Allow the computation of inflated bounds for non matrix transform operations.

This CL expands the list of transform operations for which we may compute inflated
bounds for animation.

R=hartmanng@chromium.org,ajuma@chromium.org
BUG=

Review URL: https://codereview.chromium.org/55763004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232889 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 206 insertions, 157 deletions

diff --git a/cc/animation/layer_animation_controller_unittest.cc b/cc/animation/layer_animation_controller_unittest.cc
index 0505c67..c3387f48 100644
--- a/cc/animation/layer_animation_controller_unittest.cc
+++ b/cc/animation/layer_animation_controller_unittest.cc
@@ -1260,9 +1260,11 @@ TEST(LayerAnimationControllerTest, AnimatedBounds) {
   scoped_ptr<KeyframedTransformAnimationCurve> curve3(
       KeyframedTransformAnimationCurve::Create());
   TransformOperations operations3;
+  gfx::Transform transform3;
+  transform3.Scale3d(1.0, 2.0, 3.0);
   curve3->AddKeyframe(TransformKeyframe::Create(
       0.0, operations3, scoped_ptr<TimingFunction>()));
-  operations3.AppendSkew(1.0, 2.0);
+  operations3.AppendMatrix(transform3);
   curve3->AddKeyframe(TransformKeyframe::Create(
       1.0, operations3, scoped_ptr<TimingFunction>()));
   animation = Animation::Create(
diff --git a/cc/animation/transform_operation.cc b/cc/animation/transform_operation.cc
index 889f7bd..e4d0dad 100644
--- a/cc/animation/transform_operation.cc
+++ b/cc/animation/transform_operation.cc
@@ -13,7 +13,9 @@
 
 #include "base/logging.h"
 #include "cc/animation/transform_operation.h"
+#include "cc/animation/transform_operations.h"
 #include "ui/gfx/box_f.h"
+#include "ui/gfx/transform_util.h"
 #include "ui/gfx/vector3d_f.h"
 
 namespace {
@@ -198,30 +200,6 @@ bool TransformOperation::BlendTransformOperations(
   return true;
 }
 
-static void ApplyScaleToBox(float x_scale,
-                            float y_scale,
-                            float z_scale,
-                            gfx::BoxF* box) {
-  if (x_scale < 0)
-    box->set_x(-box->right());
-  if (y_scale < 0)
-    box->set_y(-box->bottom());
-  if (z_scale < 0)
-    box->set_z(-box->front());
-  box->Scale(std::abs(x_scale), std::abs(y_scale), std::abs(z_scale));
-}
-
-static void UnionBoxWithZeroScale(gfx::BoxF* box) {
-  float min_x = std::min(box->x(), 0.f);
-  float min_y = std::min(box->y(), 0.f);
-  float min_z = std::min(box->z(), 0.f);
-  float max_x = std::max(box->right(), 0.f);
-  float max_y = std::max(box->bottom(), 0.f);
-  float max_z = std::max(box->front(), 0.f);
-  *box = gfx::BoxF(
-      min_x, min_y, min_z, max_x - min_x, max_y - min_y, max_z - min_z);
-}
-
 // If p = (px, py) is a point in the plane being rotated about (0, 0, nz), this
 // function computes the angles we would have to rotate from p to get to
 // (length(p), 0), (-length(p), 0), (0, length(p)), (0, -length(p)). If nz is
@@ -250,20 +228,6 @@ static float DegreesToRadians(float degrees) {
   return (M_PI * degrees) / 180.f;
 }
 
-// Div by zero doesn't always result in Inf as you might hope, so we'll do this
-// explicitly here.
-static float SafeDivide(float numerator, float denominator) {
-  if (numerator == 0.f)
-    return 0.f;
-
-  if (denominator == 0.f) {
-    return numerator > 0.f ? std::numeric_limits<float>::infinity()
-                           : -std::numeric_limits<float>::infinity();
-  }
-
-  return numerator / denominator;
-}
-
 static void BoundingBoxForArc(const gfx::Point3F& point,
                               const TransformOperation* from,
                               const TransformOperation* to,
@@ -291,6 +255,16 @@ static void BoundingBoxForArc(const gfx::Point3F& point,
   SkMScalar from_angle = from ? from->rotate.angle : 0.f;
   SkMScalar to_angle = to ? to->rotate.angle : 0.f;
 
