接着第三篇：https://www.jianshu.com/p/a10944f9d5e3?v=1698141883941
2.2 窗口位置计算
当WindowState加入到WindowToken并调整z-order之后，客户端会再次调用WMS执行窗口布局。
主要做了这三件事：
1.接收客户端请求
2.创建SurfaceControl
3.窗口大小位置计算
2.2.1 接收客户端请求
与addWindow流程的调用过程类似，WindowManagerService.relayoutWindow也是由客户端通过Session来调用的。
首先我们来看一下客户端给我们传递了哪些参数吧。
window：是WMS与客户端通信的Binder。
attrs：窗口的布局属性，根据attrs提供的属性来布局窗口。
requestWidth、requestHeight：客户端请求的窗口尺寸。
viewFlags：窗口的可见性。包括VISIBLE（0，view可见），INVISIBLE（4，view不可见，但是仍然占用布局空间）GONE（8，view不可见，不占用布局空间）
flags：定义一些布局行为。
outFrames：返回给客户端的，保存了重新布局之后的位置与大小。
mergedConfiguration:相关配置信息。
outSurfaceControl:返回给客户端的surfaceControl。
outInsetsState：用来保存系统中所有Insets的状态。
outActiveControls：InSetsSourceControl数组。
outSyncSeqIdBundle：与布局同步有关。
Session调用WMS.relayoutWindow将客户端传入的参数传递给WMS。
代码路径：framework/services/core/java/com/android/server/wm/Session.java
@Override
public int relayout(IWindow window, WindowManager.LayoutParams attrs,
int requestedWidth, int requestedHeight, int viewFlags, int flags,
ClientWindowFrames outFrames, MergedConfiguration mergedConfiguration,
SurfaceControl outSurfaceControl, InsetsState outInsetsState,
InsetsSourceControl[] outActiveControls, Bundle outSyncSeqIdBundle) {
if (false) Slog.d(TAG_WM, ">>>>>> ENTERED relayout from "
+ Binder.getCallingPid());
Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, mRelayoutTag);
int res = mService.relayoutWindow(this, window, attrs,
requestedWidth, requestedHeight, viewFlags, flags,
outFrames, mergedConfiguration, outSurfaceControl, outInsetsState,
outActiveControls, outSyncSeqIdBundle);
Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
if (false) Slog.d(TAG_WM, "<<<<<< EXITING relayout to "
+ Binder.getCallingPid());
return res;
}
2.2.2 relayoutWindow
在WMS.relayoutWindow中主要做了以下事情：
1.根据客户端传过来的IWindow在mWindowMap获取窗口添加阶段创建的WindowState。
2.设置DisplayContent.mLayoutNeeded以及shouldRelayout标志位
3.Surface的创建流程。
4.窗口尺寸的计算以及Surface的状态变更。
代码路径：framework/services/core/java/com/android/server/wm/WindowManagerService.java
public int relayoutWindow(Session session, IWindow client, LayoutParams attrs,
int requestedWidth, int requestedHeight, int viewVisibility, int flags,
ClientWindowFrames outFrames, MergedConfiguration mergedConfiguration,
SurfaceControl outSurfaceControl, InsetsState outInsetsState,
InsetsSourceControl[] outActiveControls, Bundle outSyncIdBundle) {
......
synchronized (mGlobalLock) {
/*1.根据客户端传过来的Iwindow从mWindowMap中获取对应的WindowState*/
final WindowState win = windowForClientLocked(session, client, false);
if (win == null) {
return 0;
}
//获取DisplayContent、DisplayPolicy以及WindowStateAnimator
final DisplayContent displayContent = win.getDisplayContent();
final DisplayPolicy displayPolicy = displayContent.getDisplayPolicy();
WindowStateAnimator winAnimator = win.mWinAnimator;
if (viewVisibility != View.GONE) {
//根据客户端请求的窗口大小设置WindowState的requestedWidth, requestedHeight
//并设置WindowState.mLayoutNeeded为true
win.setRequestedSize(requestedWidth, requestedHeight);
}
......
//根据请求的宽带和高度窗口缩放比例
win.setWindowScale(win.mRequestedWidth, win.mRequestedHeight);
......
//获取原来window的可见性，此时为INVISIBLE
final int oldVisibility = win.mViewVisibility;
......
