Native Android accessibility.

content/browser/accessibility/browser_accessibility_manager_android.cc

+// Copyright (c) 2013 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 "content/browser/accessibility/browser_accessibility_manager_android.h"
+
+#include <cmath>
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/utf_string_conversions.h"
+#include "base/values.h"
+#include "content/browser/accessibility/browser_accessibility_android.h"
+#include "content/common/accessibility_messages.h"
+#include "jni/BrowserAccessibilityManager_jni.h"
+
+using base::android::AttachCurrentThread;
+
+namespace {
+
+// Restricts |val| to the range [min, max].
+int Clamp(int val, int min, int max) {
+  return std::min(std::max(val, min), max);
+}
+
+}  // anonymous namespace
+
+namespace content {
+
+namespace aria_strings {
+  const char kAriaLivePolite[] = "polite";
+  const char kAriaLiveAssertive[] = "assertive";
+}
+
+// static
+BrowserAccessibilityManager* BrowserAccessibilityManager::Create(
+    const AccessibilityNodeData& src,
+    BrowserAccessibilityDelegate* delegate,
+    BrowserAccessibilityFactory* factory) {
+  return new BrowserAccessibilityManagerAndroid(NULL, src, delegate, factory);
+}
+
+BrowserAccessibilityManagerAndroid::BrowserAccessibilityManagerAndroid(
+    ContentViewCoreImpl* content_view_core,
+    const AccessibilityNodeData& src,
+    BrowserAccessibilityDelegate* delegate,
+    BrowserAccessibilityFactory* factory)
+    : BrowserAccessibilityManager(src, delegate, factory),
+      content_view_core_(content_view_core) {
+  if (!content_view_core)
+    return;
+  JNIEnv* env = AttachCurrentThread();
+  base::android::ScopedJavaLocalRef<jobject> content_view_core_java =
+      content_view_core->GetJavaObject();
+  java_ref_.Reset(Java_BrowserAccessibilityManager_create(
+      env, reinterpret_cast<jint>(this), content_view_core_java.obj()));
+}
+
+BrowserAccessibilityManagerAndroid::~BrowserAccessibilityManagerAndroid() {
+  if (java_ref_.is_null())
+    return;
+  JNIEnv* env = AttachCurrentThread();
+  Java_BrowserAccessibilityManager_onNativeObjectDestroyed(
+      env, java_ref_.obj());
+}
+
+// static
+AccessibilityNodeData BrowserAccessibilityManagerAndroid::GetEmptyDocument() {
+  AccessibilityNodeData empty_document;
+  empty_document.id = 0;
+  empty_document.role = AccessibilityNodeData::ROLE_ROOT_WEB_AREA;
+  empty_document.state = 1 << AccessibilityNodeData::STATE_READONLY;
+  return empty_document;
+}
+
+void BrowserAccessibilityManagerAndroid::NotifyAccessibilityEvent(
+    int type,
+    BrowserAccessibility* node) {
+  if (java_ref_.is_null())
+    return;
+
+  JNIEnv* env = AttachCurrentThread();
+  switch (type) {
+    case AccessibilityNotificationLoadComplete:
+      Java_BrowserAccessibilityManager_handlePageLoaded(
+          env, java_ref_.obj(), focus_->renderer_id());
+      break;
+    case AccessibilityNotificationFocusChanged:
+      Java_BrowserAccessibilityManager_handleFocusChanged(
+          env, java_ref_.obj(), node->renderer_id());
+      break;
+    case AccessibilityNotificationCheckStateChanged:
+      Java_BrowserAccessibilityManager_handleCheckStateChanged(
+          env, java_ref_.obj(), node->renderer_id());
+      break;
+    case AccessibilityNotificationScrolledToAnchor:
+      Java_BrowserAccessibilityManager_handleScrolledToAnchor(
+          env, java_ref_.obj(), node->renderer_id());
+      break;
+    case AccessibilityNotificationAlert:
+      Java_BrowserAccessibilityManager_announceObjectShow(
+          env, java_ref_.obj(), node->renderer_id(), JNI_TRUE);
+    case AccessibilityNotificationObjectShow:
+      Java_BrowserAccessibilityManager_announceObjectShow(
+          env, java_ref_.obj(), node->renderer_id(), JNI_FALSE);
+    case AccessibilityNotificationSelectedTextChanged:
