Rename CXFA_Box methods to make return clearer

This CL renames the methods in CXFA_Box to make it clearer they can
return nullptr.

Change-Id: I521c0e06af306f69e390a4057cabb7777a0d72f5
Reviewed-on: https://pdfium-review.googlesource.com/22740
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

7 files changed, 42 insertions, 25 deletions

diff --git a/xfa/fxfa/cxfa_ffcheckbutton.cpp b/xfa/fxfa/cxfa_ffcheckbutton.cpp
index 2f79408e74..b50349f211 100644
--- a/xfa/fxfa/cxfa_ffcheckbutton.cpp
+++ b/xfa/fxfa/cxfa_ffcheckbutton.cpp
@@ -175,7 +175,7 @@ bool CXFA_FFCheckButton::PerformLayout() {
   m_rtCheckBox = m_rtUI;
   CXFA_Border* borderUI = m_pNode->GetWidgetAcc()->GetUIBorder();
   if (borderUI) {
-    CXFA_Margin* borderMargin = borderUI->GetMargin();
+    CXFA_Margin* borderMargin = borderUI->GetMarginIfExists();
     if (borderMargin)
       XFA_RectWithoutMargin(m_rtUI, borderMargin);
   }
diff --git a/xfa/fxfa/cxfa_fffield.cpp b/xfa/fxfa/cxfa_fffield.cpp
index 53a81bdad9..b07d80f108 100644
--- a/xfa/fxfa/cxfa_fffield.cpp
+++ b/xfa/fxfa/cxfa_fffield.cpp
@@ -269,7 +269,7 @@ void CXFA_FFField::CapPlacement() {
 
   CXFA_Border* borderUI = m_pNode->GetWidgetAcc()->GetUIBorder();
   if (borderUI) {
-    CXFA_Margin* borderMargin = borderUI->GetMargin();
+    CXFA_Margin* borderMargin = borderUI->GetMarginIfExists();
     if (borderMargin)
       XFA_RectWithoutMargin(m_rtUI, borderMargin);
   }
diff --git a/xfa/fxfa/cxfa_ffpushbutton.cpp b/xfa/fxfa/cxfa_ffpushbutton.cpp
index 779fada905..85805b4d76 100644
--- a/xfa/fxfa/cxfa_ffpushbutton.cpp
+++ b/xfa/fxfa/cxfa_ffpushbutton.cpp
@@ -121,8 +121,10 @@ bool CXFA_FFPushButton::PerformLayout() {
 
 float CXFA_FFPushButton::GetLineWidth() {
   CXFA_Border* border = m_pNode->GetBorderIfExists();
-  if (border && border->GetPresence() == XFA_AttributeEnum::Visible)
-    return border->GetEdge(0)->GetThickness();
+  if (border && border->GetPresence() == XFA_AttributeEnum::Visible) {
+    CXFA_Edge* edge = border->GetEdgeIfExists(0);
+    return edge ? edge->GetThickness() : 0;
+  }
   return 0;
 }
 
diff --git a/xfa/fxfa/cxfa_ffwidget.cpp b/xfa/fxfa/cxfa_ffwidget.cpp
index cff0697c82..e28aa4314e 100644
--- a/xfa/fxfa/cxfa_ffwidget.cpp
+++ b/xfa/fxfa/cxfa_ffwidget.cpp
@@ -250,7 +250,8 @@ void XFA_BOX_GetFillPath(CXFA_Box* box,
                          CXFA_GEPath& fillPath,
                          uint16_t dwFlags) {
   if (box->IsArc() || (dwFlags & XFA_DRAWBOX_ForceRound) != 0) {
-    float fThickness = std::fmax(0.0, box->GetEdge(0)->GetThickness());
+    CXFA_Edge* edge = box->GetEdgeIfExists(0);
+    float fThickness = std::fmax(0.0, edge ? edge->GetThickness() : 0);
     float fHalf = fThickness / 2;
     XFA_AttributeEnum iHand = box->GetHand();
     if (iHand == XFA_AttributeEnum::Left)
@@ -391,12 +392,13 @@ void XFA_BOX_GetFillPath(CXFA_Box* box,
   }
 }
 
-void XFA_BOX_Fill_Radial(CXFA_Box* box,
+void XFA_BOX_Fill_Radial(CXFA_Fill* fill,
                          CXFA_Graphics* pGS,
                          CXFA_GEPath& fillPath,
                          CFX_RectF rtFill,
                          const CFX_Matrix& matrix) {
-  CXFA_Fill* fill = box->GetFill();
+  ASSERT(fill);
+
   FX_ARGB crStart = fill->GetColor(false);
   FX_ARGB crEnd = fill->GetRadialColor();
   if (!fill->IsRadialToEdge())
@@ -411,12 +413,13 @@ void XFA_BOX_Fill_Radial(CXFA_Box* box,
   pGS->FillPath(&fillPath, FXFILL_WINDING, &matrix);
 }
 
