85 lines
3.3 KiB
Java
85 lines
3.3 KiB
Java
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/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.animation;
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import android.graphics.Rect;
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/**
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* This evaluator can be used to perform type interpolation between <code>Rect</code> values.
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*/
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public class RectEvaluator implements TypeEvaluator<Rect> {
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/**
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* When null, a new Rect is returned on every evaluate call. When non-null,
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* mRect will be modified and returned on every evaluate.
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*/
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private Rect mRect;
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/**
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* Construct a RectEvaluator that returns a new Rect on every evaluate call.
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* To avoid creating an object for each evaluate call,
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* {@link RectEvaluator#RectEvaluator(android.graphics.Rect)} should be used
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* whenever possible.
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*/
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public RectEvaluator() {
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}
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/**
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* Constructs a RectEvaluator that modifies and returns <code>reuseRect</code>
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* in {@link #evaluate(float, android.graphics.Rect, android.graphics.Rect)} calls.
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* The value returned from
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* {@link #evaluate(float, android.graphics.Rect, android.graphics.Rect)} should
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* not be cached because it will change over time as the object is reused on each
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* call.
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*
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* @param reuseRect A Rect to be modified and returned by evaluate.
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*/
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public RectEvaluator(Rect reuseRect) {
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mRect = reuseRect;
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}
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/**
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* This function returns the result of linearly interpolating the start and
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* end Rect values, with <code>fraction</code> representing the proportion
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* between the start and end values. The calculation is a simple parametric
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* calculation on each of the separate components in the Rect objects
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* (left, top, right, and bottom).
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*
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* <p>If {@link #RectEvaluator(android.graphics.Rect)} was used to construct
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* this RectEvaluator, the object returned will be the <code>reuseRect</code>
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* passed into the constructor.</p>
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*
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* @param fraction The fraction from the starting to the ending values
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* @param startValue The start Rect
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* @param endValue The end Rect
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* @return A linear interpolation between the start and end values, given the
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* <code>fraction</code> parameter.
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*/
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@Override
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public Rect evaluate(float fraction, Rect startValue, Rect endValue) {
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int left = startValue.left + (int) ((endValue.left - startValue.left) * fraction);
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int top = startValue.top + (int) ((endValue.top - startValue.top) * fraction);
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int right = startValue.right + (int) ((endValue.right - startValue.right) * fraction);
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int bottom = startValue.bottom + (int) ((endValue.bottom - startValue.bottom) * fraction);
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if (mRect == null) {
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return new Rect(left, top, right, bottom);
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} else {
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mRect.set(left, top, right, bottom);
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return mRect;
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}
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}
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}
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