Android 4.2 Input Event事件處理流程---應用註冊
阿新 • • 發佈：2019-02-14
一個應用要接受Android的各種input訊息，就需要將自己註冊進去，這樣底層收到訊息後才後將訊息發給應用，應用註冊要接受訊息是在setView中觸發的。看下這個流程：
setView由WindowManagerGlobal呼叫,setView是啟動Activity過程中呼叫的：
handleLaunchActivity-->handleResumeActivity--> WindowManagerImpl.addView(decor, l)-->WindowManagerGlobal.addView(view, params, mDisplay, mParentWindow)--> root.setView(view, wparams, panelParentView);我們看一下setView
public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) { synchronized (this) { if (mView == null) { mView = view; mViewLayoutDirectionInitial = mView.getRawLayoutDirection(); mFallbackEventHandler.setView(view); mWindowAttributes.copyFrom(attrs); attrs = mWindowAttributes; // Keep track of the actual window flags supplied by the client. mClientWindowLayoutFlags = attrs.flags; setAccessibilityFocus(null, null); if (view instanceof RootViewSurfaceTaker) { mSurfaceHolderCallback = ((RootViewSurfaceTaker)view).willYouTakeTheSurface(); if (mSurfaceHolderCallback != null) { mSurfaceHolder = new TakenSurfaceHolder(); mSurfaceHolder.setFormat(PixelFormat.UNKNOWN); } } CompatibilityInfo compatibilityInfo = mCompatibilityInfo.get(); mTranslator = compatibilityInfo.getTranslator(); // If the application owns the surface, don't enable hardware acceleration if (mSurfaceHolder == null) { enableHardwareAcceleration(mView.getContext(), attrs); } boolean restore = false; if (mTranslator != null) { mSurface.setCompatibilityTranslator(mTranslator); restore = true; attrs.backup(); mTranslator.translateWindowLayout(attrs); } if (DEBUG_LAYOUT) Log.d(TAG, "WindowLayout in setView:" + attrs); if (!compatibilityInfo.supportsScreen()) { attrs.flags |= WindowManager.LayoutParams.FLAG_COMPATIBLE_WINDOW; mLastInCompatMode = true; } mSoftInputMode = attrs.softInputMode; mWindowAttributesChanged = true; mWindowAttributesChangesFlag = WindowManager.LayoutParams.EVERYTHING_CHANGED; mAttachInfo.mRootView = view; mAttachInfo.mScalingRequired = mTranslator != null; mAttachInfo.mApplicationScale = mTranslator == null ? 1.0f : mTranslator.applicationScale; if (panelParentView != null) { mAttachInfo.mPanelParentWindowToken = panelParentView.getApplicationWindowToken(); } mAdded = true; int res; /* = WindowManagerImpl.ADD_OKAY; */ // Schedule the first layout -before- adding to the window // manager, to make sure we do the relayout before receiving // any other events from the system. requestLayout(); if ((mWindowAttributes.inputFeatures & WindowManager.LayoutParams.INPUT_FEATURE_NO_INPUT_CHANNEL) == 0) { mInputChannel = new InputChannel(); } try { mOrigWindowType = mWindowAttributes.type; mAttachInfo.mRecomputeGlobalAttributes = true; collectViewAttributes(); res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes, getHostVisibility(), mDisplay.getDisplayId(), mAttachInfo.mContentInsets, mInputChannel); } catch (RemoteException e) { mAdded = false; mView = null; mAttachInfo.mRootView = null; mInputChannel = null; mFallbackEventHandler.setView(null); unscheduleTraversals(); setAccessibilityFocus(null, null); throw new RuntimeException("Adding window failed", e); } finally { if (restore) { attrs.restore(); } } if (mTranslator != null) { mTranslator.translateRectInScreenToAppWindow(mAttachInfo.mContentInsets); } mPendingContentInsets.set(mAttachInfo.mContentInsets); mPendingVisibleInsets.set(0, 0, 0, 0); if (DEBUG_LAYOUT) Log.v(TAG, "Added window " + mWindow); if (res < WindowManagerGlobal.ADD_OKAY) { mAttachInfo.mRootView = null; mAdded = false; mFallbackEventHandler.setView(null); unscheduleTraversals(); setAccessibilityFocus(null, null); switch (res) { case WindowManagerGlobal.ADD_BAD_APP_TOKEN: case WindowManagerGlobal.ADD_BAD_SUBWINDOW_TOKEN: throw new WindowManager.BadTokenException( "Unable to add window -- token " + attrs.token + " is not valid; is your activity running?"); case WindowManagerGlobal.ADD_NOT_APP_TOKEN: throw new WindowManager.BadTokenException( "Unable to add window -- token " + attrs.token + " is not for an application"); case WindowManagerGlobal.ADD_APP_EXITING: throw new WindowManager.BadTokenException( "Unable to add window -- app for token " + attrs.token + " is exiting"); case WindowManagerGlobal.ADD_DUPLICATE_ADD: throw new WindowManager.BadTokenException( "Unable to add window -- window " + mWindow + " has already been added"); case WindowManagerGlobal.ADD_STARTING_NOT_NEEDED: // Silently ignore -- we would have just removed it // right away, anyway. return; case WindowManagerGlobal.ADD_MULTIPLE_SINGLETON: throw new WindowManager.BadTokenException( "Unable to add window " + mWindow + " -- another window of this type already exists"); case WindowManagerGlobal.ADD_PERMISSION_DENIED: throw new WindowManager.BadTokenException( "Unable to add window " + mWindow + " -- permission denied for this window type"); case WindowManagerGlobal.ADD_INVALID_DISPLAY: throw new WindowManager.InvalidDisplayException( "Unable to add window " + mWindow + " -- the specified display can not be found"); } throw new RuntimeException( "Unable to add window -- unknown error code " + res); } if (view instanceof RootViewSurfaceTaker) { mInputQueueCallback = ((RootViewSurfaceTaker)view).willYouTakeTheInputQueue(); } if (mInputChannel != null) { if (mInputQueueCallback != null) { mInputQueue = new InputQueue(mInputChannel); mInputQueueCallback.onInputQueueCreated(mInputQueue); } else { mInputEventReceiver = new WindowInputEventReceiver(mInputChannel, Looper.myLooper()); } } view.assignParent(this); mAddedTouchMode = (res & WindowManagerGlobal.ADD_FLAG_IN_TOUCH_MODE) != 0; mAppVisible = (res & WindowManagerGlobal.ADD_FLAG_APP_VISIBLE) != 0; if (mAccessibilityManager.isEnabled()) { mAccessibilityInteractionConnectionManager.ensureConnection(); } if (view.getImportantForAccessibility() == View.IMPORTANT_FOR_ACCESSIBILITY_AUTO) { view.setImportantForAccessibility(View.IMPORTANT_FOR_ACCESSIBILITY_YES); } } } }
關的邏輯主要有三處，一是呼叫requestLayout函式來通知InputManager，這個Activity視窗是當前被啟用的視窗，二是呼叫sWindowSession（WindowManagerService內部類Session的遠端介面）的addToDisplay成員函式來把鍵盤訊息接收通道的一端註冊在InputManager中，三是呼叫InputQueue的registerInputChannel成員函式來把鍵盤訊息接收通道的另一端註冊在本應用程式的訊息迴圈（Looper）中。這樣，當InputManager監控到有鍵盤訊息時，就會先找到當前被啟用的視窗，然後找到其在InputManager中對應的鍵盤訊息接收通道，通過這個通道在InputManager中的一端來通知在應用程式訊息迴圈中的另一端，就把鍵盤訊息分發給當前啟用的Activity視窗了。
requestLayout最終會呼叫到WindowManagerService的relayoutWindow
public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
public int relayoutWindow(Session session, IWindow client,
WindowManager.LayoutParams attrs, int requestedWidth,
int requestedHeight, int viewVisibility, boolean insetsPending,
Rect outFrame, Rect outContentInsets, Rect outVisibleInsets,
Configuration outConfig, Surface outSurface) {
......
synchronized(mWindowMap) {
......
mInputMonitor.updateInputWindowsLw();
}
......
