WindowManagerService的getDisplayContentLocked函数的定义如下:
1 public DisplayContent getDisplayContentLocked(final int displayId) {
2 DisplayContent displayContent = mDisplayContents.get(displayId);
3 if (displayContent == null) {
4 final Display display = mDisplayManager.getDisplay(displayId);
5 if (display != null) {
6 displayContent = new DisplayContent(display);
7 mDisplayContents.put(displayId, displayContent);
8 }
9 }
10 return displayContent;
11 }
getDisplayContentLocked函数的逻辑还是比较简单的.
page12
在这篇文章里, 我们分析一下WindowState的创建过程.
WindowState类的定义如下:
final class WindowState implements WindowManagerPolicy.WindowState
WindowState类的定义如下:
1 WindowState(WindowManagerService service, Session s, IWindow c, WindowToken token,
2 WindowState attachedWindow, int seq, WindowManager.LayoutParams a,
3 int viewVisibility, final DisplayContent displayContent) {
4 mService = service;
5 mSession = s;
6 mClient = c;
7 mToken = token;
8 mOwnerUid = s.mUid;
9 mAttrs.copyFrom(a);
10 mViewVisibility = viewVisibility;
11 mDisplayContent = displayContent;
12 mPolicy = mService.mPolicy;
13 mContext = mService.mContext;
14 DeathRecipient deathRecipient = new DeathRecipient();
15 mSeq = seq;
16 mEnforceSizeCompat = (mAttrs.flags & FLAG_COMPATIBLE_WINDOW) != 0;
17 if (WindowManagerService.localLOGV) Slog.v(
18 TAG, "Window " + this + " client=" + c.asBinder()
19 + " token=" + token + " (" + mAttrs.token + ")" + " params=" + a);
20 try {
21 c.asBinder().linkToDeath(deathRecipient, 0);
22 } catch (RemoteException e) {
23 mDeathRecipient = null;
24 mAttachedWindow = null;
25 mLayoutAttached = false;
26 mIsImWindow = false;
27 mIsWallpaper = false;
28 mIsFloatingLayer = false;
29 mBaseLayer = 0;
30 mSubLayer = 0;
31 mInputWindowHandle = null;
32 mWinAnimator = null;
33 return;
34 }
35 mDeathRecipient = deathRecipient;
36
37 if ((mAttrs.type >= FIRST_SUB_WINDOW &&
38 mAttrs.type <= LAST_SUB_WINDOW)) {
39 // The multiplier here is to reserve space for multiple
40 // windows in the same type layer.
41 mBaseLayer = mPolicy.windowTypeToLayerLw(
42 attachedWindow.mAttrs.type) * WindowManagerService.TYPE_LAYER_MULTIPLIER
43 + WindowManagerService.TYPE_LAYER_OFFSET;
44 mSubLayer = mPolicy.subWindowTypeToLayerLw(a.type);
45 mAttachedWindow = attachedWindow;
46 if (WindowManagerService.DEBUG_ADD_REMOVE) Slog.v(TAG, "Adding " + this + " to " + mAttachedWindow);
47 mAttachedWindow.mChildWindows.add(this);
48 mLayoutAttached = mAttrs.type !=
49 WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
50 mIsImWindow = attachedWindow.mAttrs.type == TYPE_INPUT_METHOD
51 || attachedWindow.mAttrs.type == TYPE_INPUT_METHOD_DIALOG;
52 mIsWallpaper = attachedWindow.mAttrs.type == TYPE_WALLPAPER;
53 mIsFloatingLayer = mIsImWindow || mIsWallpaper;
54 } else {
55 // The multiplier here is to reserve space for multiple
56 // windows in the same type layer.