+  // If the axes of rotation are pointing in opposite directions, we need to
+  // flip one of the angles. Note, if both |from| and |to| exist, then axis will
+  // correspond to |from|.
+  if (from && to) {
+    gfx::Vector3dF other_axis(
+        to->rotate.axis.x, to->rotate.axis.y, to->rotate.axis.z);
+    if (gfx::DotProduct(axis, other_axis) < 0.f)
+      to_angle *= -1.f;
+  }
+
   float min_degrees =
       SkMScalarToFloat(BlendSkMScalars(from_angle, to_angle, min_progress));
   float max_degrees =
@@ -360,16 +334,11 @@ static void BoundingBoxForArc(const gfx::Point3F& point,
     double phi_x = atan2(gfx::DotProduct(v2, vx), gfx::DotProduct(v1, vx));
     double phi_z = atan2(gfx::DotProduct(v2, vz), gfx::DotProduct(v1, vz));
 
-    // NB: it is fine if the denominators here are zero and these values go to
-    // infinity; atan can handle it.
-    double tan_theta1 = SafeDivide(normal.y(), (normal.x() * normal.z()));
-    double tan_theta2 = SafeDivide(-normal.z(), (normal.x() * normal.y()));
-
-    candidates[0] = atan(tan_theta1) + phi_x;
+    candidates[0] = atan2(normal.y(), normal.x() * normal.z()) + phi_x;
     candidates[1] = candidates[0] + M_PI;
-    candidates[2] = atan(tan_theta2) + phi_x;
+    candidates[2] = atan2(-normal.z(), normal.x() * normal.y()) + phi_x;
     candidates[3] = candidates[2] + M_PI;
-    candidates[4] = atan(-tan_theta1) + phi_z;
+    candidates[4] = atan2(normal.y(), -normal.x() * normal.z()) + phi_z;
     candidates[5] = candidates[4] + M_PI;
   }
 
@@ -415,78 +384,36 @@ bool TransformOperation::BlendedBoundsForBox(const gfx::BoxF& box,
     interpolation_type = to->type;
 
   switch (interpolation_type) {
-    case TransformOperation::TransformOperationTranslate: {
-      SkMScalar from_x, from_y, from_z;
-      if (is_identity_from) {
-        from_x = from_y = from_z = 0.0;
-      } else {
-        from_x = from->translate.x;
-        from_y = from->translate.y;
-        from_z = from->translate.z;
-      }
-      SkMScalar to_x, to_y, to_z;
-      if (is_identity_to) {
-        to_x = to_y = to_z = 0.0;
-      } else {
-        to_x = to->translate.x;
-        to_y = to->translate.y;
-        to_z = to->translate.z;
-      }
+    case TransformOperation::TransformOperationIdentity:
       *bounds = box;
-      *bounds += gfx::Vector3dF(BlendSkMScalars(from_x, to_x, min_progress),
-                                BlendSkMScalars(from_y, to_y, min_progress),
-                                BlendSkMScalars(from_z, to_z, min_progress));
-      gfx::BoxF bounds_max = box;
-      bounds_max += gfx::Vector3dF(BlendSkMScalars(from_x, to_x, max_progress),
-                                   BlendSkMScalars(from_y, to_y, max_progress),
-                                   BlendSkMScalars(from_z, to_z, max_progress));
-      bounds->Union(bounds_max);
       return true;
-    }
+    case TransformOperation::TransformOperationTranslate:
+    case TransformOperation::TransformOperationSkew:
+    case TransformOperation::TransformOperationPerspective:
     case TransformOperation::TransformOperationScale: {
-      SkMScalar from_x, from_y, from_z;
-      if (is_identity_from) {
-        from_x = from_y = from_z = 1.0;
-      } else {
-        from_x = from->scale.x;
-        from_y = from->scale.y;
-        from_z = from->scale.z;
-      }
-      SkMScalar to_x, to_y, to_z;
-      if (is_identity_to) {
-        to_x = to_y = to_z = 1.0;
-      } else {
-        to_x = to->scale.x;
-        to_y = to->scale.y;
-        to_z = to->scale.z;
-      }
+      gfx::Transform from_transform;
+      gfx::Transform to_transform;
+      if (!BlendTransformOperations(from, to, min_progress, &from_transform) ||
+          !BlendTransformOperations(from, to, max_progress, &to_transform))
+        return false;
+
       *bounds = box;
-      ApplyScaleToBox(
-          SkMScalarToFloat(BlendSkMScalars(from_x, to_x, min_progress)),
-          SkMScalarToFloat(BlendSkMScalars(from_y, to_y, min_progress)),
-          SkMScalarToFloat(BlendSkMScalars(from_z, to_z, min_progress)),
-          bounds);
-      gfx::BoxF bounds_max = box;
-      ApplyScaleToBox(
-          SkMScalarToFloat(BlendSkMScalars(from_x, to_x, max_progress)),
-          SkMScalarToFloat(BlendSkMScalars(from_y, to_y, max_progress)),
-          SkMScalarToFloat(BlendSkMScalars(from_z, to_z, max_progress)),
-          &bounds_max);
-      if (!bounds->IsEmpty() && !bounds_max.IsEmpty()) {
-        bounds->Union(bounds_max);
-      } else if (!bounds->IsEmpty()) {
-        UnionBoxWithZeroScale(bounds);
-      } else if (!bounds_max.IsEmpty()) {
-        UnionBoxWithZeroScale(&bounds_max);
-        *bounds = bounds_max;
-      }
+      from_transform.TransformBox(bounds);
+
+      gfx::BoxF to_box = box;
+      to_transform.TransformBox(&to_box);
+      bounds->ExpandTo(to_box);
 
