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/*
* Copyright (C) 2015 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.android.dialer.compat;
import android.graphics.Path;
import android.graphics.PathMeasure;
import android.os.Build;
import android.view.animation.Interpolator;
import android.view.animation.PathInterpolator;
public class PathInterpolatorCompat {
public static Interpolator create(
float controlX1, float controlY1, float controlX2, float controlY2) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
return new PathInterpolator(controlX1, controlY1, controlX2, controlY2);
}
return new PathInterpolatorBase(controlX1, controlY1, controlX2, controlY2);
}
private static class PathInterpolatorBase implements Interpolator {
/** Governs the accuracy of the approximation of the {@link Path}. */
private static final float PRECISION = 0.002f;
private final float[] mX;
private final float[] mY;
public PathInterpolatorBase(Path path) {
final PathMeasure pathMeasure = new PathMeasure(path, false /* forceClosed */);
final float pathLength = pathMeasure.getLength();
final int numPoints = (int) (pathLength / PRECISION) + 1;
mX = new float[numPoints];
mY = new float[numPoints];
final float[] position = new float[2];
for (int i = 0; i < numPoints; ++i) {
final float distance = (i * pathLength) / (numPoints - 1);
pathMeasure.getPosTan(distance, position, null /* tangent */);
mX[i] = position[0];
mY[i] = position[1];
}
}
public PathInterpolatorBase(float controlX, float controlY) {
this(createQuad(controlX, controlY));
}
public PathInterpolatorBase(
float controlX1, float controlY1, float controlX2, float controlY2) {
this(createCubic(controlX1, controlY1, controlX2, controlY2));
}
private static Path createQuad(float controlX, float controlY) {
final Path path = new Path();
path.moveTo(0.0f, 0.0f);
path.quadTo(controlX, controlY, 1.0f, 1.0f);
return path;
}
private static Path createCubic(
float controlX1, float controlY1, float controlX2, float controlY2) {
final Path path = new Path();
path.moveTo(0.0f, 0.0f);
path.cubicTo(controlX1, controlY1, controlX2, controlY2, 1.0f, 1.0f);
return path;
}
@Override
public float getInterpolation(float t) {
if (t <= 0.0f) {
return 0.0f;
} else if (t >= 1.0f) {
return 1.0f;
}
// Do a binary search for the correct x to interpolate between.
int startIndex = 0;
int endIndex = mX.length - 1;
while (endIndex - startIndex > 1) {
int midIndex = (startIndex + endIndex) / 2;
if (t < mX[midIndex]) {
endIndex = midIndex;
} else {
startIndex = midIndex;
}
}
final float xRange = mX[endIndex] - mX[startIndex];
if (xRange == 0) {
return mY[startIndex];
}
final float tInRange = t - mX[startIndex];
final float fraction = tInRange / xRange;
final float startY = mY[startIndex];
final float endY = mY[endIndex];
return startY + (fraction * (endY - startY));
}
}
}
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