Use observed pointers in CPDFSDK_AnnotIterator.

fpdfsdk/cpdfsdk_annotiteration.cpp

+// Copyright 2017 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
+
+#include "fpdfsdk/cpdfsdk_annotiteration.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "fpdfsdk/cpdfsdk_annot.h"
+#include "fpdfsdk/cpdfsdk_pageview.h"
+
+CPDFSDK_AnnotIteration::CPDFSDK_AnnotIteration(CPDFSDK_PageView* pPageView,
+                                               bool bReverse) {
+  // Copying/sorting ObservedPtrs is expensive, so do it once at the end.
+  std::vector<CPDFSDK_Annot*> copiedList = pPageView->GetAnnotList();
+  std::stable_sort(copiedList.begin(), copiedList.end(),
+                   [](const CPDFSDK_Annot* p1, const CPDFSDK_Annot* p2) {
+                     return p1->GetLayoutOrder() < p2->GetLayoutOrder();
+                   });
+
+  CPDFSDK_Annot* pTopMostAnnot = pPageView->GetFocusAnnot();
+  if (pTopMostAnnot) {
+    auto it = std::find(copiedList.begin(), copiedList.end(), pTopMostAnnot);
+    if (it != copiedList.end()) {
+      copiedList.erase(it);
+      copiedList.insert(copiedList.begin(), pTopMostAnnot);
+    }
+  }
+  if (bReverse)
+    std::reverse(copiedList.begin(), copiedList.end());
+
+  m_List.reserve(copiedList.size());
+  for (const auto& pAnnot : copiedList)
+    m_List.emplace_back(pAnnot);
+}
+
+CPDFSDK_AnnotIteration::~CPDFSDK_AnnotIteration() {}