前言
在Android系统中，很多应用都需要根据具体情况来控制状态栏和导航栏的显示和隐藏，又或者将状态栏透明，实现诸如沉浸式、全面屏灯效果，而要实现这些效果，都离不开SystemUIVisibility属性。由于SystemUIVisibilityy属性主要用来控制系统状态栏和导航栏的行为，而状态栏和导航栏都属于SystemUI模块的StatusBar，所以SystemUIVisibility属性的消费者肯定包含StatusBar。另外当状态栏和导航栏发生变化的时候，窗口的布局一般也会跟着发生变化，这就意味着窗口管理者PhoneWindowManager肯定也要消费SystemUIVisibility属性。本篇文章我们就来具体分析一下和这个属性有关的代码。
一、SystemUIVisibility属性常见常见取值
1、为窗口设置SystemUIVisibility属性的方式有两种，一种是直接在窗口的WindowManager.LayoutParams对象的systemUiVisibility属性上进行设置，并通过WindowManager.updateViewLayout()方法使其生效。
public interface WindowManager extends ViewManager {
public static class LayoutParams extends ViewGroup.LayoutParams implements Parcelable {
//隐藏窗口的所有装饰，比如状态栏和导航栏
public static final int FLAG_FULLSCREEN = 0x00000400;
//控制窗口状态栏、导航栏的显示和隐藏
public int systemUiVisibility;
}
}
2、另一种是在一个已经显示在窗口上的控件中调用setSystemUiVisibility方法，传入如下属性。
public class View implements Drawable.Callback, KeyEvent.Callback,
AccessibilityEventSource {
//隐藏导航栏
public static final int SYSTEM_UI_FLAG_HIDE_NAVIGATION = 0x00000002;
//隐藏状态栏
public static final int SYSTEM_UI_FLAG_FULLSCREEN = 0x00000004;
}
这种方式最终影响的其实是窗口的WindowManager.LayoutParams对象的subtreeSystemUiVisibility属性。
public interface WindowManager extends ViewManager {
public static class LayoutParams extends ViewGroup.LayoutParams implements Parcelable {
//控制窗口状态栏、导航栏的显示和隐藏
public int subtreeSystemUiVisibility;
}
}
窗口的状态栏导航栏显示与否，最终其实是受以上两个属性共同影响的。接下来我们具体来分析一下View的setSystemUiVisibility方法是如何生效的。
二、View的setSystemUiVisibility方法调用流程
1、View的setSystemUiVisibility方法如下所示。
public class View implements Drawable.Callback, KeyEvent.Callback,
AccessibilityEventSource {
int mSystemUiVisibility;
protected ViewParent mParent;
public void setSystemUiVisibility(int visibility) {
if (visibility != mSystemUiVisibility) {
mSystemUiVisibility = visibility;//保存SystemUIVisibility属性
if (mParent != null && mAttachInfo != null && !mAttachInfo.mRecomputeGlobalAttributes) {
mParent.recomputeViewAttributes(this);//通知父控件子控件属性发生了变化
}
}
}
}
setSystemUiVisibility方法首先将属性赋值给mSystemUiVisibility，然后会调用父控件的recomputeViewAttributes方法，通知父控件子控件属性发生了变化。ViewParent是一个接口，在Android中有两个类实现了这个接口，它们分别是ViewGroup和ViewRootImpl。
2、ViewGroup和ViewRootImpl和recomputeViewAttributes方法相关的代码如下所示。
public abstract class ViewGroup extends View implements ViewParent, ViewManager {
@Override
public void recomputeViewAttributes(View child) {
if (mAttachInfo != null && !mAttachInfo.mRecomputeGlobalAttributes) {
ViewParent parent = mParent;
if (parent != null) parent.recomputeViewAttributes(this);
}
}
}
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, ThreadedRenderer.DrawCallbacks,
AttachedSurfaceControl {
final View.AttachInfo mAttachInfo;
@Override
public void recomputeViewAttributes(View child) {
checkThread();//检测线程是不是UI线程
if (mView == child) {
mAttachInfo.mRecomputeGlobalAttributes = true;//标记需要重新计算本地属性
if (!mWillDrawSoon) {
scheduleTraversals();//进一步调用scheduleTraversals方法。
}
}
}
}
结合Android 9.0系统源码_窗口管理（二）WindowManager对窗口的管理过程，我们知道包括Activity的跟布局DecorView在内的任何View，WindowManager在将它添加到窗口上的过程中，最终都会创建一个ViewRootImpl，并将View设置给ViewRootImpl，这样根View的父类就变成了ViewRootImpl。这就意味着不管任何子View调用recomputeViewAttributes方法，最终所触发的都是ViewRootImpl的recomputeViewAttributes，而ViewRootImpl会进一步调用scheduleTraversals方法。
3、ViewRootImpl和scheduleTraversals方法相关的代码如下所示。
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, ThreadedRenderer.DrawCallbacks,
AttachedSurfaceControl {
final Choreographer mChoreographer;//编舞者
final TraversalRunnable mTraversalRunnable = new TraversalRunnable();//回调对象
void scheduleTraversals() {
if (!mTraversalScheduled) {
mTraversalScheduled = true;
mTraversalBarrier = mHandler.getLooper().getQueue().postSyncBarrier();
//等待系统垂直刷新同步信号，回调TraversalRunnable对象的run方法
mChoreographer.postCallback(Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null);
notifyRendererOfFramePending();
pokeDrawLockIfNeeded();
}
}
final class TraversalRunnable implements Runnable {
@Override
public void run() {
doTraversal();//继续执行doTraversal
}
}
void doTraversal() {
if (mTraversalScheduled) {
mTraversalScheduled = false;
mHandler.getLooper().getQueue().removeSyncBarrier(mTraversalBarrier);
if (mProfile) {
Debug.startMethodTracing("ViewAncestor");
}
//执行performTraversals
performTraversals();
if (mProfile) {
Debug.stopMethodTracing();
mProfile = false;
}
}
}
}
scheduleTraversals方法会为编舞者对象设置回调，最终会等待系统垂直刷新同步信号，回调TraversalRunnable对象的run方法，该方法会调用doTraversal方法，然后进一步调用performTraversals方法。
4、ViewRootImpl的performTraversals方法代码逻辑非常多，这里只列出了我们需要关注的代码。
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, ThreadedRenderer.DrawCallbacks,
AttachedSurfaceControl {
final IWindowSession mWindowSession;//和WMS通信的Binder对象，具体为Session对象
public final WindowManager.LayoutParams mWindowAttributes = new WindowManager.LayoutParams();//窗口属性
final View.AttachInfo mAttachInfo;//控件信息
private void performTraversals() {
final View host = mView;
if (host == null || !mAdded) {
return;
}
if (mWaitForBlastSyncComplete) {
mRequestedTraverseWhilePaused = true;
return;
}
mIsInTraversal = true;
mWillDrawSoon = true;
boolean windowSizeMayChange = false;
WindowManager.LayoutParams lp = mWindowAttributes;//将当前窗口的最新属性赋值给lp
int desiredWindowWidth;
int desiredWindowHeight;
final int viewVisibility = getHostVisibility();
final boolean viewVisibilityChanged = !mFirst
&& (mViewVisibility != viewVisibility || mNewSurfaceNeeded
|| mAppVisibilityChanged);
mAppVisibilityChanged = false;
final boolean viewUserVisibilityChanged = !mFirst &&
((mViewVisibility == View.VISIBLE) != (viewVisibility == View.VISIBLE));
WindowManager.LayoutParams params = null;
...代码省略...
