import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/animation/ComputedTimingFunction.cpp

@@ -0,0 +1,194 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ComputedTimingFunction.h"
+#include "nsAlgorithm.h" // For clamped()
+#include "nsStyleUtil.h"
+
+namespace mozilla {
+
+void
+ComputedTimingFunction::Init(const nsTimingFunction &aFunction)
+{
+  mType = aFunction.mType;
+  if (nsTimingFunction::IsSplineType(mType)) {
+    mTimingFunction.Init(aFunction.mFunc.mX1, aFunction.mFunc.mY1,
+                         aFunction.mFunc.mX2, aFunction.mFunc.mY2);
+  } else {
+    mSteps = aFunction.mSteps;
+  }
+}
+
+static inline double
+StepTiming(uint32_t aSteps,
+           double aPortion,
+           ComputedTimingFunction::BeforeFlag aBeforeFlag,
+           nsTimingFunction::Type aType)
+{
+  MOZ_ASSERT(0.0 <= aPortion && aPortion <= 1.0, "out of range");
+  MOZ_ASSERT(aType == nsTimingFunction::Type::StepStart ||
+             aType == nsTimingFunction::Type::StepEnd, "invalid type");
+
+  if (aPortion == 1.0) {
+    return 1.0;
+  }
+
+  // Calculate current step using step-end behavior
+  uint32_t step = uint32_t(aPortion * aSteps); // floor
+
+  // step-start is one step ahead
+  if (aType == nsTimingFunction::Type::StepStart) {
+    step++;
+  }
+
+  // If the "before flag" is set and we are at a transition point,
+  // drop back a step (but only if we are not already at the zero point--
+  // we do this clamping here since |step| is an unsigned integer)
+  if (step != 0 &&
+      aBeforeFlag == ComputedTimingFunction::BeforeFlag::Set &&
+      fmod(aPortion * aSteps, 1) == 0) {
+    step--;
+  }
+
+  // Convert to a progress value
+  return double(step) / double(aSteps);
+}
+
+double
+ComputedTimingFunction::GetValue(
+    double aPortion,
+    ComputedTimingFunction::BeforeFlag aBeforeFlag) const
+{
+  if (HasSpline()) {
+    // Check for a linear curve.
+    // (GetSplineValue(), below, also checks this but doesn't work when
+    // aPortion is outside the range [0.0, 1.0]).
+    if (mTimingFunction.X1() == mTimingFunction.Y1() &&
+        mTimingFunction.X2() == mTimingFunction.Y2()) {
+      return aPortion;
+    }
+
+    // Ensure that we return 0 or 1 on both edges.
+    if (aPortion == 0.0) {
+      return 0.0;
+    }
+    if (aPortion == 1.0) {
+      return 1.0;
+    }
+
+    // For negative values, try to extrapolate with tangent (p1 - p0) or,
+    // if p1 is coincident with p0, with (p2 - p0).
+    if (aPortion < 0.0) {
+      if (mTimingFunction.X1() > 0.0) {
+        return aPortion * mTimingFunction.Y1() / mTimingFunction.X1();
+      } else if (mTimingFunction.Y1() == 0 && mTimingFunction.X2() > 0.0) {
+        return aPortion * mTimingFunction.Y2() / mTimingFunction.X2();
+      }
+      // If we can't calculate a sensible tangent, don't extrapolate at all.
+      return 0.0;
+    }
+
+    // For values greater than 1, try to extrapolate with tangent (p2 - p3) or,
+    // if p2 is coincident with p3, with (p1 - p3).
+    if (aPortion > 1.0) {
+      if (mTimingFunction.X2() < 1.0) {
+        return 1.0 + (aPortion - 1.0) *
+          (mTimingFunction.Y2() - 1) / (mTimingFunction.X2() - 1);
+      } else if (mTimingFunction.Y2() == 1 && mTimingFunction.X1() < 1.0) {
+        return 1.0 + (aPortion - 1.0) *
+          (mTimingFunction.Y1() - 1) / (mTimingFunction.X1() - 1);
+      }
+      // If we can't calculate a sensible tangent, don't extrapolate at all.
+      return 1.0;
+    }
+
+    return mTimingFunction.GetSplineValue(aPortion);
+  }
+
+  // Since we use endpoint-exclusive timing, the output of a steps(start) timing
+  // function when aPortion = 0.0 is the top of the first step. When aPortion is
+  // negative, however, we should use the bottom of the first step. We handle
+  // negative values of aPortion specially here since once we clamp aPortion
+  // to [0,1] below we will no longer be able to distinguish to the two cases.
+  if (aPortion < 0.0) {
+    return 0.0;
+  }
+
+  // Clamp in case of steps(end) and steps(start) for values greater than 1.
+  aPortion = clamped(aPortion, 0.0, 1.0);
+
+  return StepTiming(mSteps, aPortion, aBeforeFlag, mType);
+}
+
+int32_t
+ComputedTimingFunction::Compare(const ComputedTimingFunction& aRhs) const
+{
+  if (mType != aRhs.mType) {
+    return int32_t(mType) - int32_t(aRhs.mType);
+  }
+
+  if (mType == nsTimingFunction::Type::CubicBezier) {
+    int32_t order = mTimingFunction.Compare(aRhs.mTimingFunction);
+    if (order != 0) {
+      return order;
+    }
+  } else if (mType == nsTimingFunction::Type::StepStart ||
+             mType == nsTimingFunction::Type::StepEnd) {
+    if (mSteps != aRhs.mSteps) {
+      return int32_t(mSteps) - int32_t(aRhs.mSteps);
+    }
+  }
+
+  return 0;
+}
+
+void
+ComputedTimingFunction::AppendToString(nsAString& aResult) const
+{
+  switch (mType) {
+    case nsTimingFunction::Type::CubicBezier:
+      nsStyleUtil::AppendCubicBezierTimingFunction(mTimingFunction.X1(),
+                                                   mTimingFunction.Y1(),
+                                                   mTimingFunction.X2(),
+                                                   mTimingFunction.Y2(),
+                                                   aResult);
+      break;
+    case nsTimingFunction::Type::StepStart:
+    case nsTimingFunction::Type::StepEnd:
+      nsStyleUtil::AppendStepsTimingFunction(mType, mSteps, aResult);
+      break;
+    default:
+      nsStyleUtil::AppendCubicBezierKeywordTimingFunction(mType, aResult);
+      break;
+  }
+}
+
+/* static */ int32_t
+ComputedTimingFunction::Compare(const Maybe<ComputedTimingFunction>& aLhs,
+                                const Maybe<ComputedTimingFunction>& aRhs)
+{
+  // We can't use |operator<| for const Maybe<>& here because
+  // 'ease' is prior to 'linear' which is represented by Nothing().
+  // So we have to convert Nothing() as 'linear' and check it first.
+  nsTimingFunction::Type lhsType = aLhs.isNothing() ?
+    nsTimingFunction::Type::Linear : aLhs->GetType();
+  nsTimingFunction::Type rhsType = aRhs.isNothing() ?
+    nsTimingFunction::Type::Linear : aRhs->GetType();
+
+  if (lhsType != rhsType) {
+    return int32_t(lhsType) - int32_t(rhsType);
+  }
+
+  // Both of them are Nothing().
+  if (lhsType == nsTimingFunction::Type::Linear) {
+    return 0;
+  }
+
+  // Other types.
+  return aLhs->Compare(aRhs.value());
+}
+
+} // namespace mozilla