ADROID 2.1 架构解析 8 触摸屏

原文地址：http://blog.csdn.net/skdev/archive/2010/03/08/5357358.aspx

8

触摸屏

8.1

分类输入事件

文件：
frameworks/base/libs/ui/EventHub.cpp

// 输入事件有：键盘、轨迹球、单点触摸、多点触摸
int EventHub::open_device(const char *deviceName)
{
...
uint8_t key_bitmask[(KEY_MAX+1)/8];
memset(key_bitmask, 0, sizeof(key_bitmask));
LOGV("Getting keys...");
if (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(key_bitmask)), key_bitmask) >= 0) {
//LOGI("MAP/n");
//for (int i=0; i<((KEY_MAX+1)/8); i++) {
//    LOGI("%d: 0x%02x/n", i, key_bitmask[i]);
//}
for (int i=0; i<((BTN_MISC+7)/8); i++) {
if (key_bitmask[i] != 0) {
device->classes |= CLASS_KEYBOARD;
break;
}
}

// 是否为键盘
if ((device->classes & CLASS_KEYBOARD) != 0) {
device->keyBitmask = new uint8_t[sizeof(key_bitmask)];
if (device->keyBitmask != NULL) {
memcpy(device->keyBitmask, key_bitmask, sizeof(key_bitmask));
} else {
delete device;
LOGE("out of memory allocating key bitmask");
return -1;
}
}
}

// 是否为轨迹球
// See if this is a trackball.
if (test_bit(BTN_MOUSE, key_bitmask)) {
uint8_t rel_bitmask[(REL_MAX+1)/8];
memset(rel_bitmask, 0, sizeof(rel_bitmask));
LOGV("Getting relative controllers...");
if (ioctl(fd, EVIOCGBIT(EV_REL, sizeof(rel_bitmask)), rel_bitmask) >= 0)
{
if (test_bit(REL_X, rel_bitmask) && test_bit(REL_Y, rel_bitmask)) {
device->classes |= CLASS_TRACKBALL;
}
}
}

uint8_t abs_bitmask[(ABS_MAX+1)/8];
memset(abs_bitmask, 0, sizeof(abs_bitmask));
LOGV("Getting absolute controllers...");
ioctl(fd, EVIOCGBIT(EV_ABS, sizeof(abs_bitmask)), abs_bitmask);

// 新式的多点触摸驱动
// Is this a new modern multi-touch driver?
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 |= CLASS_TOUCHSCREEN | CLASS_TOUCHSCREEN_MT;

// 老式的单点触摸驱动
// Is this an old style single-touch driver?
} else if (test_bit(BTN_TOUCH, key_bitmask)
&& test_bit(ABS_X, abs_bitmask) && test_bit(ABS_Y, abs_bitmask)) {
device->classes |= CLASS_TOUCHSCREEN;
}
...
}

8.2

输入事件服务

文件：
frameworks/base/services/java/com/android/server/KeyInputQueue.java

8.2.1

获取事件

Thread mThread = new Thread("InputDeviceReader") {
public void run() {
if (DEBUG) Log.v(TAG, "InputDeviceReader.run()");
android.os.Process.setThreadPriority(
android.os.Process.THREAD_PRIORITY_URGENT_DISPLAY);

// 定义事件变量
RawInputEvent ev = new RawInputEvent();
while (true) {
try {
...
// block, doesn't release the monitor
// 调用readEvent，将输入事件读取到ev类，即RawInputEvent的变量里，readEvent对应jni的android_server_KeyInputQueue_readEvent
readEvent(ev);
...

8.2.2

获取触摸点数据

// 多点触摸和单点触摸的处理：保存多点或单点触摸的数据。
// 从多点触摸协议中获取位置事件
else if (ev.type == RawInputEvent.EV_ABS &&
(classes&RawInputEvent.CLASS_TOUCHSCREEN_MT) != 0) {
if (ev.scancode == RawInputEvent.ABS_MT_TOUCH_MAJOR) {
di.mAbs.changed = true;
di.mAbs.mNextData[di.mAbs.mAddingPointerOffset
+ MotionEvent.SAMPLE_PRESSURE] = ev.value;
} else if (ev.scancode == RawInputEvent.ABS_MT_POSITION_X) {
di.mAbs.changed = true;
di.mAbs.mNextData[di.mAbs.mAddingPointerOffset
+ MotionEvent.SAMPLE_X] = ev.value;
if (DEBUG_POINTERS) Log.v(TAG, "MT @"
+ di.mAbs.mAddingPointerOffset
+ " X:" + ev.value);
} else if (ev.scancode == RawInputEvent.ABS_MT_POSITION_Y) {
di.mAbs.changed = true;
di.mAbs.mNextData[di.mAbs.mAddingPointerOffset
+ MotionEvent.SAMPLE_Y] = ev.value;
if (DEBUG_POINTERS) Log.v(TAG, "MT @"
+ di.mAbs.mAddingPointerOffset
+ " Y:" + ev.value);
} else if (ev.scancode == RawInputEvent.ABS_MT_WIDTH_MAJOR) {
di.mAbs.changed = true;
di.mAbs.mNextData[di.mAbs.mAddingPointerOffset
+ MotionEvent.SAMPLE_SIZE] = ev.value;
}

