Fix partial information printed with blank window covering the center

core/include/fpdfapi/fpdf_page.h

Index: core/include/fpdfapi/fpdf_page.h
diff --git a/core/include/fpdfapi/fpdf_page.h b/core/include/fpdfapi/fpdf_page.h
index efbfa67280ce54d8f663b4918529fa2b3a8daa24..d58537aa7e5b45a1e2e4cb8479d2302c8c5decfc 100644
--- a/core/include/fpdfapi/fpdf_page.h
+++ b/core/include/fpdfapi/fpdf_page.h
@@ -67,6 +67,8 @@ class CPDF_PageObjects {
 
   FX_BOOL BackgroundAlphaNeeded() const { return m_bBackgroundAlphaNeeded; }
 
+  FX_BOOL HasImageMask() const { return m_bHasImageMask; }
+
   CFX_FloatRect CalcBoundingBox() const;
 
   CPDF_Dictionary* m_pFormDict;
@@ -89,6 +91,7 @@ class CPDF_PageObjects {
 
   CFX_PtrList m_ObjectList;
   FX_BOOL m_bBackgroundAlphaNeeded;
+  FX_BOOL m_bHasImageMask;
   FX_BOOL m_bReleaseMembers;
   CPDF_ContentParser* m_pParser;
   ParseState m_ParseState;