-void XFA_BOX_Fill_Pattern(CXFA_Box* box,
+void XFA_BOX_Fill_Pattern(CXFA_Fill* fill,
                           CXFA_Graphics* pGS,
                           CXFA_GEPath& fillPath,
                           CFX_RectF rtFill,
                           const CFX_Matrix& matrix) {
-  CXFA_Fill* fill = box->GetFill();
+  ASSERT(fill);
+
   FX_ARGB crStart = fill->GetColor(false);
   FX_ARGB crEnd = fill->GetPatternColor();
   FX_HatchStyle iHatch = FX_HatchStyle::Cross;
@@ -445,12 +448,13 @@ void XFA_BOX_Fill_Pattern(CXFA_Box* box,
   pGS->FillPath(&fillPath, FXFILL_WINDING, &matrix);
 }
 
-void XFA_BOX_Fill_Linear(CXFA_Box* box,
+void XFA_BOX_Fill_Linear(CXFA_Fill* fill,
                          CXFA_Graphics* pGS,
                          CXFA_GEPath& fillPath,
                          CFX_RectF rtFill,
                          const CFX_Matrix& matrix) {
-  CXFA_Fill* fill = box->GetFill();
+  ASSERT(fill);
+
   FX_ARGB crStart = fill->GetColor(false);
   FX_ARGB crEnd = fill->GetLinearColor();
 
@@ -488,7 +492,7 @@ void XFA_BOX_Fill(CXFA_Box* box,
                   const CFX_RectF& rtWidget,
                   const CFX_Matrix& matrix,
                   uint32_t dwFlags) {
-  CXFA_Fill* fill = box->GetFill();
+  CXFA_Fill* fill = box->GetFillIfExists();
   if (!fill || !fill->IsVisible())
     return;
 
@@ -500,13 +504,13 @@ void XFA_BOX_Fill(CXFA_Box* box,
   XFA_Element eType = fill->GetFillType();
   switch (eType) {
     case XFA_Element::Radial:
-      XFA_BOX_Fill_Radial(box, pGS, fillPath, rtWidget, matrix);
+      XFA_BOX_Fill_Radial(fill, pGS, fillPath, rtWidget, matrix);
       break;
     case XFA_Element::Pattern:
-      XFA_BOX_Fill_Pattern(box, pGS, fillPath, rtWidget, matrix);
+      XFA_BOX_Fill_Pattern(fill, pGS, fillPath, rtWidget, matrix);
       break;
     case XFA_Element::Linear:
-      XFA_BOX_Fill_Linear(box, pGS, fillPath, rtWidget, matrix);
+      XFA_BOX_Fill_Linear(fill, pGS, fillPath, rtWidget, matrix);
       break;
     default: {
       FX_ARGB cr;
@@ -559,7 +563,7 @@ void XFA_BOX_StrokeArc(CXFA_Box* box,
                        CFX_RectF rtWidget,
                        const CFX_Matrix& matrix,
                        uint32_t dwFlags) {
-  CXFA_Edge* edge = box->GetEdge(0);
+  CXFA_Edge* edge = box->GetEdgeIfExists(0);
   if (!edge || !edge->IsVisible())
     return;
 
@@ -987,7 +991,7 @@ void CXFA_FFWidget::RenderWidget(CXFA_Graphics* pGS,
     return;
 
   CFX_RectF rtBorder = GetRectWithoutRotate();
-  CXFA_Margin* margin = border->GetMargin();
+  CXFA_Margin* margin = border->GetMarginIfExists();
   if (margin)
     XFA_RectWithoutMargin(rtBorder, margin);
 
@@ -998,18 +1002,23 @@ void CXFA_FFWidget::RenderWidget(CXFA_Graphics* pGS,
 bool CXFA_FFWidget::IsLoaded() {
   return !!m_pPageView;
 }
+
 bool CXFA_FFWidget::LoadWidget() {
   PerformLayout();
   return true;
 }
+
 void CXFA_FFWidget::UnloadWidget() {}
+
 bool CXFA_FFWidget::PerformLayout() {
   RecacheWidgetRect();
   return true;
 }
+
 bool CXFA_FFWidget::UpdateFWLData() {
   return false;
 }
+
 void CXFA_FFWidget::UpdateWidgetProperty() {}
 
 void CXFA_FFWidget::DrawBorder(CXFA_Graphics* pGS,
diff --git a/xfa/fxfa/parser/cxfa_box.cpp b/xfa/fxfa/parser/cxfa_box.cpp
index 443362f449..5f8bed9aa1 100644
--- a/xfa/fxfa/parser/cxfa_box.cpp
+++ b/xfa/fxfa/parser/cxfa_box.cpp
@@ -81,7 +81,7 @@ int32_t CXFA_Box::CountEdges() {
   return CountChildren(XFA_Element::Edge, false);
 }
 
