Try to workaround some incorrect PDF

Fixes rendering of PDF where forms/patterns have more q than Q. Fixes
rendering in splash of pdf in bugs #22835, #21899 and #16402

2 files changed, 14 insertions, 0 deletions

diff --git a/poppler/Gfx.cc b/poppler/Gfx.cc
index eeefcac0..ccf818a4 100644
--- a/poppler/Gfx.cc
+++ b/poppler/Gfx.cc
@@ -4274,8 +4274,21 @@ void Gfx::doForm1(Object *str, Dict *resDict, double *matrix, double *bbox,
     baseMatrix[i] = state->getCTM()[i];
   }
 
+  GfxState *stateBefore = state;
+
   // draw the form
   display(str, gFalse);
+  
+  if (stateBefore != state) {
+    if (state->isParentState(stateBefore)) {
+      error(-1, "There's a form with more q than Q, trying to fix");
+      while (stateBefore != state) {
+        restoreState();
+      }
+    } else {
+      error(-1, "There's a form with more Q than q");
+    }
+  }
 
   if (softMask || transpGroup) {
     out->endTransparencyGroup(state);
diff --git a/poppler/GfxState.h b/poppler/GfxState.h
index 536c86ad..51a317d3 100644
--- a/poppler/GfxState.h
+++ b/poppler/GfxState.h
@@ -1269,6 +1269,7 @@ public:
   GfxState *save();
   GfxState *restore();
   GBool hasSaves() { return saved != NULL; }
+  GBool isParentState(GfxState *state) { return saved == state || (saved && saved->isParentState(state)); }
 
   // Misc
   GBool parseBlendMode(Object *obj, GfxBlendMode *mode);