Window
抽象类，顶级视图的容器，其子类只有一个 PhoneWindow
// activity
final void attach（...） {
...
mWindow = new PhoneWindow(this);
mWindow.setWindowManager((WindowManager)context.getSystemService(Context.WINDOW_SERVICE),
mToken, mComponent.flattenToString(),
(info.flags & ActivityInfo.FLAG_HARDWARE_ACCELERATED) != 0);
if (mParent != null) {
mWindow.setContainer(mParent.getWindow());
}
mWindowManager = mWindow.getWindowManager();
...
}
在 activity attach 的时候进行创建，早于 onCreate 方法。同时设置了 WindowManager，并将 WindowManger 反向设置给 Activity。
WindowManager
WindowManager 其实只是一个接口，其父类是 ViewManager，包含三个方法
public interface ViewManager
{
public void addView(View view, ViewGroup.LayoutParams params);
public void updateViewLayout(View view, ViewGroup.LayoutParams params);
public void removeView(View view);
}
ViewManager 才是通常情况下，我们添加视图用的。
其子类为：
public final class WindowManagerImpl implements WindowManager {
private final WindowManagerGlobal mGlobal = WindowManagerGlobal.getInstance();
private final Context mContext;
//创建 这个 impl 的 window 本身。
private final Window mParentWindow;
private IBinder mDefaultToken;
public WindowManagerImpl(Context context) {
this(context, null);
}
private WindowManagerImpl(Context context, Window parentWindow) {
mContext = context;
mParentWindow = parentWindow;
}
public WindowManagerImpl createLocalWindowManager(Window parentWindow) {
return new WindowManagerImpl(mContext, parentWindow);
}
public WindowManagerImpl createPresentationWindowManager(Context displayContext) {
return new WindowManagerImpl(displayContext, mParentWindow);
}
...
@Override
public void addView(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {
applyDefaultToken(params);
mGlobal.addView(view, params, mContext.getDisplay(), mParentWindow);
}
@Override
public void updateViewLayout(@NonNull View view, @NonNull ViewGroup.LayoutParams params) {
applyDefaultToken(params);
mGlobal.updateViewLayout(view, params);
}
...
@Override
public void removeView(View view) {
mGlobal.removeView(view, false);
}
...
}
内部主要是由 WindowManagerGlobal ，来进行view更新等操作。其内部就是使用了 ViewRootImpl 来直接进行 view 的相关操作。
Window 本身是无法添加视图的，都是通过 WindowManager 来进行操作的。所以创建 WindowManagerImpl，会包含一个 parentWindow。
PhoneWindow
public void setContentView(int layoutResID) {
if (mContentParent == null) {
installDecor();
}
...
mLayoutInflater.inflate(layoutResID, mContentParent);
...
}
private void installDecor() {
mForceDecorInstall = false;
if (mDecor == null) {
// 此时创建 最底层的view decorView
mDecor = generateDecor(-1);
mDecor.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
mDecor.setIsRootNamespace(true);
if (!mInvalidatePanelMenuPosted && mInvalidatePanelMenuFeatures != 0) {
mDecor.postOnAnimation(mInvalidatePanelMenuRunnable);
}
} else {
mDecor.setWindow(this);
}
if (mContentParent == null) {
//设置我们常用的 contentParent
mContentParent = generateLayout(mDecor);
// Set up decor part of UI to ignore fitsSystemWindows if appropriate.
mDecor.makeOptionalFitsSystemWindows();
final DecorContentParent decorContentParent = (DecorContentParent) mDecor.findViewById(
R.id.decor_content_parent);
if (decorContentParent != null) {
mDecorContentParent = decorContentParent;
mDecorContentParent.setWindowCallback(getCallback());
if (mDecorContentParent.getTitle() == null) {
mDecorContentParent.setWindowTitle(mTitle);
}
final int localFeatures = getLocalFeatures();
for (int i = 0; i < FEATURE_MAX; i++) {
if ((localFeatures & (1 << i)) != 0) {
mDecorContentParent.initFeature(i);
}
}
mDecorContentParent.setUiOptions(mUiOptions);
if ((mResourcesSetFlags & FLAG_RESOURCE_SET_ICON) != 0 ||
(mIconRes != 0 && !mDecorContentParent.hasIcon())) {
mDecorContentParent.setIcon(mIconRes);
} else if ((mResourcesSetFlags & FLAG_RESOURCE_SET_ICON) == 0 &&
mIconRes == 0 && !mDecorContentParent.hasIcon()) {
mDecorContentParent.setIcon(
getContext().getPackageManager().getDefaultActivityIcon());
mResourcesSetFlags |= FLAG_RESOURCE_SET_ICON_FALLBACK;
}
if ((mResourcesSetFlags & FLAG_RESOURCE_SET_LOGO) != 0 ||
(mLogoRes != 0 && !mDecorContentParent.hasLogo())) {
mDecorContentParent.setLogo(mLogoRes);
}
// Invalidate if the panel menu hasn't been created before this.
