Add localToAbsoluteTransform and localToAncestorTransform.

third_party/WebKit/Source/platform/geometry/TransformState.cpp

 /*
  * Copyright (C) 2011 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 21 matching lines @@
 TransformState& TransformState::operator=(const TransformState& other)
 {
     m_accumulatedOffset = other.m_accumulatedOffset;
     m_mapPoint = other.m_mapPoint;
     m_mapQuad = other.m_mapQuad;
     if (m_mapPoint)
         m_lastPlanarPoint = other.m_lastPlanarPoint;
     if (m_mapQuad)
         m_lastPlanarQuad = other.m_lastPlanarQuad;
     m_accumulatingTransform = other.m_accumulatingTransform;
+    m_forceAccumulatingTransform = other.m_forceAccumulatingTransform;
     m_direction = other.m_direction;
 
     m_accumulatedTransform.clear();
 
     if (other.m_accumulatedTransform)
         m_accumulatedTransform = TransformationMatrix::create(*other.m_accumulatedTransform);
 
     return *this;
 }
 
 void TransformState::translateTransform(const LayoutSize& offset)
 {
     if (m_direction == ApplyTransformDirection)
         m_accumulatedTransform->translateRight(offset.width().toDouble(), offset.height().toDouble());
     else
         m_accumulatedTransform->translate(offset.width().toDouble(), offset.height().toDouble());
 }
 
 void TransformState::translateMappedCoordinates(const LayoutSize& offset)
 {
     FloatSize adjustedOffset((m_direction == ApplyTransformDirection) ? offset : -offset);
     if (m_mapPoint)
         m_lastPlanarPoint.move(adjustedOffset);
     if (m_mapQuad)
         m_lastPlanarQuad.move(adjustedOffset);
 }
 
 void TransformState::move(const LayoutSize& offset, TransformAccumulation accumulate)
 {
+    if (m_forceAccumulatingTransform)
+        accumulate = AccumulateTransform;
+
     if (accumulate == FlattenTransform || !m_accumulatedTransform) {
         m_accumulatedOffset += offset;
     } else {
         applyAccumulatedOffset();
         if (m_accumulatingTransform && m_accumulatedTransform) {
             // If we're accumulating into an existing transform, apply the translation.
             translateTransform(offset);
         } else {
             // Just move the point and/or quad.
             translateMappedCoordinates(offset);
@@ skipping 20 matching lines @@
 void TransformState::applyTransform(const AffineTransform& transformFromContainer, TransformAccumulation accumulate, bool* wasClamped)
 {
     applyTransform(transformFromContainer.toTransformationMatrix(), accumulate, wasClamped);
 }
 
 void TransformState::applyTransform(const TransformationMatrix& transformFromContainer, TransformAccumulation accumulate, bool* wasClamped)
 {
     if (wasClamped)
         *wasClamped = false;
 
+    if (m_forceAccumulatingTransform)

[chrishtr, 2016/03/10 16:53:39]

I don't think this works in the case of a flattening transform. The
correct transformation matrix should be the transform matrix of the
element, multiplied by a flattening transform matrix. I think this amounts to
applying the same logic as in gfx::Transform::FlattenTo2d().

[dmazzoni, 2016/03/14 20:10:37]

Good catch. Fixed this and added a new test.

+        accumulate = AccumulateTransform;
+
     if (transformFromContainer.isIntegerTranslation()) {
         move(LayoutSize(LayoutUnit(transformFromContainer.e()), LayoutUnit(transformFromContainer.f())), accumulate);
         return;
     }
 
     applyAccumulatedOffset();
 
     // If we have an accumulated transform from last time, multiply in this transform
     if (m_accumulatedTransform) {
         if (m_direction == ApplyTransformDirection)
             m_accumulatedTransform = TransformationMatrix::create(transformFromContainer * *m_accumulatedTransform);
         else
             m_accumulatedTransform->multiply(transformFromContainer);
     } else if (accumulate == AccumulateTransform) {
         // Make one if we started to accumulate
         m_accumulatedTransform = TransformationMatrix::create(transformFromContainer);
     }
 
     if (accumulate == FlattenTransform) {
         const TransformationMatrix* finalTransform = m_accumulatedTransform ? m_accumulatedTransform.get() : &transformFromContainer;
         flattenWithTransform(*finalTransform, wasClamped);
     }
     m_accumulatingTransform = accumulate == AccumulateTransform;
 }
 
 void TransformState::flatten(bool* wasClamped)
 {
+    ASSERT(!m_forceAccumulatingTransform);
     if (wasClamped)
         *wasClamped = false;
 
     applyAccumulatedOffset();
 
     if (!m_accumulatedTransform) {
         m_accumulatingTransform = false;
         return;
     }
 
@@ skipping 25 matching lines @@
     quad.move(FloatSize((m_direction == ApplyTransformDirection) ? m_accumulatedOffset : -m_accumulatedOffset));
     if (!m_accumulatedTransform)
         return quad;
 
     if (m_direction == ApplyTransformDirection)
         return m_accumulatedTransform->mapQuad(quad);
 
     return m_accumulatedTransform->inverse().projectQuad(quad, wasClamped);
 }
 
+const TransformationMatrix& TransformState::accumulatedTransform() const
+{
+    ASSERT(m_forceAccumulatingTransform && m_accumulatingTransform);
+    return *m_accumulatedTransform;
+}
+
 void TransformState::flattenWithTransform(const TransformationMatrix& t, bool* wasClamped)
 {
     if (m_direction == ApplyTransformDirection) {
         if (m_mapPoint)
             m_lastPlanarPoint = t.mapPoint(m_lastPlanarPoint);
         if (m_mapQuad)
             m_lastPlanarQuad = t.mapQuad(m_lastPlanarQuad);
     } else {
         TransformationMatrix inverseTransform = t.inverse();
         if (m_mapPoint)
             m_lastPlanarPoint = inverseTransform.projectPoint(m_lastPlanarPoint);
         if (m_mapQuad)
             m_lastPlanarQuad = inverseTransform.projectQuad(m_lastPlanarQuad, wasClamped);
     }
 
     // We could throw away m_accumulatedTransform if we wanted to here, but that
     // would cause thrash when traversing hierarchies with alternating
     // preserve-3d and flat elements.
     if (m_accumulatedTransform)
         m_accumulatedTransform->makeIdentity();
     m_accumulatingTransform = false;
 }
 
 } // namespace blink