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

chrome/browser/android/contextualsearch/search_action.cc

Index: chrome/browser/android/contextualsearch/search_action.cc
diff --git a/chrome/browser/android/contextualsearch/search_action.cc b/chrome/browser/android/contextualsearch/search_action.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0e0ea3fea4540a9768d0fae64a01d0e9d881a30b
--- /dev/null
+++ b/chrome/browser/android/contextualsearch/search_action.cc
@@ -0,0 +1,204 @@
+// 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 "chrome/browser/android/contextualsearch/search_action.h"
+
+#include <set>
+
+#include "base/android/jni_string.h"
+#include "base/bind.h"
+#include "base/memory/weak_ptr.h"
+#include "base/strings/utf_string_conversions.h"
+#include "chrome/browser/android/contextualsearch/contextual_search_context.h"
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/web_contents.h"
+#include "jni/SearchAction_jni.h"
+#include "url/gurl.h"
+
+using base::android::ConvertUTF8ToJavaString;
+using base::android::JavaParamRef;
+using base::android::ScopedJavaGlobalRef;
+using content::WebContents;
+
+namespace {
+// Context length is set to 1.5K characters for historical reasons:
+// This provided the largest context that would fit in a GET request along with
+// our other required parameters."
+const int kSurroundingTextSize = 1536;
+}
+
+SearchAction::SearchAction(JNIEnv* env, jobject obj) {
+  java_object_.Reset(env, obj);
+}
+
+SearchAction::~SearchAction() {
+  // The Java object can be null in tests only, by calling the default
+  // constructor.
+  if (!java_object_.is_null()) {
+    JNIEnv* env = base::android::AttachCurrentThread();
+    Java_SearchAction_clearNativePointer(env, java_object_.obj());
+  }
+}
+
+void SearchAction::Destroy(JNIEnv* env, const JavaParamRef<jobject>& obj) {
+  delete this;
+}
+
+void SearchAction::RequestSurroundingText(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& obj,
+    const JavaParamRef<jobject>& j_web_contents) {
+  WebContents* web_contents = WebContents::FromJavaWebContents(j_web_contents);
+  DCHECK(web_contents);
+
+  GURL url(web_contents->GetURL());
+  std::string encoding(web_contents->GetEncoding());
+  search_context_.reset(new ContextualSearchContext(true, url, encoding));
+
+  content::RenderFrameHost* focused_frame = web_contents->GetFocusedFrame();
+  if (!focused_frame) {
+    OnSurroundingTextResponse(base::string16(), 0, 0);
+  } else {
+    focused_frame->RequestTextSurroundingSelection(
+        base::Bind(&SearchAction::OnSurroundingTextResponse, AsWeakPtr()),
+        kSurroundingTextSize);
+  }
+}
+
+void SearchAction::OnSurroundingTextResponse(
+    const base::string16& surrounding_text,
+    int focus_start,
+    int focus_end) {
+  // Record the context, which can be accessed later on demand.
+  search_context_->surrounding_text = surrounding_text;
+  search_context_->start_offset = focus_start;
+  search_context_->end_offset = focus_end;
+
+  // Notify Java.
+  JNIEnv* env = base::android::AttachCurrentThread();
+  Java_SearchAction_onSurroundingTextReady(env, java_object_.obj());
+}
+
+std::string SearchAction::FindFocusedWord() {
+  DCHECK(search_context_);
+
+  const base::string16& surrounding_text = search_context_->surrounding_text;
+  int focus_start = search_context_->start_offset;
+  int focus_end = search_context_->end_offset;
+  int surrounding_text_length = surrounding_text.length();
+
+  // First, we need to find the focused word boundaries.
+  int focused_word_start = focus_start;
+  int focused_word_end = focus_end;
+
+  if (surrounding_text_length > 0 &&
+      IsValidCharacter(surrounding_text[focused_word_start])) {
+    // Find focused word start (inclusive)
+    for (int i = focus_start; i >= 0; i--) {
+      focused_word_start = i;
+
+      wchar_t character;
+      if (i > 0) {
+        character = surrounding_text[i - 1];
+
+        if (!IsValidCharacter(character))
+          break;
+      }
+    }
+
+    // Find focused word end (non inclusive)
+    for (int i = focus_end; i < surrounding_text_length; i++) {
+      wchar_t character = surrounding_text[i];
+
+      if (IsValidCharacter(character)) {
+        focused_word_end = i + 1;
+      } else {
+        focused_word_end = i;
+        break;
+      }
+    }
+  }
+
+  return base::UTF16ToUTF8(surrounding_text.substr(
+      focused_word_start, focused_word_end - focused_word_start));
+}
+
+std::string SearchAction::GetSampleText(int sample_length) {
+  DCHECK(search_context_);
+
+  const base::string16& surrounding_text = search_context_->surrounding_text;
+  int focus_start = search_context_->start_offset;
+  int focus_end = search_context_->end_offset;
+  int surrounding_text_length = surrounding_text.length();
+
+  //---------------------------------------------------------------------------
+  // Cut the surrounding size so it can be sent to the Java side.
+
+  // Start equally distributing the size around the focal point.
+  int focal_point_size = focus_end - focus_start;
+  int sample_margin = (sample_length - focal_point_size) / 2;
+  int sample_start = focus_start - sample_margin;
+  int sample_end = focus_end + sample_margin;
+
+  // If the the start is out of bounds, compensate the end side.
+  if (sample_start < 0) {
+    sample_end -= sample_start;
+    sample_start = 0;
+  }
+
+  // If the the end is out of bounds, compensate the start side.
+  if (sample_end > surrounding_text_length) {
+    int diff = sample_end - surrounding_text_length;
+    sample_end = surrounding_text_length;
+    sample_start -= diff;
+  }
+
+  // Trim the start and end to make sure they are within bounds.
+  sample_start = std::max(0, sample_start);
+  sample_end = std::min(surrounding_text_length, sample_end);
+  return base::UTF16ToUTF8(
+      surrounding_text.substr(sample_start, sample_end - sample_start));
+}
+
+bool SearchAction::IsValidCharacter(int char_code) {
+  // See http://www.unicode.org/Public/UCD/latest/ucd/NamesList.txt
+  // See http://jrgraphix.net/research/unicode_blocks.php
+
+  // TODO(donnd): should not include CJK characters!
+  // TODO(donnd): consider using regular expressions.
+
+  if ((char_code >= 11264 && char_code <= 55295) ||  // Asian language symbols
+      (char_code >= 192 && char_code <= 8191) ||  // Letters in many languages
+      (char_code >= 97 && char_code <= 122) ||    // Lowercase letters
+      (char_code >= 65 && char_code <= 90) ||     // Uppercase letters
+      (char_code >= 48 && char_code <= 57)) {     // Numbers
+    return true;
+  }
+
+  return false;
+}
+
+// Testing
+
+SearchAction::SearchAction() {}
+
+void SearchAction::SetContext(std::string surrounding_text,
+                              int focus_start,
+                              int focus_end) {
+  search_context_.reset(new ContextualSearchContext(false, GURL(), ""));
+  search_context_->surrounding_text = base::UTF8ToUTF16(surrounding_text);
+  search_context_->start_offset = focus_start;
+  search_context_->end_offset = focus_end;
+}
+
+// Boilerplate
+
+bool RegisterSearchAction(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+jlong Init(JNIEnv* env, const JavaParamRef<jobject>& obj) {
+  SearchAction* content = new SearchAction(env, obj);
+  return reinterpret_cast<intptr_t>(content);
+}