創(chuàng)建window過(guò)程

當(dāng)我們調(diào)用startActivity方法之后系統(tǒng)會(huì)通過(guò)AMS等一系列的方法最后調(diào)用ActivityThread的performLaunchActivity方法，在方法里會(huì)調(diào)用attach方法

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在Activity的attach方法里面系統(tǒng)會(huì)初始化Window的實(shí)現(xiàn)類PhoneWindow并通過(guò)setWindowManager方法創(chuàng)建mWindowManager的實(shí)現(xiàn)類WindowManagerImpl

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setContentView過(guò)程

創(chuàng)建完之后ActivityThread會(huì)繼續(xù)執(zhí)行performLaunchActivity方法調(diào)用Instrumentation的callActivityOnCreate方法独悴，然后會(huì)調(diào)用activity的OnCreate

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PhoneWindow的setContentView方法源碼

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View的繪制

之后ActivityThread會(huì)繼續(xù)執(zhí)行handleResumeActivity方法里面會(huì)調(diào)用performResumeActivity調(diào)用完就會(huì)執(zhí)行Activity的onResume方法之后繼續(xù)走才開(kāi)始View的繪制所以View的繪制是在Activity生命周期onResume之后的

    @Override
    public void handleResumeActivity(IBinder token, boolean finalStateRequest, boolean isForward,
            String reason) {
        //調(diào)用Activity的onResume
        final ActivityClientRecord r = performResumeActivity(token, finalStateRequest, reason);

        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;
                ViewRootImpl impl = decor.getViewRootImpl();
                if (impl != null) {
                    impl.notifyChildRebuilt();
                }
            }
            if (a.mVisibleFromClient) {
                if (!a.mWindowAdded) {
                    a.mWindowAdded = true;
                  //調(diào)用ViewManager的實(shí)現(xiàn)類WindowManagerImpl window創(chuàng)建的時(shí)候有提到
                    wm.addView(decor, l);
                } else {
                    a.onWindowAttributesChanged(l);
                }
            }

        } else if (!willBeVisible) {
            if (localLOGV) Slog.v(TAG, "Launch " + r + " mStartedActivity set");
            r.hideForNow = true;
        }
    }

然后會(huì)執(zhí)行WindowManagerImpl的addView方法
WindowManagerImpl是通過(guò)WindowManagerGlobal的addView方法

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WindowManagerGlobal的addView方法

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View的繪制流程

在setView方法中會(huì)調(diào)用requestLayout()

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