Utils.java 文件源码

/**
 * Render an animator to pulsate a view in place.
 * @param labelToAnimate the view to pulsate.
 * @return The animator object. Use .start() to begin.
 */
public static ObjectAnimator getPulseAnimator(View labelToAnimate, float decreaseRatio,
        float increaseRatio) {
    Keyframe k0 = Keyframe.ofFloat(0f, 1f);
    Keyframe k1 = Keyframe.ofFloat(0.275f, decreaseRatio);
    Keyframe k2 = Keyframe.ofFloat(0.69f, increaseRatio);
    Keyframe k3 = Keyframe.ofFloat(1f, 1f);

    PropertyValuesHolder scaleX = PropertyValuesHolder.ofKeyframe("scaleX", k0, k1, k2, k3);
    PropertyValuesHolder scaleY = PropertyValuesHolder.ofKeyframe("scaleY", k0, k1, k2, k3);
    ObjectAnimator pulseAnimator =
            ObjectAnimator.ofPropertyValuesHolder(labelToAnimate, scaleX, scaleY);
    pulseAnimator.setDuration(PULSE_ANIMATOR_DURATION);

    return pulseAnimator;
}