android键盘映射之一

一时失言乱红尘 2022-06-13 08:22 163阅读 0赞

**按键事件**

对于按键事件，调用mDevices->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。  
C代码：

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。  
Java代码:

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;

// block, doesn't release the monitor  
                    readEvent(ev);

boolean send = false;  
                    boolean configChanged = false;  
                      
                    if (false) \{  
                        Log.i(TAG, "Input event: dev=0x"  
                                + Integer.toHexString(ev.deviceId)  
                                + " type=0x" + Integer.toHexString(ev.type)  
                                + " scancode=" + ev.scancode  
                                + " keycode=" + ev.keycode  
                                + " value=" + ev.value);  
                    \}  
                      
                    if (ev.type == RawInputEvent.EV\_DEVICE\_ADDED) \{  
                        synchronized (mFirst) \{  
                            di = newInputDevice(ev.deviceId);  
                            mDevices.put(ev.deviceId, di);  
                            configChanged = true;  
                        \}  
                    \}

......

\};