提取:
DisplayMetrics metrics = getContext().getResources().getDisplayMetrics();float dp = 20f;float fpixels = metrics.density * dp;int pixels = (int) (fpixels + 0.5f);

提取:
DisplayMetrics metrics = getContext().getResources().getDisplayMetrics();float dp = 20f;float fpixels = metrics.density * dp;int pixels = (int) (fpixels + 0.5f);