/*
 * 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 Rect values.
/**
 * 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.
/**
     * 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, RectEvaluator(Rect) should be used whenever possible. /**
     * 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 reuseRect in evaluate(float, Rect, Rect) calls. The value returned from evaluate(float, Rect, Rect) should not be cached because it will change over time as the object is reused on each call. 
Params:
reuseRect – A Rect to be modified and returned by evaluate./**
     * 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 fraction 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).
If RectEvaluator(Rect) was used to construct this RectEvaluator, the object returned will be the reuseRect
passed into the constructor.
Params:
fraction –   The fraction from the starting to the ending values
startValue – The start Rect
endValue –   The end Rect
Returns:
A linear interpolation between the start and end values, given the
        fraction parameter./**
     * 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;
        }
    }
}