}
......
} /* Updates the cached window information provided to the input dispatcher. */
public void updateInputWindowsLw(boolean force) {
if (!force && !mUpdateInputWindowsNeeded) {
return;
}
mUpdateInputWindowsNeeded = false;
if (false) Slog.d(WindowManagerService.TAG, ">>>>>> ENTERED updateInputWindowsLw");
// Populate the input window list with information about all of the windows that
// could potentially receive input.
// As an optimization, we could try to prune the list of windows but this turns
// out to be difficult because only the native code knows for sure which window
// currently has touch focus.
final WindowStateAnimator universeBackground = mService.mAnimator.mUniverseBackground;
final int aboveUniverseLayer = mService.mAnimator.mAboveUniverseLayer;
boolean addedUniverse = false;
// If there's a drag in flight, provide a pseudowindow to catch drag input
final boolean inDrag = (mService.mDragState != null);
if (inDrag) {
if (WindowManagerService.DEBUG_DRAG) {
Log.d(WindowManagerService.TAG, "Inserting drag window");
}
final InputWindowHandle dragWindowHandle = mService.mDragState.mDragWindowHandle;
if (dragWindowHandle != null) {
addInputWindowHandleLw(dragWindowHandle);
} else {
Slog.w(WindowManagerService.TAG, "Drag is in progress but there is no "
+ "drag window handle.");
}
}
final int NFW = mService.mFakeWindows.size();
for (int i = 0; i < NFW; i++) {
addInputWindowHandleLw(mService.mFakeWindows.get(i).mWindowHandle);
}
// Add all windows on the default display.
final AllWindowsIterator iterator = mService.new AllWindowsIterator(
WindowManagerService.REVERSE_ITERATOR);
while (iterator.hasNext()) {
final WindowState child = iterator.next();
final InputChannel inputChannel = child.mInputChannel;
final InputWindowHandle inputWindowHandle = child.mInputWindowHandle;
if (inputChannel == null || inputWindowHandle == null || child.mRemoved) {
// Skip this window because it cannot possibly receive input.
continue;
}
final int flags = child.mAttrs.flags;
final int type = child.mAttrs.type;
final boolean hasFocus = (child == mInputFocus);
final boolean isVisible = child.isVisibleLw();
final boolean hasWallpaper = (child == mService.mWallpaperTarget)
&& (type != WindowManager.LayoutParams.TYPE_KEYGUARD);
final boolean onDefaultDisplay = (child.getDisplayId() == Display.DEFAULT_DISPLAY);
// If there's a drag in progress and 'child' is a potential drop target,
// make sure it's been told about the drag
if (inDrag && isVisible && onDefaultDisplay) {
mService.mDragState.sendDragStartedIfNeededLw(child);
}
if (universeBackground != null && !addedUniverse
&& child.mBaseLayer < aboveUniverseLayer && onDefaultDisplay) {
final WindowState u = universeBackground.mWin;
if (u.mInputChannel != null && u.mInputWindowHandle != null) {
addInputWindowHandleLw(u.mInputWindowHandle, u, u.mAttrs.flags,
u.mAttrs.type, true, u == mInputFocus, false);
}
addedUniverse = true;
}
if (child.mWinAnimator != universeBackground) {
addInputWindowHandleLw(inputWindowHandle, child, flags, type,
isVisible, hasFocus, hasWallpaper);
}
}
// Send windows to native code.
mService.mInputManager.setInputWindows(mInputWindowHandles);
// Clear the list in preparation for the next round.
