CONFIG_UI_MODE 切换如何流畅过渡

CONFIG_UI_MODE 切换如何顺畅过渡 可以学习基于旋转屏动画实现原理。

主要涉及 framework/base/services/java/com/android/server/wm/ActivityTaskManagerService.java ActivityTaskManagerService.java

frameworks/base/services/core/java/com/android/server/wm/ScreenRotationAnimation.java ScreenRotationAnimation.java

切换config都会走到这里。 #ActivityTaskManagerService.updateGlobalConfigurationLocked()

/** Update default (global) configuration and notify listeners about changes. */
    int updateGlobalConfigurationLocked(@NonNull Configuration values, boolean initLocale,
            boolean persistent, int userId, boolean deferResume) {

        final DisplayContent defaultDisplay =
                mRootWindowContainer.getDisplayContent(DEFAULT_DISPLAY);

        mTempConfig.setTo(getGlobalConfiguration());
		//理论上要解决切换暗色模式config 卡顿问题，可以这里处理
		//这里changes可以判断是不是UIMode的config 如果（changes & ActivityInfo.CONFIG_UI_MODE）!= 0那么就是uimode的切换，
		//如果uimode切换我们就调用冻屏，（注意：原生代码这里是没有的）
		//defaultDisplay.getDisplayRotation().cancelSeamlessRotation()保证一个旋转屏动画正常执行，不会被新的DisplayContent的config中断
		//开启截图冻屏
		//mWinowManager.startFreezingDisplay(0,0, defaultDisplay)原生走旋转屏动画也会走到这里，WMS里调用startFreezingDisplay。
		//给DisplayContent设置ScreenRotationAnimation，这个ScreenRotationAnimation会从SF抽取一帧，然后做动画。
		//旋转屏动画具体参考https://www.jianshu.com/p/db47547605fb
		//https://blog.csdn.net/qq_24604069/article/details/109694113
		//https://funnyray.plus/2020/04/17/WMS%20Orientation&Rotation/
		
        final int changes = mTempConfig.updateFrom(values);
        if (changes == 0) {
            // Since calling to Activity.setRequestedOrientation leads to freezing the window with
            // setting WindowManagerService.mWaitingForConfig to true, it is important that we call
            // performDisplayOverrideConfigUpdate in order to send the new display configuration
            // (even if there are no actual changes) to unfreeze the window.
            defaultDisplay.performDisplayOverrideConfigUpdate(values, deferResume);
            return 0;
        }

        if (DEBUG_SWITCH || DEBUG_CONFIGURATION) Slog.i(TAG_CONFIGURATION,
                "Updating global configuration to: " + values);
        writeConfigurationChanged(changes);
        FrameworkStatsLog.write(FrameworkStatsLog.RESOURCE_CONFIGURATION_CHANGED,
                values.colorMode,
                values.densityDpi,
                values.fontScale,
                values.hardKeyboardHidden,
                values.keyboard,
                values.keyboardHidden,
                values.mcc,
                values.mnc,
                values.navigation,
                values.navigationHidden,
                values.orientation,
                values.screenHeightDp,
                values.screenLayout,
                values.screenWidthDp,
                values.smallestScreenWidthDp,
                values.touchscreen,
                values.uiMode);


        if (!initLocale && !values.getLocales().isEmpty() && values.userSetLocale) {
            final LocaleList locales = values.getLocales();
            int bestLocaleIndex = 0;
            if (locales.size() > 1) {
                if (mSupportedSystemLocales == null) {
                    mSupportedSystemLocales = Resources.getSystem().getAssets().getLocales();
                }
                bestLocaleIndex = Math.max(0, locales.getFirstMatchIndex(mSupportedSystemLocales));
            }
            SystemProperties.set("persist.sys.locale",
                    locales.get(bestLocaleIndex).toLanguageTag());
            LocaleList.setDefault(locales, bestLocaleIndex);

            final Message m = PooledLambda.obtainMessage(
                    ActivityTaskManagerService::sendLocaleToMountDaemonMsg, this,
                    locales.get(bestLocaleIndex));
            mH.sendMessage(m);
        }

        mTempConfig.seq = increaseConfigurationSeqLocked();

        // Update stored global config and notify everyone about the change.
        mRootWindowContainer.onConfigurationChanged(mTempConfig);

        Slog.i(TAG, "Config changes=" + Integer.toHexString(changes) + " " + mTempConfig);
        // TODO(multi-display): Update UsageEvents#Event to include displayId.
        mUsageStatsInternal.reportConfigurationChange(mTempConfig, mAmInternal.getCurrentUserId());

        // TODO: If our config changes, should we auto dismiss any currently showing dialogs?
        updateShouldShowDialogsLocked(mTempConfig);

        AttributeCache ac = AttributeCache.instance();
        if (ac != null) {
            ac.updateConfiguration(mTempConfig);
        }

        // Make sure all resources in our process are updated right now, so that anyone who is going
        // to retrieve resource values after we return will be sure to get the new ones. This is
        // especially important during boot, where the first config change needs to guarantee all
        // resources have that config before following boot code is executed.
        mSystemThread.applyConfigurationToResources(mTempConfig);

        // We need another copy of global config because we're scheduling some calls instead of
        // running them in place. We need to be sure that object we send will be handled unchanged.
        final Configuration configCopy = new Configuration(mTempConfig);
        if (persistent && Settings.System.hasInterestingConfigurationChanges(changes)) {
            final Message msg = PooledLambda.obtainMessage(
                    ActivityTaskManagerService::sendPutConfigurationForUserMsg,
                    this, userId, configCopy);
            mH.sendMessage(msg);
        }

        SparseArray<WindowProcessController> pidMap = mProcessMap.getPidMap();
        for (int i = pidMap.size() - 1; i >= 0; i--) {
            final int pid = pidMap.keyAt(i);
            final WindowProcessController app = pidMap.get(pid);
            if (DEBUG_CONFIGURATION) {
                Slog.v(TAG_CONFIGURATION, "Update process config of "
                        + app.mName + " to new config " + configCopy);
            }
            app.onConfigurationChanged(configCopy);
        }

        final Message msg = PooledLambda.obtainMessage(
                ActivityManagerInternal::broadcastGlobalConfigurationChanged,
                mAmInternal, changes, initLocale);
        mH.sendMessage(msg);

        // Override configuration of the default display duplicates global config, so we need to
        // update it also. This will also notify WindowManager about changes.
        defaultDisplay.performDisplayOverrideConfigUpdate(mRootWindowContainer.getConfiguration(),
                deferResume);

        return changes;
    }