Android多点触摸的实现

核心提示：int classes = getDeviceClasses(deviceId);String name = getDeviceName(deviceId);InputDevice.AbsoluteInfo absX;InputDevice.AbsoluteInfo absY;InputDevice.AbsoluteI

int classes = getDeviceClasses(deviceId);

String name = getDeviceName(deviceId);

InputDevice.AbsoluteInfo absX;

InputDevice.AbsoluteInfo absY;

InputDevice.AbsoluteInfo absPressure;

InputDevice.AbsoluteInfo absSize;

if ((classes&RawInputEvent.CLASS_TOUCHSCREEN_MT) != 0) {

absX = loadAbsoluteInfo(deviceId,

RawInputEvent.ABS_MT_POSITION_X, "X");

absY = loadAbsoluteInfo(deviceId,

RawInputEvent.ABS_MT_POSITION_Y, "Y");

absPressure = loadAbsoluteInfo(deviceId,

RawInputEvent.ABS_MT_TOUCH_MAJOR, "Pressure");

absSize = loadAbsoluteInfo(deviceId,

RawInputEvent.ABS_MT_WIDTH_MAJOR, "Size");

} else if ((classes&RawInputEvent.CLASS_TOUCHSCREEN) != 0) {

absX = loadAbsoluteInfo(deviceId,

RawInputEvent.ABS_X, "X");

absY = loadAbsoluteInfo(deviceId,

RawInputEvent.ABS_Y, "Y");

absPressure = loadAbsoluteInfo(deviceId,

RawInputEvent.ABS_PRESSURE, "Pressure");

absSize = loadAbsoluteInfo(deviceId,

RawInputEvent.ABS_TOOL_WIDTH, "Size");

} else {

absX = null;

absY = null;

absPressure = null;

absSize = null;

}

return new InputDevice(deviceId, classes, name, absX, absY, absPressure, absSize);

}

第四章 触摸事件 数组的处理

上面我们曾说到 generateAbsMotion 这个方法，它们在InputDevice 类的内部类 MotionState 中实现，该类被定义为 InputDevice 类的静态成员类 (static class) ，调用它们可以直接使用：

InputDeviceClass.MotionStateClass.generateAbsMotion()。

public class InputDevice {

……………………………

static class MotionState { //下面是这个内部类的几个函数

……………………………… .

/* mLastNumPointers 为上一个动作在触屏上按键的个数 */