/*
* 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 com.glview.animation;
import com.glview.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;
}
}
}