http://www.cnblogs.com/andtt/articles/2145563.html
对于按键事件,调用mDevices[i]->layoutMap->map进行映射。映射实际是由 KeyLayoutMap::map完成的,KeyLayoutMap类里读取配置文件qwerty.kl,由配置 文件 qwerty.kl 决定键值的映射关系。你可以通过修 改./development/emulator/keymaps/qwerty.kl来改变键值的映射关系。
JNI 函数
在frameworks/base/services/jni/com_android_server_KeyInputQueue.cpp文 件中,向 JAVA提供了函数android_server_KeyInputQueue_readEvent,用于读 取输入设备事件。
- static jboolean
- android_server_KeyInputQueue_readEvent(JNIEnv* env, jobject clazz,
- jobject event)
- {
- gLock.lock();
- sp hub = gHub;
- if (hub == NULL) {
- hub = new EventHub;
- gHub = hub;
- }
- gLock.unlock();
- int32_t deviceId;
- int32_t type;
- int32_t scancode, keycode;
- uint32_t flags;
- int32_t value;
- nsecs_t when;
- bool res = hub->getEvent(&deviceId, &type, &scancode, &keycode,
- &flags, &value, &when);
- env->SetIntField(event, gInputOffsets.mDeviceId, (jint)deviceId);
- env->SetIntField(event, gInputOffsets.mType, (jint)type);
- env->SetIntField(event, gInputOffsets.mScancode, (jint)scancode);
- env->SetIntField(event, gInputOffsets.mKeycode, (jint)keycode);
- env->SetIntField(event, gInputOffsets.mFlags, (jint)flags);
- env->SetIntField(event, gInputOffsets.mValue, value);
- env->SetLongField(event, gInputOffsets.mWhen,
- (jlong)(nanoseconds_to_milliseconds(when)));
- return res;
- }
readEvent调用hub->getEvent读了取事件,然后转换成JAVA的结构。
事件中转线程
在frameworks/base/services/java/com/android/server/KeyInputQueue.java 里创建了一个线程,它循环的读取事件,然后把事件放入事件队列里。
- Thread mThread = new Thread("InputDeviceReader") {
- public void run() {
- android.os.Process.setThreadPriority(
- android.os.Process.THREAD_PRIORITY_URGENT_DISPLAY);
- try {
- RawInputEvent ev = new RawInputEvent();
- while (true) {
- InputDevice di;
- readEvent(ev);
- send = preprocessEvent(di, ev);
- addLocked(di, curTime, ev.flags, ..., me);
- }
- }
- };
输入事件分发线程
在frameworks/base/services/java/com/android/server/WindowManagerService.java里创建了一个输入事件分发线程,它负责把事件分发到相应的窗口上去。
- mQueue.getEvent
- dispatchKey/dispatchPointer/dispatchTrackball
按键,触摸屏流程分析
按键触摸屏流程分析:
WindowManagerService类的构造函数
WindowManagerService()
mQueue = new KeyQ();
因为 WindowManagerService.java (frameworks\base\services\java\com\android\server)中有:
private class KeyQ extends KeyInputQueue
KeyQ 是抽象类 KeyInputQueue 的实现,所以 new KeyQ类的时候实际上在 KeyInputQueue 类中创建了
一个线程 InputDeviceReader 专门用来冲设备读取按键事件,代码:
Thread mThread = new Thread("InputDeviceReader") {
public void run()
{
在循环中调用:readEvent(ev);
...
send = preprocessEvent(di, ev);
实际调用的是 KeyQ 类的 preprocessEvent 函数
...
int keycode = rotateKeyCodeLocked(ev.keycode);
int[] map = mKeyRotationMap;
for (int i=0; i<N; i+=2)
{
if (map[i] == keyCode)
return map[i+1];
} //
addLocked(di, curTime, ev.flags,RawInputEvent.CLASS_KEYBOARD,newKeyEvent(di, di.mDownTime, curTime, down,keycode, 0, scancode,...));
QueuedEvent ev = obtainLocked(device, when, flags, classType, event);
}
}
readEvent() 实际上调用的是 com_android_server_KeyInputQueue.cpp (frameworks\base\services\jni)中的:
static jboolean android_server_KeyInputQueue_readEvent(JNIEnv* env, jobject clazz,jobject event)
bool res = hub->getEvent(&deviceId, &type, &scancode, &keycode,&flags, &value, &when);
调用的是 EventHub.cpp (frameworks\base\libs\ui)中的:
bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType,
int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags,
int32_t* outValue, nsecs_t* outWhen)
在函数中调用了读设备操作:res = read(mFDs[i].fd, &iev, sizeof(iev));
在构造函数 WindowManagerService()调用 new KeyQ() 以后接着调用了:
mInputThread = new InputDispatcherThread();
...
mInputThread.start();
来启动一个线程 InputDispatcherThread
run()
process();
QueuedEvent ev = mQueue.getEvent(...)
因为WindowManagerService类中: final KeyQ mQueue;
所以实际上 InputDispatcherThread 线程实际上从 KeyQ 的事件队列中读取按键事件。
switch (ev.classType)
case RawInputEvent.CLASS_KEYBOARD:
...
dispatchKey((KeyEvent)ev.event, 0, 0);
mQueue.recycleEvent(ev);
break;
case RawInputEvent.CLASS_TOUCHSCREEN:
//Log.i(TAG, "Read next event " + ev);
dispatchPointer(ev, (MotionEvent)ev.event, 0, 0);
break;
===============================================================
KeyInputQueue.java (frameworks\base\services\java\com\android\server):
的线程 Thread mThread = new Thread("InputDeviceReader") 本地调用:
readEvent(ev);读取按键。readEvent 调用的是文件:
com_android_server_KeyInputQueue.cpp (frameworks\base\services\jni)中的函数:
static jboolean android_server_KeyInputQueue_readEvent(JNIEnv* env, jobject clazz,
jobject event)
android_server_KeyInputQueue_readEvent中有:
hub = new EventHub;
bool res = hub->getEvent(&deviceId, &type, &scancode, &keycode,
&flags, &value, &when);
hub->getEvent 调用的是
EventHub.cpp (frameworks\base\libs\ui) 文件中的函数:
bool EventHub::getEvent(int32_t* outDeviceId, int32_t* outType,
int32_t* outScancode, int32_t* outKeycode, uint32_t *outFlags,
int32_t* outValue, nsecs_t* outWhen)
读取按键。
class RefBase::weakref_impl : public RefBase::weakref_type
在系统启动后,android 会通过
static const char *device_path = "/dev/input";
bool EventHub::openPlatformInput(void)
res = scan_dir(device_path);
通过下面的函数打开设备。
int EventHub::open_device(const char *deviceName)
{
...
fd = open(deviceName, O_RDWR);
...
mFDs[mFDCount].fd = fd;
mFDs[mFDCount].events = POLLIN;
...
ioctl(mFDs[mFDCount].fd, EVIOCGNAME(sizeof(devname)-1), devname);
...
const char* root = getenv("ANDROID_ROOT");
snprintf(keylayoutFilename, sizeof(keylayoutFilename),
"%s/usr/keylayout/%s.kl", root, tmpfn);
...
device->layoutMap->load(keylayoutFilename);
...
}
打开设备的时候,如果 device->classes&CLASS_KEYBOARD 不等于 0 表明是键盘。
常用输入设备的定义有:
enum {
CLASS_KEYBOARD = 0x00000001, //键盘
CLASS_ALPHAKEY = 0x00000002, //
CLASS_TOUCHSCREEN = 0x00000004, //触摸屏
CLASS_TRACKBALL = 0x00000008 //轨迹球
};
打开键盘设备的时候通过上面的 ioctl 获得设备名称,命令字 EVIOCGNAME 的定义在文件:
kernel/include/linux/input.h 中。
#define EVIOCGNAME(len) _IOC(_IOC_READ, ‘E‘, 0x06, len) /* get device name */
在内核键盘驱动文件 drivers/input/keyboard/pxa27x_keypad.c 中定义了设备名称:pxa27x-keypad
static struct platform_driver pxa27x_keypad_driver = {
.probe = pxa27x_keypad_probe,
.remove = __devexit_p(pxa27x_keypad_remove),
.suspend = pxa27x_keypad_suspend,
.resume = pxa27x_keypad_resume,
.driver = {
.name = "pxa27x-keypad",
.owner = THIS_MODULE,
},
};
ANDROID_ROOT 为环境变量,在android的命令模式下通过 printenv 可以知道它为: system
所以 keylayoutFilename 为:/system/usr/keylayout/pxa27x-keypad.kl
pxa27x-keypad.kl 定义了按键映射,具体内容如下:
----------------------
# NUMERIC KEYS 3x4
key 2 1
key 3 2
key 4 3
key 5 4
key 6 5
key 7 6
key 8 7
key 9 8
key 10 9
key 11 0
key 83 POUND
key 55 STAR
# FUNCTIONAL KEYS
key 231 MENU WAKE_DROPPED
key 192 BACK WAKE_DROPPED
key 193 HOME WAKE
key 107 DEL WAKE
key 102 CALL WAKE_DROPPED
key 158 ENDCALL WAKE_DROPPED
key 28 DPAD_CENTER WAKE
key 115 VOLUME_UP
key 114 VOLUME_DOWN
----------------------
如果没有定义键盘映射文件,那么默认使用系统的 /system/usr/keylayout/qwerty.kl
可以修改 /system/usr/keylayout/qwerty.kl 文件改变Android公司的按键映射。
device->layoutMap->load(keylayoutFilename) 调用的是文件:
KeyLayoutMap.cpp (frameworks\base\libs\ui)中的函数:
status_t KeyLayoutMap::load(const char* filename)通过解析 pxa27x-keypad.kl
把按键的映射关系保存在 :KeyedVector<int32_t,Key> m_keys; 中。
当获得按键事件以后调用:
status_t KeyLayoutMap::map(int32_t scancode, int32_t *keycode, uint32_t *flags)
由映射关系 KeyedVector<int32_t,Key> m_keys 把扫描码转换成andorid上层可以识别的按键。