clearInputWindowHandlesLw();
if (false) Slog.d(WindowManagerService.TAG, "<<<<<<< EXITED updateInputWindowsLw");
}void InputDispatcher::setInputWindows(const Vector<sp<InputWindowHandle> >& inputWindowHandles) {
#if DEBUG_FOCUS
ALOGD("setInputWindows");
#endif
{ // acquire lock
AutoMutex _l(mLock);
Vector<sp<InputWindowHandle> > oldWindowHandles = mWindowHandles;
mWindowHandles = inputWindowHandles;
sp<InputWindowHandle> newFocusedWindowHandle;
bool foundHoveredWindow = false;
for (size_t i = 0; i < mWindowHandles.size(); i++) {
const sp<InputWindowHandle>& windowHandle = mWindowHandles.itemAt(i);
if (!windowHandle->updateInfo() || windowHandle->getInputChannel() == NULL) {
mWindowHandles.removeAt(i--);
continue;
}
if (windowHandle->getInfo()->hasFocus) {
newFocusedWindowHandle = windowHandle;
}
if (windowHandle == mLastHoverWindowHandle) {
foundHoveredWindow = true;
}
}
if (!foundHoveredWindow) {
mLastHoverWindowHandle = NULL;
}
if (mFocusedWindowHandle != newFocusedWindowHandle) {
if (mFocusedWindowHandle != NULL) {
#if DEBUG_FOCUS
ALOGD("Focus left window: %s",
mFocusedWindowHandle->getName().string());
#endif
sp<InputChannel> focusedInputChannel = mFocusedWindowHandle->getInputChannel();
if (focusedInputChannel != NULL) {
CancelationOptions options(CancelationOptions::CANCEL_NON_POINTER_EVENTS,
"focus left window");
synthesizeCancelationEventsForInputChannelLocked(
focusedInputChannel, options);
}
}
if (newFocusedWindowHandle != NULL) {
#if DEBUG_FOCUS
ALOGD("Focus entered window: %s",
newFocusedWindowHandle->getName().string());
#endif
}
mFocusedWindowHandle = newFocusedWindowHandle;
}
for (size_t i = 0; i < mTouchState.windows.size(); i++) {
TouchedWindow& touchedWindow = mTouchState.windows.editItemAt(i);
if (!hasWindowHandleLocked(touchedWindow.windowHandle)) {
#if DEBUG_FOCUS
ALOGD("Touched window was removed: %s",
touchedWindow.windowHandle->getName().string());
#endif
sp<InputChannel> touchedInputChannel =
touchedWindow.windowHandle->getInputChannel();
if (touchedInputChannel != NULL) {
CancelationOptions options(CancelationOptions::CANCEL_POINTER_EVENTS,
"touched window was removed");
synthesizeCancelationEventsForInputChannelLocked(
touchedInputChannel, options);
}
mTouchState.windows.removeAt(i--);
}
}
// Release information for windows that are no longer present.
// This ensures that unused input channels are released promptly.
// Otherwise, they might stick around until the window handle is destroyed
// which might not happen until the next GC.
for (size_t i = 0; i < oldWindowHandles.size(); i++) {
const sp<InputWindowHandle>& oldWindowHandle = oldWindowHandles.itemAt(i);
if (!hasWindowHandleLocked(oldWindowHandle)) {
#if DEBUG_FOCUS
ALOGD("Window went away: %s", oldWindowHandle->getName().string());
#endif
oldWindowHandle->releaseInfo();
}
}
} // release lock
// Wake up poll loop since it may need to make new input dispatching choices.
mLooper->wake();
}回到Step
1中的ViewRoot.setView函式中，接下來就呼叫addToDisplay冊鍵盤訊息接收通道的一端到InputManagerService中去,addToDisplay最終呼叫WindowManagerService的addWindow
public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor {
......
public int addWindow(Session session, IWindow client,
WindowManager.LayoutParams attrs, int viewVisibility,
Rect outContentInsets, InputChannel outInputChannel) {
......
WindowState win = null;
synchronized(mWindowMap) {
......
win = new WindowState(session, client, token,
attachedWindow, attrs, viewVisibility);
......
if (outInputChannel != null) {
String name = win.makeInputChannelName();
InputChannel[] inputChannels = InputChannel.openInputChannelPair(name);
win.mInputChannel = inputChannels[0];
inputChannels[1].transferToBinderOutParameter(outInputChannel);
mInputManager.registerInputChannel(win.mInputChannel);
}
......
}
......
}
......
}建立輸入通道之前，WindowManagerService會為當前Activity視窗建立一個WindowState物件win，用來記錄這個Activity視窗的狀態資訊。當建立這對輸入管道成功以後，也會把其中的一個管道儲存在這個WindowState物件win的成員變數mInputChannel中
接下來我們就看一下InputChannel.openInputChannelPair函式的實現。最終呼叫到Jni層的android_view_InputChannel_nativeOpenInputChannelPair
static jobjectArray android_view_InputChannel_nativeOpenInputChannelPair(JNIEnv* env,
jclass clazz, jstring nameObj) {
const char* nameChars = env->GetStringUTFChars(nameObj, NULL);
String8 name(nameChars);
env->ReleaseStringUTFChars(nameObj, nameChars);
sp<InputChannel> serverChannel;
sp<InputChannel> clientChannel;
status_t result = InputChannel::openInputChannelPair(name, serverChannel, clientChannel);
if (result) {
String8 message;
message.appendFormat("Could not open input channel pair. status=%d", result);
jniThrowRuntimeException(env, message.string());
return NULL;
}
jobjectArray channelPair = env->NewObjectArray(2, gInputChannelClassInfo.clazz, NULL);
if (env->ExceptionCheck()) {
return NULL;
}
jobject serverChannelObj = android_view_InputChannel_createInputChannel(env,
new NativeInputChannel(serverChannel));
if (env->ExceptionCheck()) {
return NULL;
}
jobject clientChannelObj = android_view_InputChannel_createInputChannel(env,
new NativeInputChannel(clientChannel));
if (env->ExceptionCheck()) {
return NULL;
}
env->SetObjectArrayElement(channelPair, 0, serverChannelObj);
env->SetObjectArrayElement(channelPair, 1, clientChannelObj);
return channelPair;
}status_t InputChannel::openInputChannelPair(const String8& name,
sp<InputChannel>& outServerChannel, sp<InputChannel>& outClientChannel) {
int sockets[2];
if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sockets)) {
status_t result = -errno;
ALOGE("channel '%s' ~ Could not create socket pair. errno=%d",
name.string(), errno);
outServerChannel.clear();
outClientChannel.clear();
return result;
}
int bufferSize = SOCKET_BUFFER_SIZE;
setsockopt(sockets[0], SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
setsockopt(sockets[0], SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize));
setsockopt(sockets[1], SOL_SOCKET, SO_SNDBUF, &bufferSize, sizeof(bufferSize));
setsockopt(sockets[1], SOL_SOCKET, SO_RCVBUF, &bufferSize, sizeof(bufferSize));
String8 serverChannelName = name;
serverChannelName.append(" (server)");
outServerChannel = new InputChannel(serverChannelName, sockets[0]);
String8 clientChannelName = name;
clientChannelName.append(" (client)");
outClientChannel = new InputChannel(clientChannelName, sockets[1]);
return OK;
}這裡通過建立一對匿名的已經連線的套接字，並對這對套接字進行一些設定。這樣，這對套接字就已經建立好了，回到WindowManagerService，接下來呼叫setInputChannel設定到WindowState物件中，然後掉用registerInputChannel註冊到inputManagerService,registerInputChannel最終呼叫JNI層的NativeInputManager::registerInputChannel