+      Java_BrowserAccessibilityManager_handleTextSelectionChanged(
+          env, java_ref_.obj(), node->renderer_id());
+      break;
+    case AccessibilityNotificationChildrenChanged:
+    case AccessibilityNotificationTextChanged:
+    case AccessibilityNotificationValueChanged:
+      if (node->IsEditableText()) {
+        Java_BrowserAccessibilityManager_handleEditableTextChanged(
+            env, java_ref_.obj(), node->renderer_id());
+      } else {
+        Java_BrowserAccessibilityManager_handleContentChanged(
+            env, java_ref_.obj(), node->renderer_id());
+      }
+      break;
+    default:
+      break;
+  }
+}
+
+jint BrowserAccessibilityManagerAndroid::GetRootId(JNIEnv* env, jobject obj) {
+  return static_cast<jint>(root_->renderer_id());
+}
+
+jint BrowserAccessibilityManagerAndroid::HitTest(
+    JNIEnv* env, jobject obj, jint x, jint y) {
+  BrowserAccessibilityAndroid* result =
+      static_cast<BrowserAccessibilityAndroid*>(
+          root_->BrowserAccessibilityForPoint(gfx::Point(x, y)));
+
+  if (!result)
+    return root_->renderer_id();
+
+  if (result->IsFocusable())
+    return result->renderer_id();
+
+  // Examine the children of |result| to find the nearest accessibility focus
+  // candidate
+  BrowserAccessibility* nearest_node = FuzzyHitTest(x, y, result);
+  if (nearest_node)
+    return nearest_node->renderer_id();
+
+  return root_->renderer_id();
+}
+
+BrowserAccessibility* BrowserAccessibilityManagerAndroid::FuzzyHitTest(
+    int x, int y, BrowserAccessibility* start_node) {
+  BrowserAccessibility* nearest_node = NULL;
+  int min_distance = INT_MAX;
+  FuzzyHitTestImpl(x, y, start_node, &nearest_node, &min_distance);
+  return nearest_node;
+}
+
+// static
+void BrowserAccessibilityManagerAndroid::FuzzyHitTestImpl(
+    int x, int y, BrowserAccessibility* start_node,
+    BrowserAccessibility** nearest_candidate, int* nearest_distance) {
+  BrowserAccessibilityAndroid* node =
+      static_cast<BrowserAccessibilityAndroid*>(start_node);
+  int distance = CalculateDistanceSquared(x, y, node);
+
+  if (node->IsFocusable()) {
+    if (distance < *nearest_distance) {
+      *nearest_candidate = node;
+      *nearest_distance = distance;
+    }
+    // Don't examine any more children of focusable node
+    // TODO(aboxhall): what about focusable children?
+    return;
+  }
+
+  if (!node->ComputeName().empty()) {
+    if (distance < *nearest_distance) {
+      *nearest_candidate = node;
+      *nearest_distance = distance;
+    }
+    return;
+  }
+
+  if (!node->IsLeaf()) {
+    for (uint32 i = 0; i < node->child_count(); i++) {
+      BrowserAccessibility* child = node->GetChild(i);
+      FuzzyHitTestImpl(x, y, child, nearest_candidate, nearest_distance);
+    }
+  }
+}
+
+// static
+int BrowserAccessibilityManagerAndroid::CalculateDistanceSquared(
+    int x, int y, BrowserAccessibility* node) {
+  gfx::Rect node_bounds = node->GetLocalBoundsRect();
+  int nearest_x = Clamp(x, node_bounds.x(), node_bounds.right());
+  int nearest_y = Clamp(y, node_bounds.y(), node_bounds.bottom());
+  int dx = std::abs(x - nearest_x);
+  int dy = std::abs(y - nearest_y);
+  return dx * dx + dy * dy;
+}
+
+jint BrowserAccessibilityManagerAndroid::GetNativeNodeById(
+    JNIEnv* env, jobject obj, jint id) {
+  return reinterpret_cast<jint>(GetFromRendererID(id));
+}
+
+void BrowserAccessibilityManagerAndroid::NotifyRootChanged() {
+  JNIEnv* env = AttachCurrentThread();
+  Java_BrowserAccessibilityManager_handleNavigate(env, java_ref_.obj());
+}
+
+bool
+BrowserAccessibilityManagerAndroid::UseRootScrollOffsetsWhenComputingBounds() {
+  // The Java layer handles the root scroll offset.
+  return false;
+}
+
+bool RegisterBrowserAccessibilityManager(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace content