Android 載入鍵盤佈局檔案過程
private WindowManagerService(Context context, PowerManagerService pm,
……..
……..
mInputManager = new InputManager(context, this); //構造InputManager例項
PolicyThread
thr.start();
synchronized (thr) {
while (!thr.mRunning) {
try {
thr.wait();
} catch (InterruptedException e) {
}
}
}
mInputManager.start
// Add ourself to the Watchdog monitors.
Watchdog.getInstance().addMonitor(this);
}
三、InputManager.java是本地c程式碼的包裝類，對com_android_server_InputManager.cpp介面函式進行包裝，以提供其他java檔案調取。
1.初始化，InputManager.java建構函式中的init()最後呼叫nativeInit(mCallbacks)，
public InputManager
this.mContext = context;
this.mWindowManagerService = windowManagerService;
this.mCallbacks = new Callbacks();
init(); //呼叫init()函式
}
private void init() {
Slog.i(TAG, "Initializing input manager");
nativeInit(mCallbacks); //java介面，由本地函式實現
}
2. 啟動，InputManager.java的start()最後呼叫nativeStart()：
public void start() {
Slog.i(TAG, "Starting input manager");
nativeStart(); //java介面，由本地函式實現
}
四、com_android_server_InputManager.cpp實現InutManager.java的nativeInit(mCallbacks和nativeStart()，當然還實現了其他功能的介面函式，這裡不再介紹，對於android如何實現java和c之間的轉換，我想對於瞭解jni的來說不難理解。不懂的可以看此文章學習：http://hi.baidu.com/kellyvivian/blog/item/09cfb541179d2f3387947397.html
1.初始化，android_server_InputManager_nativeInit在被執行的時候會new一個NativeInputManager(callbacks)例項，NativeInputManager(callbacks)接著又會new一個InputManager(eventHub,
this, this)例項
static void android_server_InputManager_nativeInit(JNIEnv* env, jclass clazz,
jobject callbacks) {
if (gNativeInputManager == NULL) {
gNativeInputManager = new NativeInputManager(callbacks);
} else {
LOGE("Input manager already initialized.");
jniThrowRuntimeException(env, "Input manager already initialized.");
}
}
NativeInputManager::NativeInputManager(jobject callbacksObj) :
mFilterTouchEvents(-1), mFilterJumpyTouchEvents(-1), mVirtualKeyQuietTime(-1),
mMaxEventsPerSecond(-1) {
JNIEnv* env = jniEnv();
mCallbacksObj = env->NewGlobalRef(callbacksObj);
…….
sp<EventHub> eventHub = new EventHub();
mInputManager = new InputManager(eventHub, this, this);
}
2.啟動，android_server_InputManager_nativeStart中gNativeInputManager->getInputManager()->start()最終呼叫的是InputManager.cpp的start()函式
static void android_server_InputManager_nativeStart(JNIEnv* env, jclass clazz) {
if (checkInputManagerUnitialized(env)) {
return;
}
status_t result = gNativeInputManager->getInputManager()->start();
if (result) {
jniThrowRuntimeException(env, "Input manager could not be started.");
}
}
五、InputManager.cpp中主要有三個函式：initialize()初始化函式，在建構函式中呼叫；start()開啟執行緒函式；stop()取消執行緒函式，在虛構函式中呼叫。
1.初始化，InputManager.cpp建構函式呼叫initialize()，期間new一個InputReaderThread執行緒
InputManager::InputManager(
const sp<EventHubInterface>& eventHub,
const sp<InputReaderPolicyInterface>& readerPolicy,
const sp<InputDispatcherPolicyInterface>& dispatcherPolicy) {
mDispatcher = new InputDispatcher(dispatcherPolicy);
mReader = new InputReader(eventHub, readerPolicy, mDispatcher);
initialize();
}
void InputManager::initialize() {
mReaderThread = new InputReaderThread(mReader);
mDispatcherThread = new InputDispatcherThread(mDispatcher);
}
2.啟動，mReaderThread->run("InputReader", PRIORITY_URGENT_DISPLAY)開啟初始化時new的InputReaderThread執行緒
status_t InputManager::start() {
……..
result = mReaderThread->run("InputReader", PRIORITY_URGENT_DISPLAY);
if (result) {
LOGE("Could not start InputReader thread due to error %d.", result);
mDispatcherThread->requestExit();
return result;
}
return OK;
}
六、InputReader.cpp中定義了InputReaderThread類，繼承於Thread類
1.初始化，InputReaderThread建構函式，初始化一個Thread類
InputReaderThread::InputReaderThread(const sp<InputReaderInterface>& reader) :
Thread(/*canCallJava*/ true), mReader(reader) {
}
2.啟動，run啟動執行緒，Thread run()方法又呼叫InputReaderThread 的虛擬函式threadLoop()，接著呼叫InputReader的loopOnce()方法，最後呼叫EventHub.cpp的getEvent(&
rawEvent)方法
bool InputReaderThread::threadLoop() {
mReader->loopOnce();
return true;
}
void InputReader::loopOnce() {
RawEvent rawEvent;
mEventHub->getEvent(& rawEvent);
#if DEBUG_RAW_EVENTS
LOGD("Input event: device=%d type=0x%x scancode=%d keycode=%d value=%d",
rawEvent.deviceId, rawEvent.type, rawEvent.scanCode, rawEvent.keyCode,
rawEvent.value);
#endif
process(& rawEvent);
}
七、EventHub.cpp是android輸入系統的硬體抽象層，維護輸入裝置的執行，包括Keyboard、 TouchScreen、TraceBall等。
EventHub.cpp中依次執行getEvent()–>openPlatformInput()–>scanDir(DEVICE_PATH)–> openDevice(devname)
bool EventHub::openPlatformInput(void) {
/*
* Open platform-specific input device(s).
*/
int res, fd;
………
// Reserve fd index 0 for inotify.
struct pollfd pollfd;
pollfd.fd = fd;
pollfd.events = POLLIN;
pollfd.revents = 0;
mFds.push(pollfd);
mDevices.push(NULL);
res = scanDir(DEVICE_PATH); //DEVICE_PATH = "/dev/input"
if(res < 0) {
LOGE("scan dir failed for %s\n", DEVICE_PATH);
}
return true;
}
int EventHub::scanDir(const char *dirname)
{
……
openDevice(devname);
}
closedir(dir);
return 0;
}
openDevice方法會開啟/dev/input目錄下的所有裝置檔案，讀取name、version、id等裝置資訊，然後執行loadConfiguration()方法，如果鍵盤裝置就會執行loadKeyMap()這個方法
int EventHub::openDevice(const char *devicePath) {
……
// Load the configuration file for the device.
loadConfiguration(device);
……
if ((device->classes & INPUT_DEVICE_CLASS_KEYBOARD) != 0) {
// Load the keymap for the device.
status_t status = loadKeyMap(device);
……
}
……
}
Honeycomb與之前版本不同之處是加入loadConfiguration()方法，它獲取與當前裝置驅動Vendor、Product、Version匹配的配置檔名，或者是Vendor、Product匹配的配置檔名，具體可檢視Input.cpp中getInputDeviceConfigurationFilePathByDeviceIdentifie和getInputDeviceConfigurationFilePathByName方法。
如： kernel/ drivers/input/keyboard/atkbd.c鍵盤驅動中定義了 input_dev->id.vendor = 0×0001; input_dev->id.product = 0×0001;
input_dev->id.version = 0xab41，那麼與之對應的配置名為Vendor_0001_Product_0001_Version_ad41.idc，返回這個檔案的全路徑並賦值給device->configurationFile。如果/system/user/idc下存在此檔案，接下來呼叫PropertyMap.cpp的load()方法解析該配置檔案並將解析後的資訊儲存到device->configuration中。
void EventHub::loadConfiguration(Device* device) {
device->configurationFile = getInputDeviceConfigurationFilePathByDeviceIdentifier(
device->identifier, INPUT_DEVICE_CONFIGURATION_FILE_TYPE_CONFIGURATION);
if (device->configurationFile.isEmpty()) {
LOGD("No input device configuration file found for device ‘%s’.",
device->identifier.name.string());
} else {
status_t status = PropertyMap::load(device->configurationFile,
&device->configuration);
if (status) {
LOGE("Error loading input device configuration file for device ‘%s’. "
"Using default configuration.",
device->identifier.name.string());
}
}
}
EventHub.cpp中loadKeyMap又呼叫了Keyboard.cpp的KeyMap::load()方法
status_t EventHub::loadKeyMap(Device* device) {
return device->keyMap.load(device->identifier, device->configuration);
}
八、在Keyboard.cpp的load方法中，首先判斷deviceConfiguration引數是否為空，deviceConfiguration的賦值就是上面loadConfiguration()方法所做的工作。
如果有.idc的配置檔案，那麼獲取key為keyboard.layout的value給keyLayoutName和key為keyboard.characterMap的value給keyCharacterMapName，最後呼叫loadKeyLayout和loadKeyCharacterMap方法載入此鍵盤佈局檔案；如果沒有對應的.idc配置檔案，則deviceConfiguration為空，就會接著執行probeKeyMap(deviceIdenfifier,
String8("Generic"))方法
status_t KeyMap::load(const InputDeviceIdentifier& deviceIdenfifier,
const PropertyMap* deviceConfiguration) {
// Use the configured key layout if available.
if (deviceConfiguration) {
String8 keyLayoutName;
if (deviceConfiguration->tryGetProperty(String8("keyboard.layout"),
keyLayoutName)) {
status_t status = loadKeyLayout(deviceIdenfifier, keyLayoutName);
if (status == NAME_NOT_FOUND) {
LOGE("Configuration for keyboard device ‘%s’ requested keyboard layout ‘%s’ but "
"it was not found.",
deviceIdenfifier.name.string(), keyLayoutName.string());
}
}
String8 keyCharacterMapName;
if (deviceConfiguration->tryGetProperty(String8("keyboard.characterMap"),
keyCharacterMapName)) {
status_t status = loadKeyCharacterMap(deviceIdenfifier, keyCharacterMapName);
if (status == NAME_NOT_FOUND) {
LOGE("Configuration for keyboard device ‘%s’ requested keyboard character "
"map ‘%s’ but it was not found.",
deviceIdenfifier.name.string(), keyLayoutName.string());
}
}
if (isComplete()) {
return OK;
}
}
……
if (probeKeyMap(deviceIdenfifier, String8("Generic"))) {
return OK;
}
……
}
probeKeyMap方法判斷名為Gerneric的佈局檔案是否存在，若存在就會呼叫loadKeyLayout和loadKeyCharacterMap方法載入此鍵盤佈局檔案
bool KeyMap::probeKeyMap(const InputDeviceIdentifier& deviceIdentifier,
const String8& keyMapName) {
if (!haveKeyLayout()) {
loadKeyLayout(deviceIdentifier, keyMapName);
}
if (!haveKeyCharacterMap()) {
loadKeyCharacterMap(deviceIdentifier, keyMapName);
}
return isComplete();
}
至此，Android Honeycomb已經正確載入了鍵盤佈局檔案，那麼我們如何定製和使用自己的鍵盤佈局檔案呢？