Implement direct write fallback proxy

content/common/dwrite_text_analysis_source_win.cc

+// Copyright (c) 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 "content/common/dwrite_text_analysis_source_win.h"
+
+#include "base/logging.h"
+
+namespace content {
+
+TextAnalysisSource::~TextAnalysisSource() = default;
+
+HRESULT TextAnalysisSource::GetLocaleName(UINT32 text_position,
+                                          UINT32* text_length,
+                                          const WCHAR** locale_name) {
+  if (text_position >= text_.length() || !text_length || !locale_name)
+    return E_INVALIDARG;
+  *text_length = text_.length() - text_position;
+  *locale_name = locale_name_.c_str();
+  return S_OK;
+}
+
+HRESULT TextAnalysisSource::GetNumberSubstitution(
+    UINT32 text_position,
+    UINT32* text_length,
+    IDWriteNumberSubstitution** number_substitution) {
+  if (text_position >= text_.length() || !text_length || !number_substitution)
+    return E_INVALIDARG;
+  *text_length = text_.length() - text_position;
+  number_substitution_.CopyTo(number_substitution);
+  return S_OK;
+}
+
+DWRITE_READING_DIRECTION TextAnalysisSource::GetParagraphReadingDirection() {
+  return reading_direction_;
+}
+
+HRESULT TextAnalysisSource::GetTextAtPosition(UINT32 text_position,
+                                              const WCHAR** text_string,
+                                              UINT32* text_length) {
+  if (!text_length || !text_string)
+    return E_INVALIDARG;
+  if (text_position >= text_.length()) {
+    *text_string = nullptr;
+    *text_length = 0;
+    return S_OK;
+  }
+  *text_string = text_.c_str() + text_position;
+  *text_length = text_.length() - text_position;
+  return S_OK;
+}
+
+HRESULT TextAnalysisSource::GetTextBeforePosition(UINT32 text_position,
+                                                  const WCHAR** text_string,
+                                                  UINT32* text_length) {
+  if (!text_length || !text_string)
+    return E_INVALIDARG;
+  if (text_position < 1 || text_position > text_.length()) {
+    *text_string = nullptr;
+    *text_length = 0;
+    return S_OK;
+  }
+  *text_string = text_.c_str();
+  *text_length = text_position;
+  return S_OK;
+}
+
+HRESULT TextAnalysisSource::RuntimeClassInitialize(
+    const base::string16& text,
+    const base::string16& locale_name,
+    IDWriteNumberSubstitution* number_substitution,
+    DWRITE_READING_DIRECTION reading_direction) {
+  DCHECK(number_substitution);
+  text_ = text;
+  locale_name_ = locale_name;
+  number_substitution_ = number_substitution;
+  reading_direction_ = reading_direction;
+  return S_OK;
+}
+
+}  // namespace content