Android InputMethod 原始碼分析，顯示輸入法流程
阿新 • • 發佈：2019-01-17
1.簡介
大體流程如下：
- InputMethodManagerService（下文也稱IMMS）負責管理系統的所有輸入法，包括輸入法service(InputMethodService簡稱IMS)載入及切換。
- 程式獲得焦點時，就會通過 InputMethodManager 向 InputMethodManagerService 發出請求繫結自己到當前輸入法上。
- 當程式的某個需要輸入法的view比如 EditView 獲得焦點時，就會通過 InputMethodManager 向 InputMethodManagerService 請求顯示輸入法，而這時 InputMethodManagerService 收到請求後，會將請求的 EditText 的資料通訊介面傳送給當前輸入法，並請求顯示輸入法。輸入法收到請求後，就顯示自己的 UI dialog,同時儲存目標 view 的資料結構，當用戶實現輸入後，直接通過 view 的資料通訊介面將字元傳遞到對應的 View 。接下來就來分析這些過程。
2. InputMethodManager 建立
// ViewRootImpl.java
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, ThreadedRenderer.HardwareDrawCallbacks {
public ViewRootImpl(Context context, Display display) {
...
mWindowSession = WindowManagerGlobal.getWindowSession();
...
}
// WindowManagerGlobal.java 3. window 獲得焦點
// WindowManagerService.java
boolean updateFocusedWindowLocked(int mode, boolean updateInputWindows) {
// 計算焦點 window
WindowState newFocus = computeFocusedWindowLocked();
if (mCurrentFocus != newFocus) {
Trace.traceBegin(Trace.TRACE_TAG_WINDOW_MANAGER, "wmUpdateFocus");
// This check makes sure that we don't already have the focus
// change message pending.
mH.removeMessages(H.REPORT_FOCUS_CHANGE);
mH.sendEmptyMessage(H.REPORT_FOCUS_CHANGE);
...
return true;
}
return false;
}
private WindowState computeFocusedWindowLocked() {
final int displayCount = mDisplayContents.size();
for (int i = 0; i < displayCount; i++) {
final DisplayContent displayContent = mDisplayContents.valueAt(i);
WindowState win = findFocusedWindowLocked(displayContent);
if (win != null) {
return win;
}
}
return null;
}
// 找出 top 需要獲得焦點的 window
WindowState findFocusedWindowLocked(DisplayContent displayContent) {
final WindowList windows = displayContent.getWindowList();
for (int i = windows.size() - 1; i >= 0; i--) {
final WindowState win = windows.get(i);
if (localLOGV || DEBUG_FOCUS) Slog.v(
TAG_WM, "Looking for focus: " + i
+ " = " + win
+ ", flags=" + win.mAttrs.flags
+ ", canReceive=" + win.canReceiveKeys());
// 判斷 window 是否可以獲取焦點
if (!win.canReceiveKeys()) {
continue;
}
// win.mAppToken != null win描述的是一個Activity視窗
AppWindowToken wtoken = win.mAppToken;
// If this window's application has been removed, just skip it.
if (wtoken != null && (wtoken.removed || wtoken.sendingToBottom)) {
if (DEBUG_FOCUS) Slog.v(TAG_WM, "Skipping " + wtoken + " because "
+ (wtoken.removed ? "removed" : "sendingToBottom"));
continue;
}
// Descend through all of the app tokens and find the first that either matches
// win.mAppToken (return win) or mFocusedApp (return null).
// mFocusedApp 是 top Activity，下邊的邏輯是為了確保焦點window的app 必須是焦點程式上的，主要是為了檢測出錯誤
if (wtoken != null && win.mAttrs.type != TYPE_APPLICATION_STARTING &&
mFocusedApp != null) {
ArrayList<Task> tasks = displayContent.getTasks();
for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
AppTokenList tokens = tasks.get(taskNdx).mAppTokens;
int tokenNdx = tokens.size() - 1;
for ( ; tokenNdx >= 0; --tokenNdx) {
final AppWindowToken token = tokens.get(tokenNdx);
if (wtoken == token) {
break;
}
if (mFocusedApp == token && token.windowsAreFocusable()) {
// Whoops, we are below the focused app whose windows are focusable...
