Not for review: Move the implementation of WebTransformOperations into chromium

cc/transform_operations.cc

+// Copyright 2013 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 <algorithm>
+#include <cmath>
+#include <limits>
+#include <vector>
+
+#include "cc/transform_operations.h"
+
+using WebKit::WebTransformationMatrix;
+
+namespace {
+const double EPSILON = 1e-4;

[jamesr, 2013/01/14 22:03:00]

use chromium style kEpsilon

it's pretty weird for this file to declare its own epsilon - why?

[Ian Vollick, 2013/01/15 15:02:38]

I used this epsilon when checking if two rotations used the same axis. The
allowable error there is pretty big, much bigger than
numeric_limits<double>::epsilon, etc. Perhaps this constant should have a more
explicit name like kAngleEpsilon?

+}
+
+namespace cc {
+
+struct TransformOperation {
+  enum Type {
+    TransformOperationTranslate,
+    TransformOperationRotate,
+    TransformOperationScale,
+    TransformOperationSkew,
+    TransformOperationPerspective,
+    TransformOperationMatrix,
+    TransformOperationIdentity
+  };
+
+  TransformOperation()
+  : type(TransformOperationIdentity) {

[jamesr, 2013/01/14 22:03:00]

this should be indented 4 spaces from the previous line

+  }
+
+  Type type;
+  WebKit::WebTransformationMatrix matrix;
+
+  union {
+    double perspective_depth;
+
+    struct {
+      double x, y;
+    } skew;
+
+    struct {
+      double x, y, z;
+    } scale;
+
+    struct {
+      double x, y, z;
+    } translate;
+
+    struct {
+      struct {
+        double x, y, z;
+      } axis;
+
+      double angle;
+    } rotate;
+  };
+
+  bool IsIdentity() const { return matrix.isIdentity(); }
+};
+
+TransformOperations::TransformOperations() {
+  Initialize();
+}
+
+TransformOperations::TransformOperations(const TransformOperations& other) {
+  Initialize(other);
+}
+
+TransformOperations::~TransformOperations() {
+}
+
+struct TransformOperationsPrivate {
+  std::vector<TransformOperation> operations;
+};
+
+WebTransformationMatrix TransformOperations::Apply() const {
+  WebTransformationMatrix to_return;
+  for (size_t i = 0; i < private_->operations.size(); ++i)
+    to_return.multiply(private_->operations[i].matrix);
+  return to_return;
+}
+
+static bool IsIdentity(const TransformOperation* operation) {
+    return !operation || operation->IsIdentity();
+}
+
+static bool ShareSameAxis(const TransformOperation* from,
+                          const TransformOperation* to,
+                          double& axis_x, double& axis_y, double& axis_z,
+                          double& angle_from) {
+  if (IsIdentity(from) && IsIdentity(to))
+    return false;
+
+  if (IsIdentity(from) && !IsIdentity(to)) {
+    axis_x = to->rotate.axis.x;
+    axis_y = to->rotate.axis.y;
+    axis_z = to->rotate.axis.z;
+    angle_from = 0;
+    return true;
+  }
+
+  if (!IsIdentity(from) && IsIdentity(to)) {
+    axis_x = from->rotate.axis.x;
+    axis_y = from->rotate.axis.y;
+    axis_z = from->rotate.axis.z;
+    angle_from = from->rotate.angle;
+    return true;
+  }
+
+  double length_2 = from->rotate.axis.x * from->rotate.axis.x +
+                    from->rotate.axis.y * from->rotate.axis.y +
+                    from->rotate.axis.z * from->rotate.axis.z;
+  double other_length_2 = to->rotate.axis.x * to->rotate.axis.x +
+                          to->rotate.axis.y * to->rotate.axis.y +
+                          to->rotate.axis.z * to->rotate.axis.z;
+
+  if (length_2 <= EPSILON || other_length_2 <= EPSILON)
+    return false;
+
+  double dot = to->rotate.axis.x * from->rotate.axis.x +
+               to->rotate.axis.y * from->rotate.axis.y +
+               to->rotate.axis.z * from->rotate.axis.z;
+  double error = std::fabs(1.0 - (dot * dot) / (length_2 * other_length_2));
+  bool result = error < EPSILON;
+  if (result) {
+    axis_x = to->rotate.axis.x;
+    axis_y = to->rotate.axis.y;
+    axis_z = to->rotate.axis.z;
+    // If the axes are pointing in opposite directions, we need to reverse
+    // the angle.
+    angle_from = dot > 0 ? from->rotate.angle : -from->rotate.angle;
+  }
+  return result;
+}
+
+static double BlendDoubles(double from, double to, double progress) {
