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..e8c9e6ed9c0bf246b1dbfb5269094ec2b9ba2d54 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,
@@ -68,34 +69,35 @@ 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;
+  for (auto& child : children_) {
+    DCHECK_EQ(child->parent_, this);
+    child->parent_ = nullptr;
   }
 }
 
 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());
 
-  children_.push_back(child);
+  // The new child goes to front of the list of siblings.
+  children_.push_front(child);

[boliu, 2017/02/05 19:20:23]

I think we should keep this push_back to match cc::Layer

however since cc paints in layer order, the view that's at the top is the last
one, so when doing hit testing, should hit test from the *end* of the child list

[Jinsuk Kim, 2017/02/06 02:23:44]

Done. Hit testing is reversed order is done in OnTouchEventInternal.

   if (child->parent_)
     child->RemoveFromParent();
   child->parent_ = this;
@@ -106,6 +108,11 @@ void ViewAndroid::RemoveFromParent() {
     parent_->RemoveChild(this);
 }
 
+void ViewAndroid::SetLayout(const gfx::Rect& bounds, bool match_parent) {
+  bounds_.SetRect(bounds.x(), bounds.y(), bounds.width(), bounds.height());
+  match_parent_ = match_parent;
+}
+
 ViewAndroid::ScopedAnchorView ViewAndroid::AcquireAnchorView() {
   ScopedJavaLocalRef<jobject> delegate(GetViewAndroidDelegate());
   if (delegate.is_null())
@@ -116,15 +123,19 @@ 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 +186,14 @@ 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 +204,24 @@ bool ViewAndroid::StartDragAndDrop(const JavaRef<jstring>& jtext,
                                                    jimage);
 }
 
+bool ViewAndroid::OnTouchEventInternal(const MotionEventData& event) {
+  if (!children_.empty()) {
+    gfx::Point delta = bounds_.origin();
+    const MotionEventData& e =
+        delta.IsOrigin() ? event : event.Offset(-delta.x(), -delta.y());
+
+    for (auto& child: children_) {
+      if (child->match_parent_ || child->bounds_.Contains(e.GetX(), e.GetY())) {
+        if (child->OnTouchEventInternal(e))
+          return true;
+      }
+    }
+  }
+
+  if (client_ && client_->OnTouchEvent(event))
+    return true;
+
+  return false;
+}
+
 }  // namespace ui