// No focus for you!!!
if (localLOGV || DEBUG_FOCUS_LIGHT) Slog.v(TAG_WM,
"findFocusedWindow: Reached focused app=" + mFocusedApp);
return null;
}
}
if (tokenNdx >= 0) {
// Early exit from loop, must have found the matching token.
break;
}
}
}
if (DEBUG_FOCUS_LIGHT) Slog.v(TAG_WM, "findFocusedWindow: Found new focus @ " + i +
" = " + win);
return win;
}
if (DEBUG_FOCUS_LIGHT) Slog.v(TAG_WM, "findFocusedWindow: No focusable windows.");
return null;
}
@Override
public void handleMessage(Message msg) {
if (DEBUG_WINDOW_TRACE) {
Slog.v(TAG_WM, "handleMessage: entry what=" + msg.what);
}
switch (msg.what) {
case REPORT_FOCUS_CHANGE: {
WindowState lastFocus;
WindowState newFocus;
AccessibilityController accessibilityController = null;
synchronized(mWindowMap) {
// TODO(multidisplay): Accessibility supported only of default desiplay.
if (mAccessibilityController != null && getDefaultDisplayContentLocked()
.getDisplayId() == Display.DEFAULT_DISPLAY) {
accessibilityController = mAccessibilityController;
}
lastFocus = mLastFocus;
newFocus = mCurrentFocus;
if (lastFocus == newFocus) {
// Focus is not changing, so nothing to do.
return;
}
mLastFocus = newFocus;
if (DEBUG_FOCUS_LIGHT) Slog.i(TAG_WM, "Focus moving from " + lastFocus +
" to " + newFocus);
if (newFocus != null && lastFocus != null
&& !newFocus.isDisplayedLw()) {
//Slog.i(TAG_WM, "Delaying loss of focus...");
mLosingFocus.add(lastFocus);
lastFocus = null;
}
}
// First notify the accessibility manager for the change so it has
// the windows before the newly focused one starts firing eventgs.
if (accessibilityController != null) {
accessibilityController.onWindowFocusChangedNotLocked();
}
//System.out.println("Changing focus from " + lastFocus
// + " to " + newFocus);
if (newFocus != null) {
if (DEBUG_FOCUS_LIGHT) Slog.i(TAG_WM, "Gaining focus: " + newFocus);
// 通知新的焦點程式 獲得了焦點
newFocus.reportFocusChangedSerialized(true, mInTouchMode);
notifyFocusChanged();
}
if (lastFocus != null) {
if (DEBUG_FOCUS_LIGHT) Slog.i(TAG_WM, "Losing focus: " + lastFocus);
// 通知老的焦點程式 獲得了焦點
lastFocus.reportFocusChangedSerialized(false, mInTouchMode);
}
} break;
...
}
// WindowState.java
/**
* Report a focus change. Must be called with no locks held, and consistently
* from the same serialized thread (such as dispatched from a handler).
*/
public void reportFocusChangedSerialized(boolean focused, boolean inTouchMode) {
try {
// 通過 Binder 告知 client端 其獲得或失去了焦點
mClient.windowFocusChanged(focused, inTouchMode);
} catch (RemoteException e) {
}
if (mFocusCallbacks != null) {
final int N = mFocusCallbacks.beginBroadcast();
for (int i=0; i<N; i++) {
IWindowFocusObserver obs = mFocusCallbacks.getBroadcastItem(i);
try {
if (focused) {
obs.focusGained(mWindowId.asBinder());
} else {
obs.focusLost(mWindowId.asBinder());
}
} catch (RemoteException e) {
}
}
mFocusCallbacks.finishBroadcast();
}
}
4.程式變更焦點，程式獲得焦點變更事件
// ViewRootImpl.java
public void windowFocusChanged(boolean hasFocus, boolean inTouchMode) {
Message msg = Message.obtain();
msg.what = MSG_WINDOW_FOCUS_CHANGED;
msg.arg1 = hasFocus ? 1 : 0;
msg.arg2 = inTouchMode ? 1 : 0;
mHandler.sendMessage(msg);
}
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_WINDOW_FOCUS_CHANGED: {
if (mAdded) {
boolean hasWindowFocus = msg.arg1 != 0;
mAttachInfo.mHasWindowFocus = hasWindowFocus;
profileRendering(hasWindowFocus);
if (hasWindowFocus) {
...
}
mLastWasImTarget = WindowManager.LayoutParams
.mayUseInputMethod(mWindowAttributes.flags);
InputMethodManager imm = InputMethodManager.peekInstance();
if (imm != null && mLastWasImTarget && !isInLocalFocusMode()) {
imm.onPreWindowFocus(mView, hasWindowFocus);
}
if (mView != null) {
mAttachInfo.mKeyDispatchState.reset();
// 6.1 呼叫根 view的 dispatchWindowFocusChanged()，通知view程式獲得焦點
mView.dispatchWindowFocusChanged(hasWindowFocus);
mAttachInfo.mTreeObserver.dispatchOnWindowFocusChange(hasWindowFocus);
}
// Note: must be done after the focus change callbacks,
// so all of the view state is set up correctly.
if (hasWindowFocus) {
if (imm != null && mLastWasImTarget && !isInLocalFocusMode()) {
// 6.2 通知 InputMethodManager 該 window 獲得焦點
imm.onPostWindowFocus(mView, mView.findFocus(),
mWindowAttributes.softInputMode,
!mHasHadWindowFocus, mWindowAttributes.flags);
}
// Clear the forward bit. We can just do this directly, since
// the window manager doesn't care about it.
mWindowAttributes.softInputMode &=
~WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION;
((WindowManager.LayoutParams)mView.getLayoutParams())
.softInputMode &=
~WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION;
mHasHadWindowFocus = true;
}
}
} break;
...
}
}
一.1 焦點View向IMMS請求繫結輸入法
6.1 之後的流程
// ViewGroup.java
@Override
public void dispatchWindowFocusChanged(boolean hasFocus) {
super.dispatchWindowFocusChanged(hasFocus);
final int count = mChildrenCount;
final View[] children = mChildren;
for (int i = 0; i < count; i++) {
children[i].dispatchWindowFocusChanged(hasFocus);
}
}
// View.java
/**
* Called when the window containing this view gains or loses window focus.
* ViewGroups should override to route to their children.
*
* @param hasFocus True if the window containing this view now has focus,
* false otherwise.
*/
public void dispatchWindowFocusChanged(boolean hasFocus) {
onWindowFocusChanged(hasFocus);
}
/**
* Called when the window containing this view gains or loses focus. Note
* that this is separate from view focus: to receive key events, both
* your view and its window must have focus. If a window is displayed
* on top of yours that takes input focus, then your own window will lose
* focus but the view focus will remain unchanged.
*
* @param hasWindowFocus True if the window containing this view now has
* focus, false otherwise.
*/
public void onWindowFocusChanged(boolean hasWindowFocus) {
InputMethodManager imm = InputMethodManager.peekInstance();
if (!hasWindowFocus) {
if (isPressed()) {
setPressed(false);
}
if (imm != null && (mPrivateFlags & PFLAG_FOCUSED) != 0) {
imm.focusOut(this);
}
removeLongPressCallback();
removeTapCallback();
onFocusLost();
} else if (imm != null && (mPrivateFlags & PFLAG_FOCUSED) != 0) {
// 獲得焦點的 view 通過 InputMethodManager 向 Service 通知自己獲得焦點
imm.focusIn(this);
}
refreshDrawableState();
}
// InputMethodManager.java
/**
* Call this when a view receives focus.
* @hide
*/
public void focusIn(View view) {
synchronized (mH) {
focusInLocked(view);
}
}
// InputMethodManager.java
/**
* Call this when a view receives focus.
* @hide
*/
public void focusIn(View view) {
synchronized (mH) {
focusInLocked(view);
}
}
void focusInLocked(View view) {
if (DEBUG) Log.v(TAG, "focusIn: " + dumpViewInfo(view));
if (view != null && view.isTemporarilyDetached()) {
// This is a request from a view that is temporarily detached from a window.
if (DEBUG) Log.v(TAG, "Temporarily detached view, ignoring");
return;
}
if (mCurRootView != view.getRootView()) {
// This is a request from a window that isn't in the window with
// IME focus, so ignore it.
if (DEBUG) Log.v(TAG, "Not IME target window, ignoring");
return;
}
mNextServedView = view;// 儲存焦點view的變數
scheduleCheckFocusLocked(view);
}
static void scheduleCheckFocusLocked(View view) {
ViewRootImpl viewRootImpl = view.getViewRootImpl();
if (viewRootImpl != null) {
viewRootImpl.dispatchCheckFocus();
}
}
// ViewRootImpl.java
public void dispatchCheckFocus() {
if (!mHandler.hasMessages(MSG_CHECK_FOCUS)) {
// This will result in a call to checkFocus() below.
mHandler.sendEmptyMessage(MSG_CHECK_FOCUS);
}
}
case MSG_CHECK_FOCUS: {
InputMethodManager imm = InputMethodManager.peekInstance();
if (imm != null) {
imm.checkFocus();
}
} break;
// InputMethodManager.java
/**
* @hide
*/
public void checkFocus() {
// 確認當前 focused view 是否已經呼叫過 startInputInner() 來繫結輸入法，
// 因為前面 mView.dispatchWindowFocusChanged() 已經完成了 focused view 的繫結，
// 大部分情況下，該函式返回 false , 不會再次呼叫 startInputInner()
if (checkFocusNoStartInput(false)) {
startInputInner(InputMethodClient.START_INPUT_REASON_CHECK_FOCUS, null, 0, 0, 0);
}
}
private boolean checkFocusNoStartInput(boolean forceNewFocus) {
// This is called a lot, so short-circuit before locking.
if (mServedView == mNextServedView && !forceNewFocus) {
return false;
}
final ControlledInputConnectionWrapper ic;
synchronized (mH) {
if (mServedView == mNextServedView && !forceNewFocus) {
return false;
}
if (DEBUG) Log.v(TAG, "checkFocus: view=" + mServedView
+ " next=" + mNextServedView
+ " forceNewFocus=" + forceNewFocus
+ " package="
+ (mServedView != null ? mServedView.getContext().getPackageName() : "<none>"));
if (mNextServedView == null) {
finishInputLocked();
// In this case, we used to have a focused view on the window,
// but no longer do. We should make sure the input method is
// no longer shown, since it serves no purpose.
closeCurrentInput();
return false;
}
ic = mServedInputConnectionWrapper;
mServedView = mNextServedView;
mCurrentTextBoxAttribute = null;
mCompletions = null;
mServedConnecting = true;
}
if (ic != null) {
ic.finishComposingText();
}
return true;
}
boolean startInputInner(@InputMethodClient.StartInputReason final int startInputReason,
IBinder windowGainingFocus, int controlFlags, int softInputMode,
int windowFlags) {
final View view;
synchronized (mH) {
// 獲得上面的焦點view
view = mServedView;
// Make sure we have a window token for the served view.
if (DEBUG) {
Log.v(TAG, "Starting input: view=" + dumpViewInfo(view) +
" reason=" + InputMethodClient.getStartInputReason(startInputReason));
}
if (view == null) {
if (DEBUG) Log.v(TAG, "ABORT input: no served view!");
return false;
}
}
// Now we need to get an input connection from the served view.
// This is complicated in a couple ways: we can't be holding our lock
// when calling out to the view, and we need to make sure we call into
// the view on the same thread that is driving its view hierarchy.
Handler vh = view.getHandler();
if (vh == null) {
// If the view doesn't have a handler, something has changed out
// from under us, so just close the current input.
// If we don't close the current input, the current input method can remain on the
// screen without a connection.
if (DEBUG) Log.v(TAG, "ABORT input: no handler for view! Close current input.");
closeCurrentInput();
return false;
}
if (vh.getLooper() != Looper.myLooper()) {
// The view is running on a different thread than our own, so
// we need to reschedule our work for over there.
if (DEBUG) Log.v(TAG, "Starting input: reschedule to view thread");
vh.post(new Runnable() {
@Override
public void run() {
startInputInner(startInputReason, null, 0, 0, 0);
}
});
return false;
}
// Okay we are now ready to call into the served view and have it
// do its stuff.
// Life is good: let's hook everything up!
EditorInfo tba = new EditorInfo();
// Note: Use Context#getOpPackageName() rather than Context#getPackageName() so that the
// system can verify the consistency between the uid of this process and package name passed
// from here. See comment of Context#getOpPackageName() for details.
tba.packageName = view.getContext().getOpPackageName();
tba.fieldId = view.getId();
// 建立資料通訊連線介面 InputConnection
// InputMethodService 後面就是通過這個connection將輸入法的字元傳給該view
InputConnection ic = view.onCreateInputConnection(tba);
if (DEBUG) Log.v(TAG, "Starting input: tba=" + tba + " ic=" + ic);
synchronized (mH) {
// Now that we are locked again, validate that our state hasn't
// changed.
if (mServedView != view || !mServedConnecting) {
// Something else happened, so abort.
if (DEBUG) Log.v(TAG,
"Starting input: finished by someone else. view=" + dumpViewInfo(view)
+ " mServedView=" + dumpViewInfo(mServedView)
+ " mServedConnecting=" + mServedConnecting);
return false;
}
// If we already have a text box, then this view is already
// connected so we want to restart it.
if (mCurrentTextBoxAttribute == null) {
controlFlags |= CONTROL_START_INITIAL;
}
// Hook 'em up and let 'er rip.
mCurrentTextBoxAttribute = tba;
mServedConnecting = false;
if (mServedInputConnectionWrapper != null) {
mServedInputConnectionWrapper.deactivate();
mServedInputConnectionWrapper = null;
}
ControlledInputConnectionWrapper servedContext;
final int missingMethodFlags;
if (ic != null) {
mCursorSelStart = tba.initialSelStart;
mCursorSelEnd = tba.initialSelEnd;
mCursorCandStart = -1;
mCursorCandEnd = -1;
mCursorRect.setEmpty();
mCursorAnchorInfo = null;
final Handler icHandler;
missingMethodFlags = InputConnectionInspector.getMissingMethodFlags(ic);
if ((missingMethodFlags & InputConnectionInspector.MissingMethodFlags.GET_HANDLER)
!= 0) {
// InputConnection#getHandler() is not implemented.
