureEvent::ScrollUnits::PrecisePixels);
+      scroll_x_ = (scroll_ratio_ * gesture->data.scrollBegin.deltaXHint);
+      scroll_y_ = (scroll_ratio_ * gesture->data.scrollBegin.deltaYHint);
+      SetPointer(env, 0, 0);
+      Inject(env, Action::ActionStart, gesture->timeStampSeconds());
+      SetPointer(env, scroll_x_, scroll_y_);
+      // Send a move immediately so that we can't accidentally trigger a click.
+      Inject(env, Action::ActionMove, gesture->timeStampSeconds());
+      break;
+    case blink::WebGestureEvent::GestureScrollEnd:
+      Inject(env, Action::ActionEnd, gesture->timeStampSeconds());
+      break;
+    case blink::WebGestureEvent::GestureScrollUpdate:
+      scroll_x_ += (scroll_ratio_ * gesture->data.scrollUpdate.deltaX);
+      scroll_y_ += (scroll_ratio_ * gesture->data.scrollUpdate.deltaY);
+      SetPointer(env, scroll_x_, scroll_y_);
+      Inject(env, Action::ActionMove, gesture->timeStampSeconds());
+      break;
+    case blink::WebGestureEvent::GestureTapDown:
+      SetPointer(env, gesture->x, gesture->y);
+      Inject(env, Action::ActionStart, gesture->timeStampSeconds());
+      Inject(env, Action::ActionEnd, gesture->timeStampSeconds());
+      break;
+    case blink::WebGestureEvent::GestureFlingCancel:
+      Inject(env, Action::ActionCancel, gesture->timeStampSeconds());
+      break;
+    case blink::WebGestureEvent::GestureFlingStart:
+      // Flings are automatically generated for android UI. Ignore this input.
+      break;
+    case blink::WebMouseEvent::MouseEnter:
+      SetPointer(env, mouse->x, mouse->y);
+      Inject(env, Action::ActionHoverEnter, gesture->timeStampSeconds());
+      break;
+    case blink::WebMouseEvent::MouseMove:
+      SetPointer(env, mouse->x, mouse->y);
+      Inject(env, Action::ActionHoverMove, gesture->timeStampSeconds());
+      break;
+    case blink::WebMouseEvent::MouseLeave:
+      SetPointer(env, mouse->x, mouse->y);
+      Inject(env, Action::ActionHoverExit, gesture->timeStampSeconds());
+      break;
+    default:
+      NOTREACHED();
+      break;
+  }
+}
+
+void AndroidUiGestureTarget::SetPointer(JNIEnv* env, int x, int y) {
+  content::Java_MotionEventSynthesizer_setPointer(env, event_synthesizer_, 0, x,
+                                                  y, 0);
+}
+
+void AndroidUiGestureTarget::SetScrollDeltas(JNIEnv* env,

[cjgrant, 2017/02/16 15:29:34]

nit: I think the style guide prefers packing as many args onto each line as will
fit, no?

[mthiesse, 2017/02/16 15:53:49]

Apparently not, git cl format sets it to this.

+                                             int x,
+                                             int y,
+                                             int dx,
+                                             int dy) {
+  content::Java_MotionEventSynthesizer_setScrollDeltas(env, event_synthesizer_,
+                                                       x, y, dx, dy);
+}
+
+void AndroidUiGestureTarget::Inject(JNIEnv* env,
+                                    Action action,
+                                    double time_in_seconds) {
+  content::Java_MotionEventSynthesizer_inject(
+      env, event_synthesizer_, static_cast<int>(action), 1,
+      static_cast<int64_t>(time_in_seconds * 1000.0));
+}
+
+}  // namespace vr_shell