Add new public APIs to find the z-order for links and widgets.

core/src/fpdfdoc/doc_form.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../../include/fpdfdoc/fpdf_doc.h"
 #include "doc_utils.h"
 
 const int nMaxRecursion = 32;
@@ skipping 848 matching lines @@
     if (!m_ControlMap.Lookup(pAnnot, (void*&)pControl)) {
       continue;
     }
     if (index == count) {
       return pControl;
     }
     count++;
   }
   return NULL;
 }
+
 CPDF_FormControl* CPDF_InterForm::GetControlAtPoint(CPDF_Page* pPage,
                                                     FX_FLOAT pdf_x,
-                                                    FX_FLOAT pdf_y) const {
+                                                    FX_FLOAT pdf_y,
+                                                    int* z_order) const {
   CPDF_Array* pAnnotList = pPage->m_pFormDict->GetArray("Annots");
-  if (pAnnotList == NULL) {
-    return NULL;
+  if (!pAnnotList)
+    return nullptr;
+
+  for (FX_DWORD i = pAnnotList->GetCount(); i > 0; --i) {
+    FX_DWORD annot_index = i - 1;
+    CPDF_Dictionary* pAnnot = pAnnotList->GetDict(annot_index);
+    if (!pAnnot)
+      continue;
+
+    CPDF_FormControl* pControl;
+    if (!m_ControlMap.Lookup(pAnnot, (void*&)pControl))
+      continue;
+
+    CFX_FloatRect rect = pControl->GetRect();
+    if (!rect.Contains(pdf_x, pdf_y))
+      continue;
+
+    if (z_order)
+      *z_order = annot_index;
+    return pControl;
   }
-  for (FX_DWORD i = pAnnotList->GetCount(); i > 0; i--) {
-    CPDF_Dictionary* pAnnot = pAnnotList->GetDict(i - 1);
-    if (pAnnot == NULL) {
-      continue;
-    }
-    CPDF_FormControl* pControl;
-    if (!m_ControlMap.Lookup(pAnnot, (void*&)pControl)) {
-      continue;
-    }
-    CFX_FloatRect rect = pControl->GetRect();
-    if (rect.Contains(pdf_x, pdf_y)) {
-      return pControl;
-    }
-  }
-  return NULL;
+  return nullptr;
 }
+
 CPDF_FormControl* CPDF_InterForm::GetControlByDict(
     CPDF_Dictionary* pWidgetDict) const {
   CPDF_FormControl* pControl = NULL;
   m_ControlMap.Lookup(pWidgetDict, (void*&)pControl);
   return pControl;
 }
 FX_DWORD CPDF_InterForm::CountInternalFields(
     const CFX_WideString& csFieldName) const {
   if (!m_pFormDict) {
     return 0;
@@ skipping 714 matching lines @@
         continue;
       }
       CPDF_FormControl* pControl = NULL;
       if (m_ControlMap.Lookup(pAnnotDict, (void*&)pControl)) {
         return iNewPage;
       }
     }
   } while (TRUE);
   return -1;
 }