//代表现在没有surface但应该很快就有标志位
win.mRelayoutCalled = true;
win.mInRelayout = true;
//将当前窗口的可见性有原来的INVISIBLE调整为VISIBLE
win.setViewVisibility(viewVisibility);
ProtoLog.i(WM_DEBUG_SCREEN_ON,
"Relayout %s: oldVis=%d newVis=%d. %s", win, oldVisibility,
viewVisibility, new RuntimeException().fillInStackTrace());
/*2.1.将displayContent中的布局标志为mLayoutNeeded置为true*/
win.setDisplayLayoutNeeded();
win.mGivenInsetsPending = (flags & WindowManagerGlobal.RELAYOUT_INSETS_PENDING) != 0;
// We should only relayout if the view is visible, it is a starting window, or the
// associated appToken is not hidden.
/*2.2.判断是否允许relayout，此时为true*/
//判断条件：view可见且（activityRecord不为空，或者布局类型为TYPE_APPLICATION_STARTING，或者窗口已经告诉客户端可以显示）
final boolean shouldRelayout = viewVisibility == View.VISIBLE &&
(win.mActivityRecord == null || win.mAttrs.type == TYPE_APPLICATION_STARTING
|| win.mActivityRecord.isClientVisible());
......
// Create surfaceControl before surface placement otherwise layout will be skipped
// (because WS.isGoneForLayout() is true when there is no surface.
/*3.surface的创建流程*/
if (shouldRelayout) {
try {
//进入creatSurfaceControl开始创建SurfaceControl
result = createSurfaceControl(outSurfaceControl, result, win, winAnimator);
} catch (Exception e) {
......
return 0;
}
}
// We may be deferring layout passes at the moment, but since the client is interested
// in the new out values right now we need to force a layout.
/*4.窗口尺寸的计算以及Surface的状态变更*/
//WindowSurfacePlacer在WMS初始化的时候创建
mWindowPlacerLocked.performSurfacePlacement(true /* force */);
......
//填充计算好的frame返回给客户端，更新mergedConfiguration对象
win.fillClientWindowFramesAndConfiguration(outFrames, mergedConfiguration,
false /* useLatestConfig */, shouldRelayout);
// Set resize-handled here because the values are sent back to the client.
win.onResizeHandled();
......
}
Binder.restoreCallingIdentity(origId);
//返回result
return result;
}
2.2.3 创建SurfaceControl
在relayoutWindow中创建SurfaceControl
result = createSurfaceControl(outSurfaceControl, result, win, winAnimator);
关于SurfaceControl的创建在WMS中主要做两件事：
1.调用WindwoStateAnimator执行具体的SurfaceControl的创建。
2.将创建的SurfaceControl赋值给客户端的outSurfaceControl。
代码路径：framework/services/core/java/com/android/server/wm/WindowManagerService.java
private int createSurfaceControl(SurfaceControl outSurfaceControl, int result,
WindowState win, WindowStateAnimator winAnimator) {
......
WindowSurfaceController surfaceController;
try {
Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "createSurfaceControl");
/*
* WindowStateAnimator用来帮助WindowState管理animator和surface基本操作的
* 1.WMS将创建的surfaceContorl的操作交给windowAnimator来处理
*/
surfaceController = winAnimator.createSurfaceLocked();
} finally {
Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
}
if (surfaceController != null) {
/*2.将WMS的SurfaceControl赋值给客户端的outSurfaceControl*/
surfaceController.getSurfaceControl(outSurfaceControl);
ProtoLog.i(WM_SHOW_TRANSACTIONS, "OUT SURFACE %s: copied", outSurfaceControl);
} else {
// For some reason there isn't a surface. Clear the
// caller's object so they see the same state.
ProtoLog.w(WM_ERROR, "Failed to create surface control for %s", win);
outSurfaceControl.release();
}
return result;
}
在WindowStateAnimator中创建SurfaceControl主要经过以下三个步骤：
1.重置Surface标志位，变更mDrawState状态为DRAW_PENDING。
2.通过实例化WindowSurfaceController来创建SurfaceControl。
3.处理Surface标志位，将其置为true，标志着当前WindowState已经有surface了
代码路径：framework/services/core/java/com/android/server/wm/WindowStateAnimator.java
WindowSurfaceController createSurfaceLocked() {
final WindowState w = mWin;
//首先判断是否存在mSurfaceController
if (mSurfaceController != null) {
return mSurfaceController;
}
/*1.1.设置WindowState的mHasSurface设置为false*/
w.setHasSurface(false);
ProtoLog.i(WM_DEBUG_ANIM, "createSurface %s: mDrawState=DRAW_PENDING", this);
/*1.2.将WindowStateAnimator中的DrawState设置为DRAW_PENDING*/
resetDrawState();
mService.makeWindowFreezingScreenIfNeededLocked(w);
/*1.3.将surface创建flag设置为hidden*/
int flags = SurfaceControl.HIDDEN;
//获取windowState的布局参数
final WindowManager.LayoutParams attrs = w.mAttrs;
// Set up surface control with initial size.