// 处理单点触摸位置事件
// Process position events from single touch protocol.
} else if (ev.type == RawInputEvent.EV_ABS &&
(classes&RawInputEvent.CLASS_TOUCHSCREEN) != 0) {
if (ev.scancode == RawInputEvent.ABS_X) {
di.mAbs.changed = true;
di.curTouchVals[MotionEvent.SAMPLE_X] = ev.value;
} else if (ev.scancode == RawInputEvent.ABS_Y) {
di.mAbs.changed = true;
di.curTouchVals[MotionEvent.SAMPLE_Y] = ev.value;
} else if (ev.scancode == RawInputEvent.ABS_PRESSURE) {
di.mAbs.changed = true;
di.curTouchVals[MotionEvent.SAMPLE_PRESSURE] = ev.value;
di.curTouchVals[MotionEvent.NUM_SAMPLE_DATA
+ MotionEvent.SAMPLE_PRESSURE] = ev.value;
} else if (ev.scancode == RawInputEvent.ABS_TOOL_WIDTH) {
di.mAbs.changed = true;
di.curTouchVals[MotionEvent.SAMPLE_SIZE] = ev.value;
di.curTouchVals[MotionEvent.NUM_SAMPLE_DATA
+ MotionEvent.SAMPLE_SIZE] = ev.value;
}

}

8.2.3

获取转换后触点数据

if (doMotion) {
// XXX Need to be able to generate
// multiple events here, for example
// if two fingers change up/down state
// at the same time.
do {
// 获取转换后触摸点数据并加入到输入事件队列。
me = ms.generateAbsMotion(di, curTime,
curTimeNano, mDisplay,
mOrientation, mGlobalMetaState);
if (DEBUG_POINTERS) Log.v(TAG, "Absolute: x="
+ di.mAbs.mNextData[MotionEvent.SAMPLE_X]
+ " y="
+ di.mAbs.mNextData[MotionEvent.SAMPLE_Y]
+ " ev=" + me);
if (me != null) {
if (WindowManagerPolicy.WATCH_POINTER) {
Log.i(TAG, "Enqueueing: " + me);
}
addLocked(di, curTimeNano, ev.flags,
RawInputEvent.CLASS_TOUCHSCREEN, me);
}
} while (ms.hasMore());
}

8.3

读取触摸点数据的流程

// 文件：frameworks/base/services/java/com/android/server/KeyInputQueue.java
readEvent(ev);
di.curTouchVals[MotionEvent.SAMPLE_X] = ev.value;
// 文件：frameworks/base/services/jni/com_android_server_KeyInputQueue.cpp
{ "readEvent",       "(Landroid/view/RawInputEvent;)Z",
(void*) android_server_KeyInputQueue_readEvent },
..
static jboolean
android_server_KeyInputQueue_readEvent(JNIEnv* env, jobject clazz,
jobject event)
{
...
bool res = hub->getEvent(&deviceId, &type, &scancode, &keycode,
&flags, &value, &when);
...
}
// 文件：frameworks/base/libs/ui/EventHub.cpp
bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType,
int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags,
int32_t* outValue, nsecs_t* outWhen)
{
...
res = read(mFDs[i].fd, &iev, sizeof(iev));

...

*outValue = iev.value;
..
}

8.4

触点数据转换

// 文件： frameworks/base/services/java/com/android/server/InutDevice.java

// 将原始数据点转化为显示屏对应的数据，一般触摸屏校正就在这里对数据点进行较正的。
MotionEvent generateAbsMotion(InputDevice device, long curTime,
long curTimeNano, Display display, int orientation,
int metaState) {

if (mSkipLastPointers) {
mSkipLastPointers = false;
mLastNumPointers = 0;
}

if (mNextNumPointers <= 0 && mLastNumPointers <= 0) {
return null;
}

final int lastNumPointers = mLastNumPointers;
final int nextNumPointers = mNextNumPointers;
if (mNextNumPointers > MAX_POINTERS) {
Log.w("InputDevice", "Number of pointers " + mNextNumPointers
+ " exceeded maximum of " + MAX_POINTERS);
mNextNumPointers = MAX_POINTERS;
}

int upOrDownPointer = updatePointerIdentifiers();

final float[] reportData = mReportData;
final int[] rawData;
if (KeyInputQueue.BAD_TOUCH_HACK) {
rawData = generateAveragedData(upOrDownPointer, lastNumPointers,
nextNumPointers);
} else {
rawData = mLastData;
}

final int numPointers = mLastNumPointers;

if (DEBUG_POINTERS) Log.v("InputDevice", "Processing "
+ numPointers + " pointers (going from " + lastNumPointers
+ " to " + nextNumPointers + ")");