       return true;
     }
-    case TransformOperation::TransformOperationIdentity:
-      *bounds = box;
-      return true;
     case TransformOperation::TransformOperationRotate: {
+      SkMScalar axis_x = 0;
+      SkMScalar axis_y = 0;
+      SkMScalar axis_z = 1;
+      SkMScalar from_angle = 0;
+      if (!ShareSameAxis(from, to, &axis_x, &axis_y, &axis_z, &from_angle))
+        return false;
+
       bool first_point = true;
       for (int i = 0; i < 8; ++i) {
         gfx::Point3F corner = box.origin();
@@ -504,8 +431,6 @@ bool TransformOperation::BlendedBoundsForBox(const gfx::BoxF& box,
       }
       return true;
     }
-    case TransformOperation::TransformOperationSkew:
-    case TransformOperation::TransformOperationPerspective:
     case TransformOperation::TransformOperationMatrix:
       return false;
   }
diff --git a/cc/animation/transform_operations_unittest.cc b/cc/animation/transform_operations_unittest.cc
index 49b208e..831ce71 100644
--- a/cc/animation/transform_operations_unittest.cc
+++ b/cc/animation/transform_operations_unittest.cc
@@ -11,6 +11,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/animation/tween.h"
 #include "ui/gfx/box_f.h"
+#include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/vector3d_f.h"
 
 namespace cc {
@@ -886,6 +887,30 @@ TEST(TransformOperationTest, BlendedBoundsForRotationAllExtrema) {
             bounds.ToString());
 }
 
+TEST(TransformOperationTest, BlendedBoundsForRotationDifferentAxes) {
+  // We can handle rotations about a single axis. If the axes are different,
+  // we revert to matrix interpolation for which inflated bounds cannot be
+  // computed.
+  TransformOperations operations_from;
+  operations_from.AppendRotate(1.f, 1.f, 1.f, 30.f);
+  TransformOperations operations_to_same;
+  operations_to_same.AppendRotate(1.f, 1.f, 1.f, 390.f);
+  TransformOperations operations_to_opposite;
+  operations_to_opposite.AppendRotate(-1.f, -1.f, -1.f, 390.f);
+  TransformOperations operations_to_different;
+  operations_to_different.AppendRotate(1.f, 3.f, 1.f, 390.f);
+
+  gfx::BoxF box(1.f, 0.f, 0.f, 0.f, 0.f, 0.f);
+  gfx::BoxF bounds;
+
+  EXPECT_TRUE(operations_to_same.BlendedBoundsForBox(
+      box, operations_from, 0.f, 1.f, &bounds));
+  EXPECT_TRUE(operations_to_opposite.BlendedBoundsForBox(
+      box, operations_from, 0.f, 1.f, &bounds));
+  EXPECT_FALSE(operations_to_different.BlendedBoundsForBox(
+      box, operations_from, 0.f, 1.f, &bounds));
+}
+
 TEST(TransformOperationTest, BlendedBoundsForRotationPointOnAxis) {
   // Checks that if the point to rotate is sitting on the axis of rotation, that
   // it does not get affected.
@@ -968,7 +993,80 @@ struct TestProgress {
   float max_progress;
 };
 