//收集mView的属性，判断是否需要更新params
if (collectViewAttributes()) {
params = lp;
}
...代码省略...
//此方法最终会触发WindowManagerService的relayoutWindow方法
relayoutWindow(params, viewVisibility, insetsPending);
...代码省略...
//测量
performMeasure(childWidthMeasureSpec, childHeightMeasureSpec);
...代码省略...
//布局
performLayout(lp, mWidth, mHeight);
...代码省略...
//绘制
performDraw();
...代码省略...
}
private int relayoutWindow(WindowManager.LayoutParams params, int viewVisibility,
boolean insetsPending) throws RemoteException {
...代码省略...
//调用IWindowSession的relayout方法，该方法最终会触发WindowManagerService的relayoutWindow方法
int relayoutResult = mWindowSession.relayout(mWindow, mSeq, params,
(int) (mView.getMeasuredWidth() * appScale + 0.5f),
(int) (mView.getMeasuredHeight() * appScale + 0.5f), viewVisibility,
insetsPending ? WindowManagerGlobal.RELAYOUT_INSETS_PENDING : 0, frameNumber,
mWinFrame, mPendingOverscanInsets, mPendingContentInsets, mPendingVisibleInsets,
mPendingStableInsets, mPendingOutsets, mPendingBackDropFrame, mPendingDisplayCutout,
mPendingMergedConfiguration, mSurface);
}
}
performTraversals首先调用collectViewAttributes方法收集所有子View的属性，然后调用relayoutWindow方法，该方法最终会触发WindowManagerService的relayoutWindow方法，然后回继续调用触发View测量的performMeasure方法，触发View布局的performLayout方法和触发View绘制的performDraw方法。
三、获取最新的SystemUIVisibility属性
1、ViewRootImpl的collectViewAttributes方法是一个很关键的方法，此方法会重新计算最新的SystemUIVisibility属性。
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, ThreadedRenderer.DrawCallbacks,
AttachedSurfaceControl {
public final WindowManager.LayoutParams mWindowAttributes = new WindowManager.LayoutParams();//窗口属性
final View.AttachInfo mAttachInfo;//控件信息
private boolean collectViewAttributes() {
//判断是否需要重新计算本地属性
if (mAttachInfo.mRecomputeGlobalAttributes) {
//Log.i(mTag, "Computing view hierarchy attributes!");
mAttachInfo.mRecomputeGlobalAttributes = false;
boolean oldScreenOn = mAttachInfo.mKeepScreenOn;
mAttachInfo.mKeepScreenOn = false;
//清空已经存在的SystemUiVisibility属性
mAttachInfo.mSystemUiVisibility = 0;
mAttachInfo.mHasSystemUiListeners = false;
//重新获取窗口视图mView最新的的SystemUI属性，赋值给mAttachInfo
mView.dispatchCollectViewAttributes(mAttachInfo, 0);
...代码暂时省略...
}
return false;
}
}
collectViewAttributes首先会清空当前窗口视图mView已经存在的SystemUiVisibility属性，然后调用View的dispatchCollectViewAttributes方法重新获取最新的的SystemUiVisibility属性。
2、View的dispatchCollectViewAttributes方法如下所示。
public class View implements Drawable.Callback, KeyEvent.Callback,
AccessibilityEventSource {
int mSystemUiVisibility;
void dispatchCollectViewAttributes(AttachInfo attachInfo, int visibility) {
performCollectViewAttributes(attachInfo, visibility);
}
void performCollectViewAttributes(AttachInfo attachInfo, int visibility) {
if ((visibility & VISIBILITY_MASK) == VISIBLE) {
if ((mViewFlags & KEEP_SCREEN_ON) == KEEP_SCREEN_ON) {
attachInfo.mKeepScreenOn = true;
}
//将最新的systemuivisiblity赋予AttachInfo的mSystemUiVisibility 属性
attachInfo.mSystemUiVisibility |= mSystemUiVisibility;
//设置最新的SystemUiVisibility监听对象，如果不为空，则将AttachInfo的mHasSystemUiListeners属性设置为true。
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnSystemUiVisibilityChangeListener != null) {
attachInfo.mHasSystemUiListeners = true;
}
}
}
}
3、接着看ViewRootImpl的collectViewAttributes方法。
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, ThreadedRenderer.DrawCallbacks,
AttachedSurfaceControl {
public final WindowManager.LayoutParams mWindowAttributes = new WindowManager.LayoutParams();//窗口属性
final View.AttachInfo mAttachInfo;//控件信息
private boolean collectViewAttributes() {
//判断是否需要重新计算本地属性
if (mAttachInfo.mRecomputeGlobalAttributes) {
...代码省略...
