Add localToAbsoluteTransform and localToAncestorTransform.

third_party/WebKit/Source/core/layout/LayoutObjectTest.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/LayoutObject.h"
 
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 104 matching lines @@
         "</div>");
     LayoutBlock* container = toLayoutBlock(getLayoutObjectByElementId("container"));
     LayoutText* text = toLayoutText(container->lastChild());
 
     container->setScrollTop(LayoutUnit(50));
     LayoutRect rect(0, 60, 20, 20);
     text->mapToVisibleRectInAncestorSpace(container, rect, nullptr);
     EXPECT_TRUE(rect == LayoutRect(0, 10, 20, 20));
 }
 
+TEST_F(LayoutObjectTest, LocalToAbsoluteTransform)
+{
+    setBodyInnerHTML(
+        "<div id='container' style='position: absolute; left: 0; top: 0;'>"
+        "  <div id='scale' style='transform: scale(2.0); transform-origin: left top;'>"
+        "    <div id='child'></div>"
+        "  </div>"
+        "</div>");
+    LayoutBoxModelObject* container = toLayoutBoxModelObject(getLayoutObjectByElementId("container"));
+    TransformationMatrix containerMatrix = container->localToAbsoluteTransform();
+    EXPECT_TRUE(containerMatrix.isIdentity());
+
+    LayoutObject* child = getLayoutObjectByElementId("child");
+    TransformationMatrix childMatrix = child->localToAbsoluteTransform();
+    EXPECT_FALSE(childMatrix.isIdentityOrTranslation());
+    EXPECT_TRUE(childMatrix.isAffine());
+    EXPECT_EQ(0.0, childMatrix.projectPoint(FloatPoint(0.0, 0.0)).x());
+    EXPECT_EQ(0.0, childMatrix.projectPoint(FloatPoint(0.0, 0.0)).y());
+    EXPECT_EQ(20.0, childMatrix.projectPoint(FloatPoint(10.0, 20.0)).x());
+    EXPECT_EQ(40.0, childMatrix.projectPoint(FloatPoint(10.0, 20.0)).y());
+}
+
+TEST_F(LayoutObjectTest, LocalToAncestorTransform)
+{
+    setBodyInnerHTML(
+        "<div id='container'>"
+        "  <div id='rotate1' style='transform: rotate(45deg); transform-origin: left top;'>"
+        "    <div id='rotate2' style='transform: rotate(90deg); transform-origin: left top;'>"
+        "      <div id='child'></div>"
+        "    </div>"
+        "  </div>"
+        "</div>");
+    LayoutBoxModelObject* container = toLayoutBoxModelObject(getLayoutObjectByElementId("container"));
+    LayoutBoxModelObject* rotate1 = toLayoutBoxModelObject(getLayoutObjectByElementId("rotate1"));
+    LayoutBoxModelObject* rotate2 = toLayoutBoxModelObject(getLayoutObjectByElementId("rotate2"));
+    LayoutObject* child = getLayoutObjectByElementId("child");
+    TransformationMatrix matrix;
+
+    matrix = child->localToAncestorTransform(rotate2);
+    EXPECT_TRUE(matrix.isIdentity());
+
+    // Allow a maximum error of half a pixel.
+    const float kMaxError = 0.5;

[szager1, 2016/03/08 23:34:15]

Internally, TransformState uses LayoutUnit's.  I kinda think this should be
LayoutUnit::epsilon(), and use sqrt() from <math.h> to generate the expected
values.

[dmazzoni, 2016/03/09 18:14:59]

Done.

+
+    // Sotate (100, 0) 90 degrees to (0, 100)

[szager1, 2016/03/08 23:34:15]

typo

[dmazzoni, 2016/03/09 18:14:59]

Done.

+    matrix = child->localToAncestorTransform(rotate1);
+    EXPECT_FALSE(matrix.isIdentity());
+    EXPECT_TRUE(matrix.isAffine());
+    EXPECT_NEAR(0.0, matrix.projectPoint(FloatPoint(100.0, 0.0)).x(), kMaxError);
+    EXPECT_NEAR(100.0, matrix.projectPoint(FloatPoint(100.0, 0.0)).y(), kMaxError);
+
+    // Rotate (100, 0) 135 degrees to (-70.7, 70.7)
+    matrix = child->localToAncestorTransform(container);
+    EXPECT_FALSE(matrix.isIdentity());
+    EXPECT_TRUE(matrix.isAffine());
+    EXPECT_NEAR(-70.7, matrix.projectPoint(FloatPoint(100.0, 0.0)).x(), kMaxError);
+    EXPECT_NEAR(70.7, matrix.projectPoint(FloatPoint(100.0, 0.0)).y(), kMaxError);
+}
+
 } // namespace blink