Add EventForwarder for routing touch events

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 "base/android/jni_string.h"
 #include "cc/layers/layer.h"
 #include "jni/ViewAndroidDelegate_jni.h"
+#include "ui/android/event_handler.h"
+#include "ui/android/view_client.h"
 #include "ui/android/window_android.h"
-#include "ui/display/display.h"
-#include "ui/display/screen.h"
+#include "ui/base/layout.h"
 #include "url/gurl.h"
 
 namespace ui {
 
 using base::android::ConvertUTF8ToJavaString;
 using base::android::JavaRef;
 using base::android::ScopedJavaLocalRef;
 
 ViewAndroid::ScopedAnchorView::ScopedAnchorView(
     JNIEnv* env,
@@ skipping 38 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(ViewClient* view_client)
+    : parent_(nullptr), client_(view_client) {}
 
-ViewAndroid::ViewAndroid() : parent_(nullptr) {}
+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;
   }
 }
 
 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);
 }
 
+float ViewAndroid::GetDipScale() {
+  return ui::GetScaleFactorForNativeView(this);
+}
+
+EventHandler* ViewAndroid::CreateEventHandler() {
+  DCHECK(!ViewTreeHasEventHandler(GetViewRoot()))
+      << "Root of the ViewAndroid can have at most one handler.";
+  event_handler_.reset(EventHandler::Create(this));
+  return event_handler_.get();
+}
+
+ViewAndroid* ViewAndroid::GetViewRoot() {
+  DCHECK(parent_) << "View is not attached to a tree yet.";
+
+  // The root of VA tree is that of WCVA for now.
+  return parent_ == GetWindowAndroid() ? this : nullptr;
+}
+
 void ViewAndroid::AddChild(ViewAndroid* child) {
   DCHECK(child);
   DCHECK(std::find(children_.begin(), children_.end(), child) ==
          children_.end());
+  DCHECK(!ViewTreeHasEventHandler(child) ||
+         !ViewTreeHasEventHandler(GetViewRoot()))
+      << "Only one event handler is allowed.";
 
+  // 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;
 }
 
+// static
+bool ViewAndroid::ViewTreeHasEventHandler(ViewAndroid* view) {
+  if (view->has_event_handler())
+    return true;
+  for (auto& child : view->children_) {
+    if (child->has_event_handler())
+      return true;
+  }
+  return false;
+}
+
 void ViewAndroid::RemoveFromParent() {
   if (parent_)
     parent_->RemoveChild(this);
 }
 
 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);
 }
 
 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();
-  int left_margin = std::round(bounds.x() * scale);
-  int top_margin = std::round((content_offset().y() + bounds.y()) * scale);
+  float dip_scale = GetDipScale();
+  int left_margin = std::round(bounds.x() * dip_scale);
+  int top_margin = std::round((content_offset().y() + bounds.y()) * dip_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);
+      bounds.height(), dip_scale, left_margin, top_margin);
 }
 
 ScopedJavaLocalRef<jobject> ViewAndroid::GetContainerView() {
   ScopedJavaLocalRef<jobject> delegate(GetViewAndroidDelegate());
   if (delegate.is_null())
     return nullptr;
 
   JNIEnv* env = base::android::AttachCurrentThread();
   return Java_ViewAndroidDelegate_getContainerView(env, delegate);
 }
@@ skipping 24 matching lines @@
 }
 
 cc::Layer* ViewAndroid::GetLayer() const {
   return layer_.get();
 }
 
 void ViewAndroid::SetLayer(scoped_refptr<cc::Layer> layer) {
   layer_ = layer;
 }
 
+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));

[boliu, 2017/02/28 22:44:54]

can you write this in a way such that when it fails, it prints out an useful
error message of what exactly was wrong? like maybe print out the actual values,
or split into multiple DCHECKs

[Jinsuk Kim, 2017/03/02 04:08:35]

Added a message about the condition when |match_parent| is true.

+  origin_.SetPoint(x, y);
+  size_.SetSize(width, height);
+  match_parent_ = match_parent;
+}
+
 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);
 }
 
@@ skipping 30 matching lines @@
   ScopedJavaLocalRef<jobject> delegate(GetViewAndroidDelegate());
   if (delegate.is_null())
     return;
   JNIEnv* env = base::android::AttachCurrentThread();
   ScopedJavaLocalRef<jstring> jcontent_url =
       ConvertUTF8ToJavaString(env, content_url.spec());
   Java_ViewAndroidDelegate_onStartContentIntent(env, delegate, jcontent_url,
                                                 is_main_frame);
 }
 
+bool ViewAndroid::OnTouchEvent(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)->OnTouchEvent(e))
+        return true;
+    }
+  }
+
+  if (client_ && client_->OnTouchEvent(event))
+    return true;
+
+  return false;
+}
+
+bool ViewAndroid::OnMouseEvent(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)->OnMouseEvent(e))
+        return true;
+    }
+  }
+
+  if (client_ && client_->OnMouseEvent(event))
+    return true;
+
+  return false;
+}
+
 }  // namespace ui