LinearInterpolator线性插值器,直接返回输入值。
/**
-
An interpolator where the rate of change is constant
*/
@HasNativeInterpolator
public class LinearInterpolator implements Interpolator, NativeInterpolatorFactory {
public LinearInterpolator() {
}
public LinearInterpolator(Context context, AttributeSet attrs) {
}
public float getInterpolation(float input) {
return input;
}
/** @hide */
@Override
public long createNativeInterpolator() {
return NativeInterpolatorFactoryHelper.createLinearInterpolator();
}
}
DecelerateInterpolator
可以通过 XML 进行动画属性设置，通过 XML 可以设置其中的 mFactor 变量，其值默认是1.0；值越大其变化越快；得到的结果就是，开始的时候更加的快，其结果就是更加的慢。getInterpolation(float)描述的是一个初中学的抛物方程。
/**
-
An interpolator where the rate of change starts out quickly and
-
and then decelerates.
*/
@HasNativeInterpolator
public class DecelerateInterpolator implements Interpolator, NativeInterpolatorFactory {
public DecelerateInterpolator() {
}
/**
-
Constructor
-
@param factor Degree to which the animation should be eased. Setting factor to 1.0f produces
-
an upside-down y=x^2 parabola. Increasing factor above 1.0f makes exaggerates the -
ease-out effect (i.e., it starts even faster and ends evens slower)
*/
public DecelerateInterpolator(float factor) {
mFactor = factor;
}
public DecelerateInterpolator(Context context, AttributeSet attrs) {
this(context.getResources(), context.getTheme(), attrs);
}
/** @hide */
public DecelerateInterpolator(Resources res, Theme theme, AttributeSet attrs) {
TypedArray a;
if (theme != null) {
a = theme.obtainStyledAttributes(attrs, R.styleable.DecelerateInterpolator, 0, 0);
} else {
a = res.obtainAttributes(attrs, R.styleable.DecelerateInterpolator);
}
mFactor = a.getFloat(R.styleable.DecelerateInterpolator_factor, 1.0f);
a.recycle();
}
public float getInterpolation(float input) {
float result;
if (mFactor == 1.0f) {
result = (float)(1.0f - (1.0f - input) * (1.0f - input));
} else {
result = (float)(1.0f - Math.pow((1.0f - input), 2 * mFactor));
}
return result;
}
private float mFactor = 1.0f;
/** @hide */
@Override
public long createNativeInterpolator() {
return NativeInterpolatorFactoryHelper.createDecelerateInterpolator(mFactor);
}
}
===
C++ 的版本实现 ：
===========
float Elastic::easeIn (float t, float b , float c, float d) {
if (t==0) return b; if ((t/=d)==1) return b+c;
float p=d*.3f;
float a=c;
float s=p/4;
float postFix =apow(2,10(t-=1)); // this is a fix, again, with post-increment operators
return -(postFix * sin((td-s)(2*PI)/p )) + b;
}
float Elastic::easeOut(float t,float b , float c, float d) {
if (t==0) return b; if ((t/=d)==1) return b+c;
float p=d*.3f;
float a=c;
float s=p/4;
return (apow(2,-10t) * sin( (td-s)(2*PI)/p ) + c + b);
}
float Elastic::easeInOut(float t,float b , float c, float d) {
if (t==0) return b; if ((t/=d/2)==2) return b+c;
float p=d*(.3f*1.5f);
float a=c;
float s=p/4;
if (t < 1) {
float postFix =apow(2,10(t-=1)); // postIncrement is evil
return -.5f*(postFix* sin( (td-s)(2*PI)/p )) + b;
}
float postFix = apow(2,-10(t-=1)); // postIncrement is evil
return postFix * sin( (td-s)(2PI)/p ).5f + c + b;
}
参数的意思：
-
t – 动画中当前的时间
-
b – 开始值
-
c – 结束值
-
d – 动画的总时间
看下Java的第一行前三个的：
public class Sine {
public static float easeIn(float t,float b , float c, float d) {
return -c * (float)Math.cos(t/d * (Math.PI/2)) + c + b;
}
public static float easeOut(float t,float b , float c, float d) {
return c * (float)Math.sin(t/d * (Math.PI/2)) + b;
}
public static float easeInOut(float t,float b , float c, float d) {
return -c/2 * ((float)Math.cos(Math.PI*t/d) - 1) + b;
}
}
虽然 Java 的也有了，但是话说这个怎么用啊，跟上面的Interpolator如何联系起来啊？
一个简单的方法：首先把 d 总时间设置为固定值 1.0 ，把 b 开始值设置为 0.0 把结束值设置为1.0，然后把 t 当作上面 Interpolator 中的 float getInterpolation(float input);传入值，此时不就能用上了。
举个Case
======
/**
- Created by Qiujuer on 2015/1/5.
*/
public class InSineInterpolator implements Interpolator{
public static float easeIn(float t,float b , float c, float d) {
return -c * (float)Math.cos(t/d * (Math.PI/2)) + c + b;
}
@Override
public float getInterpolation(float input) {
return easeIn(input, 0, 1, 1);
}
}
使用
==
//AnimatorSet
mAnimatorSet = new AnimatorSet();
mAnimatorSet.playTogether(aPaintX, aPaintY, aRadius, aBackground);
mAnimatorSet.setInterpolator(new InSineInterpolator());
mAnimatorSet.start();
可以看出使用与上面 Android 自带的完全一样，当然这个只是个 Case ，具体使用中你可以随意封装，前提是别改动了主要部分。
/**
-
An interpolator where the rate of change starts out quickly and
-
and then decelerates.
*/
@HasNativeInterpolator
public class DecelerateInterpolator implements Interpolator, NativeInterpolatorFactory {
public DecelerateInterpolator() {
}
/**
-
Constructor
-
@param factor Degree to which the animation should be eased. Setting factor to 1.0f produces
-
an upside-down y=x^2 parabola. Increasing factor above 1.0f makes exaggerates the -
ease-out effect (i.e., it starts even faster and ends evens slower)
*/
public DecelerateInterpolator(float factor) {
mFactor = factor;
}
public DecelerateInterpolator(Context context, AttributeSet attrs) {
this(context.getResources(), context.getTheme(), attrs);
}
/** @hide */
public DecelerateInterpolator(Resources res, Theme theme, AttributeSet attrs) {