57 mBaseLayer = mPolicy.windowTypeToLayerLw(a.type)
58 * WindowManagerService.TYPE_LAYER_MULTIPLIER
59 + WindowManagerService.TYPE_LAYER_OFFSET;
60 mSubLayer = 0;
61 mAttachedWindow = null;
62 mLayoutAttached = false;
63 mIsImWindow = mAttrs.type == TYPE_INPUT_METHOD
64 || mAttrs.type == TYPE_INPUT_METHOD_DIALOG;
65 mIsWallpaper = mAttrs.type == TYPE_WALLPAPER;
66 mIsFloatingLayer = mIsImWindow || mIsWallpaper;
67 }
68
69 WindowState appWin = this;
70 while (appWin.mAttachedWindow != null) {
71 appWin = appWin.mAttachedWindow;
72 }
73 WindowToken appToken = appWin.mToken;
74 while (appToken.appWindowToken == null) {
75 WindowToken parent = mService.mTokenMap.get(appToken.token);
76 if (parent == null || appToken == parent) {
77 break;
78 }
79 appToken = parent;
80 }
81 mRootToken = appToken;
82 mAppToken = appToken.appWindowToken;
83
84 mWinAnimator = new WindowStateAnimator(this);
85 mWinAnimator.mAlpha = a.alpha;
86
87 mRequestedWidth = 0;
88 mRequestedHeight = 0;
89 mLastRequestedWidth = 0;
90 mLastRequestedHeight = 0;
91 mXOffset = 0;
92 mYOffset = 0;
93 mLayer = 0;
94 mInputWindowHandle = new InputWindowHandle(
95 mAppToken != null ? mAppToken.mInputApplicationHandle : null, this,
96 displayContent.getDisplayId());
97 }
第6行(WindowState->WindowState)会将IWindow接口保存到成员变量mClient中去.
page13
WindowState的attach函数的定义如下:
1 void attach() {
2 if (WindowManagerService.localLOGV) Slog.v(
3 TAG, "Attaching " + this + " token=" + mToken
4 + ", list=" + mToken.windows);
5 mSession.windowAddedLocked();
6 }
第5行(WindowState->attach)会调用Session的windowAddedLocked函数, 关于Session的windowAddedLocked函数的详细分析可以参考page14文件.
page14
这里我们分析一下Session的windowAddedLocked函数的实现, Session的windowAddedLocked函数的定义如下:
1 void windowAddedLocked() {
2 if (mSurfaceSession == null) {
3 if (WindowManagerService.localLOGV) Slog.v(
4 WindowManagerService.TAG, "First window added to " + this + ", creating SurfaceSession");
5 mSurfaceSession = new SurfaceSession();
6 if (WindowManagerService.SHOW_TRANSACTIONS) Slog.i(
7 WindowManagerService.TAG, " NEW SURFACE SESSION " + mSurfaceSession);
8 mService.mSessions.add(this);
9 }
10 mNumWindow++;
11 }
第2行(Session->windowAddedLocked)判断是否已经创建过SurfaceSession, 如果是就不用在创建了. 由此可知, 每一个Activity都对应有一个SurfaceSession对象.
第5行(Session->windowAddedLocked)会创建一个SurfaceSession对象, 关于SurfaceSession对象的创建过程可以参考page15文件.
第8行(Session->windowAddedLocked)会将本Session加入到mService.mSessions中去, mService.mSessions的定义如下:
final HashSet
mSessions保存着当前活跃的连接
最后, 第10行(Session->windowAddedLocked)会将window的数量加1.
page15
这里我们关注一下SurfaceSession对象的创建, SurfaceSession类的构造函数的定义如下:
1 public SurfaceSession() {
2 mNativeClient = nativeCreate();
3 }
第2行(SurfaceSession->SurfaceSession)会调用nativeCreate函数, nativeCreate函数的定义如下:
private static native int nativeCreate();
这是个native函数, 最终会调用android_view_surfaceSession.cpp中的nativeCreate函数, android_view_surfaceSession.cpp中的nativeCreate函数的定义如下:
1 static jint nativeCreate(JNIEnv* env, jclass clazz) {
2 SurfaceComposerClient* client = new SurfaceComposerClient();
3 client->incStrong(clazz);
4 return reinterpret_cast
5 }
我靠, 我靠, 我靠!看到了吧, 第三行(android_view_surfaceSession.cpp::nativeCreate)会创建一个SurfaceComposerClient, 是不是很熟悉.