try {
......
/*2.创建WindowSurfaceController*/
//attrs.getTitle().toString()为当前activity的全路径名
//format为位图格式
//flags为surface创建的标志位（如：HIDDED(0x04,surface创建为隐藏)，SKIP_SCREENSHOT(0x040，截屏时跳过此图层将不会包含在非主显示器上),SECURE(0X080,禁止复制表面的内容，屏幕截图和次要的非安全显示将呈现黑色内容而不是surface内容)等）
//attrs.type为窗口类型
mSurfaceController = new WindowSurfaceController(attrs.getTitle().toString(), format,
flags, this, attrs.type);
mSurfaceController.setColorSpaceAgnostic((attrs.privateFlags
& WindowManager.LayoutParams.PRIVATE_FLAG_COLOR_SPACE_AGNOSTIC) != 0);
/*3.将WindowState的hasSurface标志设置为true，标志着道歉WindowState已经有surface了*/
w.setHasSurface(true);
......
} catch (OutOfResourcesException e) {
......
} catch (Exception e) {
......
}
......
return mSurfaceController;
}
SurfaceControl的创建过程为典型的建造者模式
接下来看看WindowSurfaceController的构造方法
代码路径：framework/services/core/java/com/android/server/wm/WindowSurfaceController.java
WindowSurfaceController(String name, int format, int flags, WindowStateAnimator animator,
int windowType) {
//设置WindowStateAnimator
mAnimator = animator;
//窗口名
title = name;
//WMS对象
mService = animator.mService;
//WindowState对象
final WindowState win = animator.mWin;
//窗口类型
mWindowType = windowType;
//IWindowSession对象
mWindowSession = win.mSession;
Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "new SurfaceControl");
//makeSurface最终会调用到DisplayContent的makeChildSurface方法，返回SurfaceControl.Builder
final SurfaceControl.Builder b = win.makeSurface()
.setParent(win.getSurfaceControl())
.setName(name)
.setFormat(format)
.setFlags(flags)
.setMetadata(METADATA_WINDOW_TYPE, windowType)
.setMetadata(METADATA_OWNER_UID, mWindowSession.mUid)
.setMetadata(METADATA_OWNER_PID, mWindowSession.mPid)
.setCallsite("WindowSurfaceController");
......
//获取SurfaceControl实例对象
mSurfaceControl = b.build();
Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
}
两个关键方法win.makeSurface()和b.build()
1.final SurfaceControl.Builder b = win.makeSurface()
我们先来看看win.makeSurface()，windowState中没有makeSurface()方法，因此调用其父类WindowContainer的makeSurface()方法
代码路径：framework/services/core/java/com/android/server/wm/WindowContainer.java
SurfaceControl.Builder makeSurface() {
final WindowContainer p = getParent();
return p.makeChildSurface(this);
}
/**
* @param child The WindowContainer this child surface is for, or null if the Surface
* is not assosciated with a WindowContainer (e.g. a surface used for Dimming).
*/
SurfaceControl.Builder makeChildSurface(WindowContainer child) {
final WindowContainer p = getParent();
// Give the parent a chance to set properties. In hierarchy v1 we rely
// on this to set full-screen dimensions on all our Surface-less Layers.
