Add helper methods for getting objects in CPDF_FormField.

Consolidate calls to FPDF_GetFieldAttr() and make it more obvious to
readers what objects are being retrieved.

Change-Id: If348122bb23fa9e1e7857e30428cad929f74fbf7
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/59941
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

core/fpdfdoc/cpdf_formfield.cpp

diff --git a/core/fpdfdoc/cpdf_formfield.cpp b/core/fpdfdoc/cpdf_formfield.cpp
index 3de2bea..7bd99ea 100644
--- a/core/fpdfdoc/cpdf_formfield.cpp
+++ b/core/fpdfdoc/cpdf_formfield.cpp
@@ -172,8 +172,7 @@
     case kRichText:
     case kFile:
     default: {
-      const CPDF_Object* pDV =
-          FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kDV);
+      const CPDF_Object* pDV = GetDefaultValueObject();
       WideString csDValue;
       if (pDV)
         csDValue = pDV->GetUnicodeText();
@@ -181,8 +180,7 @@
       WideString csValue;
       {
         // Limit the scope of |pV| because it may get invalidated below.
-        const CPDF_Object* pV =
-            FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kV);
+        const CPDF_Object* pV = GetValueObject();
         if (pV)
           csValue = pV->GetUnicodeText();
       }
@@ -294,11 +292,10 @@
     return GetCheckValue(bDefault);
 
   const CPDF_Object* pValue =
-      FPDF_GetFieldAttr(m_pDict.Get(), bDefault ? pdfium::form_fields::kDV
-                                                : pdfium::form_fields::kV);
+      bDefault ? GetDefaultValueObject() : GetValueObject();
   if (!pValue) {
     if (!bDefault && m_Type != kText)
-      pValue = FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kDV);
+      pValue = GetDefaultValueObject();
     if (!pValue)
       return WideString();
   }
@@ -410,13 +407,9 @@
 }
 
 int CPDF_FormField::CountSelectedItems() const {
-  const CPDF_Object* pValue =
-      FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kV);
-  if (!pValue) {
-    pValue = FPDF_GetFieldAttr(m_pDict.Get(), "I");
-    if (!pValue)
-      return 0;
-  }
+  const CPDF_Object* pValue = GetValueOrSelectedIndicesObject();
+  if (!pValue)
+    return 0;
 
   if (pValue->IsString() || pValue->IsNumber())
     return pValue->GetString().IsEmpty() ? 0 : 1;
@@ -425,13 +418,10 @@
 }
 
 int CPDF_FormField::GetSelectedIndex(int index) const {
-  const CPDF_Object* pValue =
-      FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kV);
-  if (!pValue) {
-    pValue = FPDF_GetFieldAttr(m_pDict.Get(), "I");
-    if (!pValue)
-      return -1;
-  }
+  const CPDF_Object* pValue = GetValueOrSelectedIndicesObject();
+  if (!pValue)
+    return -1;
+
   if (pValue->IsNumber())
     return pValue->GetInteger();
 
@@ -485,13 +475,9 @@
     return true;
 
   WideString opt_value = GetOptionValue(index);
-  const CPDF_Object* pValue =
-      FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kV);
-  if (!pValue) {
-    pValue = FPDF_GetFieldAttr(m_pDict.Get(), "I");
-    if (!pValue)
-      return false;
-  }
+  const CPDF_Object* pValue = GetValueOrSelectedIndicesObject();
+  if (!pValue)
+    return false;
 
   if (pValue->IsString())
     return pValue->GetUnicodeText() == opt_value;
@@ -562,8 +548,7 @@
 
 void CPDF_FormField::SetItemSelectionUnselected(int index,
                                                 const WideString& opt_value) {
-  const CPDF_Object* pValue =
-      FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kV);
+  const CPDF_Object* pValue = GetValueObject();
   if (!pValue)
     return;
 