for (int i=0; i<numPointers; i++) {
final int pos = i * MotionEvent.NUM_SAMPLE_DATA;
reportData[pos + MotionEvent.SAMPLE_X] = rawData[pos + MotionEvent.SAMPLE_X];
reportData[pos + MotionEvent.SAMPLE_Y] = rawData[pos + MotionEvent.SAMPLE_Y];
reportData[pos + MotionEvent.SAMPLE_PRESSURE] = rawData[pos + MotionEvent.SAMPLE_PRESSURE];
reportData[pos + MotionEvent.SAMPLE_SIZE] = rawData[pos + MotionEvent.SAMPLE_SIZE];
}

int action;
int edgeFlags = 0;
if (nextNumPointers != lastNumPointers) {
if (nextNumPointers > lastNumPointers) {
if (lastNumPointers == 0) {
action = MotionEvent.ACTION_DOWN;
mDownTime = curTime;
} else {
action = MotionEvent.ACTION_POINTER_DOWN
| (upOrDownPointer << MotionEvent.ACTION_POINTER_ID_SHIFT);
}
} else {
if (numPointers == 1) {
action = MotionEvent.ACTION_UP;
} else {
action = MotionEvent.ACTION_POINTER_UP
| (upOrDownPointer << MotionEvent.ACTION_POINTER_ID_SHIFT);
}
}
currentMove = null;
} else {
action = MotionEvent.ACTION_MOVE;
}

final int dispW = display.getWidth()-1;
final int dispH = display.getHeight()-1;
int w = dispW;
int h = dispH;
if (orientation == Surface.ROTATION_90
|| orientation == Surface.ROTATION_270) {
int tmp = w;
w = h;
h = tmp;
}

final AbsoluteInfo absX = device.absX;
final AbsoluteInfo absY = device.absY;
final AbsoluteInfo absPressure = device.absPressure;
final AbsoluteInfo absSize = device.absSize;
for (int i=0; i<numPointers; i++) {
final int j = i * MotionEvent.NUM_SAMPLE_DATA;

if (absX != null) {
reportData[j + MotionEvent.SAMPLE_X] =
((reportData[j + MotionEvent.SAMPLE_X]-absX.minValue)
/ absX.range) * w;
}
if (absY != null) {
reportData[j + MotionEvent.SAMPLE_Y] =
((reportData[j + MotionEvent.SAMPLE_Y]-absY.minValue)
/ absY.range) * h;
}
if (absPressure != null) {
reportData[j + MotionEvent.SAMPLE_PRESSURE] =
((reportData[j + MotionEvent.SAMPLE_PRESSURE]-absPressure.minValue)
/ (float)absPressure.range);
}
if (absSize != null) {
reportData[j + MotionEvent.SAMPLE_SIZE] =
((reportData[j + MotionEvent.SAMPLE_SIZE]-absSize.minValue)
/ (float)absSize.range);
}

switch (orientation) {
case Surface.ROTATION_90: {
final float temp = reportData[j + MotionEvent.SAMPLE_X];
reportData[j + MotionEvent.SAMPLE_X] = reportData[j + MotionEvent.SAMPLE_Y];
reportData[j + MotionEvent.SAMPLE_Y] = w-temp;
break;
}
case Surface.ROTATION_180: {
reportData[j + MotionEvent.SAMPLE_X] = w-reportData[j + MotionEvent.SAMPLE_X];
reportData[j + MotionEvent.SAMPLE_Y] = h-reportData[j + MotionEvent.SAMPLE_Y];
break;
}
case Surface.ROTATION_270: {
final float temp = reportData[j + MotionEvent.SAMPLE_X];
reportData[j + MotionEvent.SAMPLE_X] = h-reportData[j + MotionEvent.SAMPLE_Y];
reportData[j + MotionEvent.SAMPLE_Y] = temp;
break;
}
}
}

// We only consider the first pointer when computing the edge
// flags, since they are global to the event.
if (action == MotionEvent.ACTION_DOWN) {
if (reportData[MotionEvent.SAMPLE_X] <= 0) {
edgeFlags |= MotionEvent.EDGE_LEFT;
} else if (reportData[MotionEvent.SAMPLE_X] >= dispW) {
edgeFlags |= MotionEvent.EDGE_RIGHT;
}
if (reportData[MotionEvent.SAMPLE_Y] <= 0) {
edgeFlags |= MotionEvent.EDGE_TOP;
} else if (reportData[MotionEvent.SAMPLE_Y] >= dispH) {
edgeFlags |= MotionEvent.EDGE_BOTTOM;
}
}

if (currentMove != null) {
if (false) Log.i("InputDevice", "Adding batch x="
+ reportData[MotionEvent.SAMPLE_X]
+ " y=" + reportData[MotionEvent.SAMPLE_Y]
+ " to " + currentMove);
currentMove.addBatch(curTime, reportData, metaState);
if (WindowManagerPolicy.WATCH_POINTER) {
Log.i("KeyInputQueue", "Updating: " + currentMove);
}
return null;
}

MotionEvent me = MotionEvent.obtainNano(mDownTime, curTime,
curTimeNano, action, numPointers, mPointerIds, reportData,
metaState, xPrecision, yPrecision, device.id, edgeFlags);
if (action == MotionEvent.ACTION_MOVE) {
currentMove = me;
}

if (nextNumPointers < lastNumPointers) {
removeOldPointer(upOrDownPointer);
}

return me;
}