1.Java层事件分发
1.1在 "APP客户端注册触膜/键盘事件监听"这篇讲了事件注册的整体流程，但具体接收到事件后APP是怎么处理的？接下来我们重点分析
a.13行addToDisplay调用到WMS
b.WMS创建好Socketpair后，把他的一端返回到app既mInputChannel
c.app马上就创建WindowInputEventReceiver来监听mInputChannel既23行
d.如果有Event就会回调34行onInputEvent函数
e.经过一系列内部发方法最后85行调用deliverInputEvent，这里面会有责任链模式把所有stage链式调度一遍
f.最后调用到了processPointerEvent函数的77行，既Docerview的dispatchPointerEvent
ViewRootImpl.java
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, ThreadedRenderer.DrawCallbacks {
public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
...
requestLayout();
if ((mWindowAttributes.inputFeatures
& WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL) == 0) {
mInputChannel = new InputChannel();
}
...
//addToDisplay发起Binder调用，wms端肯定也会有对应函数响应
res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
getHostVisibility(), mDisplay.getDisplayId(),
mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
mAttachInfo.mOutsets, mInputChannel);
...
if (mInputChannel != null) {
if (mInputQueueCallback != null) {
mInputQueue = new InputQueue();
mInputQueueCallback.onInputQueueCreated(mInputQueue);
}
mInputEventReceiver = new WindowInputEventReceiver(mInputChannel,
Looper.myLooper());
}
...
}
final class WindowInputEventReceiver extends InputEventReceiver {
public WindowInputEventReceiver(InputChannel inputChannel, Looper looper) {
super(inputChannel, looper);
}
@Override
public void onInputEvent(InputEvent event, int displayId) {
enqueueInputEvent(event, this, 0, true);
}
...
}
void enqueueInputEvent(InputEvent event,
InputEventReceiver receiver, int flags, boolean processImmediately) {
...
doProcessInputEvents();
}
void doProcessInputEvents() {
...
deliverInputEvent(q);
}
}
private void deliverInputEvent(QueuedInputEvent q) {
...
stage.deliver(q);
...
}
abstract class InputStage {
...
public final void deliver(QueuedInputEvent q) {
...
apply(q, onProcess(q));
}
...
}
final class ViewPostImeInputStage extends InputStage {
protected int onProcess(QueuedInputEvent q) {
...
return processPointerEvent(q);
...
}
private int processPointerEvent(QueuedInputEvent q) {
final MotionEvent event = (MotionEvent)q.mEvent;
mAttachInfo.mUnbufferedDispatchRequested = false;
mAttachInfo.mHandlingPointerEvent = true;
//看到了曙光mView就是Docerview
boolean handled = mView.dispatchPointerEvent(event);
maybeUpdatePointerIcon(event);
maybeUpdateTooltip(event);
mAttachInfo.mHandlingPointerEvent = false;
if (mAttachInfo.mUnbufferedDispatchRequested && !mUnbufferedInputDispatch) {
mUnbufferedInputDispatch = true;
if (mConsumeBatchedInputScheduled) {
scheduleConsumeBatchedInputImmediately();
}
}
return handled ? FINISH_HANDLED : FORWARD;
}
}
}
View.java
public class View implements Drawable.Callback, KeyEvent.Callback,AccessibilityEventSource{
...
public final boolean dispatchPointerEvent(MotionEvent event) {
if (event.isTouchEvent()) {
//终于到了dispatchTouchEvent
return dispatchTouchEvent(event);
} else {
return dispatchGenericMotionEvent(event);
}
}
public boolean dispatchTouchEvent(MotionEvent event) {
...
if (onFilterTouchEventForSecurity(event)) {
...
if (!result && onTouchEvent(event)) {
result = true;
}
}
...
return result;
}
}
2.C++接受事件转到java处理
2.1InputEventReceiver 构造函数调用了nativeInit函数进入native层
InputEventReceiver.java
public abstract class InputEventReceiver {
...
public InputEventReceiver(InputChannel inputChannel, Looper looper) {
mInputChannel = inputChannel;
mMessageQueue = looper.getQueue();
mReceiverPtr = nativeInit(new WeakReference<InputEventReceiver>(this),
inputChannel, mMessageQueue);
}
private void dispatchInputEvent(int seq, InputEvent event, int displayId) {
mSeqMap.put(event.getSequenceNumber(), seq);
onInputEvent(event, displayId);
}
...
