Introduce ViewRoot to forward input/view events to native

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 "jni/ViewRoot_jni.h"
+#include "ui/android/view_client.h"
 #include "ui/android/window_android.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 
 namespace ui {
 
+using base::android::JavaParamRef;
 using base::android::JavaRef;
 using base::android::ScopedJavaLocalRef;
 
 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());
@@ skipping 33 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(ViewClient* client) : parent_(nullptr),
+                                               client_(client),
+                                               physical_width_pix_(0),
+                                               physical_height_pix_(0) {}
+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;
   }
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  const ScopedJavaLocalRef<jobject> handler = event_handler_.get(env);
+  if (!handler.is_null())
+    Java_ViewRoot_onDestroyNativeView(env, handler);
 }
 
 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(std::find(children_.begin(), children_.end(), child) ==
          children_.end());
+  DCHECK(!HasViewRootInTreeHierarchy() ||
+         !child->HasViewRootInSubtree());
 
   children_.push_back(child);
   if (child->parent_)
     child->RemoveFromParent();
   child->parent_ = this;
+  if (physical_width_pix_ || physical_height_pix_) {
+    child->OnPhysicalBackingSizeChanged(physical_width_pix_,
+                                        physical_height_pix_);
+  }
 }
 
 void ViewAndroid::RemoveFromParent() {
   if (parent_)
     parent_->RemoveChild(this);
 }
 
 ViewAndroid::ScopedAnchorView ViewAndroid::AcquireAnchorView() {
   ScopedJavaLocalRef<jobject> delegate(GetViewAndroidDelegate());
   if (delegate.is_null())
@@ skipping 32 matching lines @@
       std::find(children_.begin(), children_.end(), child);
   DCHECK(it != children_.end());
   children_.erase(it);
   child->parent_ = nullptr;
 }
 
 WindowAndroid* ViewAndroid::GetWindowAndroid() const {
   return parent_ ? parent_->GetWindowAndroid() : nullptr;
 }
 
+ScopedJavaLocalRef<jobject> ViewAndroid::CreateViewRoot() {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  return Java_ViewRoot_create(env, reinterpret_cast<intptr_t>(this));
+}
+
+bool ViewAndroid::HasViewRoot() {
+  return !event_handler_.is_uninitialized();
+}
+
 const ScopedJavaLocalRef<jobject> ViewAndroid::GetViewAndroidDelegate()
     const {
   JNIEnv* env = base::android::AttachCurrentThread();
   const ScopedJavaLocalRef<jobject> delegate = delegate_.get(env);
   if (!delegate.is_null())
     return delegate;
 
   return parent_ ? parent_->GetViewAndroidDelegate() : delegate;
 }
 
 cc::Layer* ViewAndroid::GetLayer() const {
   return layer_.get();
 }
 
 void ViewAndroid::SetLayer(scoped_refptr<cc::Layer> layer) {
   layer_ = layer;
+  UpdateLayerBounds();
+}
+
+ScopedJavaLocalRef<jobject> ViewAndroid::GetViewRoot() {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  if (!HasViewRoot()) {

[Jinsuk Kim, 2016/12/19 04:40:58]

HasViewRoot() makes this method simpler.

[boliu, 2016/12/19 17:33:09]

simpler appears to be wrong though..

this is not the same check as before
HasViewRoot checks whether the reference itself is null
the previous check checks whether the referent is null (whether it's never set
or already garbage collected)

Also in this code, there is no longer any strong reference between
CreateViewRoot and the return statement, meaning if gc kicks in at the exact
right time, then (in theory) the newly created ViewRoot can be immediately
collected

[Jinsuk Kim, 2016/12/19 22:59:34]

Hm reverted.

+    DCHECK(!HasViewRootInTreeHierarchy());
+    event_handler_ = JavaObjectWeakGlobalRef(env, CreateViewRoot());

[boliu, 2016/12/19 17:33:09]

rename the var name view_root_?

[Jinsuk Kim, 2016/12/19 22:59:34]

Done.

+  }
+  return event_handler_.get(env);
+}
+
+bool ViewAndroid::HasViewRootInTreeHierarchy() {
+  ViewAndroid* view = parent_;
+  while (view) {
+    if (view->HasViewRoot())
+      return true;
+    view = view->parent_;
+  }
+  return HasViewRootInSubtree();
+}
+
+bool ViewAndroid::HasViewRootInSubtree() {
+  if (HasViewRoot())
+    return true;
+  for (auto& child : children_) {
+    if (child->HasViewRootInSubtree())
+      return true;
+  }
+  return false;
 }
 
 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);
 }
 
+gfx::Size ViewAndroid::GetPhysicalBackingSize() {
+  return gfx::Size(physical_width_pix_, physical_height_pix_);
+}
+
+void ViewAndroid::UpdateLayerBounds() {
+  if (layer_)
+    layer_->SetBounds(GetPhysicalBackingSize());
+}
+
+void ViewAndroid::OnPhysicalBackingSizeChanged(int width, int height) {
+  if (width == physical_width_pix_ && height == physical_height_pix_)
+    return;
+
+  physical_width_pix_ = width;
+  physical_height_pix_ = height;
+  UpdateLayerBounds();
+
+  if (client_)
+    client_->OnPhysicalBackingSizeChanged(width, height);
+
+  for (auto& child : children_)
+    child->OnPhysicalBackingSizeChanged(width, height);
+}
+
+// static
+void OnPhysicalBackingSizeChanged(JNIEnv* env,
+                                  const JavaParamRef<jclass>& jcaller,
+                                  jlong native_view,
+                                  int width,
+                                  int height) {
+  ViewAndroid* view_android = reinterpret_cast<ViewAndroid*>(native_view);
+  view_android->OnPhysicalBackingSizeChanged(width, height);
+}
+
+bool RegisterViewRoot(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
 }  // namespace ui