Bug 1273705 - Add convenience methods to check if a margin is 'auto' on either side in an axis. r=dholbert

layout/generic/WritingModes.h

@@ -1856,6 +1856,18 @@ inline nsStyleUnit nsStyleSides::GetBEndUnit(mozilla::WritingMode aWM) const
   return GetUnit(aWM, mozilla::eLogicalSideBEnd);
 }
 
+inline bool nsStyleSides::HasBlockAxisAuto(mozilla::WritingMode aWM) const
+{
+  return GetBStartUnit(aWM) == eStyleUnit_Auto ||
+         GetBEndUnit(aWM) == eStyleUnit_Auto;
+}
+
+inline bool nsStyleSides::HasInlineAxisAuto(mozilla::WritingMode aWM) const
+{
+  return GetIStartUnit(aWM) == eStyleUnit_Auto ||
+         GetIEndUnit(aWM) == eStyleUnit_Auto;
+}
+
 inline nsStyleCoord nsStyleSides::Get(mozilla::WritingMode aWM,
                                       mozilla::LogicalSide aSide) const
 {
@@ -2001,4 +2013,15 @@ nsStyleDisplay::PhysicalBreakType(mozilla::WritingMode aWM) const
   return mBreakType;
 }
 
+inline bool
+nsStyleMargin::HasBlockAxisAuto(mozilla::WritingMode aWM) const
+{
+  return mMargin.HasBlockAxisAuto(aWM);
+}
+inline bool
+nsStyleMargin::HasInlineAxisAuto(mozilla::WritingMode aWM) const
+{
+  return mMargin.HasInlineAxisAuto(aWM);
+}
+
 #endif // WritingModes_h_

layout/style/nsStyleCoord.h

@@ -295,6 +295,10 @@ public:
   inline nsStyleUnit GetIEndUnit(mozilla::WritingMode aWritingMode) const;
   inline nsStyleUnit GetBEndUnit(mozilla::WritingMode aWritingMode) const;
 
+  // Return true if either the start or end side in the axis is 'auto'.
+  inline bool HasBlockAxisAuto(mozilla::WritingMode aWritingMode) const;
+  inline bool HasInlineAxisAuto(mozilla::WritingMode aWritingMode) const;
+
   inline nsStyleCoord Get(mozilla::WritingMode aWritingMode,
                           mozilla::LogicalSide aSide) const;
   inline nsStyleCoord GetIStart(mozilla::WritingMode aWritingMode) const;

layout/style/nsStyleStruct.h

@@ -822,8 +822,6 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleMargin
     return nsChangeHint(0);
   }
 
-  nsStyleSides  mMargin;          // [reset] coord, percent, calc, auto
-
   bool GetMargin(nsMargin& aMargin) const
   {
     if (mMargin.ConvertsToLength()) {
@@ -841,6 +839,13 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleMargin
       aMargin.Side(side) = mMargin.ToLength(side);
     }
   }
+
+  // Return true if either the start or end side in the axis is 'auto'.
+  // (defined in WritingModes.h since we need the full WritingMode type)
+  inline bool HasBlockAxisAuto(mozilla::WritingMode aWM) const;
+  inline bool HasInlineAxisAuto(mozilla::WritingMode aWM) const;
+
+  nsStyleSides  mMargin; // [reset] coord, percent, calc, auto
 };
 
 struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStylePadding