Use a vector inside CPDF_CharPosList.

Change-Id: I3f83e9f94e3c6802d453057b6b5bff91dc5afa76
Reviewed-on: https://pdfium-review.googlesource.com/c/50076
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

core/fpdfapi/render/cpdf_charposlist.cpp

diff --git a/core/fpdfapi/render/cpdf_charposlist.cpp b/core/fpdfapi/render/cpdf_charposlist.cpp
index b59564d..8603531 100644
--- a/core/fpdfapi/render/cpdf_charposlist.cpp
+++ b/core/fpdfapi/render/cpdf_charposlist.cpp
@@ -15,17 +15,17 @@
                                    const std::vector<float>& charPos,
                                    CPDF_Font* pFont,
                                    float FontSize) {
-  m_pCharPos = FX_Alloc(TextCharPos, charCodes.size());
-  m_nChars = 0;
+  m_CharPos.reserve(charCodes.size());
   CPDF_CIDFont* pCIDFont = pFont->AsCIDFont();
   bool bVertWriting = pCIDFont && pCIDFont->IsVertWriting();
-  for (size_t iChar = 0; iChar < charCodes.size(); ++iChar) {
-    uint32_t CharCode = charCodes[iChar];
+  for (size_t i = 0; i < charCodes.size(); ++i) {
+    uint32_t CharCode = charCodes[i];
     if (CharCode == static_cast<uint32_t>(-1))
       continue;
 
     bool bVert = false;
-    TextCharPos& charpos = m_pCharPos[m_nChars++];
+    m_CharPos.emplace_back();
+    TextCharPos& charpos = m_CharPos.back();
     if (pCIDFont)
       charpos.m_bFontStyle = true;
     WideString unicode = pFont->UnicodeFromCharCode(CharCode);
@@ -58,7 +58,7 @@
     else
       charpos.m_FontCharWidth = 0;
 
-    charpos.m_Origin = CFX_PointF(iChar > 0 ? charPos[iChar - 1] : 0, 0);
+    charpos.m_Origin = CFX_PointF(i > 0 ? charPos[i - 1] : 0, 0);
     charpos.m_bGlyphAdjust = false;
 
     float scalingFactor = 1.0f;
@@ -113,14 +113,12 @@
   }
 }
 
-CPDF_CharPosList::~CPDF_CharPosList() {
-  FX_Free(m_pCharPos);
-}
+CPDF_CharPosList::~CPDF_CharPosList() = default;
 
 uint32_t CPDF_CharPosList::GetCount() const {
-  return m_nChars;
+  return pdfium::CollectionSize<uint32_t>(m_CharPos);
 }
 
 const TextCharPos& CPDF_CharPosList::GetAt(size_t index) const {
-  return m_pCharPos[index];
+  return m_CharPos[index];
 }

core/fpdfapi/render/cpdf_charposlist.h

diff --git a/core/fpdfapi/render/cpdf_charposlist.h b/core/fpdfapi/render/cpdf_charposlist.h
index a8872a0..9635f1b 100644
--- a/core/fpdfapi/render/cpdf_charposlist.h
+++ b/core/fpdfapi/render/cpdf_charposlist.h
@@ -22,14 +22,12 @@
                    float font_size);
   ~CPDF_CharPosList();
 
-  uint32_t empty() const { return m_nChars == 0; }
+  uint32_t empty() const { return m_CharPos.empty(); }
   uint32_t GetCount() const;
   const TextCharPos& GetAt(size_t index) const;
 
  private:
-  // TODO(thestig): Convert to unique_ptr or vector.
-  TextCharPos* m_pCharPos = nullptr;
-  uint32_t m_nChars = 0;
+  std::vector<TextCharPos> m_CharPos;
 };
 
 #endif  // CORE_FPDFAPI_RENDER_CPDF_CHARPOSLIST_H_