-TEST(TransformOperationsTest, BlendedBoundsForRotationEmpiricalTests) {
+static void ExpectBoxesApproximatelyEqual(const gfx::BoxF& lhs,
+                                          const gfx::BoxF& rhs,
+                                          float tolerance) {
+  EXPECT_NEAR(lhs.x(), rhs.x(), tolerance);
+  EXPECT_NEAR(lhs.y(), rhs.y(), tolerance);
+  EXPECT_NEAR(lhs.z(), rhs.z(), tolerance);
+  EXPECT_NEAR(lhs.width(), rhs.width(), tolerance);
+  EXPECT_NEAR(lhs.height(), rhs.height(), tolerance);
+  EXPECT_NEAR(lhs.depth(), rhs.depth(), tolerance);
+}
+
+static void EmpiricallyTestBounds(const TransformOperations& from,
+                                  const TransformOperations& to,
+                                  SkMScalar min_progress,
+                                  SkMScalar max_progress,
+                                  bool test_containment_only) {
+  gfx::BoxF box(200.f, 500.f, 100.f, 100.f, 300.f, 200.f);
+  gfx::BoxF bounds;
+  EXPECT_TRUE(
+      to.BlendedBoundsForBox(box, from, min_progress, max_progress, &bounds));
+
+  bool first_time = true;
+  gfx::BoxF empirical_bounds;
+  static const size_t kNumSteps = 10;
+  for (size_t step = 0; step < kNumSteps; ++step) {
+    float t = step / (kNumSteps - 1.f);
+    t = gfx::Tween::FloatValueBetween(t, min_progress, max_progress);
+    gfx::Transform partial_transform = to.Blend(from, t);
+    gfx::BoxF transformed = box;
+    partial_transform.TransformBox(&transformed);
+
+    if (first_time) {
+      empirical_bounds = transformed;
+      first_time = false;
+    } else {
+      empirical_bounds.Union(transformed);
+    }
+  }
+
+  if (test_containment_only) {
+    gfx::BoxF unified_bounds = bounds;
+    unified_bounds.Union(empirical_bounds);
+    // Convert to the screen space rects these boxes represent.
+    gfx::Rect bounds_rect = ToEnclosingRect(
+        gfx::RectF(bounds.x(), bounds.y(), bounds.width(), bounds.height()));
+    gfx::Rect unified_bounds_rect =
+        ToEnclosingRect(gfx::RectF(unified_bounds.x(),
+                                   unified_bounds.y(),
+                                   unified_bounds.width(),
+                                   unified_bounds.height()));
+    EXPECT_EQ(bounds_rect.ToString(), unified_bounds_rect.ToString());
+  } else {
+    // Our empirical estimate will be a little rough since we're only doing
+    // 100 samples.
+    static const float kTolerance = 1e-2f;
+    ExpectBoxesApproximatelyEqual(empirical_bounds, bounds, kTolerance);
+  }
+}
+
+static void EmpiricallyTestBoundsEquality(const TransformOperations& from,
+                                          const TransformOperations& to,
+                                          SkMScalar min_progress,
+                                          SkMScalar max_progress) {
+  EmpiricallyTestBounds(from, to, min_progress, max_progress, false);
+}
+
+static void EmpiricallyTestBoundsContainment(const TransformOperations& from,
+                                             const TransformOperations& to,
+                                             SkMScalar min_progress,
+                                             SkMScalar max_progress) {
+  EmpiricallyTestBounds(from, to, min_progress, max_progress, true);
+}
+
+TEST(TransformOperationTest, BlendedBoundsForRotationEmpiricalTests) {
   // Sets up various axis angle combinations, computes the bounding box and
   // empirically tests that the transformed bounds are indeed contained by the
   // computed bounding box.
@@ -1012,7 +1110,6 @@ TEST(TransformOperationsTest, BlendedBoundsForRotationEmpiricalTests) {
     { -.25f, 1.25f },
   };
 
