@Override
    public void postPerformLongClick() {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                performLongClick();
            }
        };

        if (!this.post(runnable)) {
            performLongClick();
        }
    }
In this, you can set TouchEffectDrawable,
to init TouchEffectDrawable.
<p>
If you not need touch effect,
you should set NULL.
<p>
But, if need it,
you should call {@link TouchEffectDrawable#setEffect(Effect)}

@param touchDrawable TouchEffectDrawable
caprice/ui/src/main/java/net/qiujuer/genius/ui/widget/Button.java