[css-typed-om] add toMatrix() method in CSSTransformValue.idl

third_party/WebKit/LayoutTests/typedcssom/cssTransformValue.html

Index: third_party/WebKit/LayoutTests/typedcssom/cssTransformValue.html
diff --git a/third_party/WebKit/LayoutTests/typedcssom/cssTransformValue.html b/third_party/WebKit/LayoutTests/typedcssom/cssTransformValue.html
index 15e5224ce93c49a2b71603c0437c06cb06a98c37..69119fb2a0f7d5eabde47c9759045d7af1ac4251 100644
--- a/third_party/WebKit/LayoutTests/typedcssom/cssTransformValue.html
+++ b/third_party/WebKit/LayoutTests/typedcssom/cssTransformValue.html
@@ -3,6 +3,7 @@
 <script src="../resources/testharnessreport.js"></script>
 
 <script>
+var EPSILON = 1e-6; // float epsilon
 
 test(function() {
   var transformValueObject = new CSSTransformValue();
@@ -44,4 +45,37 @@ test(function() {
   assert_equals(newTransformArray[2].constructor.name, CSSScale.name);
 }, "CSSTransformValue can iterate through all its all its transformComponent members");
 
+test(function() {
+  var transformArray = [new CSSScale(2,2)];
+  var transformValue = new CSSTransformValue(transformArray);
+
+  var expectedMatrix = new DOMMatrix();
+  expectedMatrix.scaleSelf(2, 2);
+
+  assert_matrix_approx_equals(transformValue.toMatrix(), expectedMatrix);
+}, "toMatrix() returns DOMMatrix Object - single CSSTransformComponent");
+
+test(function() {
+  var transformMatrix = new DOMMatrixReadOnly([1,1,1,1,1,1]);
+  var transformArray = [new CSSScale(2,2) , new CSSMatrixComponent(transformMatrix), new CSSScale(5,6)];
+  var transformValue = new CSSTransformValue(transformArray);
+
+  var expectedMatrix = new DOMMatrix();
+  expectedMatrix.scaleSelf(2, 2);
+  expectedMatrix.multiplySelf(transformMatrix);
+  expectedMatrix.scaleSelf(5, 6);
+
+  assert_matrix_approx_equals(transformValue.toMatrix(), expectedMatrix);
+},  "toMatrix() returns DOMMatrix Object - multiple CSSTransformComponent");
+
+function assert_array_approx_equals(actual, expected) {
+  for (var i = 0; i < actual.length; i++) {
+    assert_approx_equals(actual[i], expected[i], EPSILON);
+  }
+}
+
+function assert_matrix_approx_equals(actual, expected) {
+  assert_array_approx_equals(actual.toFloat64Array(), expected.toFloat64Array());
+}
+
 </script>