// Panel menu invalidation is deferred avoiding application onCreateOptionsMenu
// being called in the middle of onCreate or similar.
// A pending invalidation will typically be resolved before the posted message
// would run normally in order to satisfy instance state restoration.
PanelFeatureState st = getPanelState(FEATURE_OPTIONS_PANEL, false);
if (!isDestroyed() && (st == null || st.menu == null) && !mIsStartingWindow) {
invalidatePanelMenu(FEATURE_ACTION_BAR);
}
}
if (mDecor.getBackground() == null && mBackgroundFallbackResource != 0) {
mDecor.setBackgroundFallback(mBackgroundFallbackResource);
}
}
}
当 Activity 第一次 setContent 时，会将底层的 DecorView 和 ContentParent 给创建出来，并且将用户自己 view 添加到 ContentParent 上面。
此时 Window 和 DecorView 还没有产生联系。这两步都是创建并设置 decorView 相关。
ActivityThread.handleResumeActivity
public void handleResumeActivity(IBinder token, boolean finalStateRequest, boolean isForward,String reason) {
//这里面其实已经调到了 activity.performResume(r.startsNotResumed, reason)，因此此时 onResume 其实已经执行结束了。
final ActivityClientRecord r = performResumeActivity(token, finalStateRequest, reason);
final Activity a = r.activity;
if (r.window == null && !a.mFinished && willBeVisible) {
r.window = r.activity.getWindow();
View decor = r.window.getDecorView();
decor.setVisibility(View.INVISIBLE);
ViewManager wm = a.getWindowManager();
WindowManager.LayoutParams l = r.window.getAttributes();
a.mDecor = decor;
...
if (a.mVisibleFromClient) {
if (!a.mWindowAdded) {
a.mWindowAdded = true;
wm.addView(decor, l);
}
}
}
}
在 handleResumeActivity 方法中，在onResume之后，会正式把 DecorView 和 Window 想关联起来。
WindowManagerGlobal.addView
之前我们分析了，WindowManager 其实是 WindowManagerImpl，因此直接看 WindowManagerImpl 的 addView 方法
public void addView(View view, ViewGroup.LayoutParams params, Display display, Window parentWindow) {
...
ViewRootImpl root;
View panelParentView = null;
...
synchronized (mLock) {
...
// If this is a panel window, then find the window it is being
// attached to for future reference.
if (wparams.type >= WindowManager.LayoutParams.FIRST_SUB_WINDOW &&
wparams.type <= WindowManager.LayoutParams.LAST_SUB_WINDOW) {
final int count = mViews.size();
for (int i = 0; i < count; i++) {
if (mRoots.get(i).mWindow.asBinder() == wparams.token) {
panelParentView = mViews.get(i);
}
}
}
root = new ViewRootImpl(view.getContext(), display);
view.setLayoutParams(wparams);
mViews.add(view);
mRoots.add(root);
mParams.add(wparams);
...
root.setView(view, wparams, panelParentView);
...
}
}
到这里，添加之后，会有一个ViewRootImpl生成，来真正复制添加一个decor。WindowManagerGlobal 这里其实只是吧相应的 decor 和 ViewRootImpl 保存了起来。
因此一个 Decor 和 ViewRootImpl 应该是一一对应的。因此 decor 和 ViewRootImpl 就这样的绑定了起来。
public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
...
requestLayout();
...
}
public void requestLayout() {
if (!mHandlingLayoutInLayoutRequest) {
checkThread();
mLayoutRequested = true;
scheduleTraversals();
}
}
到这里就熟悉了，开始遍历进行view的布局绘制等操作了。