//移除被禁用的SystemUiVisibility属性
mAttachInfo.mSystemUiVisibility &= ~mAttachInfo.mDisabledSystemUiVisibility;
//让params引用指向mWindowAttributes对象
WindowManager.LayoutParams params = mWindowAttributes;
mAttachInfo.mSystemUiVisibility |= getImpliedSystemUiVisibility(params);
if (mAttachInfo.mKeepScreenOn != oldScreenOn
|| mAttachInfo.mSystemUiVisibility != params.subtreeSystemUiVisibility
|| mAttachInfo.mHasSystemUiListeners != params.hasSystemUiListeners) {
applyKeepScreenOnFlag(params);
//将重新获取的窗口视图mView的SystemUiVisibility保存到窗口的LayoutParams属性中
params.subtreeSystemUiVisibility = mAttachInfo.mSystemUiVisibility;
params.hasSystemUiListeners = mAttachInfo.mHasSystemUiListeners;
//调用View的dispatchWindowSystemUiVisiblityChanged方法
mView.dispatchWindowSystemUiVisiblityChanged(mAttachInfo.mSystemUiVisibility);
return true;
}
}
return false;
}
}
在重新获得mView的SystemUiVisibility属性之后，首先会从该属性中移除被禁用的SystemUiVisibility属性，然后让params引用指向mWindowAttributes对象，并将重新获取的保存在mAttachInfo对象中的SystemUiVisibility属性保存到当前窗口的LayoutParams属性中，最后会调用当前View的dispatchWindowSystemUiVisiblityChanged方法。
4、View的dispatchWindowSystemUiVisiblityChanged方法如下所示。
public class View implements Drawable.Callback, KeyEvent.Callback,
AccessibilityEventSource {
@Deprecated
public void dispatchWindowSystemUiVisiblityChanged(int visible) {
onWindowSystemUiVisibilityChanged(visible);//调用onWindowSystemUiVisibilityChanged方法
}
public void onWindowSystemUiVisibilityChanged(int visible) {
//默认为空实现
}
}
该方法会进一步调用onWindowSystemUiVisibilityChanged方法，onWindowSystemUiVisibilityChanged方法默认为空实现，但是如果当前mView为DecorView时则不同，DecorView实现了此方法。
四、DecorView更新状态栏和导航栏背景颜色
1、DecorView的onWindowSystemUiVisibilityChanged方法如下所示。
public class DecorView extends FrameLayout implements RootViewSurfaceTaker, WindowCallbacks {
@Override
public void onWindowSystemUiVisibilityChanged(int visible) {
//调用updateColorViews方法
updateColorViews(null /* insets */, true /* animate */);
}
}
onWindowSystemUiVisibilityChanged方法会调用一个updateColorViews这个关键方法。
2、updateColorViews会调用updateColorViewInt方法更新导航栏和状态栏的背景颜色。
public class DecorView extends FrameLayout implements RootViewSurfaceTaker, WindowCallbacks {
WindowInsets updateColorViews(WindowInsets insets, boolean animate) {
//获取窗口的SystemUIVisibility属性
int sysUiVisibility = attrs.systemUiVisibility | getWindowSystemUiVisibility();
//判断窗口类型是否是输入法
final boolean isImeWindow = mWindow.getAttributes().type == WindowManager.LayoutParams.TYPE_INPUT_METHOD;
//判断窗口类型不是浮动窗口和输入法，则让SystemUIVisibility属性生效
if (!mWindow.mIsFloating || isImeWindow) {
//获取是否禁止窗口动画的标记
boolean disallowAnimate = !isLaidOut();
disallowAnimate |= ((mLastWindowFlags ^ attrs.flags)
& FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS) != 0;
mLastWindowFlags = attrs.flags;
if (insets != null) {
mLastTopInset = getColorViewTopInset(insets.getStableInsetTop(),
insets.getSystemWindowInsetTop());
mLastBottomInset = getColorViewBottomInset(insets.getStableInsetBottom(),
insets.getSystemWindowInsetBottom());
mLastRightInset = getColorViewRightInset(insets.getStableInsetRight(),
insets.getSystemWindowInsetRight());
mLastLeftInset = getColorViewRightInset(insets.getStableInsetLeft(),
insets.getSystemWindowInsetLeft());
// Don't animate if the presence of stable insets has changed, because that
// indicates that the window was either just added and received them for the
// first time, or the window size or position has changed.
boolean hasTopStableInset = insets.getStableInsetTop() != 0;
disallowAnimate |= (hasTopStableInset != mLastHasTopStableInset);
mLastHasTopStableInset = hasTopStableInset;
boolean hasBottomStableInset = insets.getStableInsetBottom() != 0;
disallowAnimate |= (hasBottomStableInset != mLastHasBottomStableInset);
mLastHasBottomStableInset = hasBottomStableInset;
boolean hasRightStableInset = insets.getStableInsetRight() != 0;
disallowAnimate |= (hasRightStableInset != mLastHasRightStableInset);
mLastHasRightStableInset = hasRightStableInset;
boolean hasLeftStableInset = insets.getStableInsetLeft() != 0;
disallowAnimate |= (hasLeftStableInset != mLastHasLeftStableInset);
mLastHasLeftStableInset = hasLeftStableInset;
mLastShouldAlwaysConsumeNavBar = insets.shouldAlwaysConsumeNavBar();
}
boolean navBarToRightEdge = isNavBarToRightEdge(mLastBottomInset, mLastRightInset);
boolean navBarToLeftEdge = isNavBarToLeftEdge(mLastBottomInset, mLastLeftInset);
int navBarSize = getNavBarSize(mLastBottomInset, mLastRightInset, mLastLeftInset);
//更新导航栏颜色，mNavigationColorViewState为导航栏的相关筛选条件
updateColorViewInt(mNavigationColorViewState, sysUiVisibility,
mWindow.mNavigationBarColor, mWindow.mNavigationBarDividerColor, navBarSize/*导航栏高度*/,
navBarToRightEdge || navBarToLeftEdge, navBarToLeftEdge,
0 /* sideInset */, animate && !disallowAnimate, false /* force */);
boolean statusBarNeedsRightInset = navBarToRightEdge
&& mNavigationColorViewState.present;
boolean statusBarNeedsLeftInset = navBarToLeftEdge
&& mNavigationColorViewState.present;
int statusBarSideInset = statusBarNeedsRightInset ? mLastRightInset
: statusBarNeedsLeftInset ? mLastLeftInset : 0;
//更新状态栏颜色，mStatusColorViewState为状态栏的相关筛选条件
updateColorViewInt(mStatusColorViewState, sysUiVisibility,
calculateStatusBarColor(), 0, mLastTopInset/*状态栏高度*/,
false /* matchVertical */, statusBarNeedsLeftInset, statusBarSideInset,
animate && !disallowAnimate,
mForceWindowDrawsStatusBarBackground);
}
...代码省略...
