Bug 779395 - Add support for skew transforms to compositor-driven animations r=dbaron

gfx/layers/Layers.cpp

@@ -284,14 +284,21 @@ CreateCSSValueList(const InfallibleTArray<TransformFunction>& aFunctions)
       {
         float x = aFunctions[i].get_SkewX().x();
         arr = nsStyleAnimation::AppendTransformFunction(eCSSKeyword_skewx, resultTail);
-        arr->Item(1).SetFloatValue(x, eCSSUnit_Number);
+        arr->Item(1).SetFloatValue(x, eCSSUnit_Radian);
         break;
       }
       case TransformFunction::TSkewY:
       {
         float y = aFunctions[i].get_SkewY().y();
         arr = nsStyleAnimation::AppendTransformFunction(eCSSKeyword_skewy, resultTail);
-        arr->Item(1).SetFloatValue(y, eCSSUnit_Number);
+        arr->Item(1).SetFloatValue(y, eCSSUnit_Radian);
+        break;
+      }
+      case TransformFunction::TSkew:
+      {
+        arr = nsStyleAnimation::AppendTransformFunction(eCSSKeyword_skew, resultTail);
+        arr->Item(1).SetFloatValue(aFunctions[i].get_Skew().x(), eCSSUnit_Radian);
+        arr->Item(2).SetFloatValue(aFunctions[i].get_Skew().y(), eCSSUnit_Radian);
         break;
       }
       case TransformFunction::TTransformMatrix:

gfx/layers/ipc/LayerTransaction.ipdlh

@@ -100,6 +100,7 @@ struct Scale {
   float y;
   float z;
 };
+struct Skew { float x; float y; };
 struct SkewX { float x; };
 struct SkewY { float y; };
 struct TransformMatrix { gfx3DMatrix value; };
@@ -117,6 +118,7 @@ union TransformFunction {
   Rotation;
   Rotation3D;
   Scale;
+  Skew;
   SkewX;
   SkewY;
   Translation;

layout/base/nsDisplayList.cpp

@@ -201,16 +201,27 @@ static void AddTransformFunctions(nsCSSValueList* aList,
       }
       case eCSSKeyword_skewx:
       {
-        double x = array->Item(1).GetFloatValue();
+        double x = array->Item(1).GetAngleValueInRadians();
         aFunctions.AppendElement(SkewX(x));
         break;
       }
       case eCSSKeyword_skewy:
       {
-        double y = array->Item(1).GetFloatValue();
+        double y = array->Item(1).GetAngleValueInRadians();
         aFunctions.AppendElement(SkewY(y));
         break;
       }
+      case eCSSKeyword_skew:
+      {
+        double x = array->Item(1).GetAngleValueInRadians();
+        // skew(x) is shorthand for skew(x, 0)
+        double y = 0;
+        if (array->Count() == 3) {
+          y = array->Item(2).GetAngleValueInRadians();
+        }
+        aFunctions.AppendElement(Skew(x, y));
+        break;
+      }
       case eCSSKeyword_matrix:
       {
         gfx3DMatrix matrix;