return p.makeChildSurface(child)
.setParent(mSurfaceControl);
}
最终会调用到DisplayContent的makeChildSurface
代码路径：framework/services/core/java/com/android/server/wm/DisplayContent.java
@Override
SurfaceControl.Builder makeChildSurface(WindowContainer child) {
//此时child为WindowState
//获取SurfaceSession，SurfaceSession的创建在Session.windowAddedLocked中，其最开始调用在WindowManagerService.addWindow中win.attach()中创建
SurfaceSession s = child != null ? child.getSession() : getSession();
//返回SurfaceControl.Builder
final SurfaceControl.Builder b = mWmService.makeSurfaceBuilder(s).setContainerLayer();
if (child == null) {
return b;
}
//设置SurfaceControl.Builder的name以及parent
return b.setName(child.getName())
.setParent(mSurfaceControl);
}
最终会调用到DisplayContent的makeChildSurface
代码路径：framework/services/core/java/com/android/server/wm/DisplayContent.java
@Override
SurfaceControl.Builder makeChildSurface(WindowContainer child) {
//此时child为WindowState
//获取SurfaceSession，SurfaceSession的创建在Session.windowAddedLocked中，其最开始调用在WindowManagerService.addWindow中win.attach()中创建
SurfaceSession s = child != null ? child.getSession() : getSession();
//返回SurfaceControl.Builder
final SurfaceControl.Builder b = mWmService.makeSurfaceBuilder(s).setContainerLayer();
if (child == null) {
return b;
}
//设置SurfaceControl.Builder的name以及parent
return b.setName(child.getName())
.setParent(mSurfaceControl);
}
2.mSurfaceControl = b.build();
再来看看b.build()，调用SurfaceControl中的build
代码路径：framework/core/java/android/view/SurfaceControl.java
/**
* Construct a new {@link SurfaceControl} with the set parameters. The builder
* remains valid.
*/
@NonNull
public SurfaceControl build() {
//检查width以及height，初始都应该为0
if (mWidth < 0 || mHeight < 0) {
throw new IllegalStateException(
"width and height must be positive or unset");
}
if ((mWidth > 0 || mHeight > 0) && (isEffectLayer() || isContainerLayer())) {
throw new IllegalStateException(
"Only buffer layers can set a valid buffer size.");
}
if ((mFlags & FX_SURFACE_MASK) == FX_SURFACE_NORMAL) {
setBLASTLayer();
}
//创建SurfaceControl的实例
return new SurfaceControl(
mSession, mName, mWidth, mHeight, mFormat, mFlags, mParent, mMetadata,
mLocalOwnerView, mCallsite);
}
/**
* @param session The surface session, must not be null.
* @param name The surface name, must not be null.
* @param w The surface initial width.
* @param h The surface initial height.
* @param flags The surface creation flags.
* @param metadata Initial metadata.
* @param callsite String uniquely identifying callsite that created this object. Used for
* leakage tracking.
* @throws throws OutOfResourcesException If the SurfaceControl cannot be created.
*/
private SurfaceControl(SurfaceSession session, String name, int w, int h, int format, int flags,
SurfaceControl parent, SparseIntArray metadata, WeakReference<View> localOwnerView,
String callsite)
throws OutOfResourcesException, IllegalArgumentException {
if (name == null) {
throw new IllegalArgumentException("name must not be null");
}
mName = name;
mWidth = w;
mHeight = h;
mLocalOwnerView = localOwnerView;
//创建Parcel用来传递数据
Parcel metaParcel = Parcel.obtain();
try {
......
//调用native层
mNativeObject = nativeCreate(session, name, w, h, format, flags,
parent != null ? parent.mNativeObject : 0, metaParcel);
} finally {
metaParcel.recycle();
}
if (mNativeObject == 0) {
throw new OutOfResourcesException(
"Couldn't allocate SurfaceControl native object");
}
mNativeHandle = nativeGetHandle(mNativeObject);
mCloseGuard.openWithCallSite("release", callsite);
}
SurfaceControl的构造方法调用完成后，返回查看前面
result = createSurfaceControl(outSurfaceControl, result, win, winAnimator);
2.2.4 计算窗口大小位置
在relayoutWindow中计算窗口大小位置
mWindowPlacerLocked.performSurfacePlacement(true /* force */);
该流程我们分为三部分介绍：
1.该部分处理有关窗口布局循环的逻辑。
2.该部分处理Surface的状态变更，以及调用layoutWindowLw的流程。
3.计算窗口位置大小。
1.处理窗口布局循环
performSurfacePlacement是一个确定所有窗口的Surface的如何摆放，如何显示、显示在什么位置、显示区域多大的一个入口方法。
该方法主要设置了布局的循环条件，当mTraversalScheduled 标志位为true，且loopCount大于0。将会调用performSurfacePlacementLoop执行布局操作。
代码路径：framework/services/core/java/com/android/server/wm/WindowSurfacePlacer.java
final void performSurfacePlacement(boolean force) {
if (mDeferDepth > 0 && !force) {
mDeferredRequests++;
return;
}
//将循环的最大次数设置为6次
int loopCount = 6;
do {
//将该标志为设置为false
mTraversalScheduled = false;
//执行窗口布局操作
performSurfacePlacementLoop();
mService.mAnimationHandler.removeCallbacks(mPerformSurfacePlacement);
loopCount--;
//只有当mTraversalScheduled为true且循环次数大于0时，才会再次循环执行布局
} while (mTraversalScheduled && loopCount > 0);
mService.mRoot.mWallpaperActionPending = false;
}
performSurfacePlacementLoop方法主要做两件事：
1.调用RootWindowContainer对所有窗口执行布局操作，
2.处理是否再次进行布局的逻辑。如果DisplayContent.mLayoutNeeded标志位为true且布局循环次数小于6次，则会将mTraversalScheduled标志位置为true，在performSurfacePlacement中会再次调用performSurfacePlacementLoop。
private void performSurfacePlacementLoop() {
//若当前已经进行布局操作，则无需重复调用直接返回
if (mInLayout) {
......
