ViewRoot class for event forwarding on Android

ui/android/view_android.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 "ui/android/view_android.h"
 
 #include <algorithm>
 
 #include "base/android/jni_android.h"
 #include "cc/layers/layer.h"
 #include "jni/ViewAndroidDelegate_jni.h"
 #include "ui/android/window_android.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 
 namespace ui {
 
 using base::android::JavaRef;
 using base::android::ScopedJavaLocalRef;
 
+// ViewAndroid::ScopedAndroidView
 ViewAndroid::ScopedAnchorView::ScopedAnchorView(
     JNIEnv* env,
     const JavaRef<jobject>& jview,
     const JavaRef<jobject>& jdelegate)
     : view_(env, jview.obj()), delegate_(env, jdelegate.obj()) {
   // If there's a view, then we need a delegate to remove it.
   DCHECK(!jdelegate.is_null() || jview.is_null());
 }
 
 ViewAndroid::ScopedAnchorView::ScopedAnchorView() { }
@@ skipping 30 matching lines @@
   view_.reset();
   delegate_.reset();
 }
 
 const base::android::ScopedJavaLocalRef<jobject>
 ViewAndroid::ScopedAnchorView::view() const {
   JNIEnv* env = base::android::AttachCurrentThread();
   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;
 }
 
 void ViewAndroid::RemoveFromParent() {
   if (parent_)
     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())
     return ViewAndroid::ScopedAnchorView();
 
   JNIEnv* env = base::android::AttachCurrentThread();
   return ViewAndroid::ScopedAnchorView(
       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();
   Java_ViewAndroidDelegate_setViewPosition(
       env, delegate, anchor, bounds.x(), bounds.y(), bounds.width(),
       bounds.height(), scale, left_margin, top_margin);
 }
 
 ScopedJavaLocalRef<jobject> ViewAndroid::GetContainerView() {
   ScopedJavaLocalRef<jobject> delegate(GetViewAndroidDelegate());
@@ skipping 30 matching lines @@
 }
 
 cc::Layer* ViewAndroid::GetLayer() const {
   return layer_.get();
 }
 
 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());
   if (delegate.is_null())
     return false;
   JNIEnv* env = base::android::AttachCurrentThread();
   return Java_ViewAndroidDelegate_startDragAndDrop(env, delegate, 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