icHandler = null;
} else {
icHandler = ic.getHandler();
}
// 將 InputConnection 封裝為 binder 物件，這個是真正可以實現跨程序通訊的封裝類
servedContext = new ControlledInputConnectionWrapper(
icHandler != null ? icHandler.getLooper() : vh.getLooper(), ic, this);
} else {
servedContext = null;
missingMethodFlags = 0;
}
mServedInputConnectionWrapper = servedContext;
try {
if (DEBUG) Log.v(TAG, "START INPUT: view=" + dumpViewInfo(view) + " ic="
+ ic + " tba=" + tba + " controlFlags=#"
+ Integer.toHexString(controlFlags));
final InputBindResult res = mService.startInputOrWindowGainedFocus(
startInputReason, mClient, windowGainingFocus, controlFlags, softInputMode,
windowFlags, tba, servedContext, missingMethodFlags);
if (DEBUG) Log.v(TAG, "Starting input: Bind result=" + res);
if (res != null) {
if (res.id != null) {
setInputChannelLocked(res.channel);
mBindSequence = res.sequence;
// 獲得輸入法的通訊介面
mCurMethod = res.method;
mCurId = res.id;
mNextUserActionNotificationSequenceNumber =
res.userActionNotificationSequenceNumber;
if (mServedInputConnectionWrapper != null) {
mServedInputConnectionWrapper.setInputMethodId(mCurId);
}
} else {
if (res.channel != null && res.channel != mCurChannel) {
res.channel.dispose();
}
if (mCurMethod == null) {
// This means there is no input method available.
if (DEBUG) Log.v(TAG, "ABORT input: no input method!");
return true;
}
}
} else {
if (startInputReason
== InputMethodClient.START_INPUT_REASON_WINDOW_FOCUS_GAIN) {
// We are here probably because of an obsolete window-focus-in message sent
// to windowGainingFocus. Since IMMS determines whether a Window can have
// IME focus or not by using the latest window focus state maintained in the
// WMS, this kind of race condition cannot be avoided. One obvious example
// would be that we have already received a window-focus-out message but the
// UI thread is still handling previous window-focus-in message here.
// TODO: InputBindResult should have the error code.
if (DEBUG) Log.w(TAG, "startInputOrWindowGainedFocus failed. "
+ "Window focus may have already been lost. "
+ "win=" + windowGainingFocus + " view=" + dumpViewInfo(view));
if (!mActive) {
// mHasBeenInactive is a latch switch to forcefully refresh IME focus
// state when an inactive (mActive == false) client is gaining window
// focus. In case we have unnecessary disable the latch due to this
// spurious wakeup, we re-enable the latch here.
// TODO: Come up with more robust solution.
mHasBeenInactive = true;
}
}
}
if (mCurMethod != null && mCompletions != null) {
try {
mCurMethod.displayCompletions(mCompletions);
} catch (RemoteException e) {
}
}
} catch (RemoteException e) {
Log.w(TAG, "IME died: " + mCurId, e);
}
}
return true;
}
// InputMethodManagerService.java
@Override
public InputBindResult startInputOrWindowGainedFocus(
/* @InputMethodClient.StartInputReason */ final int startInputReason,
IInputMethodClient client, IBinder windowToken, int controlFlags, int softInputMode,
int windowFlags, @Nullable EditorInfo attribute, IInputContext inputContext,
/* @InputConnectionInspector.missingMethods */ final int missingMethods) {
if (windowToken != null) {
// focusIn 不走該分支
return windowGainedFocus(startInputReason, client, windowToken, controlFlags,
softInputMode, windowFlags, attribute, inputContext, missingMethods);
} else {
// view 獲得焦點，IMMS將這個 view 和 輸入法繫結
return startInput(startInputReason, client, inputContext, missingMethods, attribute,
controlFlags);
}
}
一.2 IMMS處理view繫結輸入法事件
// InputMethodManagerService.java
@Override
public InputBindResult startInputOrWindowGainedFocus(
/* @InputMethodClient.StartInputReason */ final int startInputReason,
IInputMethodClient client, IBinder windowToken, int controlFlags, int softInputMode,