return;
}
......
//将该标志位置为true，表示正在处于布局过程中
mInLayout = true;
......
try {
/*1.调用RootWindowContainer的performSurfacePlacement()方法对所有窗口执行布局操作*/
mService.mRoot.performSurfacePlacement();
mInLayout = false;
if (mService.mRoot.isLayoutNeeded()) {
/*2.若需要布局，且布局次数小于6次，则需要再次请求布局*/
if (++mLayoutRepeatCount < 6) {
//该方法中会将mTraversalScheduled标志位设置位true
requestTraversal();
} else {
Slog.e(TAG, "Performed 6 layouts in a row. Skipping");
mLayoutRepeatCount = 0;
}
} else {
mLayoutRepeatCount = 0;
}
if (mService.mWindowsChanged && !mService.mWindowChangeListeners.isEmpty()) {
mService.mH.removeMessages(REPORT_WINDOWS_CHANGE);
mService.mH.sendEmptyMessage(REPORT_WINDOWS_CHANGE);
}
} catch (RuntimeException e) {
mInLayout = false;
Slog.wtf(TAG, "Unhandled exception while laying out windows", e);
}
}
2.处理所有Surface的状态变更，以及调用layoutWindowLw的流程
mService.mRoot.performSurfacePlacement();
上面说到在RootWindowContainer.performSurfacePlacement()中调用了performSurfaceNoTrace()方法，该方法为实际的处理布局的方法，主要处理以下流程：
1.如果有焦点变化，更新焦点。
2.执行窗口尺寸计算，surface状态变更等操作。
3.将Surface状态变更为HAS_DRAWN，触发App触发动画。该过程在finishdrawing()中再详细分析。
4.如果壁纸有变化，更新壁纸。
5.再次处理焦点变化。
6.如果过程中由size或者位置变化，则通知客户端重新relayout。
7.销毁不可见的窗口
代码路径：framework/services/core/java/com/android/server/wm/RootWindowContainer.java
void performSurfacePlacement() {
Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "performSurfacePlacement");
try {
//调用performSurfacePlacementNoTrace()
performSurfacePlacementNoTrace();
} finally {
Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
}
}
// "Something has changed! Let's make it correct now."
// TODO: Super long method that should be broken down...
void performSurfacePlacementNoTrace() {
......
/*1.如果有焦点变化，更新焦点*/
if (mWmService.mFocusMayChange) {
mWmService.mFocusMayChange = false;
mWmService.updateFocusedWindowLocked(
UPDATE_FOCUS_WILL_PLACE_SURFACES, false /*updateInputWindows*/);
}
......
Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "applySurfaceChanges");
//开启事务，获取GlobalTransactionWrapper对象
mWmService.openSurfaceTransaction();
try {
/*2.执行窗口尺寸计算，surface状态变更等操作*/
applySurfaceChangesTransaction();
} catch (RuntimeException e) {
Slog.wtf(TAG, "Unhandled exception in Window Manager", e);
} finally {
//关闭事务
mWmService.closeSurfaceTransaction("performLayoutAndPlaceSurfaces");
Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
if (SHOW_LIGHT_TRANSACTIONS) {
Slog.i(TAG,
"<<< CLOSE TRANSACTION performLayoutAndPlaceSurfaces");
}
}
......
