Use strict types in FPDF API, try #3

Rather than messing with actual inheritence, add type-checking wrappers
and just blatantly cast to incomplete types.  Along the way, this points
out places where we would downcast without checking, which I fix.

Change-Id: Ieb303eb46ad8522dfe082454f1f10f247ffd52d5
Reviewed-on: https://pdfium-review.googlesource.com/32030
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>

1 files changed, 10 insertions, 7 deletions

diff --git a/fpdfsdk/fpdf_editpath.cpp b/fpdfsdk/fpdf_editpath.cpp
index 82c7ca13ef..aca2bebf81 100644
--- a/fpdfsdk/fpdf_editpath.cpp
+++ b/fpdfsdk/fpdf_editpath.cpp
@@ -42,10 +42,6 @@ CPDF_PathObject* CPDFPathObjectFromFPDFPageObject(FPDF_PAGEOBJECT page_object) {
   return obj ? obj->AsPath() : nullptr;
 }
 
-const FX_PATHPOINT* FXPathPointFromFPDFPathSegment(FPDF_PATHSEGMENT segment) {
-  return static_cast<const FX_PATHPOINT*>(segment);
-}
-
 unsigned int GetAlphaAsUnsignedInt(float alpha) {
   return static_cast<unsigned int>(alpha * 255.f + 0.5f);
 }
@@ -57,7 +53,9 @@ FPDF_EXPORT FPDF_PAGEOBJECT FPDF_CALLCONV FPDFPageObj_CreateNewPath(float x,
   auto pPathObj = pdfium::MakeUnique<CPDF_PathObject>();
   pPathObj->m_Path.AppendPoint(CFX_PointF(x, y), FXPT_TYPE::MoveTo, false);
   pPathObj->DefaultStates();
-  return pPathObj.release();  // Caller takes ownership.
+
+  // Caller takes ownership.
+  return FPDFPageObjectFromCPDFPageObject(pPathObj.release());
 }
 
 FPDF_EXPORT FPDF_PAGEOBJECT FPDF_CALLCONV FPDFPageObj_CreateNewRect(float x,
@@ -67,7 +65,9 @@ FPDF_EXPORT FPDF_PAGEOBJECT FPDF_CALLCONV FPDFPageObj_CreateNewRect(float x,
   auto pPathObj = pdfium::MakeUnique<CPDF_PathObject>();
   pPathObj->m_Path.AppendRect(x, y, x + w, y + h);
   pPathObj->DefaultStates();
-  return pPathObj.release();  // Caller takes ownership.
+
+  // Caller takes ownership.
+  return FPDFPageObjectFromCPDFPageObject(pPathObj.release());
 }
 
 FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
@@ -156,7 +156,10 @@ FPDFPath_GetPathSegment(FPDF_PAGEOBJECT path, int index) {
     return nullptr;
 
   const std::vector<FX_PATHPOINT>& points = pPathObj->m_Path.GetPoints();
-  return pdfium::IndexInBounds(points, index) ? &points[index] : nullptr;
+  if (!pdfium::IndexInBounds(points, index))
+    return nullptr;
+
+  return FPDFPathSegmentFromFXPathPoint(&points[index]);
 }
 
 FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV FPDFPath_MoveTo(FPDF_PAGEOBJECT path,