int windowFlags, @Nullable EditorInfo attribute, IInputContext inputContext,
/* @InputConnectionInspector.missingMethods */ final int missingMethods) {
if (windowToken != null) {
// focusIn 不走該分支
return windowGainedFocus(startInputReason, client, windowToken, controlFlags,
softInputMode, windowFlags, attribute, inputContext, missingMethods);
} else {
// view 獲得焦點，IMMS將這個 view 和 輸入法繫結
return startInput(startInputReason, client, inputContext, missingMethods, attribute,
controlFlags);
}
}
private InputBindResult startInput(
/* @InputMethodClient.StartInputReason */ final int startInputReason,
IInputMethodClient client, IInputContext inputContext,
/* @InputConnectionInspector.missingMethods */ final int missingMethods,
@Nullable EditorInfo attribute, int controlFlags) {
if (!calledFromValidUser()) {
return null;
}
synchronized (mMethodMap) {
if (DEBUG) {
Slog.v(TAG, "startInput: reason="
+ InputMethodClient.getStartInputReason(startInputReason)
+ " client = " + client.asBinder()
+ " inputContext=" + inputContext
+ " missingMethods="
+ InputConnectionInspector.getMissingMethodFlagsAsString(missingMethods)
+ " attribute=" + attribute
+ " controlFlags=#" + Integer.toHexString(controlFlags));
}
final long ident = Binder.clearCallingIdentity();
try {
return startInputLocked(startInputReason, client, inputContext, missingMethods,
attribute, controlFlags);
} finally {
Binder.restoreCallingIdentity(ident);
}
}
}
InputBindResult startInputLocked(
/* @InputMethodClient.StartInputReason */ final int startInputReason,
IInputMethodClient client, IInputContext inputContext,
/* @InputConnectionInspector.missingMethods */ final int missingMethods,
@Nullable EditorInfo attribute, int controlFlags) {
// If no method is currently selected, do nothing.
if (mCurMethodId == null) {
return mNoBinding;
}
// 程式在 Service 端 對應的資料結構
ClientState cs = mClients.get(client.asBinder());
...
return startInputUncheckedLocked(cs, inputContext, missingMethods, attribute,
controlFlags);
}
InputBindResult startInputUncheckedLocked(@NonNull ClientState cs, IInputContext inputContext,
/* @InputConnectionInspector.missingMethods */ final int missingMethods,
@NonNull EditorInfo attribute, int controlFlags) {
// If no method is currently selected, do nothing.
if (mCurMethodId == null) {
return mNoBinding;
}
if (!InputMethodUtils.checkIfPackageBelongsToUid(mAppOpsManager, cs.uid,
attribute.packageName)) {
Slog.e(TAG, "Rejecting this client as it reported an invalid package name."
+ " uid=" + cs.uid + " package=" + attribute.packageName);
return mNoBinding;
}
if (mCurClient != cs) {
// 如果新程式和當前活動的程式不同，取消當前活動程式與輸入法的繫結
// Was the keyguard locked when switching over to the new client?
mCurClientInKeyguard = isKeyguardLocked();
// If the client is changing, we need to switch over to the new
// one.
unbindCurrentClientLocked(InputMethodClient.UNBIND_REASON_SWITCH_CLIENT);
if (DEBUG) Slog.v(TAG, "switching to client: client="
+ cs.client.asBinder() + " keyguard=" + mCurClientInKeyguard);
// If the screen is on, inform the new client it is active
if (mIsInteractive) {
executeOrSendMessage(cs.client, mCaller.obtainMessageIO(
MSG_SET_ACTIVE, mIsInteractive ? 1 : 0, cs));
}
}
// Bump up the sequence for this client and attach it.
mCurSeq++;
if (mCurSeq <= 0) mCurSeq = 1;
// 將新程式設定為當前活動的程式
mCurClient = cs;
mCurInputContext = inputContext;
mCurInputContextMissingMethods = missingMethods;
mCurAttribute = attribute;
// Check if the input method is changing.
if (mCurId != null && mCurId.equals(mCurMethodId)) {
if (cs.curSession != null) {
// Fast case: if we are already connected to the input method,
// then just return it.