@@ -604,8 +589,7 @@
 
 int CPDF_FormField::GetDefaultSelectedItem() const {
   ASSERT(GetType() == kComboBox || GetType() == kListBox);
-  const CPDF_Object* pValue =
-      FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kDV);
+  const CPDF_Object* pValue = GetDefaultValueObject();
   if (!pValue)
     return -1;
   WideString csDV = pValue->GetUnicodeText();
@@ -693,8 +677,7 @@
       m_pDict->SetNewFor<CPDF_Name>(pdfium::form_fields::kV, csBExport);
     } else {
       ByteString csV;
-      const CPDF_Object* pV =
-          FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kV);
+      const CPDF_Object* pV = GetValueObject();
       if (pV)
         csV = pV->GetString();
       if (csV == csBExport)
@@ -752,12 +735,12 @@
 }
 
 int CPDF_FormField::CountSelectedOptions() const {
-  const CPDF_Array* pArray = ToArray(FPDF_GetFieldAttr(m_pDict.Get(), "I"));
+  const CPDF_Array* pArray = ToArray(GetSelectedIndicesObject());
   return pArray ? pArray->size() : 0;
 }
 
 int CPDF_FormField::GetSelectedOptionIndex(int index) const {
-  const CPDF_Array* pArray = ToArray(FPDF_GetFieldAttr(m_pDict.Get(), "I"));
+  const CPDF_Array* pArray = ToArray(GetSelectedIndicesObject());
   if (!pArray)
     return -1;
 
@@ -768,7 +751,7 @@
 }
 
 bool CPDF_FormField::IsOptionSelected(int iOptIndex) const {
-  const CPDF_Array* pArray = ToArray(FPDF_GetFieldAttr(m_pDict.Get(), "I"));
+  const CPDF_Array* pArray = ToArray(GetSelectedIndicesObject());
   if (!pArray)
     return false;
 
@@ -916,6 +899,25 @@
   }
 }
 
+const CPDF_Object* CPDF_FormField::GetDefaultValueObject() const {
+  return FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kDV);
+}
+
+const CPDF_Object* CPDF_FormField::GetValueObject() const {
+  return FPDF_GetFieldAttr(m_pDict.Get(), pdfium::form_fields::kV);
+}
+
+const CPDF_Object* CPDF_FormField::GetSelectedIndicesObject() const {
+  ASSERT(GetType() == kComboBox || GetType() == kListBox);
+  return FPDF_GetFieldAttr(m_pDict.Get(), "I");
+}
+
+const CPDF_Object* CPDF_FormField::GetValueOrSelectedIndicesObject() const {
+  ASSERT(GetType() == kComboBox || GetType() == kListBox);
+  const CPDF_Object* pValue = GetValueObject();
+  return pValue ? pValue : GetSelectedIndicesObject();
+}
+
 const std::vector<UnownedPtr<CPDF_FormControl>>& CPDF_FormField::GetControls()
     const {
   return m_pForm->GetControlsForField(this);

core/fpdfdoc/cpdf_formfield.h

diff --git a/core/fpdfdoc/cpdf_formfield.h b/core/fpdfdoc/cpdf_formfield.h
index 960fb0e..4c59591 100644
--- a/core/fpdfdoc/cpdf_formfield.h
+++ b/core/fpdfdoc/cpdf_formfield.h
@@ -189,6 +189,16 @@
   bool NotifyListOrComboBoxBeforeChange(const WideString& value);
   void NotifyListOrComboBoxAfterChange();
 
+  const CPDF_Object* GetDefaultValueObject() const;
+  const CPDF_Object* GetValueObject() const;
+
+  // For choice fields.
+  const CPDF_Object* GetSelectedIndicesObject() const;
+
+  // For choice fields.
+  // Value object takes precedence over selected indices object.
+  const CPDF_Object* GetValueOrSelectedIndicesObject() const;
+
   const std::vector<UnownedPtr<CPDF_FormControl>>& GetControls() const;
 
   CPDF_FormField::Type m_Type = kUnknown;