After http://crrev.com/202755, timing functions can now produce values outside the range [0, 1]. Unfortunately, these values are getting clamped when they are used for blending. This CL removes that extra clamping and adds unit tests for this extrapolation.

BUG=178299
R=ajuma@chromium.org

Review URL: https://codereview.chromium.org/15972006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@203808 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 128 insertions, 31 deletions

diff --git a/cc/animation/transform_operation.cc b/cc/animation/transform_operation.cc
index e1468bf..854901d 100644
--- a/cc/animation/transform_operation.cc
+++ b/cc/animation/transform_operation.cc
@@ -74,12 +74,6 @@ static bool ShareSameAxis(const TransformOperation* from,
 }
 
 static double BlendDoubles(double from, double to, double progress) {
-  if (progress <= 0.0)
-    return from;
-
-  if (progress >= 1.0)
-    return to;
-
   return from * (1 - progress) + to * progress;
 }
 
diff --git a/cc/animation/transform_operations.cc b/cc/animation/transform_operations.cc
index 8826d29..d74f1a5 100644
--- a/cc/animation/transform_operations.cc
+++ b/cc/animation/transform_operations.cc
@@ -164,16 +164,6 @@ bool TransformOperations::BlendInternal(const TransformOperations& from,
     return true;
   }
 
-  if (progress <= 0.0) {
-    *result = from.Apply();
-    return true;
-  }
-
-  if (progress >= 1.0) {
-    *result = Apply();
-    return true;
-  }
-
   if (!ComputeDecomposedTransform() || !from.ComputeDecomposedTransform())
     return false;
 
diff --git a/cc/animation/transform_operations_unittest.cc b/cc/animation/transform_operations_unittest.cc
index 7e344c7..8fc9b94 100644
--- a/cc/animation/transform_operations_unittest.cc
+++ b/cc/animation/transform_operations_unittest.cc
@@ -432,6 +432,22 @@ TEST(TransformOperationTest, BlendRotationFromIdentity) {
 
     EXPECT_TRANSFORMATION_MATRIX_EQ(
         expected, operations.Blend(*identity_operations[i], progress));
+
+    progress = -0.5;
+
+    expected.MakeIdentity();
+    expected.RotateAbout(gfx::Vector3dF(0, 0, 1), -180);
+
+    EXPECT_TRANSFORMATION_MATRIX_EQ(
+        expected, operations.Blend(*identity_operations[i], progress));
+
+    progress = 1.5;
+
+    expected.MakeIdentity();
+    expected.RotateAbout(gfx::Vector3dF(0, 0, 1), 540);
+
+    EXPECT_TRANSFORMATION_MATRIX_EQ(
+        expected, operations.Blend(*identity_operations[i], progress));
   }
 }
 
@@ -450,6 +466,22 @@ TEST(TransformOperationTest, BlendTranslationFromIdentity) {
 
     EXPECT_TRANSFORMATION_MATRIX_EQ(
         expected, operations.Blend(*identity_operations[i], progress));
+
+    progress = -0.5;
+
+    expected.MakeIdentity();
+    expected.Translate3d(-1, -1, -1);
+
+    EXPECT_TRANSFORMATION_MATRIX_EQ(
+        expected, operations.Blend(*identity_operations[i], progress));
+
+    progress = 1.5;
+
+    expected.MakeIdentity();
+    expected.Translate3d(3, 3, 3);
+
+    EXPECT_TRANSFORMATION_MATRIX_EQ(
+        expected, operations.Blend(*identity_operations[i], progress));
   }
 }
 
@@ -468,6 +500,22 @@ TEST(TransformOperationTest, BlendScaleFromIdentity) {
 
     EXPECT_TRANSFORMATION_MATRIX_EQ(
         expected, operations.Blend(*identity_operations[i], progress));
+
+    progress = -0.5;
+
+    expected.MakeIdentity();
+    expected.Scale3d(0, 0, 0);
+
+    EXPECT_TRANSFORMATION_MATRIX_EQ(
+        expected, operations.Blend(*identity_operations[i], progress));
+
+    progress = 1.5;
+
+    expected.MakeIdentity();
+    expected.Scale3d(4, 4, 4);
+
+    EXPECT_TRANSFORMATION_MATRIX_EQ(
+        expected, operations.Blend(*identity_operations[i], progress));
   }
 }
 
@@ -487,6 +535,24 @@ TEST(TransformOperationTest, BlendSkewFromIdentity) {
 
     EXPECT_TRANSFORMATION_MATRIX_EQ(
         expected, operations.Blend(*identity_operations[i], progress));
+
+    progress = -0.5;
+
+    expected.MakeIdentity();
+    expected.SkewX(-1);
+    expected.SkewY(-1);
+
+    EXPECT_TRANSFORMATION_MATRIX_EQ(
+        expected, operations.Blend(*identity_operations[i], progress));
+
+    progress = 1.5;
+
+    expected.MakeIdentity();
+    expected.SkewX(3);
+    expected.SkewY(3);
+
+    EXPECT_TRANSFORMATION_MATRIX_EQ(
+        expected, operations.Blend(*identity_operations[i], progress));
   }
 }
 
@@ -601,5 +667,45 @@ TEST(TransformOperationTest, BlendPerspectiveToIdentity) {
   }
 }
 
