public void setInitialDisplaySize(Display display, int width, int height)函数
int shortSizeDp = shortSize * DisplayMetrics.DENSITY_DEFAULT / DisplayMetrics.DENSITY_DEVICE;
if (shortSizeDp < 600) {
// 0-599dp: "phone" UI with a separate status & navigation bar
mHasSystemNavBar = false;
mNavigationBarCanMove = true;
} else if (shortSizeDp < 720) {
// 600-719dp: "phone" UI with modifications for larger screens
mHasSystemNavBar = false;
mNavigationBarCanMove = false;
} else {
// 720dp: "tablet" UI with a single combined status & navigation bar
mHasSystemNavBar = true;
mNavigationBarCanMove = false;
}