}
}
关于DecorView更新状态栏、导航栏背景颜色的具体过程，请参考Android 9.0系统源码_SystemUI（八）PhoneWindow更新状态栏和导航栏背景颜色的流程解析。
五、WindowManagerService的relayoutWindow方法
1、重新回到第二节第4步ViewRootImpl的performTraversals方法中。
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, ThreadedRenderer.DrawCallbacks,
AttachedSurfaceControl {
final IWindowSession mWindowSession;//和WMS通信的Binder对象，具体为Session对象
public final WindowManager.LayoutParams mWindowAttributes = new WindowManager.LayoutParams();//窗口属性
final View.AttachInfo mAttachInfo;//控件信息
private void performTraversals() {
...代码省略...
//收集mView的属性，判断是否需要更新params
if (collectViewAttributes()) {
params = lp;
}
...代码省略...
//此方法最终会触发WindowManagerService的relayoutWindow方法
relayoutWindow(params, viewVisibility, insetsPending);
...代码省略...
//测量
performMeasure(childWidthMeasureSpec, childHeightMeasureSpec);
...代码省略...
//布局
performLayout(lp, mWidth, mHeight);
...代码省略...
//绘制
performDraw();
...代码省略...
}
private int relayoutWindow(WindowManager.LayoutParams params, int viewVisibility,
boolean insetsPending) throws RemoteException {
...代码省略...
//调用IWindowSession的relayout方法，该方法最终会触发WindowManagerService的relayoutWindow方法
int relayoutResult = mWindowSession.relayout(mWindow, mSeq, params,
(int) (mView.getMeasuredWidth() * appScale + 0.5f),
(int) (mView.getMeasuredHeight() * appScale + 0.5f), viewVisibility,
insetsPending ? WindowManagerGlobal.RELAYOUT_INSETS_PENDING : 0, frameNumber,
mWinFrame, mPendingOverscanInsets, mPendingContentInsets, mPendingVisibleInsets,
mPendingStableInsets, mPendingOutsets, mPendingBackDropFrame, mPendingDisplayCutout,
mPendingMergedConfiguration, mSurface);
}
}
在调用collectViewAttributes获取最新的systemUIVisibiliy属性之后，会调用relayoutWindow方法，该方法进一步调用IWindowSession的relayout方法，IWindowSession的具体实现类为Session。
2、Session的relayout方法如下所示。
class Session extends IWindowSession.Stub implements IBinder.DeathRecipient {
final WindowManagerService mService;
@Override
public int relayout(IWindow window, WindowManager.LayoutParams attrs,
int requestedWidth, int requestedHeight, int viewFlags, int flags, long frameNumber,
ClientWindowFrames outFrames, MergedConfiguration mergedConfiguration,
SurfaceControl outSurfaceControl, InsetsState outInsetsState,
InsetsSourceControl[] outActiveControls, Point outSurfaceSize) {
int res = mService.relayoutWindow(this, window, attrs,
requestedWidth, requestedHeight, viewFlags, flags, frameNumber,
outFrames, mergedConfiguration, outSurfaceControl, outInsetsState,
outActiveControls, outSurfaceSize);
return res;
}
}
relayout方法会进一步调用WindowManagerService的relayoutWindow方法。
3、WindowManagerService的relayoutWindow方法如下所示。
public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs {
public int relayoutWindow(Session session, IWindow client, int seq, LayoutParams attrs/**窗口属性**/,
int requestedWidth, int requestedHeight, int viewVisibility/**根View控件是否可见**/, int flags,
long frameNumber, Rect outFrame, Rect outOverscanInsets, Rect outContentInsets,
Rect outVisibleInsets, Rect outStableInsets, Rect outOutsets, Rect outBackdropFrame,
DisplayCutout.ParcelableWrapper outCutout, MergedConfiguration mergedConfiguration,
Surface outSurface) {
int result = 0;
boolean configChanged;
//是否有状态栏的使用权限
final boolean hasStatusBarPermission =
mContext.checkCallingOrSelfPermission(permission.STATUS_BAR)
== PackageManager.PERMISSION_GRANTED;
//是否有状态栏服务的使用权限
final boolean hasStatusBarServicePermission =
mContext.checkCallingOrSelfPermission(permission.STATUS_BAR_SERVICE)
== PackageManager.PERMISSION_GRANTED;
long origId = Binder.clearCallingIdentity();
final int displayId;
synchronized(mWindowMap) {
//获取当前要操作的窗口对象
WindowState win = windowForClientLocked(session, client, false);
if (win == null) {
return 0;
}
//获取窗口所属的屏幕设备id
displayId = win.getDisplayId();
//窗口动画
WindowStateAnimator winAnimator = win.mWinAnimator;
if (viewVisibility != View.GONE) {
win.setRequestedSize(requestedWidth, requestedHeight);
}
win.setFrameNumber(frameNumber);
int attrChanges = 0;
int flagChanges = 0;
if (attrs != null) {
//如果窗口属性不为空，这里会对窗口的相关属性进行一次预处理
mPolicy.adjustWindowParamsLw(win, attrs, hasStatusBarServicePermission);
// if they don't have the permission, mask out the status bar bits
if (seq == win.mSeq) {
int systemUiVisibility = attrs.systemUiVisibility
| attrs.subtreeSystemUiVisibility;
if ((systemUiVisibility & DISABLE_MASK) != 0) {
if (!hasStatusBarPermission) {