// 連線已經建立，開始繫結
return attachNewInputLocked(
(controlFlags&InputMethodManager.CONTROL_START_INITIAL) != 0);
}
if (mHaveConnection) {
if (mCurMethod != null) {
// 如果 輸入法的連線 已經建立，直接傳遞給程式 client 端
// Return to client, and we will get back with it when
// we have had a session made for it.
requestClientSessionLocked(cs);
return new InputBindResult(null, null, mCurId, mCurSeq,
mCurUserActionNotificationSequenceNumber);
} else if (SystemClock.uptimeMillis()
< (mLastBindTime+TIME_TO_RECONNECT)) {
// In this case we have connected to the service, but
// don't yet have its interface. If it hasn't been too
// long since we did the connection, we'll return to
// the client and wait to get the service interface so
// we can report back. If it has been too long, we want
// to fall through so we can try a disconnect/reconnect
// to see if we can get back in touch with the service.
return new InputBindResult(null, null, mCurId, mCurSeq,
mCurUserActionNotificationSequenceNumber);
} else {
EventLog.writeEvent(EventLogTags.IMF_FORCE_RECONNECT_IME,
mCurMethodId, SystemClock.uptimeMillis()-mLastBindTime, 0);
}
}
}
// 啟動輸入法並建立連線
return startInputInnerLocked();
}
InputBindResult startInputInnerLocked() {
if (mCurMethodId == null) {
return mNoBinding;
}
if (!mSystemReady) {
// If the system is not yet ready, we shouldn't be running third
// party code.
return new InputBindResult(null, null, mCurMethodId, mCurSeq,
mCurUserActionNotificationSequenceNumber);
}
InputMethodInfo info = mMethodMap.get(mCurMethodId);
if (info == null) {
throw new IllegalArgumentException("Unknown id: " + mCurMethodId);
}
unbindCurrentMethodLocked(true);
// 啟動輸入法Service
mCurIntent = new Intent(InputMethod.SERVICE_INTERFACE);
mCurIntent.setComponent(info.getComponent());
mCurIntent.putExtra(Intent.EXTRA_CLIENT_LABEL,
com.android.internal.R.string.input_method_binding_label);
mCurIntent.putExtra(Intent.EXTRA_CLIENT_INTENT, PendingIntent.getActivity(
mContext, 0, new Intent(Settings.ACTION_INPUT_METHOD_SETTINGS), 0));
if (bindCurrentInputMethodService(mCurIntent, this, Context.BIND_AUTO_CREATE
| Context.BIND_NOT_VISIBLE | Context.BIND_NOT_FOREGROUND
| Context.BIND_SHOWING_UI)) {
mLastBindTime = SystemClock.uptimeMillis();
mHaveConnection = true;
mCurId = info.getId();
// mCurToken 是給輸入法Service 來繫結輸入法window的
// 通過 mCurToken ，InputMethodManagerService 直接管理 輸入法window
mCurToken = new Binder();
try {
if (true || DEBUG) Slog.v(TAG, "Adding window token: " + mCurToken);
mIWindowManager.addWindowToken(mCurToken,
WindowManager.LayoutParams.TYPE_INPUT_METHOD);
} catch (RemoteException e) {
}
return new InputBindResult(null, null, mCurId, mCurSeq,
mCurUserActionNotificationSequenceNumber);
} else {
mCurIntent = null;
Slog.w(TAG, "Failure connecting to input method service: "
+ mCurIntent);
}
return null;
}
private boolean bindCurrentInputMethodService(
Intent service, ServiceConnection conn, int flags) {
if (service == null || conn == null) {
Slog.e(TAG, "--- bind failed: service = " + service + ", conn = " + conn);
return false;
}
return mContext.bindServiceAsUser(service, conn, flags,
new UserHandle(mSettings.getCurrentUserId()));
}
// AbstractInputMethodService.java<