}
2.2Native里面创建了与Java层InputEventReceiver对象相对应的NativeInputEventReceiver，这是Android一惯的的套路
android_view_InputEventReceiver.cpp
static jlong nativeInit(JNIEnv* env, jclass clazz, jobject receiverWeak,
jobject inputChannelObj, jobject messageQueueObj) {
sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env,
inputChannelObj);
...
sp<MessageQueue> messageQueue = android_os_MessageQueue_getMessageQueue(env, messageQueueObj);
...
sp<NativeInputEventReceiver> receiver = new NativeInputEventReceiver(env,
receiverWeak, inputChannel, messageQueue);
status_t status = receiver->initialize();
...
}
2.3关键代码addFd(fd, 0, events, this, NULL);这一步是把InputChannel(socket)的文件描述符fd添加的主线程的事件处理Looper中做监听，只要有事件就会调用回调即this,
android_view_InputEventReceiver.cpp
NativeInputEventReceiver::NativeInputEventReceiver(JNIEnv* env,
jobject receiverWeak, const sp<InputChannel>& inputChannel,
const sp<MessageQueue>& messageQueue) :
mReceiverWeakGlobal(env->NewGlobalRef(receiverWeak)),
mInputConsumer(inputChannel), mMessageQueue(messageQueue),
mBatchedInputEventPending(false), mFdEvents(0) {
}
status_t NativeInputEventReceiver::initialize() {
setFdEvents(ALOOPER_EVENT_INPUT);
return OK;
}
void NativeInputEventReceiver::setFdEvents(int events) {
if (mFdEvents != events) {
mFdEvents = events;
int fd = mInputConsumer.getChannel()->getFd();
if (events) {
//这里的this就会回调到1.6的consumeEvents
mMessageQueue->getLooper()->addFd(fd, 0, events, this, NULL);
} else {
mMessageQueue->getLooper()->removeFd(fd);
}
}
}
int NativeInputEventReceiver::handleEvent(int receiveFd, int events, void* data) {
...
if (events & ALOOPER_EVENT_INPUT) {
JNIEnv* env = AndroidRuntime::getJNIEnv();
status_t status = consumeEvents(env, false /*consumeBatches*/, -1, NULL);
mMessageQueue->raiseAndClearException(env, "handleReceiveCallback");
return status == OK || status == NO_MEMORY ? 1 : 0;
}
...
}
2.4读取事件并回到Java
a.第37行会调用到2.1 11 到15行dispatchInputEvent
b.dispatchInputEvent会调用到1.1 31到35行onInputEvent回到了1.1流程直到view的dispatchPointerEvent
status_t NativeInputEventReceiver::consumeEvents(JNIEnv* env,
bool consumeBatches, nsecs_t frameTime, bool* outConsumedBatch) {
...
for (;;) {
uint32_t seq;
InputEvent* inputEvent;
int32_t displayId;
//从文件描述符读取事件赋值给inputEvent
status_t status = mInputConsumer.consume(&mInputEventFactory,
consumeBatches, frameTime, &seq, &inputEvent, &displayId);
...
jobject inputEventObj;
switch (inputEvent->getType()) {
case AINPUT_EVENT_TYPE_KEY:
...
inputEventObj = android_view_KeyEvent_fromNative(env,
static_cast<KeyEvent*>(inputEvent));
break;
case AINPUT_EVENT_TYPE_MOTION: {
...
//下面只是拷贝一份事件无他
MotionEvent* motionEvent = static_cast<MotionEvent*>(inputEvent);
if ((motionEvent->getAction() & AMOTION_EVENT_ACTION_MOVE) && outConsumedBatch) {
*outConsumedBatch = true;
}
inputEventObj = android_view_MotionEvent_obtainAsCopy(env, motionEvent);
break;
}
default:
assert(false); // InputConsumer should prevent this from ever happening
inputEventObj = NULL;
}
...
//关键代码回调到Java层，InputEventReceiver.java的dispatchInputEvent方法中
env->CallVoidMethod(receiverObj.get(),
gInputEventReceiverClassInfo.dispatchInputEvent, seq, inputEventObj,
displayId);
...
}
}
2.总结
1.App添加窗口时会向wms请求，wms会创建一个socketpair的俩端一个端发给返回app，一端注册到InputManagerService中，当InputManagerService收到事件的时候就会通过socket夸进程通信，传回app端对应窗口
2.APP端会把得到socket文件描述符添加Looper中监听，当有事件时候会从c++层反射回调Java 层 的InputEventReceiver的dispatchInputEvent方法中
3.InputEventReceiver是ViewRoot的内部类，DecorView是ViewRoot 的成员变量。dispatchInputEvent经过一系列调用最终取到DecorView，调用DecorView的dispatchTouchEvent把事件分发
