ViewRoot class for event forwarding on Android

ui/android/view_android.cc

Index: ui/android/view_android.cc
diff --git a/ui/android/view_android.cc b/ui/android/view_android.cc
index 6c55a7bf9df724ce0eea47170c138cd146ba2d85..43f084fcf737da20491fae94808a83471544bcda 100644
--- a/ui/android/view_android.cc
+++ b/ui/android/view_android.cc
@@ -18,6 +18,7 @@ namespace ui {
 using base::android::JavaRef;
 using base::android::ScopedJavaLocalRef;
 
+// ViewAndroid::ScopedAndroidView
 ViewAndroid::ScopedAnchorView::ScopedAnchorView(
     JNIEnv* env,
     const JavaRef<jobject>& jview,
@@ -68,44 +69,65 @@ ViewAndroid::ScopedAnchorView::view() const {
   return view_.get(env);
 }
 
-ViewAndroid::ViewAndroid(const JavaRef<jobject>& delegate)
-    : parent_(nullptr)
-    , delegate_(base::android::AttachCurrentThread(),
-                delegate.obj()) {}
-
-ViewAndroid::ViewAndroid() : parent_(nullptr) {}
+// ViewAndroid
+ViewAndroid::ViewAndroid(ViewClient* client) : parent_(nullptr),
+                                               client_(client) {}
+ViewAndroid::ViewAndroid() : ViewAndroid(nullptr) {}
 
 ViewAndroid::~ViewAndroid() {
   RemoveFromParent();
 
-  for (std::list<ViewAndroid*>::iterator it = children_.begin();
-       it != children_.end(); it++) {
-    DCHECK_EQ((*it)->parent_, this);
-    (*it)->parent_ = nullptr;
-  }
+  auto children_copy = std::list<ViewAndroid*>(children_);
+  for (auto& child : children_copy)
+    RemoveChild(child);
 }
 
 void ViewAndroid::SetDelegate(const JavaRef<jobject>& delegate) {
+  // A ViewAndroid may have its own delegate or otherwise will
+  // use the next available parent's delegate.
   JNIEnv* env = base::android::AttachCurrentThread();
   delegate_ = JavaObjectWeakGlobalRef(env, delegate);
 }
 
 void ViewAndroid::AddChild(ViewAndroid* child) {
   DCHECK(child);
+  DCHECK(!child->IsViewRoot());  // ViewRoot cannot be a child.
   DCHECK(std::find(children_.begin(), children_.end(), child) ==
          children_.end());
 
+  // The new child goes to the top, which is the end of the list.
   children_.push_back(child);
   if (child->parent_)
     child->RemoveFromParent();
   child->parent_ = this;
 }
 
+void ViewAndroid::MoveToTop(ViewAndroid* child) {
+  DCHECK(child);
+  auto it = std::find(children_.begin(), children_.end(), child);
+  DCHECK(it != children_.end());
+
+  // Top element is placed at the end of the list.
+  if (*it != children_.back())
+    children_.splice(children_.rbegin().base(), children_, it);
+}
+
 void ViewAndroid::RemoveFromParent() {
   if (parent_)
     parent_->RemoveChild(this);
 }
 
+void ViewAndroid::SetLayout(int x,
+                            int y,
+                            int width,
+                            int height,
+                            bool match_parent) {
+  DCHECK(!match_parent || (x == 0 && y == 0 && width == 0 && height == 0));
+  origin_.SetPoint(x, y);
+  size_.SetSize(width, height);
+  match_parent_ = match_parent;
+}
+
 ViewAndroid::ScopedAnchorView ViewAndroid::AcquireAnchorView() {
   ScopedJavaLocalRef<jobject> delegate(GetViewAndroidDelegate());
   if (delegate.is_null())
@@ -116,15 +138,19 @@ ViewAndroid::ScopedAnchorView ViewAndroid::AcquireAnchorView() {
       env, Java_ViewAndroidDelegate_acquireView(env, delegate), delegate);
 }
 
+float ViewAndroid::GetDipScale() {
+  return display::Screen::GetScreen()
+      ->GetDisplayNearestWindow(this)
+      .device_scale_factor();
+}
+
 void ViewAndroid::SetAnchorRect(const JavaRef<jobject>& anchor,
                                 const gfx::RectF& bounds) {
   ScopedJavaLocalRef<jobject> delegate(GetViewAndroidDelegate());
   if (delegate.is_null())
     return;
 
-  float scale = display::Screen::GetScreen()
-      ->GetDisplayNearestWindow(this)
-      .device_scale_factor();
+  float scale = GetDipScale();
   int left_margin = std::round(bounds.x() * scale);
   int top_margin = std::round((content_offset().y() + bounds.y()) * scale);
   JNIEnv* env = base::android::AttachCurrentThread();
@@ -175,6 +201,14 @@ void ViewAndroid::SetLayer(scoped_refptr<cc::Layer> layer) {
   layer_ = layer;
 }
 
+ViewAndroid* ViewAndroid::GetViewRoot() {
+  return parent_ ? parent_->GetViewRoot() : nullptr;
+}
+
+bool ViewAndroid::IsViewRoot() {
+  return GetViewRoot() == this;
+}
+
 bool ViewAndroid::StartDragAndDrop(const JavaRef<jstring>& jtext,
                                    const JavaRef<jobject>& jimage) {
   ScopedJavaLocalRef<jobject> delegate(GetViewAndroidDelegate());
@@ -185,4 +219,26 @@ bool ViewAndroid::StartDragAndDrop(const JavaRef<jstring>& jtext,
                                                    jimage);
 }
 
+bool ViewAndroid::OnTouchEventInternal(const MotionEventData& event) {
+  if (!children_.empty()) {
+    const MotionEventData& e =
+      origin_.IsOrigin() ? event : event.Offset(-origin_.x(), -origin_.y());
+
+    for (auto it = children_.rbegin(); it != children_.rend(); ++it) {
+      bool matched = (*it)->match_parent_;
+      if (!matched) {
+        gfx::Rect bound((*it)->origin_, (*it)->size_);
+        matched = bound.Contains(e.GetX(), e.GetY());
+      }
+      if (matched && (*it)->OnTouchEventInternal(e))
+        return true;
+    }
+  }
+
+  if (client_ && client_->OnTouchEvent(event))
+    return true;
+
+  return false;
+}
+
 }  // namespace ui