/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. 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 distributed under the
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* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package com.android.systemui.qs;
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import android.graphics.Path;
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import android.view.animation.BaseInterpolator;
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import android.view.animation.Interpolator;
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public class PathInterpolatorBuilder {
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// This governs how accurate the approximation of the Path is.
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private static final float PRECISION = 0.002f;
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private float[] mX; // x coordinates in the line
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private float[] mY; // y coordinates in the line
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private float[] mDist; // Cumulative percentage length of the line
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public PathInterpolatorBuilder(Path path) {
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initPath(path);
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}
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public PathInterpolatorBuilder(float controlX, float controlY) {
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initQuad(controlX, controlY);
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}
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public PathInterpolatorBuilder(float controlX1, float controlY1, float controlX2,
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float controlY2) {
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initCubic(controlX1, controlY1, controlX2, controlY2);
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}
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private void initQuad(float controlX, float controlY) {
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Path path = new Path();
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path.moveTo(0, 0);
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path.quadTo(controlX, controlY, 1f, 1f);
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initPath(path);
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}
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private void initCubic(float x1, float y1, float x2, float y2) {
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Path path = new Path();
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path.moveTo(0, 0);
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path.cubicTo(x1, y1, x2, y2, 1f, 1f);
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initPath(path);
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}
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private void initPath(Path path) {
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float[] pointComponents = path.approximate(PRECISION);
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int numPoints = pointComponents.length / 3;
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if (pointComponents[1] != 0 || pointComponents[2] != 0
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|| pointComponents[pointComponents.length - 2] != 1
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|| pointComponents[pointComponents.length - 1] != 1) {
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throw new IllegalArgumentException("The Path must start at (0,0) and end at (1,1)");
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}
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mX = new float[numPoints];
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mY = new float[numPoints];
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mDist = new float[numPoints];
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float prevX = 0;
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float prevFraction = 0;
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int componentIndex = 0;
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for (int i = 0; i < numPoints; i++) {
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float fraction = pointComponents[componentIndex++];
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float x = pointComponents[componentIndex++];
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float y = pointComponents[componentIndex++];
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if (fraction == prevFraction && x != prevX) {
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throw new IllegalArgumentException(
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"The Path cannot have discontinuity in the X axis.");
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}
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if (x < prevX) {
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throw new IllegalArgumentException("The Path cannot loop back on itself.");
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}
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mX[i] = x;
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mY[i] = y;
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if (i > 0) {
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float dx = mX[i] - mX[i - 1];
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float dy = mY[i] - mY[i - 1];
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float dist = (float) Math.sqrt(dx * dx + dy * dy);
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mDist[i] = mDist[i - 1] + dist;
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}
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prevX = x;
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prevFraction = fraction;
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}
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// Scale down dist to 0-1.
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float max = mDist[mDist.length - 1];
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for (int i = 0; i < numPoints; i++) {
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mDist[i] /= max;
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}
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}
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public Interpolator getXInterpolator() {
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return new PathInterpolator(mDist, mX);
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}
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public Interpolator getYInterpolator() {
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return new PathInterpolator(mDist, mY);
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}
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private static class PathInterpolator extends BaseInterpolator {
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private final float[] mX; // x coordinates in the line
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private final float[] mY; // y coordinates in the line
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private PathInterpolator(float[] xs, float[] ys) {
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mX = xs;
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mY = ys;
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}
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@Override
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public float getInterpolation(float t) {
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if (t <= 0) {
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return 0;
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} else if (t >= 1) {
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return 1;
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}
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// Do a binary search for the correct x to interpolate between.
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int startIndex = 0;
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int endIndex = mX.length - 1;
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while (endIndex - startIndex > 1) {
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int midIndex = (startIndex + endIndex) / 2;
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if (t < mX[midIndex]) {
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endIndex = midIndex;
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} else {
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startIndex = midIndex;
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}
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}
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float xRange = mX[endIndex] - mX[startIndex];
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if (xRange == 0) {
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return mY[startIndex];
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}
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float tInRange = t - mX[startIndex];
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float fraction = tInRange / xRange;
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float startY = mY[startIndex];
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float endY = mY[endIndex];
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return startY + (fraction * (endY - startY));
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}
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}
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}
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