Activity各个生命周期如何处理窗口

我就是我 2022-03-15 10:20 163阅读 0赞

**1.在ActivityThread\#handleLaunchActivity():**

activity.attach(appContext, this, getInstrumentation(), r.token,
                            r.ident, app, r.intent, r.activityInfo, title, r.parent,
                            r.embeddedID, r.lastNonConfigurationInstances, config,
                            r.referrer, r.voiceInteractor, window, r.configCallback);

**activity.attach(...)方法**中，创建PnoneWindow,代码如下：

//... ...
    mWindow = new PhoneWindow(this, window, activityConfigCallback);
            mWindow.setWindowControllerCallback(this);
            mWindow.setCallback(this);
            mWindow.setOnWindowDismissedCallback(this);
            mWindow.getLayoutInflater().setPrivateFactory(this);
            if (info.softInputMode != WindowManager.LayoutParams.SOFT_INPUT_STATE_UNSPECIFIED) {
                mWindow.setSoftInputMode(info.softInputMode);
            }
            if (info.uiOptions != 0) {
                mWindow.setUiOptions(info.uiOptions);
            }
    //... ...
    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();
            mCurrentConfig = config;
    
            mWindow.setColorMode(info.colorMode);

此时还不会创建DecorView，在onCreate()中调用setContentView时，就会调用getWindow().setContentView，此时在PhoneWindow\#setContentView()方法中调用installDecor()方法去创建一个DecorView。如果没有调用setContentView,那么installDecor()方法将延迟到handleResumeActivity()中，Activity.getWindow.getDecor()时，PhoneWindow\#getDecor()方法如下：

@Override
        public final View getDecorView() {
            if (mDecor == null || mForceDecorInstall) {
                installDecor();
            }
            return mDecor;
        }

**2.在ActivityThread\#handleResumeActivity()：**

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;
                l.type = WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
                l.softInputMode |= forwardBit;
                if (r.mPreserveWindow) {
                    a.mWindowAdded = true;
                    r.mPreserveWindow = false;
                    // Normally the ViewRoot sets up callbacks with the Activity
                    // in addView->ViewRootImpl#setView. If we are instead reusing
                    // the decor view we have to notify the view root that the
                    // callbacks may have changed.
                    ViewRootImpl impl = decor.getViewRootImpl();
                    if (impl != null) {
                        impl.notifyChildRebuilt();
                    }
                }
                if (a.mVisibleFromClient) {
                    if (!a.mWindowAdded) {
                        a.mWindowAdded = true;
                        wm.addView(decor, l);
                    } else {
                        // The activity will get a callback for this {@link LayoutParams} change
                        // earlier. However, at that time the decor will not be set (this is set
                        // in this method), so no action will be taken. This call ensures the
                        // callback occurs with the decor set.
                        a.onWindowAttributesChanged(l);
                    }
                }
    
                // If the window has already been added, but during resume
                // we started another activity, then don't yet make the
                // window visible.
            }

将PhoneWindow的decorView取出来，使用Activity.mWindowManager以decorView为参数添加窗口。

最终WindowManagerImpl将调用WindowManagerGlobal\#addView(...)，在WindowManagerGlobal\#addView(...)中将创建ViewRootImpl，最后确立ViewRootImpl、View、LayoutParams三元组。最后使用ViewRootImpl\#setView(...)，在setView()中通过IWindowSession.addToDisplay(IWindow,LayoutParams,InputChannel,...)正式向WMS注册一个窗口,并得到了一个监听输入事件的管道，在接下来的遍历控件树的布局窗口阶段通过IWindowSession.relayoutWindow(Surface)才正在获得一个窗口，即可以通过得到的Surface，遍历控件树的绘制阶段在Surface上绘图，并最终提交到SurfaceFlinger，这样窗口内容就可以显示了