systemUiVisibility &= ~DISABLE_MASK;
}
}
win.mSystemUiVisibility = systemUiVisibility;
}
if (win.mAttrs.type != attrs.type) {
throw new IllegalArgumentException(
"Window type can not be changed after the window is added.");
}
// Odd choice but less odd than embedding in copyFrom()
if ((attrs.privateFlags & WindowManager.LayoutParams.PRIVATE_FLAG_PRESERVE_GEOMETRY)
!= 0) {
attrs.x = win.mAttrs.x;
attrs.y = win.mAttrs.y;
attrs.width = win.mAttrs.width;
attrs.height = win.mAttrs.height;
}
//检测窗口标记和样式是否发生了变化
flagChanges = win.mAttrs.flags ^= attrs.flags;
attrChanges = win.mAttrs.copyFrom(attrs);
if ((attrChanges & (WindowManager.LayoutParams.LAYOUT_CHANGED
| WindowManager.LayoutParams.SYSTEM_UI_VISIBILITY_CHANGED)) != 0) {
win.mLayoutNeeded = true;
}
if (win.mAppToken != null && ((flagChanges & FLAG_SHOW_WHEN_LOCKED) != 0
|| (flagChanges & FLAG_DISMISS_KEYGUARD) != 0)) {
win.mAppToken.checkKeyguardFlagsChanged();
}
if (((attrChanges & LayoutParams.ACCESSIBILITY_TITLE_CHANGED) != 0)
&& (mAccessibilityController != null)
&& (win.getDisplayId() == DEFAULT_DISPLAY)) {
// No move or resize, but the controller checks for title changes as well
mAccessibilityController.onSomeWindowResizedOrMovedLocked();
}
if ((flagChanges & PRIVATE_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS) != 0) {
updateNonSystemOverlayWindowsVisibilityIfNeeded(
win, win.mWinAnimator.getShown());
}
}
...代码省略...
if (focusMayChange) {
//System.out.println("Focus may change: " + win.mAttrs.getTitle());
if (updateFocusedWindowLocked(UPDATE_FOCUS_WILL_PLACE_SURFACES,
false /*updateInputWindows*/)) {
imMayMove = false;
}
//System.out.println("Relayout " + win + ": focus=" + mCurrentFocus);
}
...代码省略...
}
}
relayoutWindow方法会调用一个关键方法updateFocusedWindowLocked。
4、WindowManagerService的updateFocusedWindowLocked方法如下所示。
public class WindowManagerService extends IWindowManager.Stub
implements Watchdog.Monitor, WindowManagerPolicy.WindowManagerFuncs {
//窗口管理策略的接口类WindowManagerPolicy（WMP），它用来定义一个窗口策略所要遵循的通用规范。
final WindowManagerPolicy mPolicy;
//根窗口
RootWindowContainer mRoot;
private WindowManagerService(Context context, InputManagerService inputManager,
boolean haveInputMethods, boolean showBootMsgs, boolean onlyCore,
WindowManagerPolicy policy) {
...代码省略...
mPolicy = policy;
mRoot = new RootWindowContainer(this);
...代码省略...
}
boolean updateFocusedWindowLocked(int mode, boolean updateInputWindows) {
//获取当前最新的焦点窗口
WindowState newFocus = mRoot.computeFocusedWindow();
if (mCurrentFocus != newFocus) {//如果窗口焦点发生了变化
Trace.traceBegin(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);
// TODO(multidisplay): Focused windows on default display only.
final DisplayContent displayContent = getDefaultDisplayContentLocked();
boolean imWindowChanged = false;
if (mInputMethodWindow != null) {//如果输入法窗口不为空
final WindowState prevTarget = mInputMethodTarget;
final WindowState newTarget =
displayContent.computeImeTarget(true /* updateImeTarget*/);
imWindowChanged = prevTarget != newTarget;
if (mode != UPDATE_FOCUS_WILL_ASSIGN_LAYERS
&& mode != UPDATE_FOCUS_WILL_PLACE_SURFACES) {
final int prevImeAnimLayer = mInputMethodWindow.mWinAnimator.mAnimLayer;
displayContent.assignWindowLayers(false /* setLayoutNeeded */);
imWindowChanged |=
prevImeAnimLayer != mInputMethodWindow.mWinAnimator.mAnimLayer;
}
}
if (imWindowChanged) {//输入法窗口发生了变化
mWindowsChanged = true;
displayContent.setLayoutNeeded();
newFocus = mRoot.computeFocusedWindow();
}
if (DEBUG_FOCUS_LIGHT || localLOGV) Slog.v(TAG_WM, "Changing focus from " +
mCurrentFocus + " to " + newFocus + " Callers=" + Debug.getCallers(4));
final WindowState oldFocus = mCurrentFocus;
mCurrentFocus = newFocus;
mLosingFocus.remove(newFocus);
if (mCurrentFocus != null) {
mWinAddedSinceNullFocus.clear();
mWinRemovedSinceNullFocus.clear();
}
//调用WindowManagerPolicy的focusChangedLw方法
int focusChanged = mPolicy.focusChangedLw(oldFocus, newFocus);
if (imWindowChanged && oldFocus != mInputMethodWindow) {
// Focus of the input method window changed. Perform layout if needed.
if (mode == UPDATE_FOCUS_PLACING_SURFACES) {
displayContent.performLayout(true /*initial*/, updateInputWindows);
focusChanged &= ~FINISH_LAYOUT_REDO_LAYOUT;
} else if (mode == UPDATE_FOCUS_WILL_PLACE_SURFACES) {
// Client will do the layout, but we need to assign layers
// for handleNewWindowLocked() below.
