1 files changed, 44 insertions, 0 deletions
diff --git a/actionbarsherlock/src/com/actionbarsherlock/internal/nineoldandroids/animation/TypeEvaluator.java b/actionbarsherlock/src/com/actionbarsherlock/internal/nineoldandroids/animation/TypeEvaluator.java
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+++ b/actionbarsherlock/src/com/actionbarsherlock/internal/nineoldandroids/animation/TypeEvaluator.java
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+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.actionbarsherlock.internal.nineoldandroids.animation;
+
+/**
+ * Interface for use with the {@link ValueAnimator#setEvaluator(TypeEvaluator)} function. Evaluators
+ * allow developers to create animations on arbitrary property types, by allowing them to supply
+ * custom evaulators for types that are not automatically understood and used by the animation
+ * system.
+ *
+ * @see ValueAnimator#setEvaluator(TypeEvaluator)
+ */
+public interface TypeEvaluator<T> {
+
+    /**
+     * This function returns the result of linearly interpolating the start and end values, with
+     * <code>fraction</code> representing the proportion between the start and end values. The
+     * calculation is a simple parametric calculation: <code>result = x0 + t * (v1 - v0)</code>,
+     * where <code>x0</code> is <code>startValue</code>, <code>x1</code> is <code>endValue</code>,
+     * and <code>t</code> is <code>fraction</code>.
+     *
+     * @param fraction   The fraction from the starting to the ending values
+     * @param startValue The start value.
+     * @param endValue   The end value.
+     * @return A linear interpolation between the start and end values, given the
+     *         <code>fraction</code> parameter.
+     */
+    public T evaluate(float fraction, T startValue, T endValue);
+
+}
+\ No newline at end of file