+  return from * (1 - progress) + to * progress;
+}
+
+static bool BlendTransformOperations(const TransformOperation* from,
+                                     const TransformOperation* to,
+                                     double progress,
+                                     WebTransformationMatrix& result) {
+  if (IsIdentity(from) && IsIdentity(to))
+    return true;
+
+  TransformOperation::Type interpolation_type =
+      TransformOperation::TransformOperationIdentity;
+  if (IsIdentity(to))
+    interpolation_type = from->type;
+  else
+    interpolation_type = to->type;
+
+  switch (interpolation_type) {
+  case TransformOperation::TransformOperationTranslate: {
+    double from_x = IsIdentity(from) ? 0 : from->translate.x;
+    double from_y = IsIdentity(from) ? 0 : from->translate.y;
+    double from_z = IsIdentity(from) ? 0 : from->translate.z;
+    double to_x = IsIdentity(to) ? 0 : to->translate.x;
+    double to_y = IsIdentity(to) ? 0 : to->translate.y;
+    double to_z = IsIdentity(to) ? 0 : to->translate.z;
+    result.translate3d(BlendDoubles(from_x, to_x, progress),
+                       BlendDoubles(from_y, to_y, progress),
+                       BlendDoubles(from_z, to_z, progress));
+    break;
+  }
+  case TransformOperation::TransformOperationRotate: {
+    double axis_x = 0;
+    double axis_y = 0;
+    double axis_z = 1;
+    double from_angle = 0;
+    double to_angle = IsIdentity(to) ? 0 : to->rotate.angle;
+    if (ShareSameAxis(from, to, axis_x, axis_y, axis_z, from_angle))
+      result.rotate3d(axis_x, axis_y, axis_z,
+                      BlendDoubles(from_angle, to_angle, progress));
+    else {
+      WebTransformationMatrix to_matrix;
+      if (!IsIdentity(to))
+        to_matrix = to->matrix;
+      WebTransformationMatrix from_matrix;
+      if (!IsIdentity(from))
+        from_matrix = from->matrix;
+      result = to_matrix;
+      if (!result.blend(from_matrix, progress))
+        return false;
+    }
+    break;
+  }
+  case TransformOperation::TransformOperationScale: {
+    double from_x = IsIdentity(from) ? 1 : from->scale.x;
+    double from_y = IsIdentity(from) ? 1 : from->scale.y;
+    double from_z = IsIdentity(from) ? 1 : from->scale.z;
+    double to_x = IsIdentity(to) ? 1 : to->scale.x;
+    double to_y = IsIdentity(to) ? 1 : to->scale.y;
+    double to_z = IsIdentity(to) ? 1 : to->scale.z;
+    result.scale3d(BlendDoubles(from_x, to_x, progress),
+                   BlendDoubles(from_y, to_y, progress),
+                   BlendDoubles(from_z, to_z, progress));
+    break;
+  }
+  case TransformOperation::TransformOperationSkew: {
+    double from_x = IsIdentity(from) ? 0 : from->skew.x;
+    double from_y = IsIdentity(from) ? 0 : from->skew.y;
+    double to_x = IsIdentity(to) ? 0 : to->skew.x;
+    double to_y = IsIdentity(to) ? 0 : to->skew.y;
+    result.skewX(BlendDoubles(from_x, to_x, progress));
+    result.skewY(BlendDoubles(from_y, to_y, progress));
+    break;
+  }
+  case TransformOperation::TransformOperationPerspective: {
+    double from_perspective_depth = IsIdentity(from) ?
+        std::numeric_limits<double>::max() : from->perspective_depth;
+    double to_perspective_depth = IsIdentity(to) ?
+        std::numeric_limits<double>::max() : to->perspective_depth;
+    result.applyPerspective(
+        BlendDoubles(from_perspective_depth, to_perspective_depth, progress));
+    break;
+  }
+  case TransformOperation::TransformOperationMatrix: {
+    WebTransformationMatrix to_matrix;
+    if (!IsIdentity(to))
+      to_matrix = to->matrix;
+    WebTransformationMatrix from_matrix;
+    if (!IsIdentity(from))
+      from_matrix = from->matrix;
+    result = to_matrix;
+    if (!result.blend(from_matrix, progress))
+      return false;
+    break;
+  }
+  case TransformOperation::TransformOperationIdentity:
+    // Do nothing.
+    break;
+  }
+
+  return true;
+}
+
+WebTransformationMatrix TransformOperations::Blend(
+    const TransformOperations& from, double progress) const {
+  WebTransformationMatrix to_return;
+  BlendInternal(from, progress, to_return);
+  return to_return;
+}
+
+bool TransformOperations::MatchesTypes(const TransformOperations& other) const {
+  if (IsIdentity() || other.IsIdentity())
