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

/*
 * Copyright (C) 2011 Apple Inc.  All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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#include "platform/geometry/TransformState.h"

namespace blink {

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.reset();

  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);
    }
  }
  m_accumulatingTransform = accumulate == AccumulateTransform;
}

void TransformState::applyAccumulatedOffset() {
  LayoutSize offset = m_accumulatedOffset;
  m_accumulatedOffset = LayoutSize();
  if (!offset.isZero()) {
    if (m_accumulatedTransform) {
      translateTransform(offset);
      flatten();
    } else {
      translateMappedCoordinates(offset);
    }
  }
}

// FIXME: We transform AffineTransform to TransformationMatrix. This is rather
// inefficient.
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 (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) {
    if (m_forceAccumulatingTransform) {
      m_accumulatedTransform->flattenTo2d();
    } else {
      const TransformationMatrix* finalTransform =
          m_accumulatedTransform ? m_accumulatedTransform.get()
                                 : &transformFromContainer;
      flattenWithTransform(*finalTransform, wasClamped);
    }
  }
  m_accumulatingTransform =
      accumulate == AccumulateTransform || m_forceAccumulatingTransform;
}

void TransformState::flatten(bool* wasClamped) {
  ASSERT(!m_forceAccumulatingTransform);
  if (wasClamped)
    *wasClamped = false;

  applyAccumulatedOffset();

  if (!m_accumulatedTransform) {
    m_accumulatingTransform = false;
    return;
  }

  flattenWithTransform(*m_accumulatedTransform, wasClamped);
}

FloatPoint TransformState::mappedPoint(bool* wasClamped) const {
  if (wasClamped)
    *wasClamped = false;

  FloatPoint point = m_lastPlanarPoint;
  point.move((m_direction == ApplyTransformDirection) ? m_accumulatedOffset
                                                      : -m_accumulatedOffset);
  if (!m_accumulatedTransform)
    return point;

  if (m_direction == ApplyTransformDirection)
    return m_accumulatedTransform->mapPoint(point);

  return m_accumulatedTransform->inverse().projectPoint(point, wasClamped);
}

FloatQuad TransformState::mappedQuad(bool* wasClamped) const {
  if (wasClamped)
    *wasClamped = false;

  FloatQuad quad = m_lastPlanarQuad;
  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