+TEST(TransformOperationTest, ExtrapolatePerspectiveBlending) {
+  TransformOperations operations1;
+  operations1.AppendPerspective(1000);
+
+  TransformOperations operations2;
+  operations2.AppendPerspective(500);
+
+  gfx::Transform expected;
+  expected.ApplyPerspectiveDepth(250);
+
+  EXPECT_TRANSFORMATION_MATRIX_EQ(
+      expected, operations1.Blend(operations2, -0.5));
+
+  expected.MakeIdentity();
+  expected.ApplyPerspectiveDepth(1250);
+
+  EXPECT_TRANSFORMATION_MATRIX_EQ(
+      expected, operations1.Blend(operations2, 1.5));
+}
+
+TEST(TransformOperationTest, ExtrapolateMatrixBlending) {
+  gfx::Transform transform1;
+  transform1.Translate3d(1, 1, 1);
+  TransformOperations operations1;
+  operations1.AppendMatrix(transform1);
+
+  gfx::Transform transform2;
+  transform2.Translate3d(3, 3, 3);
+  TransformOperations operations2;
+  operations2.AppendMatrix(transform2);
+
+  gfx::Transform expected;
+  EXPECT_TRANSFORMATION_MATRIX_EQ(
+      expected, operations1.Blend(operations2, 1.5));
+
+  expected.Translate3d(4, 4, 4);
+  EXPECT_TRANSFORMATION_MATRIX_EQ(
+      expected, operations1.Blend(operations2, -0.5));
+}
+
 }  // namespace
 }  // namespace cc
diff --git a/ui/gfx/transform.cc b/ui/gfx/transform.cc
index 5e87998..09a213e 100644
--- a/ui/gfx/transform.cc
+++ b/ui/gfx/transform.cc
@@ -365,14 +365,6 @@ bool Transform::TransformRectReverse(RectF* rect) const {
 }
 
 bool Transform::Blend(const Transform& from, double progress) {
-  if (progress <= 0.0) {
-    *this = from;
-    return true;
-  }
-
-  if (progress >= 1.0)
-    return true;
-
   DecomposedTransform to_decomp;
   DecomposedTransform from_decomp;
   if (!DecomposeTransform(&to_decomp, *this) ||
diff --git a/ui/gfx/transform_unittest.cc b/ui/gfx/transform_unittest.cc
index 72abeef..7ccde8c 100644
--- a/ui/gfx/transform_unittest.cc
+++ b/ui/gfx/transform_unittest.cc
@@ -12,6 +12,7 @@
 #include <limits>
 
 #include "base/basictypes.h"
+#include "base/logging.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/point3_f.h"
@@ -654,7 +655,7 @@ TEST(XFormTest, SetRotate2D) {
 
 TEST(XFormTest, BlendTranslate) {
   Transform from;
-  for (int i = 0; i < 10; ++i) {
+  for (int i = -5; i < 15; ++i) {
     Transform to;
     to.Translate3d(1, 1, 1);
     double t = i / 9.0;
@@ -674,7 +675,7 @@ TEST(XFormTest, BlendRotate) {
   };
   Transform from;
   for (size_t index = 0; index < ARRAYSIZE_UNSAFE(axes); ++index) {
-    for (int i = 0; i < 10; ++i) {
+    for (int i = -5; i < 15; ++i) {
       Transform to;
       to.RotateAbout(axes[index], 90);
       double t = i / 9.0;
@@ -698,7 +699,7 @@ TEST(XFormTest, BlendRotateFollowsShortestPath) {
     Vector3dF(1, 1, 1)
   };
   for (size_t index = 0; index < ARRAYSIZE_UNSAFE(axes); ++index) {
-    for (int i = 0; i < 10; ++i) {
+    for (int i = -5; i < 15; ++i) {
       Transform from1;
       from1.RotateAbout(axes[index], 130.0);
       Transform to1;
@@ -734,7 +735,7 @@ TEST(XFormTest, CanBlend180DegreeRotation) {
   };
   Transform from;
   for (size_t index = 0; index < ARRAYSIZE_UNSAFE(axes); ++index) {
-    for (int i = 0; i < 10; ++i) {
+    for (int i = -5; i < 15; ++i) {
       Transform to;
       to.RotateAbout(axes[index], 180);
       double t = i / 9.0;
@@ -750,7 +751,7 @@ TEST(XFormTest, CanBlend180DegreeRotation) {
 
 TEST(XFormTest, BlendScale) {
   Transform from;
-  for (int i = 0; i < 10; ++i) {
+  for (int i = -5; i < 15; ++i) {
     Transform to;
     to.Scale3d(5, 4, 3);
     double t = i / 9.0;
@@ -776,15 +777,29 @@ TEST(XFormTest, BlendSkew) {
   }
 }
 
+TEST(XFormTest, ExtrapolateSkew) {
+  Transform from;
+  for (int i = -1; i < 2; ++i) {
+    Transform to;
+    to.SkewX(20);
+    double t = i;
+    Transform expected;
+    expected.SkewX(t * 20);
+    EXPECT_TRUE(to.Blend(from, t));
+    EXPECT_TRUE(MatricesAreNearlyEqual(expected, to));
+  }
+}
+
 TEST(XFormTest, BlendPerspective) {
   Transform from;
   from.ApplyPerspectiveDepth(200);
-  for (int i = 0; i < 2; ++i) {
+  for (int i = -1; i < 3; ++i) {
     Transform to;
     to.ApplyPerspectiveDepth(800);
     double t = i;
+    double depth = 1.0 / ((1.0 / 200) * (1.0 - t) + (1.0 / 800) * t);
     Transform expected;
-    expected.ApplyPerspectiveDepth(t * 600 + 200);
+    expected.ApplyPerspectiveDepth(depth);
     EXPECT_TRUE(to.Blend(from, t));
     EXPECT_TRUE(MatricesAreNearlyEqual(expected, to));
   }