/*3.将Surface状态变更为HAS_DRAWN，触发App触发动画。该过程在“2.3.3mDrawState变更为HAS_DRAW”流程中再详细分析*/
checkAppTransitionReady(surfacePlacer);
......
/*4.遍历所有DisplayContent，如果壁纸有变化，更新壁纸*/
for (int displayNdx = 0; displayNdx < mChildren.size(); ++displayNdx) {
final DisplayContent displayContent = mChildren.get(displayNdx);
//判断DisplayContent的壁纸是否需要改变
if (displayContent.mWallpaperMayChange) {
ProtoLog.v(WM_DEBUG_WALLPAPER, "Wallpaper may change! Adjusting");
displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;
if (DEBUG_LAYOUT_REPEATS) {
surfacePlacer.debugLayoutRepeats("WallpaperMayChange",
displayContent.pendingLayoutChanges);
}
}
}
/*5.在此处理焦点变化*/
if (mWmService.mFocusMayChange) {
mWmService.mFocusMayChange = false;
mWmService.updateFocusedWindowLocked(UPDATE_FOCUS_PLACING_SURFACES,
false /*updateInputWindows*/);
}
......
/*6.如果过程中size或者位置变化，则通知客户端重新relayout*/
handleResizingWindows();
if (mWmService.mDisplayFrozen) {
ProtoLog.v(WM_DEBUG_ORIENTATION,
"With display frozen, orientationChangeComplete=%b",
mOrientationChangeComplete);
}
if (mOrientationChangeComplete) {
if (mWmService.mWindowsFreezingScreen != WINDOWS_FREEZING_SCREENS_NONE) {
mWmService.mWindowsFreezingScreen = WINDOWS_FREEZING_SCREENS_NONE;
mWmService.mLastFinishedFreezeSource = mLastWindowFreezeSource;
mWmService.mH.removeMessages(WINDOW_FREEZE_TIMEOUT);
}
mWmService.stopFreezingDisplayLocked();
}
// Destroy the surface of any windows that are no longer visible.
/*7.销毁不可见的窗口*/
i = mWmService.mDestroySurface.size();
if (i > 0) {
do {
i--;
WindowState win = mWmService.mDestroySurface.get(i);
win.mDestroying = false;
final DisplayContent displayContent = win.getDisplayContent();
if (displayContent.mInputMethodWindow == win) {
displayContent.setInputMethodWindowLocked(null);
}
if (displayContent.mWallpaperController.isWallpaperTarget(win)) {
displayContent.pendingLayoutChanges |= FINISH_LAYOUT_REDO_WALLPAPER;
}
win.destroySurfaceUnchecked();
} while (i > 0);
mWmService.mDestroySurface.clear();
}
......
}
在applySurfaceChangesTransaction();方法中其主要执行：
1.水印、StrictMode警告框以及模拟器显示的布局。
2.遍历所有DisplayContent执行其applySurfaceChangesTransaction
我们一起看看这个方法
private void applySurfaceChangesTransaction() {
mHoldScreenWindow = null;
mObscuringWindow = null;
// TODO(multi-display): Support these features on secondary screens.
/*1.水印、StrictMode警告框以及模拟器显示的布局*/
//获取手机默认DisplayContent的信息
final DisplayContent defaultDc = mWmService.getDefaultDisplayContentLocked();
final DisplayInfo defaultInfo = defaultDc.getDisplayInfo();
final int defaultDw = defaultInfo.logicalWidth;
final int defaultDh = defaultInfo.logicalHeight;
//布局水印
if (mWmService.mWatermark != null) {
mWmService.mWatermark.positionSurface(defaultDw, defaultDh, mDisplayTransaction);
}
//布局StrictMode警告框
if (mWmService.mStrictModeFlash != null) {
mWmService.mStrictModeFlash.positionSurface(defaultDw, defaultDh, mDisplayTransaction);
}
//布局模拟器显示覆盖
if (mWmService.mEmulatorDisplayOverlay != null) {
mWmService.mEmulatorDisplayOverlay.positionSurface(defaultDw, defaultDh,
mWmService.getDefaultDisplayRotation(), mDisplayTransaction);
}
/*2.遍历RootWindowContainer下所有DisplayContent执行其applySurfaceChangesTransaction()*/
final int count = mChildren.size();
for (int j = 0; j < count; ++j) {
final DisplayContent dc = mChildren.get(j);
dc.applySurfaceChangesTransaction();
}
// Give the display manager a chance to adjust properties like display rotation if it needs
// to.