+    return true;
+
+  if (private_->operations.size() != other.private_->operations.size())
+    return false;
+
+  for (size_t i = 0; i < private_->operations.size(); ++i) {
+    if (private_->operations[i].type != other.private_->operations[i].type
+      && !private_->operations[i].IsIdentity()
+      && !other.private_->operations[i].IsIdentity())
+      return false;
+  }
+
+  return true;
+}
+
+bool TransformOperations::CanBlendWith(
+    const TransformOperations& other) const {
+  WebTransformationMatrix dummy;
+  return BlendInternal(other, 0.5, dummy);
+}
+
+void TransformOperations::AppendTranslate(double x, double y, double z) {
+  TransformOperation to_add;
+  to_add.matrix.translate3d(x, y, z);
+  to_add.type = TransformOperation::TransformOperationTranslate;
+  to_add.translate.x = x;
+  to_add.translate.y = y;
+  to_add.translate.z = z;
+  private_->operations.push_back(to_add);
+}
+
+void TransformOperations::AppendRotate(double x, double y, double z,
+                                       double degrees) {
+  TransformOperation to_add;
+  to_add.matrix.rotate3d(x, y, z, degrees);
+  to_add.type = TransformOperation::TransformOperationRotate;
+  to_add.rotate.axis.x = x;
+  to_add.rotate.axis.y = y;
+  to_add.rotate.axis.z = z;
+  to_add.rotate.angle = degrees;
+  private_->operations.push_back(to_add);
+}
+
+void TransformOperations::AppendScale(double x, double y, double z) {
+  TransformOperation to_add;
+  to_add.matrix.scale3d(x, y, z);
+  to_add.type = TransformOperation::TransformOperationScale;
+  to_add.scale.x = x;
+  to_add.scale.y = y;
+  to_add.scale.z = z;
+  private_->operations.push_back(to_add);
+}
+
+void TransformOperations::AppendSkew(double x, double y) {
+  TransformOperation to_add;
+  to_add.matrix.skewX(x);
+  to_add.matrix.skewY(y);
+  to_add.type = TransformOperation::TransformOperationSkew;
+  to_add.skew.x = x;
+  to_add.skew.y = y;
+  private_->operations.push_back(to_add);
+}
+
+void TransformOperations::AppendPerspective(double depth) {
+  TransformOperation to_add;
+  to_add.matrix.applyPerspective(depth);
+  to_add.type = TransformOperation::TransformOperationPerspective;
+  to_add.perspective_depth = depth;
+  private_->operations.push_back(to_add);
+}
+
+void TransformOperations::AppendMatrix(const WebTransformationMatrix& matrix) {
+  TransformOperation to_add;
+  to_add.matrix = matrix;
+  to_add.type = TransformOperation::TransformOperationMatrix;
+  private_->operations.push_back(to_add);
+}
+
+void TransformOperations::AppendIdentity() {
+  private_->operations.push_back(TransformOperation());
+}
+
+bool TransformOperations::IsIdentity() const {
+  for (size_t i = 0; i < private_->operations.size(); ++i) {
+    if (!private_->operations[i].IsIdentity())
+      return false;
+  }
+  return true;
+}
+
+void TransformOperations::Initialize() {
+  private_.reset(new TransformOperationsPrivate);
+}
+
+void TransformOperations::Initialize(const TransformOperations& other) {
+  if (private_.get() != other.private_.get())
+    private_.reset(new TransformOperationsPrivate(*other.private_.get()));
+  else
+    Initialize();
+}
+
+bool TransformOperations::BlendInternal(const TransformOperations& from,
+                                        double progress,
+                                        WebTransformationMatrix& result) const {
+  bool from_identity = from.IsIdentity();
+  bool to_identity = IsIdentity();
+  if (from_identity && to_identity)
+    return true;
+
+  if (MatchesTypes(from)) {
+    size_t num_operations =
+        std::max(from_identity ? 0 : from.private_->operations.size(),
+                 to_identity ? 0 : private_->operations.size());
+    for (size_t i = 0; i < num_operations; ++i) {
+      WebTransformationMatrix blended;
+      if (!BlendTransformOperations(
+          from_identity ? 0 : &from.private_->operations[i],
+          to_identity ? 0 : &private_->operations[i],
+          progress,
+          blended))
+          return false;
+      result.multiply(blended);
+    }
+    return true;
+  }
+
+  result = Apply();
+  WebTransformationMatrix from_transform = from.Apply();
+  return result.blend(from_transform, progress);
+}
+
+}  // namespace cc