__set_bit(INPUT_PROP_DIRECT, input_dev->propbit);
INPUT_PROP_DIRECT特性表明设备的坐标直接和屏幕坐标向对应（无需琐碎的转换操作，像缩放，反转，旋转等）。非直接输入设备则需要一些必要的变换，比如触摸板上绝对到相对的变换。典型的直接输入设备有：触摸屏，手写板；非直接输入设备有：触摸板，鼠标。
frameworks/native/services/inputflinger/InputReader.cpp if (getEventHub()->hasInputProperty(getDeviceId(), INPUT_PROP_DIRECT)) { // The device is a touch screen. mParameters.deviceType = ParametersDEVICE_TYPE_TOUCH_SCREEN; } else if (getEventHub()->hasInputProperty(getDeviceId(), INPUT_PROP_POINTER)) { // The device is a pointing device like a track pad. mParameters.deviceType = ParametersDEVICE_TYPE_POINTER; } else if (getEventHub()->hasRelativeAxis(getDeviceId(), REL_X) || getEventHub()->hasRelativeAxis(getDeviceId(), REL_Y)) { // The device is a cursor device with a touch pad attached. // By default don't use the touch pad to move the pointer. mParameters.deviceType = ParametersDEVICE_TYPE_TOUCH_PAD; } else { // The device is a touch pad of unknown purpose. mParameters.deviceType = ParametersDEVICE_TYPE_POINTER; }