mWmService.mDisplayManagerInternal.performTraversal(mDisplayTransaction);
SurfaceControl.mergeToGlobalTransaction(mDisplayTransaction);
}
接下来继续跟踪dc.applySurfaceChangesTransaction();
该方法主要
1.遍历所有窗口，计算窗口的布局大小，具体流程查看performLayoutNoTrace。（主要跟踪点）
2.surface的状态更改。（见“2.3.3mDrawState变更为HAS_DRAW”流程”）
3.处理surface的位置、大小以及显示等。（见“2.3.4 show Surface”流程”）
代码路径：framework/services/core/java/com/android/server/wm/DisplayContent.java
void applySurfaceChangesTransaction() {
//获取WindowSurfacePlacer
final WindowSurfacePlacer surfacePlacer = mWmService.mWindowPlacerLocked;
......
// Perform a layout, if needed.
/*1.执行布局，该方法最终会调用performLayoutNoTrace，计算窗口的布局参数*/
performLayout(true /* initial */, false /* updateInputWindows */);
......
Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "applyWindowSurfaceChanges");
try {
/*2.遍历所有窗口，主要是改变surface的状态。见“2.3.3mDrawState变更为HAS_DRAW”流程*/
forAllWindows(mApplySurfaceChangesTransaction, true /* traverseTopToBottom */);
} finally {
Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
}
/*3.处理各个surface的位置、大小以及是否要在屏幕上显示等。后面finishDrawing()流程中再跟踪*/
prepareSurfaces();
......
}
继续跟踪performLayout(true /* initial /, false / updateInputWindows */);
该方法主要就是调用performLayoutNoTrace()方法，首先判断布局标志位mLayoutNeeded，该标志位在WMS.relayoutWindow中被置为true。
false则直接返回不会进行布局操作。
true则分别遍历父窗口和子窗口进行布局，我们暂且只分析父窗口的布局操作，查看mPerformLayout。
void performLayout(boolean initial, boolean updateInputWindows) {
Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, "performLayout");
try {
//调用performLayoutNoTrace
performLayoutNoTrace(initial, updateInputWindows);
} finally {
Trace.traceEnd(TRACE_TAG_WINDOW_MANAGER);
}
}
private void performLayoutNoTrace(boolean initial, boolean updateInputWindows) {
/*1.判断是否需要布局，不需要则直接返回，即判断布局标志位mLayoutNeeded是否为true*/
if (!isLayoutNeeded()) {
return;
}
//将DisplayContent.mLayoutNeeded属性置为false
clearLayoutNeeded();
......
// First perform layout of any root windows (not attached to another window).
/*2.对所有顶级窗口进行布局*/
//最终会回调mPerformLayout
forAllWindows(mPerformLayout, true /* traverseTopToBottom */);
// Now perform layout of attached windows, which usually depend on the position of the
// window they are attached to. XXX does not deal with windows that are attached to windows
// that are themselves attached.
/*3.处理子窗口的布局*/
//最终会回调mPerformLayoutAttached
forAllWindows(mPerformLayoutAttached, true /* traverseTopToBottom */);
......
}
forAllWindows(mPerformLayoutAttached, true /* traverseTopToBottom */);
当遍历到DisplayContent下的每个窗口时都会执行mPerformLayout，该方法会将WindowState.mLayoutNeeded标志位置false，并将具体的布局操作交给DisplayPolicy进行处理，见“3. 计算窗口位置大小“。
private final Consumer<WindowState> mPerformLayout = w -> {
//如果当前窗口为子窗口则直接返回
if (w.mLayoutAttached) {
return;
}
// Don't do layout of a window if it is not visible, or soon won't be visible, to avoid
// wasting time and funky changes while a window is animating away.
//先判断当前窗口是否会不可见
final boolean gone = w.isGoneForLayout();
......