displayContent.assignWindowLayers(false /* setLayoutNeeded */);
}
}
if ((focusChanged & FINISH_LAYOUT_REDO_LAYOUT) != 0) {
// The change in focus caused us to need to do a layout. Okay.
displayContent.setLayoutNeeded();
if (mode == UPDATE_FOCUS_PLACING_SURFACES) {
displayContent.performLayout(true /*initial*/, updateInputWindows);
}
}
if (mode != UPDATE_FOCUS_WILL_ASSIGN_LAYERS) {
// If we defer assigning layers, then the caller is responsible for
// doing this part.
mInputMonitor.setInputFocusLw(mCurrentFocus, updateInputWindows);
}
displayContent.adjustForImeIfNeeded();
// We may need to schedule some toast windows to be removed. The toasts for an app that
// does not have input focus are removed within a timeout to prevent apps to redress
// other apps' UI.
displayContent.scheduleToastWindowsTimeoutIfNeededLocked(oldFocus, newFocus);
Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
return true;
}
return false;
}
}
updateFocusedWindowLocked首先是获取最新的焦点窗口，之后还会判断当前窗口焦点是否发生了变化，如果发生了变化，则会调用WindowManagerPolicy的focusChangedLw方法。
六、PhoneWindowManager的updateSystemUiVisibilityLw方法
1、WindowManagerPolicy是一个抽象接口。
public interface WindowManagerPolicy extends WindowManagerPolicyConstants {
/**
* 一个新的窗口持有了焦点
*/
public int focusChangedLw(WindowState lastFocus, WindowState newFocus);
}
2、结合Android 9.0系统源码_窗口管理（一）WindowManagerService的启动流程这篇文章我们可以知道，SystemServer在创建WindowManagerService对象的时候，将PhoneWindowManager对象实例赋值给了mPolicy。
public final class SystemServer {
private void startOtherServices() {
...代码省略...
wm = WindowManagerService.main(context, inputManager,
mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL,
!mFirstBoot, mOnlyCore, new PhoneWindowManager());
...代码省略...
}
}
3、来看下PhoneWindowManager是如何实现focusChangedLw方法的。
public class PhoneWindowManager implements WindowManagerPolicy {
@Override
public int focusChangedLw(WindowState lastFocus, WindowState newFocus) {
mFocusedWindow = newFocus;
if ((updateSystemUiVisibilityLw()&SYSTEM_UI_CHANGING_LAYOUT) != 0) {
// If the navigation bar has been hidden or shown, we need to do another
// layout pass to update that window.
return FINISH_LAYOUT_REDO_LAYOUT;
}
return 0;
}
//更新窗口的SystemUiVisibility属性参数
private int updateSystemUiVisibilityLw() {
//获取当前的焦点窗口
WindowState winCandidate = mFocusedWindow != null ? mFocusedWindow
: mTopFullscreenOpaqueWindowState;
//如果不存在焦点窗口则直接返回
if (winCandidate == null) {
return 0;
}
if (winCandidate.getAttrs().token == mImmersiveModeConfirmation.getWindowToken()) {
winCandidate = isStatusBarKeyguard() ? mStatusBar : mTopFullscreenOpaqueWindowState;
if (winCandidate == null) {
return 0;
}
}
final WindowState win = winCandidate;
if ((win.getAttrs().privateFlags & PRIVATE_FLAG_KEYGUARD) != 0 && mKeyguardOccluded) {
return 0;
}
int tmpVisibility = PolicyControl.getSystemUiVisibility(win, null)
& ~mResettingSystemUiFlags
& ~mForceClearedSystemUiFlags;
if (mForcingShowNavBar && win.getSurfaceLayer() < mForcingShowNavBarLayer) {
tmpVisibility &= ~PolicyControl.adjustClearableFlags(win, View.SYSTEM_UI_CLEARABLE_FLAGS);
}
//获取和SystemUIVisibility相关的各种窗口参数
final int fullscreenVisibility = updateLightStatusBarLw(0 /* vis */,
mTopFullscreenOpaqueWindowState, mTopFullscreenOpaqueOrDimmingWindowState);
final int dockedVisibility = updateLightStatusBarLw(0 /* vis */,
mTopDockedOpaqueWindowState, mTopDockedOpaqueOrDimmingWindowState);
mWindowManagerFuncs.getStackBounds(
WINDOWING_MODE_UNDEFINED, ACTIVITY_TYPE_HOME, mNonDockedStackBounds);
mWindowManagerFuncs.getStackBounds(
WINDOWING_MODE_SPLIT_SCREEN_PRIMARY, ACTIVITY_TYPE_STANDARD, mDockedStackBounds);
final int visibility = updateSystemBarsLw(win, mLastSystemUiFlags, tmpVisibility);
final int diff = visibility ^ mLastSystemUiFlags;
final int fullscreenDiff = fullscreenVisibility ^ mLastFullscreenStackSysUiFlags;
final int dockedDiff = dockedVisibility ^ mLastDockedStackSysUiFlags;
final boolean needsMenu = win.getNeedsMenuLw(mTopFullscreenOpaqueWindowState);
if (diff == 0 && fullscreenDiff == 0 && dockedDiff == 0 && mLastFocusNeedsMenu == needsMenu
&& mFocusedApp == win.getAppToken()
&& mLastNonDockedStackBounds.equals(mNonDockedStackBounds)
&& mLastDockedStackBounds.equals(mDockedStackBounds)) {
return 0;
}
mLastSystemUiFlags = visibility;
mLastFullscreenStackSysUiFlags = fullscreenVisibility;
mLastDockedStackSysUiFlags = dockedVisibility;
mLastFocusNeedsMenu = needsMenu;
mFocusedApp = win.getAppToken();
final Rect fullscreenStackBounds = new Rect(mNonDockedStackBounds);
final Rect dockedStackBounds = new Rect(mDockedStackBounds);
mHandler.post(new Runnable() {
@Override
public void run() {
StatusBarManagerInternal statusbar = getStatusBarManagerInternal();
if (statusbar != null) {