-CXFA_Edge* CXFA_Box::GetEdge(int32_t nIndex) {
+CXFA_Edge* CXFA_Box::GetEdgeIfExists(int32_t nIndex) {
   if (nIndex == 0)
     return JSObject()->GetOrCreateProperty<CXFA_Edge>(nIndex,
                                                       XFA_Element::Edge);
@@ -104,15 +104,15 @@ Optional<int32_t> CXFA_Box::GetSweepAngle() {
   return JSObject()->TryInteger(XFA_Attribute::SweepAngle, false);
 }
 
-CXFA_Fill* CXFA_Box::GetFill() const {
+CXFA_Fill* CXFA_Box::GetFillIfExists() const {
   return JSObject()->GetProperty<CXFA_Fill>(0, XFA_Element::Fill);
 }
 
-CXFA_Fill* CXFA_Box::GetOrCreateFill() {
+CXFA_Fill* CXFA_Box::GetOrCreateFillIfPossible() {
   return JSObject()->GetOrCreateProperty<CXFA_Fill>(0, XFA_Element::Fill);
 }
 
-CXFA_Margin* CXFA_Box::GetMargin() {
+CXFA_Margin* CXFA_Box::GetMarginIfExists() {
   return GetChild<CXFA_Margin>(0, XFA_Element::Margin, false);
 }
 
@@ -144,6 +144,8 @@ std::vector<CXFA_Stroke*> CXFA_Box::GetStrokesInternal(bool bNull) {
       corner = JSObject()->GetProperty<CXFA_Corner>(i, XFA_Element::Corner);
     }
 
+    // TODO(dsinclair): If i == 0 and GetOrCreateProperty failed, we can end up
+    // with a null corner in the first position.
     if (corner || i == 0) {
       strokes[j] = corner;
     } else if (!bNull) {
@@ -160,6 +162,8 @@ std::vector<CXFA_Stroke*> CXFA_Box::GetStrokesInternal(bool bNull) {
     else
       edge = JSObject()->GetProperty<CXFA_Edge>(i, XFA_Element::Edge);
 
+    // TODO(dsinclair): If i == 0 and GetOrCreateProperty failed, we can end up
+    // with a null edge in the first position.
     if (edge || i == 0) {
       strokes[j] = edge;
     } else if (!bNull) {
diff --git a/xfa/fxfa/parser/cxfa_box.h b/xfa/fxfa/parser/cxfa_box.h
index c85d0164af..216a981c83 100644
--- a/xfa/fxfa/parser/cxfa_box.h
+++ b/xfa/fxfa/parser/cxfa_box.h
@@ -30,10 +30,10 @@ class CXFA_Box : public CXFA_Node {
   std::tuple<XFA_AttributeEnum, bool, float> Get3DStyle();
 
   int32_t CountEdges();
-  CXFA_Edge* GetEdge(int32_t nIndex);
-  CXFA_Fill* GetFill() const;
-  CXFA_Fill* GetOrCreateFill();
-  CXFA_Margin* GetMargin();
+  CXFA_Edge* GetEdgeIfExists(int32_t nIndex);
+  CXFA_Fill* GetFillIfExists() const;
+  CXFA_Fill* GetOrCreateFillIfPossible();
+  CXFA_Margin* GetMarginIfExists();
 
   std::vector<CXFA_Stroke*> GetStrokes();
 
diff --git a/xfa/fxfa/parser/cxfa_edge.h b/xfa/fxfa/parser/cxfa_edge.h
index 8bf9f6ea28..36fee55624 100644
--- a/xfa/fxfa/parser/cxfa_edge.h
+++ b/xfa/fxfa/parser/cxfa_edge.h
@@ -11,6 +11,8 @@
 
 class CXFA_Edge : public CXFA_Stroke {
  public:
+  static constexpr FX_ARGB kDefaultColor = 0xFF000000;
+
   CXFA_Edge(CXFA_Document* doc, XFA_PacketType packet);
   ~CXFA_Edge() override;
 };