[TTS] Gather surrounding text on Tap before any UX.

chrome/browser/android/contextualsearch/search_action.h

+// 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.
+
+#ifndef CHROME_BROWSER_ANDROID_CONTEXTUALSEARCH_SEARCH_ACTION_H_
+#define CHROME_BROWSER_ANDROID_CONTEXTUALSEARCH_SEARCH_ACTION_H_
+
+#include <memory>
+
+#include "base/android/jni_android.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/weak_ptr.h"
+#include "base/strings/string_util.h"
+
+struct ContextualSearchContext;
+
+// Represents the native side of a Java Search Action, which knows how to do a
+// Contextual Search.
+// This is part of the 2016-refactoring, see go/cs-refactoring-2016.
+// Gathers text surrounding the selection from the page and makes it accessible
+// to Java.
+// TODO(donnd): add capability to "resolve" the best search term for the section
+// of the page based on a server request or local text analysis.
+class SearchAction : public base::SupportsWeakPtr<SearchAction> {
+ public:
+  // Constructs a new Search Action linked to the given Java object.
+  SearchAction(JNIEnv* env, jobject obj);
+  virtual ~SearchAction();
+
+  // Should be called when this native object is no longer needed (calls the
+  // destructor).
+  void Destroy(JNIEnv* env, const base::android::JavaParamRef<jobject>& obj);
+
+  // Requests the text surrounding the selection for the given WebContents Java
+  // object.  The surrounding text will be made available through a call to
+  // |OnSurroundingTextResponse|.
+  void RequestSurroundingText(
+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& obj,
+      const base::android::JavaParamRef<jobject>& j_web_contents);
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(SearchActionTest, IsValidCharacterTest);
+  FRIEND_TEST_ALL_PREFIXES(SearchActionTest, FindFocusedWordTest);
+  FRIEND_TEST_ALL_PREFIXES(SearchActionTest, SampleSurroundingsTest);
+
+  // Analyzes the surrounding text and makes it available to the Java
+  // SearchAction object in a call to SearchAction#onSurroundingTextResponse.
+  void OnSurroundingTextResponse(const base::string16& surrounding_text,
+                                 int focus_start,
+                                 int focus_end);
+
+  // Expands the given focus to find the start and end word boundary.
+  // Returns a pair whose first member is the start offset and second member
+  // is the end offset of the word.  If the focus is not within a word then
+  // the focus inputs are returned.
+  static std::pair<int, int> FindFocusedWord(
+      const base::string16& surrounding_text,
+      int focus_start,
+      int focus_end);
+
+  // Returns a sample of the given surrounding text with length <= the given
+  // |surrounding_text_sample_limit|.  The |focus_start| and |focus_end|
+  // determine which part of the given text will be sampled with the focus
+  // being centered as best as possible in the sample.
+  // Returns a pair with the first member being the sampled text string and
+  // the second member being the offset of the start of the sample within
+  // the given input text.
+  static std::pair<base::string16, int> SampleSurroundings(
+      const base::string16& surrounding_text,
+      int focus_start,
+      int focus_end,
+      int surrounding_text_sample_limit);
+
+  // Determines if the given character is a valid part of a word to search for.
+  static bool IsValidCharacter(int char_code);
+
+  // The linked Java object.
+  base::android::ScopedJavaGlobalRef<jobject> java_object_;
+
+  // The current search context, or null.
+  std::shared_ptr<ContextualSearchContext> search_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(SearchAction);
+};
+
+bool RegisterSearchAction(JNIEnv* env);
+
+#endif  // CHROME_BROWSER_ANDROID_CONTEXTUALSEARCH_SEARCH_ACTION_H_