252 lines
8.0 KiB
Java
252 lines
8.0 KiB
Java
/*
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* Copyright (C) 2014 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.Path;
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import android.graphics.PointF;
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import java.util.ArrayList;
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/**
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* PathKeyframes relies on approximating the Path as a series of line segments.
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* The line segments are recursively divided until there is less than 1/2 pixel error
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* between the lines and the curve. Each point of the line segment is converted
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* to a Keyframe and a linear interpolation between Keyframes creates a good approximation
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* of the curve.
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* <p>
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* PathKeyframes is optimized to reduce the number of objects created when there are
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* many keyframes for a curve.
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* </p>
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* <p>
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* Typically, the returned type is a PointF, but the individual components can be extracted
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* as either an IntKeyframes or FloatKeyframes.
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* </p>
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* @hide
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*/
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public class PathKeyframes implements Keyframes {
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private static final int FRACTION_OFFSET = 0;
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private static final int X_OFFSET = 1;
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private static final int Y_OFFSET = 2;
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private static final int NUM_COMPONENTS = 3;
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private static final ArrayList<Keyframe> EMPTY_KEYFRAMES = new ArrayList<Keyframe>();
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private PointF mTempPointF = new PointF();
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private float[] mKeyframeData;
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public PathKeyframes(Path path) {
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this(path, 0.5f);
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}
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public PathKeyframes(Path path, float error) {
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if (path == null || path.isEmpty()) {
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throw new IllegalArgumentException("The path must not be null or empty");
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}
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mKeyframeData = path.approximate(error);
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}
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@Override
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public ArrayList<Keyframe> getKeyframes() {
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return EMPTY_KEYFRAMES;
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}
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@Override
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public Object getValue(float fraction) {
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int numPoints = mKeyframeData.length / 3;
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if (fraction < 0) {
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return interpolateInRange(fraction, 0, 1);
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} else if (fraction > 1) {
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return interpolateInRange(fraction, numPoints - 2, numPoints - 1);
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} else if (fraction == 0) {
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return pointForIndex(0);
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} else if (fraction == 1) {
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return pointForIndex(numPoints - 1);
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} else {
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// Binary search for the correct section
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int low = 0;
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int high = numPoints - 1;
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while (low <= high) {
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int mid = (low + high) / 2;
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float midFraction = mKeyframeData[(mid * NUM_COMPONENTS) + FRACTION_OFFSET];
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if (fraction < midFraction) {
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high = mid - 1;
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} else if (fraction > midFraction) {
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low = mid + 1;
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} else {
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return pointForIndex(mid);
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}
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}
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// now high is below the fraction and low is above the fraction
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return interpolateInRange(fraction, high, low);
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}
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}
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private PointF interpolateInRange(float fraction, int startIndex, int endIndex) {
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int startBase = (startIndex * NUM_COMPONENTS);
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int endBase = (endIndex * NUM_COMPONENTS);
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float startFraction = mKeyframeData[startBase + FRACTION_OFFSET];
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float endFraction = mKeyframeData[endBase + FRACTION_OFFSET];
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float intervalFraction = (fraction - startFraction)/(endFraction - startFraction);
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float startX = mKeyframeData[startBase + X_OFFSET];
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float endX = mKeyframeData[endBase + X_OFFSET];
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float startY = mKeyframeData[startBase + Y_OFFSET];
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float endY = mKeyframeData[endBase + Y_OFFSET];
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float x = interpolate(intervalFraction, startX, endX);
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float y = interpolate(intervalFraction, startY, endY);
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mTempPointF.set(x, y);
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return mTempPointF;
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}
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@Override
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public void setEvaluator(TypeEvaluator evaluator) {
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}
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@Override
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public Class getType() {
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return PointF.class;
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}
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@Override
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public Keyframes clone() {
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Keyframes clone = null;
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try {
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clone = (Keyframes) super.clone();
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} catch (CloneNotSupportedException e) {}
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return clone;
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}
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private PointF pointForIndex(int index) {
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int base = (index * NUM_COMPONENTS);
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int xOffset = base + X_OFFSET;
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int yOffset = base + Y_OFFSET;
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mTempPointF.set(mKeyframeData[xOffset], mKeyframeData[yOffset]);
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return mTempPointF;
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}
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private static float interpolate(float fraction, float startValue, float endValue) {
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float diff = endValue - startValue;
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return startValue + (diff * fraction);
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}
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/**
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* Returns a FloatKeyframes for the X component of the Path.
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* @return a FloatKeyframes for the X component of the Path.
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*/
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public FloatKeyframes createXFloatKeyframes() {
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return new FloatKeyframesBase() {
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@Override
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public float getFloatValue(float fraction) {
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PointF pointF = (PointF) PathKeyframes.this.getValue(fraction);
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return pointF.x;
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}
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};
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}
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/**
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* Returns a FloatKeyframes for the Y component of the Path.
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* @return a FloatKeyframes for the Y component of the Path.
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*/
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public FloatKeyframes createYFloatKeyframes() {
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return new FloatKeyframesBase() {
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@Override
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public float getFloatValue(float fraction) {
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PointF pointF = (PointF) PathKeyframes.this.getValue(fraction);
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return pointF.y;
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}
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};
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}
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/**
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* Returns an IntKeyframes for the X component of the Path.
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* @return an IntKeyframes for the X component of the Path.
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*/
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public IntKeyframes createXIntKeyframes() {
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return new IntKeyframesBase() {
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@Override
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public int getIntValue(float fraction) {
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PointF pointF = (PointF) PathKeyframes.this.getValue(fraction);
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return Math.round(pointF.x);
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}
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};
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}
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/**
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* Returns an IntKeyframeSet for the Y component of the Path.
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* @return an IntKeyframeSet for the Y component of the Path.
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*/
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public IntKeyframes createYIntKeyframes() {
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return new IntKeyframesBase() {
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@Override
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public int getIntValue(float fraction) {
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PointF pointF = (PointF) PathKeyframes.this.getValue(fraction);
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return Math.round(pointF.y);
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}
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};
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}
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private abstract static class SimpleKeyframes implements Keyframes {
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@Override
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public void setEvaluator(TypeEvaluator evaluator) {
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}
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@Override
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public ArrayList<Keyframe> getKeyframes() {
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return EMPTY_KEYFRAMES;
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}
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@Override
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public Keyframes clone() {
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Keyframes clone = null;
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try {
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clone = (Keyframes) super.clone();
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} catch (CloneNotSupportedException e) {}
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return clone;
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}
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}
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abstract static class IntKeyframesBase extends SimpleKeyframes implements IntKeyframes {
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@Override
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public Class getType() {
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return Integer.class;
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}
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@Override
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public Object getValue(float fraction) {
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return getIntValue(fraction);
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}
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}
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abstract static class FloatKeyframesBase extends SimpleKeyframes
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implements FloatKeyframes {
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@Override
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public Class getType() {
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return Float.class;
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}
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@Override
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public Object getValue(float fraction) {
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return getFloatValue(fraction);
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}
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}
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}
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