Android多点触摸的实现——16patch(一)

1、Android多点触摸的实现1.6patch（一）第一章摘要在Linux内核支持的基础上，Android在其2.0源码中加入多点触摸功能。由此触摸屏在Android的frameworks被完全分为2种实现途径：单点触摸屏的单点方式，多点触摸屏的单点和多点方式。第二章软件位在Linux的input.h中，多点触摸功能依赖于以下几个主要的软件位：.#define SYN_REPORT 0#define SYN_CONFIG 1#define SYN_MT_REPORT 2.#define ABS_MT_TOUCH_MAJOR0x30/* Major axis of touching ellipse

2、 */#define ABS_MT_TOUCH_MINOR0x31/* Minor axis (omit if circular) */#define ABS_MT_WIDTH_MAJOR0x32/* Major axis of approaching ellipse */#define ABS_MT_WIDTH_MINOR0x33/* Minor axis (omit if circular) */#define ABS_MT_ORIENTATION0x34/* Ellipse orientation */#define ABS_MT_POSITION_X0x35/* Center X el

3、lipse position */#define ABS_MT_POSITION_Y0x36/* Center Y ellipse position */#define ABS_MT_TOOL_TYPE0x37/* Type of touching device */#define ABS_MT_BLOB_ID 0x38/* Group a set of packets as a blob */在Android中对应的软件位定义在RawInputEvent.java中:.public class RawInputEvent . public static final int CLASS_TOU

4、CHSCREEN_MT = 0x00000010;. public static final int ABS_MT_TOUCH_MAJOR = 0x30; public static final int ABS_MT_TOUCH_MINOR = 0x31; public static final int ABS_MT_WIDTH_MAJOR = 0x32; public static final int ABS_MT_WIDTH_MINOR = 0x33; public static final int ABS_MT_ORIENTATION = 0x34; public static fina

5、l int ABS_MT_POSITION_X = 0x35; public static final int ABS_MT_POSITION_Y = 0x36; public static final int ABS_MT_TOOL_TYPE = 0x37; public static final int ABS_MT_BLOB_ID = 0x38;.public static final int SYN_REPORT = 0; public static final int SYN_CONFIG = 1;public static final int SYN_MT_REPORT = 2;.

6、在Android中，多点触摸的实现方法在具体的代码实现中和单点是完全区分开的。在Android代码的EventHub.cpp中，单点屏和多点屏由如下代码段来判定：int EventHub:open_device(const char *deviceName)if (test_bit(ABS_MT_TOUCH_MAJOR, abs_bitmask)&& test_bit(ABS_MT_POSITION_X, abs_bitmask)&& test_bit(ABS_MT_POSITION_Y, abs_bitmask) device->classes |= C

7、LASS_TOUCHSCREEN | CLASS_TOUCHSCREEN_MT;/ LOGI("It is a multi-touch screen!"); /single-touch?else if (test_bit(BTN_TOUCH, key_bitmask)&& test_bit(ABS_X, abs_bitmask) && test_bit(ABS_Y, abs_bitmask) device->classes |= CLASS_TOUCHSCREEN;/ LOGI("It is a single-touch sc

8、reen!");.我们知道，在触摸屏驱动中，通常在probe函数中会调用input_set_abs_params给设备的input_dev结构体初始化，这些input_dev的参数会在Android的EventHub.cpp中被读取。如上可知，如果我们的触摸屏想被当成多点屏被处理，只需要在驱动中给input_dev额外增加以下几个参数即可：input_set_abs_params(mcs_data.input, ABS_MT_POSITION_X, pdata->abs_x_min, pdata->abs_x_max, 0, 0);input_set_abs_params

9、(mcs_data.input, ABS_MT_POSITION_Y, pdata->abs_y_min, pdata->abs_y_max, 0, 0);input_set_abs_params(mcs_data.input, ABS_MT_TOUCH_MAJOR, 0, 15, 0, 0); /相当于单点屏的ABX_PRESSUREinput_set_abs_params(mcs_data.input, ABS_MT_WIDTH_MAJOR, 0, 15, 0, 0); /相当于单点屏的ABS_TOOL_WIDTH注：为了让我们的驱动代码支持所有的Android版本，无论是多点

10、屏还是单点屏，一般都会保留单点屏的事件，如ABS_TOUCH, ABS_PRESSURE, ABS_X, ABS_Y等。另外，由于在Android2.0前支持多点的frameworks大多是用HAT0X,HAT0Y来实现的，所以一般也会上报这2个事件。第三章同步方式由于多点触摸技术需要采集到多个点，然后再一起处理这些点，所以在软件实现中需要保证每一波点的准确性和完整性。因此，Linux内核提供了input_mt_sync(struct input_dev * input)函数。在每波的每个点上报后需要紧跟一句input_mt_sync(), 当这波所有点上报后再使用input_sync()进行