//最终会触发状态栏管理服务StatusBarManagerService的setSystemUiVisibility方法，
//通知状态栏和底部栏进行样式调整
statusbar.setSystemUiVisibility(visibility, fullscreenVisibility,
dockedVisibility, 0xffffffff, fullscreenStackBounds,
dockedStackBounds, win.toString());
statusbar.topAppWindowChanged(needsMenu);
}
}
});
return diff;
}
//获取StatusBarManagerInternal对象实例
StatusBarManagerInternal getStatusBarManagerInternal() {
synchronized (mServiceAquireLock) {
if (mStatusBarManagerInternal == null) {
mStatusBarManagerInternal =
LocalServices.getService(StatusBarManagerInternal.class);
}
return mStatusBarManagerInternal;
}
}
}
PhoneWindowManager的focusChangedLw方法直接调用了updateSystemUiVisibilityLw方法，此方法会对窗口的SystemUiVisibility属性做一些处理，最终调用状态栏管理服务StatusBarManagerService的setSystemUiVisibility方法，通知状态栏和底部栏进行样式调整。
4、updateSystemUiVisibilityLw方法中有用到对SystemUIVisibility属性做处理的几个关键方法：updateLightStatusBarLw、chooseNavigationColorWindowLw、updateLightNavigationBarLw和updateSystemBarsLw，这里一并贴出，有兴趣的可以看下。
public class PhoneWindowManager implements WindowManagerPolicy {
private int updateLightStatusBarLw(int vis, WindowState opaque, WindowState opaqueOrDimming) {
final boolean onKeyguard = isStatusBarKeyguard() && !mKeyguardOccluded;
final WindowState statusColorWin = onKeyguard ? mStatusBar : opaqueOrDimming;
if (statusColorWin != null && (statusColorWin == opaque || onKeyguard)) {
// If the top fullscreen-or-dimming window is also the top fullscreen, respect
// its light flag.
vis &= ~View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;
vis |= PolicyControl.getSystemUiVisibility(statusColorWin, null)
& View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;
} else if (statusColorWin != null && statusColorWin.isDimming()) {
// Otherwise if it's dimming, clear the light flag.
vis &= ~View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;
}
return vis;
}
@VisibleForTesting
@Nullable
static WindowState chooseNavigationColorWindowLw(WindowState opaque,
WindowState opaqueOrDimming, WindowState imeWindow,
@NavigationBarPosition int navBarPosition) {
// If the IME window is visible and FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS is set, then IME
// window can be navigation color window.
final boolean imeWindowCanNavColorWindow = imeWindow != null
&& imeWindow.isVisibleLw()
&& navBarPosition == NAV_BAR_BOTTOM
&& (PolicyControl.getWindowFlags(imeWindow, null)
& WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS) != 0;
if (opaque != null && opaqueOrDimming == opaque) {
// If the top fullscreen-or-dimming window is also the top fullscreen, respect it
// unless IME window is also eligible, since currently the IME window is always show
// above the opaque fullscreen app window, regardless of the IME target window.
// TODO(b/31559891): Maybe we need to revisit this condition once b/31559891 is fixed.
return imeWindowCanNavColorWindow ? imeWindow : opaque;
}
if (opaqueOrDimming == null || !opaqueOrDimming.isDimming()) {
// No dimming window is involved. Determine the result only with the IME window.
return imeWindowCanNavColorWindow ? imeWindow : null;
}
if (!imeWindowCanNavColorWindow) {
// No IME window is involved. Determine the result only with opaqueOrDimming.
return opaqueOrDimming;
}
// The IME window and the dimming window are competing. Check if the dimming window can be
// IME target or not.
if (LayoutParams.mayUseInputMethod(PolicyControl.getWindowFlags(opaqueOrDimming, null))) {
// The IME window is above the dimming window.
return imeWindow;
} else {
// The dimming window is above the IME window.
return opaqueOrDimming;
}
}
@VisibleForTesting
static int updateLightNavigationBarLw(int vis, WindowState opaque, WindowState opaqueOrDimming,
WindowState imeWindow, WindowState navColorWin) {
if (navColorWin != null) {
if (navColorWin == imeWindow || navColorWin == opaque) {
// Respect the light flag.
vis &= ~View.SYSTEM_UI_FLAG_LIGHT_NAVIGATION_BAR;
vis |= PolicyControl.getSystemUiVisibility(navColorWin, null)
& View.SYSTEM_UI_FLAG_LIGHT_NAVIGATION_BAR;
} else if (navColorWin == opaqueOrDimming && navColorWin.isDimming()) {
// Clear the light flag for dimming window.
vis &= ~View.SYSTEM_UI_FLAG_LIGHT_NAVIGATION_BAR;
}
}
return vis;
}
private int updateSystemBarsLw(WindowState win, int oldVis, int vis) {
final boolean dockedStackVisible =
mWindowManagerInternal.isStackVisible(WINDOWING_MODE_SPLIT_SCREEN_PRIMARY);
final boolean freeformStackVisible =
mWindowManagerInternal.isStackVisible(WINDOWING_MODE_FREEFORM);
final boolean resizing = mWindowManagerInternal.isDockedDividerResizing();
// We need to force system bars when the docked stack is visible, when the freeform stack
// is visible but also when we are resizing for the transitions when docked stack
// visibility changes.
