Coalesce redundant path points.

There exists PDFs with many redundant path points, and keeping track of
them all uses a lot of memory.

BUG=chromium:679353

Change-Id: I514610cbba181658b6396e30f5bf58a3661359f5
Reviewed-on: https://pdfium-review.googlesource.com/3110
Reviewed-by: Nicolás Peña <npm@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/core/fpdfapi/page/cpdf_streamcontentparser.cpp b/core/fpdfapi/page/cpdf_streamcontentparser.cpp
index 798b9d4f4e..d8b176b288 100644
--- a/core/fpdfapi/page/cpdf_streamcontentparser.cpp
+++ b/core/fpdfapi/page/cpdf_streamcontentparser.cpp
@@ -1440,6 +1440,15 @@ void CPDF_StreamContentParser::AddPathPoint(float x,
                                             float y,
                                             FXPT_TYPE type,
                                             bool close) {
+  // If the path point is the same move as the previous one and neither of them
+  // closes the path, then just skip it.
+  if (!close && type == FXPT_TYPE::MoveTo && m_PathPointCount &&
+      !m_pPathPoints[m_PathPointCount - 1].m_CloseFigure &&
+      m_pPathPoints[m_PathPointCount - 1].m_Type == type &&
+      m_PathCurrentX == x && m_PathCurrentY == y) {
+    return;
+  }
+
   m_PathCurrentX = x;
   m_PathCurrentY = y;
   if (type == FXPT_TYPE::MoveTo && !close) {