1 files changed, 84 insertions, 0 deletions
diff --git a/android/animation/RectEvaluator.java b/android/animation/RectEvaluator.java
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+++ b/android/animation/RectEvaluator.java
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+/*
+ * Copyright (C) 2013 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 android.animation;
+
+import android.graphics.Rect;
+
+/**
+ * This evaluator can be used to perform type interpolation between <code>Rect</code> values.
+ */
+public class RectEvaluator implements TypeEvaluator<Rect> {
+
+    /**
+     * When null, a new Rect is returned on every evaluate call. When non-null,
+     * mRect will be modified and returned on every evaluate.
+     */
+    private Rect mRect;
+
+    /**
+     * Construct a RectEvaluator that returns a new Rect on every evaluate call.
+     * To avoid creating an object for each evaluate call,
+     * {@link RectEvaluator#RectEvaluator(android.graphics.Rect)} should be used
+     * whenever possible.
+     */
+    public RectEvaluator() {
+    }
+
+    /**
+     * Constructs a RectEvaluator that modifies and returns <code>reuseRect</code>
+     * in {@link #evaluate(float, android.graphics.Rect, android.graphics.Rect)} calls.
+     * The value returned from
+     * {@link #evaluate(float, android.graphics.Rect, android.graphics.Rect)} should
+     * not be cached because it will change over time as the object is reused on each
+     * call.
+     *
+     * @param reuseRect A Rect to be modified and returned by evaluate.
+     */
+    public RectEvaluator(Rect reuseRect) {
+        mRect = reuseRect;
+    }
+
+    /**
+     * This function returns the result of linearly interpolating the start and
+     * end Rect values, with <code>fraction</code> representing the proportion
+     * between the start and end values. The calculation is a simple parametric
+     * calculation on each of the separate components in the Rect objects
+     * (left, top, right, and bottom).
+     *
+     * <p>If {@link #RectEvaluator(android.graphics.Rect)} was used to construct
+     * this RectEvaluator, the object returned will be the <code>reuseRect</code>
+     * passed into the constructor.</p>
+     *
+     * @param fraction   The fraction from the starting to the ending values
+     * @param startValue The start Rect
+     * @param endValue   The end Rect
+     * @return A linear interpolation between the start and end values, given the
+     *         <code>fraction</code> parameter.
+     */
+    @Override
+    public Rect evaluate(float fraction, Rect startValue, Rect endValue) {
+        int left = startValue.left + (int) ((endValue.left - startValue.left) * fraction);
+        int top = startValue.top + (int) ((endValue.top - startValue.top) * fraction);
+        int right = startValue.right + (int) ((endValue.right - startValue.right) * fraction);
+        int bottom = startValue.bottom + (int) ((endValue.bottom - startValue.bottom) * fraction);
+        if (mRect == null) {
+            return new Rect(left, top, right, bottom);
+        } else {
+            mRect.set(left, top, right, bottom);
+            return mRect;
+        }
+    }
+}