11、同步。例如一波要上报3个点：/* 上报点1*/.input_mt_sync(input);/* 上报点2*/.input_mt_sync(input);/* 上报点3*/.input_mt_sync(input);input_sync(input);注：即使是仅上报一个点的单点事件，也需要一次input_my_sync。在Android的KeyInputQueue.java中，系统创建了一个线程，然后把所有的Input事件放入一个队列：public abstract class KeyInputQueue Thread mThread = new Thread("InputDevic

12、eReader") public void run() android.os.Process.setThreadPriority( android.os.Process.THREAD_PRIORITY_URGENT_DISPLAY); try RawInputEvent ev = new RawInputEvent(); while (true) InputDevice di; / block, doesn't release the monitor readEvent(ev);if (ev.type = RawInputEvent.EV_DEVICE_ADDED) sync

13、hronized (mFirst) di = newInputDevice(ev.deviceId); mDevices.put(ev.deviceId, di); configChanged = true; else if (ev.type = RawInputEvent.EV_DEVICE_REMOVED) synchronized (mFirst) Log.i(TAG, "Device removed: id=0x" + Integer.toHexString(ev.deviceId); di = mDevices.get(ev.deviceId); if (di !

14、= null) mDevices.delete(ev.deviceId); configChanged = true; else Log.w(TAG, "Bad device id: " + ev.deviceId); else di = getInputDevice(ev.deviceId); / first crack at it send = preprocessEvent(di, ev); if (ev.type = RawInputEvent.EV_KEY) di.mMetaKeysState = makeMetaState(ev.keycode, ev.valu

15、e != 0, di.mMetaKeysState); mHaveGlobalMetaState = false; if (di = null) continue; if (configChanged) synchronized (mFirst) addLocked(di, SystemClock.uptimeMillis(), 0, RawInputEvent.CLASS_CONFIGURATION_CHANGED, null); if (!send) continue; synchronized (mFirst) . if (type = RawInputEvent.EV_KEY &

16、;& (classes&RawInputEvent.CLASS_KEYBOARD) != 0 && (scancode < RawInputEvent.BTN_FIRST | scancode > RawInputEvent.BTN_LAST) /* 键盘按键事件 */ . else if (ev.type = RawInputEvent.EV_KEY) /* 下面是EV_KEY事件分支，只支持单点的触摸屏有按键事件， * 而支持多点的触摸屏没有按键事件，只有绝对坐标事件*/ if (ev.scancode = RawInputEvent.BTN_T

17、OUCH && (classes&(RawInputEvent.CLASS_TOUCHSCREEN |RawInputEvent.CLASS_TOUCHSCREEN_MT) = RawInputEvent.CLASS_TOUCHSCREEN) /* 只支持单点的触摸屏的按键事件 */ else if (ev.scancode = RawInputEvent.BTN_MOUSE && (classes&RawInputEvent.CLASS_TRACKBALL) != 0) /* 鼠标和轨迹球 */ . else if (ev.type = Raw

18、InputEvent.EV_ABS && (classes&RawInputEvent.CLASS_TOUCHSCREEN_MT) != 0) /* 下面才是多点触摸屏上报的事件 */ if (ev.scancode = RawInputEvent.ABS_MT_TOUCH_MAJOR) di.mAbs.changed = true; di.mAbs.mNextDatadi.mAbs.mAddingPointerOffset + MotionEvent.SAMPLE_PRESSURE = ev.value; else if (ev.scancode = RawInput

19、Event.ABS_MT_POSITION_X) di.mAbs.changed = true; di.mAbs.mNextDatadi.mAbs.mAddingPointerOffset + MotionEvent.SAMPLE_X = ev.value; else if (ev.scancode = RawInputEvent.ABS_MT_POSITION_Y) di.mAbs.changed = true; di.mAbs.mNextDatadi.mAbs.mAddingPointerOffset + MotionEvent.SAMPLE_Y = ev.value; else if (

20、ev.scancode = RawInputEvent.ABS_MT_WIDTH_MAJOR) di.mAbs.changed = true; di.mAbs.mNextDatadi.mAbs.mAddingPointerOffset + MotionEvent.SAMPLE_SIZE = ev.value; /* 上面这段就是多点触摸屏要用到的事件上报部分; * 使用一个数组mNextData来保存，其中di.mAbs.mAddingPointerOffset * 是当前点的偏移量，在每个点中还在MotionEvent中定义了X,Y,PRESSURE * SIZE等偏移量，多点触摸屏的压力值