// If this view is GONE, then skip it -- keep the current frame, and let the caller know
// so they can ignore it if they want. (We do the normal layout for INVISIBLE windows,
// since that means "perform layout as normal, just don't display").
if (!gone || !w.mHaveFrame || w.mLayoutNeeded) {
if (mTmpInitial) {
//设置窗口布局WindowFrames.mContentChanged为false
w.resetContentChanged();
}
w.mSurfacePlacementNeeded = true;
//此处将WindowState.mLayoutNeeded标志位置为false
w.mLayoutNeeded = false;
//判断当前窗口是否是第一次布局
final boolean firstLayout = !w.isLaidOut();
//调用DisplayPolicy.layoutWindowLw进行布局，根据DisplayFrames对象对WindowState.mWindowFrames中的各个Rect对象属性进行确定
getDisplayPolicy().layoutWindowLw(w, null, mDisplayFrames);
w.mLayoutSeq = mLayoutSeq;
// If this is the first layout, we need to initialize the last frames and inset values,
// as otherwise we'd immediately cause an unnecessary resize.
if (firstLayout) {
// The client may compute its actual requested size according to the first layout,
// so we still request the window to resize if the current frame is empty.
if (!w.getFrame().isEmpty()) {
w.updateLastFrames();
}
w.onResizeHandled();
}
if (DEBUG_LAYOUT) Slog.v(TAG, " LAYOUT: mFrame=" + w.getFrame()
+ " mParentFrame=" + w.getParentFrame()
+ " mDisplayFrame=" + w.getDisplayFrame());
}
};
3.计算窗口位置大小
getDisplayPolicy().layoutWindowLw(w, null, mDisplayFrames);
layoutWindowLw主要做了以下三件事
1.首先会获DisplayFrames：DisplayContent新建时创建，内部数据由屏幕提供。
2.其次调用WindowLayout.computeFrames计算窗口布局大小。
3.最后调用WindowState.setFrames将计算的布局参数赋值给当前窗口的windowFrames。
代码路径：framework/services/core/java/com/android/server/wm/DisplayPolicy.java
/**
* Called for each window attached to the window manager as layout is proceeding. The
* implementation of this function must take care of setting the window's frame, either here or
* in finishLayout().
*
* @param win The window being positioned.
* @param attached For sub-windows, the window it is attached to; this
* window will already have had layoutWindow() called on it
* so you can use its Rect. Otherwise null.
* @param displayFrames The display frames.
*/
public void layoutWindowLw(WindowState win, WindowState attached, DisplayFrames displayFrames) {
//判断是否需要跳过布局
if (win.skipLayout()) {
return;
}
// This window might be in the simulated environment.
// We invoke this to get the proper DisplayFrames.
/*1.获取DisplayFrames*/
displayFrames = win.getDisplayFrames(displayFrames);
//获取某个方向的窗口布局参数
final WindowManager.LayoutParams attrs = win.getLayoutingAttrs(displayFrames.mRotation);
//null
final Rect attachedWindowFrame = attached != null ? attached.getFrame() : null;
// If this window has different LayoutParams for rotations, we cannot trust its requested
// size. Because it might have not sent its requested size for the new rotation.
final boolean trustedSize = attrs == win.mAttrs;
final int requestedWidth = trustedSize ? win.mRequestedWidth : UNSPECIFIED_LENGTH;
final int requestedHeight = trustedSize ? win.mRequestedHeight : UNSPECIFIED_LENGTH;
/*2.调用WindowLayout.computeFrames计算窗口布局大小*/
mWindowLayout.computeFrames(attrs, win.getInsetsState(), displayFrames.mDisplayCutoutSafe,
win.getBounds(), win.getWindowingMode(), requestedWidth, requestedHeight,
win.getRequestedVisibilities(), attachedWindowFrame, win.mGlobalScale,
sTmpClientFrames);
/*3.将计算的布局参数赋值给windowFrames*/
win.setFrames(sTmpClientFrames, win.mRequestedWidth, win.mRequestedHeight);
}
先来看看computeFrames
mWindowLayout.computeFrames(attrs, win.getInsetsState(), displayFrames.mDisplayCutoutSafe,
win.getBounds(), win.getWindowingMode(), requestedWidth, requestedHeight,
win.getRequestedVisibilities(), attachedWindowFrame, win.mGlobalScale,
sTmpClientFrames);
留坑
再来看看setFrames
win.setFrames(sTmpClientFrames, win.mRequestedWidth, win.mRequestedHeight);
留坑
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版权声明：本文为CSDN博主「yi诺千金」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/yimelancholy/article/details/130339779
