Lazy generate an "AP" when an Annot's hidden state changes

core/fpdfdoc/cpdf_annot.cpp

Index: core/fpdfdoc/cpdf_annot.cpp
diff --git a/core/fpdfdoc/cpdf_annot.cpp b/core/fpdfdoc/cpdf_annot.cpp
index df12e9a82ef7428c7800f109e41eb89b973bc68f..76d3f9c6d4855b08f2e109b307627b3b27a297aa 100644
--- a/core/fpdfdoc/cpdf_annot.cpp
+++ b/core/fpdfdoc/cpdf_annot.cpp
@@ -22,6 +22,14 @@ CPDF_Annot::CPDF_Annot(CPDF_Dictionary* pDict, CPDF_Document* pDocument)
     : m_pAnnotDict(pDict),
       m_pDocument(pDocument),
       m_sSubtype(m_pAnnotDict->GetStringBy("Subtype")) {
+  GenerateAPIfNeeded();
+}
+
+CPDF_Annot::~CPDF_Annot() {
+  ClearCachedAP();
+}
+
+void CPDF_Annot::GenerateAPIfNeeded() {
   if (m_sSubtype == "Circle")
     CPVT_GenerateAP::GenerateCircleAP(m_pDocument, m_pAnnotDict);
   else if (m_sSubtype == "Highlight")
@@ -40,10 +48,6 @@ CPDF_Annot::CPDF_Annot(CPDF_Dictionary* pDict, CPDF_Document* pDocument)
     CPVT_GenerateAP::GenerateUnderlineAP(m_pDocument, m_pAnnotDict);
 }
 
-CPDF_Annot::~CPDF_Annot() {
-  ClearCachedAP();
-}
-
 void CPDF_Annot::ClearCachedAP() {
   m_APMap.clear();
 }
@@ -149,6 +153,13 @@ FX_BOOL CPDF_Annot::DrawAppearance(CPDF_Page* pPage,
   if (IsAnnotationHidden(m_pAnnotDict))
     return FALSE;
 
+  // It might happen that by the time this annotation instance was created,
+  // it was flagged as "hidden" (e.g. /F 2), and hence CPVT_GenerateAP decided
+  // to not "generate" its AP.
+  // If for a reason the object is no longer hidden, but still does not have
+  // its "AP" generated, generate it now.
+  GenerateAPIfNeeded();
+
   CFX_Matrix matrix;
   CPDF_Form* pForm =
       FPDFDOC_Annot_GetMatrix(pPage, this, mode, pUser2Device, matrix);