mForceShowSystemBars = dockedStackVisible || freeformStackVisible || resizing;
final boolean forceOpaqueStatusBar = mForceShowSystemBars && !mForceStatusBarFromKeyguard;
// apply translucent bar vis flags
WindowState fullscreenTransWin = isStatusBarKeyguard() && !mKeyguardOccluded
? mStatusBar
: mTopFullscreenOpaqueWindowState;
vis = mStatusBarController.applyTranslucentFlagLw(fullscreenTransWin, vis, oldVis);
vis = mNavigationBarController.applyTranslucentFlagLw(fullscreenTransWin, vis, oldVis);
final int dockedVis = mStatusBarController.applyTranslucentFlagLw(
mTopDockedOpaqueWindowState, 0, 0);
final boolean fullscreenDrawsStatusBarBackground =
drawsStatusBarBackground(vis, mTopFullscreenOpaqueWindowState);
final boolean dockedDrawsStatusBarBackground =
drawsStatusBarBackground(dockedVis, mTopDockedOpaqueWindowState);
// prevent status bar interaction from clearing certain flags
int type = win.getAttrs().type;
boolean statusBarHasFocus = type == TYPE_STATUS_BAR;
if (statusBarHasFocus && !isStatusBarKeyguard()) {
int flags = View.SYSTEM_UI_FLAG_FULLSCREEN
| View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
| View.SYSTEM_UI_FLAG_IMMERSIVE
| View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
| View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;
if (mKeyguardOccluded) {
flags |= View.STATUS_BAR_TRANSLUCENT | View.NAVIGATION_BAR_TRANSLUCENT;
}
vis = (vis & ~flags) | (oldVis & flags);
}
if (fullscreenDrawsStatusBarBackground && dockedDrawsStatusBarBackground) {
vis |= View.STATUS_BAR_TRANSPARENT;
vis &= ~View.STATUS_BAR_TRANSLUCENT;
} else if ((!areTranslucentBarsAllowed() && fullscreenTransWin != mStatusBar)
|| forceOpaqueStatusBar) {
vis &= ~(View.STATUS_BAR_TRANSLUCENT | View.STATUS_BAR_TRANSPARENT);
}
vis = configureNavBarOpacity(vis, dockedStackVisible, freeformStackVisible, resizing);
// update status bar
boolean immersiveSticky =
(vis & View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY) != 0;
final boolean hideStatusBarWM =
mTopFullscreenOpaqueWindowState != null
&& (PolicyControl.getWindowFlags(mTopFullscreenOpaqueWindowState, null)
& WindowManager.LayoutParams.FLAG_FULLSCREEN) != 0;
final boolean hideStatusBarSysui =
(vis & View.SYSTEM_UI_FLAG_FULLSCREEN) != 0;
final boolean hideNavBarSysui =
(vis & View.SYSTEM_UI_FLAG_HIDE_NAVIGATION) != 0;
final boolean transientStatusBarAllowed = mStatusBar != null
&& (statusBarHasFocus || (!mForceShowSystemBars
&& (hideStatusBarWM || (hideStatusBarSysui && immersiveSticky))));
final boolean transientNavBarAllowed = mNavigationBar != null
&& !mForceShowSystemBars && hideNavBarSysui && immersiveSticky;
final long now = SystemClock.uptimeMillis();
final boolean pendingPanic = mPendingPanicGestureUptime != 0
&& now - mPendingPanicGestureUptime <= PANIC_GESTURE_EXPIRATION;
if (pendingPanic && hideNavBarSysui && !isStatusBarKeyguard() && mKeyguardDrawComplete) {
// The user performed the panic gesture recently, we're about to hide the bars,
// we're no longer on the Keyguard and the screen is ready. We can now request the bars.
mPendingPanicGestureUptime = 0;
mStatusBarController.showTransient();
if (!isNavBarEmpty(vis)) {
mNavigationBarController.showTransient();
}
}
final boolean denyTransientStatus = mStatusBarController.isTransientShowRequested()
&& !transientStatusBarAllowed && hideStatusBarSysui;
final boolean denyTransientNav = mNavigationBarController.isTransientShowRequested()
&& !transientNavBarAllowed;
if (denyTransientStatus || denyTransientNav || mForceShowSystemBars) {
// clear the clearable flags instead
clearClearableFlagsLw();
vis &= ~View.SYSTEM_UI_CLEARABLE_FLAGS;
}
final boolean immersive = (vis & View.SYSTEM_UI_FLAG_IMMERSIVE) != 0;
immersiveSticky = (vis & View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY) != 0;
final boolean navAllowedHidden = immersive || immersiveSticky;
if (hideNavBarSysui && !navAllowedHidden
&& getWindowLayerLw(win) > getWindowLayerFromTypeLw(TYPE_INPUT_CONSUMER)) {
// We can't hide the navbar from this window otherwise the input consumer would not get
// the input events.
vis = (vis & ~View.SYSTEM_UI_FLAG_HIDE_NAVIGATION);
}
vis = mStatusBarController.updateVisibilityLw(transientStatusBarAllowed, oldVis, vis);
// update navigation bar
boolean oldImmersiveMode = isImmersiveMode(oldVis);
boolean newImmersiveMode = isImmersiveMode(vis);
if (win != null && oldImmersiveMode != newImmersiveMode) {
final String pkg = win.getOwningPackage();
mImmersiveModeConfirmation.immersiveModeChangedLw(pkg, newImmersiveMode,
isUserSetupComplete(), isNavBarEmpty(win.getSystemUiVisibility()));
}
vis = mNavigationBarController.updateVisibilityLw(transientNavBarAllowed, oldVis, vis);
final WindowState navColorWin = chooseNavigationColorWindowLw(
mTopFullscreenOpaqueWindowState, mTopFullscreenOpaqueOrDimmingWindowState,
mWindowManagerFuncs.getInputMethodWindowLw(), mNavigationBarPosition);
vis = updateLightNavigationBarLw(vis, mTopFullscreenOpaqueWindowState,
mTopFullscreenOpaqueOrDimmingWindowState,
mWindowManagerFuncs.getInputMethodWindowLw(), navColorWin);
return vis;
}
}
七、状态栏管理服务传递SystemUIVisibility属性给状态栏
1、在第六节第2步的最后，PhoneWindowManager最终会调用StatusBarManagerInternal的setSystemUiVisibility方法，StatusBarManagerInternal是一个抽象接口。
public interface StatusBarManagerInternal {
void setSystemUiVisibility(int vis, int fullscreenStackVis, int dockedStackVis, int mask,
Rect fullscreenBounds, Rect dockedBounds, String cause);
}
2、