status_t NativeInputManager::registerInputChannel(JNIEnv* env,
const sp<InputChannel>& inputChannel,
const sp<InputWindowHandle>& inputWindowHandle, bool monitor) {
return mInputManager->getDispatcher()->registerInputChannel(
inputChannel, inputWindowHandle, monitor);
}status_t InputDispatcher::registerInputChannel(const sp<InputChannel>& inputChannel,
const sp<InputWindowHandle>& inputWindowHandle, bool monitor) {
#if DEBUG_REGISTRATION
ALOGD("channel '%s' ~ registerInputChannel - monitor=%s", inputChannel->getName().string(),
toString(monitor));
#endif
{ // acquire lock
AutoMutex _l(mLock);
if (getConnectionIndexLocked(inputChannel) >= 0) {
ALOGW("Attempted to register already registered input channel '%s'",
inputChannel->getName().string());
return BAD_VALUE;
}
sp<Connection> connection = new Connection(inputChannel, inputWindowHandle, monitor);
int fd = inputChannel->getFd();
mConnectionsByFd.add(fd, connection);
if (monitor) {
mMonitoringChannels.push(inputChannel);
}
mLooper->addFd(fd, 0, ALOOPER_EVENT_INPUT, handleReceiveCallback, this);
} // release lock
// Wake the looper because some connections have changed.
mLooper->wake();
return OK;
}這裡通過Looper類的addFd成函式新增進去的了，在新增的時候，指定回撥函式handleReceiveCallback，即當這個檔案描述符所指向的檔案有新的內容可讀時，Looper就會呼叫這個hanldeReceiveCallback函式，
分析到這裡，Server端的InputChannel就註冊完成了，我們再看一下Client端通道的註冊流程，回到setView，接下來呼叫
mInputEventReceiver = new WindowInputEventReceiver(mInputChannel,
Looper.myLooper());
註冊Client端的通道，WindowInputEventReceiver繼承於InputEventReceiver，最終會呼叫基類的建構函式
public InputEventReceiver(InputChannel inputChannel, Looper looper) {
if (inputChannel == null) {
throw new IllegalArgumentException("inputChannel must not be null");
}
if (looper == null) {
throw new IllegalArgumentException("looper must not be null");
}
mInputChannel = inputChannel;
mMessageQueue = looper.getQueue();
mReceiverPtr = nativeInit(this, inputChannel, mMessageQueue);
mCloseGuard.open("dispose");
}static jint nativeInit(JNIEnv* env, jclass clazz, jobject receiverObj,
jobject inputChannelObj, jobject messageQueueObj) {
sp<InputChannel> inputChannel = android_view_InputChannel_getInputChannel(env,
inputChannelObj);
if (inputChannel == NULL) {
jniThrowRuntimeException(env, "InputChannel is not initialized.");
return 0;
}
sp<MessageQueue> messageQueue = android_os_MessageQueue_getMessageQueue(env, messageQueueObj);
if (messageQueue == NULL) {
jniThrowRuntimeException(env, "MessageQueue is not initialized.");
return 0;
}
sp<NativeInputEventReceiver> receiver = new NativeInputEventReceiver(env,
receiverObj, inputChannel, messageQueue);
status_t status = receiver->initialize();
if (status) {
String8 message;
message.appendFormat("Failed to initialize input event receiver. status=%d", status);
jniThrowRuntimeException(env, message.string());
return 0;
}
receiver->incStrong(gInputEventReceiverClassInfo.clazz); // retain a reference for the object
return reinterpret_cast<jint>(receiver.get());
}
status_t NativeInputEventReceiver::initialize() {
int receiveFd = mInputConsumer.getChannel()->getFd();
mMessageQueue->getLooper()->addFd(receiveFd, 0, ALOOPER_EVENT_INPUT, this, NULL);
return OK;
}到這裡通道就已經註冊好了，我們後面再看input訊息是是怎麼傳給應用的。