Created
March 17, 2015 11:22
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Cubic Bezier Android interpolator
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package com.infojobs.app.base.utils.animation; | |
import android.graphics.PointF; | |
import android.view.animation.Interpolator; | |
/** | |
* Derived from: https://github.com/rdallasgray/bez | |
*/ | |
public class CubicBezierInterpolator implements Interpolator { | |
//A cool decelerated interpolated. It's like the wet version of Alex Bailon dreams | |
public static final CubicBezierInterpolator STANDARD_CURVE = new CubicBezierInterpolator(.29, .09, .24, .99); | |
//A really UGLY interpolator. Only useful to see if the interpolatod is being applied | |
public static final CubicBezierInterpolator FATALE_CURVE = new CubicBezierInterpolator(0, 1.34, 1, 1.81); | |
protected PointF start; | |
protected PointF end; | |
protected PointF a = new PointF(); | |
protected PointF b = new PointF(); | |
protected PointF c = new PointF(); | |
public CubicBezierInterpolator(PointF start, PointF end) throws IllegalArgumentException { | |
if (start.x < 0 || start.x > 1) { | |
throw new IllegalArgumentException("startX value must be in the range [0, 1]"); | |
} | |
if (end.x < 0 || end.x > 1) { | |
throw new IllegalArgumentException("endX value must be in the range [0, 1]"); | |
} | |
this.start = start; | |
this.end = end; | |
} | |
public CubicBezierInterpolator(float startX, float startY, float endX, float endY) { | |
this(new PointF(startX, startY), new PointF(endX, endY)); | |
} | |
public CubicBezierInterpolator(double startX, double startY, double endX, double endY) { | |
this((float) startX, (float) startY, (float) endX, (float) endY); | |
} | |
@Override | |
public float getInterpolation(float time) { | |
return getBezierCoordinateY(getXForTime(time)); | |
} | |
protected float getBezierCoordinateY(float time) { | |
c.y = 3 * start.y; | |
b.y = 3 * (end.y - start.y) - c.y; | |
a.y = 1 - c.y - b.y; | |
return time * (c.y + time * (b.y + time * a.y)); | |
} | |
protected float getXForTime(float time) { | |
float x = time; | |
float z; | |
for (int i = 1; i < 14; i++) { | |
z = getBezierCoordinateX(x) - time; | |
if (Math.abs(z) < 1e-3) { | |
break; | |
} | |
x -= z / getXDerivate(x); | |
} | |
return x; | |
} | |
private float getXDerivate(float t) { | |
return c.x + t * (2 * b.x + 3 * a.x * t); | |
} | |
private float getBezierCoordinateX(float time) { | |
c.x = 3 * start.x; | |
b.x = 3 * (end.x - start.x) - c.x; | |
a.x = 1 - c.x - b.x; | |
return time * (c.x + time * (b.x + time * a.x)); | |
} | |
} |
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