-  size_t num_steps = 150;
   for (size_t i = 0; i < arraysize(axes); ++i) {
     for (size_t j = 0; j < arraysize(angles); ++j) {
       for (size_t k = 0; k < arraysize(progress); ++k) {
@@ -1023,48 +1120,10 @@ TEST(TransformOperationsTest, BlendedBoundsForRotationEmpiricalTests) {
         operations_from.AppendRotate(x, y, z, angles[j].theta_from);
         TransformOperations operations_to;
         operations_to.AppendRotate(x, y, z, angles[j].theta_to);
-
-        gfx::BoxF box(2.f, 5.f, 6.f, 1.f, 3.f, 2.f);
-        gfx::BoxF bounds;
-
-        EXPECT_TRUE(operations_to.BlendedBoundsForBox(box,
-                                                      operations_from,
-                                                      progress[k].min_progress,
-                                                      progress[k].max_progress,
-                                                      &bounds));
-        bool first_point = true;
-        gfx::BoxF empirical_bounds;
-        for (size_t step = 0; step < num_steps; ++step) {
-          float t = step / (num_steps - 1.f);
-          t = gfx::Tween::FloatValueBetween(
-              t, progress[k].min_progress, progress[k].max_progress);
-          gfx::Transform partial_rotation =
-              operations_to.Blend(operations_from, t);
-
-          for (int corner = 0; corner < 8; ++corner) {
-            gfx::Point3F point = box.origin();
-            point += gfx::Vector3dF(corner & 1 ? box.width() : 0.f,
-                                    corner & 2 ? box.height() : 0.f,
-                                    corner & 4 ? box.depth() : 0.f);
-            partial_rotation.TransformPoint(&point);
-            if (first_point) {
-              empirical_bounds.set_origin(point);
-              first_point = false;
-            } else {
-              empirical_bounds.ExpandTo(point);
-            }
-          }
-        }
-
-        // Our empirical estimate will be a little rough since we're only doing
-        // 100 samples.
-        static const float kTolerance = 1e-2f;
-        EXPECT_NEAR(empirical_bounds.x(), bounds.x(), kTolerance);
-        EXPECT_NEAR(empirical_bounds.y(), bounds.y(), kTolerance);
-        EXPECT_NEAR(empirical_bounds.z(), bounds.z(), kTolerance);
-        EXPECT_NEAR(empirical_bounds.width(), bounds.width(), kTolerance);
-        EXPECT_NEAR(empirical_bounds.height(), bounds.height(), kTolerance);
-        EXPECT_NEAR(empirical_bounds.depth(), bounds.depth(), kTolerance);
+        EmpiricallyTestBoundsContainment(operations_from,
+                                         operations_to,
+                                         progress[k].min_progress,
+                                         progress[k].max_progress);
       }
     }
   }
@@ -1097,6 +1156,69 @@ TEST(TransformOperationTest, PerspectiveMatrixAndTransformBlendingEquivalency) {
     }
 }
 
+struct TestPerspectiveDepths {
+  float from_depth;
+  float to_depth;
+};
+
+TEST(TransformOperationTest, BlendedBoundsForPerspective) {
+  TestPerspectiveDepths perspective_depths[] = {
+    { 600.f, 400.f },
+    { 800.f, 1000.f },
+    { 800.f, std::numeric_limits<float>::infinity() },
+  };
+
+  TestProgress progress[] = {
+    { 0.f, 1.f },
+    { -0.1f, 1.1f },
+  };
+
+  for (size_t i = 0; i < arraysize(perspective_depths); ++i) {
+    for (size_t j = 0; j < arraysize(progress); ++j) {
+      TransformOperations operations_from;
+      operations_from.AppendPerspective(perspective_depths[i].from_depth);
+      TransformOperations operations_to;
+      operations_to.AppendPerspective(perspective_depths[i].to_depth);
+      EmpiricallyTestBoundsEquality(operations_from,
+                                    operations_to,
+                                    progress[j].min_progress,
+                                    progress[j].max_progress);
+    }
+  }
+}
+
+struct TestSkews {
+  float from_x;
+  float from_y;
+  float to_x;
+  float to_y;
+};
+
+TEST(TransformOperationTest, BlendedBoundsForSkew) {
+  TestSkews skews[] = {
+    { 1.f, 0.5f, 0.5f, 1.f },
+    { 2.f, 1.f, 0.5f, 0.5f },
+  };
+
+  TestProgress progress[] = {
+    { 0.f, 1.f },
+    { -0.1f, 1.1f },
+  };
+
+  for (size_t i = 0; i < arraysize(skews); ++i) {
+    for (size_t j = 0; j < arraysize(progress); ++j) {
+      TransformOperations operations_from;
+      operations_from.AppendSkew(skews[i].from_x, skews[i].from_y);
+      TransformOperations operations_to;
+      operations_to.AppendSkew(skews[i].to_x, skews[i].to_y);
+      EmpiricallyTestBoundsEquality(operations_from,
+                                    operations_to,
+                                    progress[j].min_progress,
+                                    progress[j].max_progress);
+    }
+  }
+}
+
 TEST(TransformOperationTest, BlendedBoundsForSequence) {
   TransformOperations operations_from;
   operations_from.AppendTranslate(2.0, 4.0, -1.0);