Android animation interpolator: decelerate
DecelerateInterpolator:
y = (1 - (1 - t)^2f)
f值越大,開始時迅速移動,結束時緩慢(與Acceletate相反)
Demo:
Source:
@HasNativeInterpolator
public class DecelerateInterpolator extends BaseInterpolator implements 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);
setChangingConfiguration(a.getChangingConfigurations());
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));
// y = (1 - (1 - t)^2f)
}
return result;
}
private float mFactor = 1.0f;
@Override
public long createNativeInterpolator() {
return NativeInterpolatorFactoryHelper.createDecelerateInterpolator(mFactor);
}
}