21、由绝对坐标事件ABS_MT_TOUCH_MAJOR确定。 */ else if (ev.type = RawInputEvent.EV_ABS && (classes&RawInputEvent.CLASS_TOUCHSCREEN) != 0) /* 这里是对单点触摸屏上报坐标事件的新的处理方法，同样使用了数组来保存 */ if (ev.scancode = RawInputEvent.ABS_X) di.mAbs.changed = true; di.curTouchValsMotionEvent.SAMPLE_X = ev.value; else if (ev.sc

22、ancode = RawInputEvent.ABS_Y) di.mAbs.changed = true; di.curTouchValsMotionEvent.SAMPLE_Y = ev.value; else if (ev.scancode = RawInputEvent.ABS_PRESSURE) di.mAbs.changed = true; di.curTouchValsMotionEvent.SAMPLE_PRESSURE = ev.value; di.curTouchValsMotionEvent.NUM_SAMPLE_DATA + MotionEvent.SAMPLE_PRES

23、SURE = ev.value; else if (ev.scancode = RawInputEvent.ABS_TOOL_WIDTH) di.mAbs.changed = true; di.curTouchValsMotionEvent.SAMPLE_SIZE = ev.value; di.curTouchValsMotionEvent.NUM_SAMPLE_DATA + MotionEvent.SAMPLE_SIZE = ev.value; . /* 下面是关键的同步处理方法 */ if (ev.type = RawInputEvent.EV_SYN && ev.scan

24、code = RawInputEvent.SYN_MT_REPORT && di.mAbs != null) /* 在这里实现了对SYN_MT_REPORT事件的处理， * 改变了di.mAbs.mAddingPointerOffset的值，从而将 * 新增的点的参数保存到下一组偏移量的位置。 */ . final int newOffset = (num <= InputDevice.MAX_POINTERS) ? (num * MotionEvent.NUM_SAMPLE_DATA) : (InputDevice.MAX_POINTERS * MotionEvent.

25、NUM_SAMPLE_DATA); di.mAbs.mAddingPointerOffset = newOffset; di.mAbs.mNextDatanewOffset + MotionEvent.SAMPLE_PRESSURE = 0; . else if (send | (ev.type = RawInputEvent.EV_SYN && ev.scancode = RawInputEvent.SYN_REPORT) /* 这里实现了对SYN_REPORT事件的处理 * 如果是单点触摸屏，即使用di.curTouchVals数组保存的点 * 转化为多点触摸屏的mNext

26、Data数组保存 * 最后是调用InputDevice中的generateAbsMotion处理这个数组。这个函数 * 的具体实现方法将在后面补充 */ . ms.finish(); /重置所有点和偏移量 .由于上层的代码仍然使用ABS_X, ABS_Y这些事件，为了使多点触摸屏代码有良好的兼容性，在KeyInputQueue.java的最后，我们将多点事件类型转化为单点事件类型，返回一个新的InputDevice:private InputDevice newInputDevice(int deviceId) int classes = getDeviceClasses(deviceId);

27、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, &qu

28、ot;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

29、&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 = loadAbsolute

30、Info(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Input

31、Device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 */int mLastNumPointers = 0;final int mLastData = new intMotionEvent.NUM_SAMPLE_DATA * MAX_POINTERS;/* mNe

32、xtNumPointers 为下一个动作在触屏上按键的个数 */* 通过对这2个值大小的判断，可以确认新的动作方式 */int mNextNumPointers = 0;final int mNextData = new int(MotionEvent.NUM_SAMPLE_DATA * MAX_POINTERS) + MotionEvent.NUM_SAMPLE_DATA;. int generateAveragedData(int upOrDownPointer, int lastNumPointers, int nextNumPointers) /平滑处理 . private boole

33、an assignPointer(int nextIndex, boolean allowOverlap) /指派按键 private int updatePointerIdentifiers() /更新按键ID . void removeOldPointer(int index) MotionEvent generateAbsMotion(InputDevice device, long curTime, long curTimeNano, Display display, int orientation, int metaState) int upOrDownPointer = updat

34、ePointerIdentifiers(); final int numPointers = mLastNumPointers; /* 对行为的判断 */ if (nextNumPointers != lastNumPointers) /前后在触屏上点个数不同，说明有手指up或down if (nextNumPointers > lastNumPointers) if (lastNumPointers = 0) /上次触屏上没有按键，新值又大，说明有按键按下 action = MotionEvent.ACTION_DOWN; mDownTime = curTime; else /有新点按下，分配给新点ID号 action = MotionEvent.ACTION_POINTER_DOWN | (upOrDownPointer <&