Android(安卓)fw修改让app方向跟随系统方向

平台：qcom msm8953 android7.1

现象：客户app或者应用商城下载的app在我们自己的Android板上运行是，会出现反方向显示的情况，如系统方向是90°，运行某些app,app打开后会是270°的方向。

解决方法：

思路1：理清AndroidGUI系统显示框架，刚开始从底层想去理清AndroidGUI系统显示框架，结果越看涉及的知识越来愈多，最后看的头脑一点都不清醒了，越看越糊涂，更别说解决这个bug了。于是开始转向思路2；

思路2：之前有了解过Android系统屏幕旋转是基于WMS和PMS的，另外，做过一段时间的Android应用开发，知道在Android应用中是可以通过xml去设置应用显示的方向的，于是结合这两点，开始往这方面靠。

首先找到一篇文章https://blog.csdn.net/jinzhuojun/article/details/50085491，大家可以结合这个阅读下源码，我在PMS，和WMS中分别加了点打印，然后抓取打开会出现问题的app,找到了一些信息，发现在我打开app的时候产生屏幕旋转的现象在WMS中会进入

updateRotationUncheckedLocked这个方法，紧接着在这个方法中，我发现在该方法中运行到如图所示的时候，对屏幕方向进行了修改

那么看到这里图中第一句赋值语句中的右值的值是从何而来呢？往上跟踪源码发现，是经过rotationForOrientationLw这个方法而来，那这个方法在哪定义和实现的呢？继续跟踪可以看到是mPolicy中的一个方法，那么继续找到何处继承了这个代理类，最终跟踪到PMS中找到了该方法的实现。

 @Override    public int rotationForOrientationLw(int orientation, int lastRotation) {        if (true) {            Slog.v(TAG, "rotationForOrientationLw(orient="                    + orientation + ", last=" + lastRotation                    + "); user=" + mUserRotation + " "                    + ((mUserRotationMode == WindowManagerPolicy.USER_ROTATION_LOCKED)                    ? "USER_ROTATION_LOCKED" : "")            );        }        .......            if (DEBUG_LAYOUT) Slog.i(TAG, "orientation: " + orientation);            if (getScreenWidth(mContext) < getScreenHeight(mContext)) {  //Determine the physical screen direction                Slog.v(TAG, "width < height");                switch (lastRotation) //Make the app direction follow system                {                    case Surface.ROTATION_0:                        mPortraitRotation = Surface.ROTATION_0;  //shu  portrait                        mUpsideDownRotation = Surface.ROTATION_180; // fan shu                        mLandscapeRotation = Surface.ROTATION_90; // heng  landscape                        mSeascapeRotation = Surface.ROTATION_270; //fan heng                        break;                    case Surface.ROTATION_90:                        mPortraitRotation = Surface.ROTATION_90;  //shu  portrait                        mUpsideDownRotation = Surface.ROTATION_270; // fan shu                        mLandscapeRotation = Surface.ROTATION_0; // heng  landscape                        mSeascapeRotation = Surface.ROTATION_180; //fan heng                        break;                    case Surface.ROTATION_180:                        mPortraitRotation = Surface.ROTATION_180;  //shu  portrait                        mUpsideDownRotation = Surface.ROTATION_0; // fan shu                        mLandscapeRotation = Surface.ROTATION_270; // heng  landscape                        mSeascapeRotation = Surface.ROTATION_90; //fan heng                        break;                    case Surface.ROTATION_270:                        mPortraitRotation = Surface.ROTATION_270;  //shu  portrait                        mUpsideDownRotation = Surface.ROTATION_90; // fan shu                        mLandscapeRotation = Surface.ROTATION_180; // heng  landscape                        mSeascapeRotation = Surface.ROTATION_0; //fan heng                        break;                }            } else {                Slog.v(TAG, "width > height");                switch (lastRotation)//Make the app direction follow system                {                    case Surface.ROTATION_0:                        mPortraitRotation = Surface.ROTATION_0;  //shu  portrait                        mUpsideDownRotation = Surface.ROTATION_180; // fan shu                        mLandscapeRotation = Surface.ROTATION_90; // heng  landscape                        mSeascapeRotation = Surface.ROTATION_270; //fan heng                        break;                    case Surface.ROTATION_90:                        mPortraitRotation = Surface.ROTATION_90;  //shu  portrait                        mUpsideDownRotation = Surface.ROTATION_270; // fan shu                        mLandscapeRotation = Surface.ROTATION_0; // heng  landscape                        mSeascapeRotation = Surface.ROTATION_180; //fan heng                        break;                    case Surface.ROTATION_180:                        mPortraitRotation = Surface.ROTATION_180;  //shu  portrait                        mUpsideDownRotation = Surface.ROTATION_0; // fan shu                        mLandscapeRotation = Surface.ROTATION_270; // heng  landscape                        mSeascapeRotation = Surface.ROTATION_90; //fan heng                        break;                    case Surface.ROTATION_270:                        mPortraitRotation = Surface.ROTATION_270;                        mUpsideDownRotation = Surface.ROTATION_90;                        mLandscapeRotation = Surface.ROTATION_180;                        mSeascapeRotation = Surface.ROTATION_0;                        break;                }            }            switch (orientation) {                case ActivityInfo.SCREEN_ORIENTATION_PORTRAIT:  //portrait                    // Return portrait unless overridden.                    if (isAnyPortrait(preferredRotation)) {                        Slog.v(TAG, "preferredRotation:" + preferredRotation);                        return preferredRotation;                    }                    Slog.v(TAG, "mPortraitRotation:" + mPortraitRotation);                    return mPortraitRotation;                case ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE: //landscape                    // Return landscape unless overridden.                    if (isLandscapeOrSeascape(preferredRotation)) {                        return preferredRotation;                    }                    return mLandscapeRotation;                case ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT: //reversePortrait >= api 9                    // Return reverse portrait unless overridden.                    if (isAnyPortrait(preferredRotation)) {                        return preferredRotation;                    }                    return mUpsideDownRotation;                case ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE: //reverseLandscape >= api 9                    // Return seascape unless overridden.                    if (isLandscapeOrSeascape(preferredRotation)) {                        return preferredRotation;                    }                    return mSeascapeRotation;                case ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE:                case ActivityInfo.SCREEN_ORIENTATION_USER_LANDSCAPE:                    // Return either landscape rotation.                    if (isLandscapeOrSeascape(preferredRotation)) {                        return preferredRotation;                    }                    if (isLandscapeOrSeascape(lastRotation)) {                        return lastRotation;                    }                    return mLandscapeRotation;                case ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT:                case ActivityInfo.SCREEN_ORIENTATION_USER_PORTRAIT:                    // Return either portrait rotation.                    if (isAnyPortrait(preferredRotation)) {                        return preferredRotation;                    }                    if (isAnyPortrait(lastRotation)) {                        return lastRotation;                    }                    return mPortraitRotation;                default:                    // For USER, UNSPECIFIED, NOSENSOR, SENSOR and FULL_SENSOR,                    // just return the preferred orientation we already calculated.                    if (preferredRotation >= 0) {                        return preferredRotation;                    }                    //return Surface.ROTATION_0;                    return mDefaultOrientation;            }        }    }

代码略长，省略部分，只看重点，在这个方法中添加一些打印发现，这里正是对app 通过设置xml配置屏幕方向的一些分类情况处理，我们可以看到图中 switch (orientation) 处，这里分别对应了应用层的一些设置，如：“portrait”,"landscape"等，

那么分析到这里，我想是不是可以在这个分类处理之前做些处理，让app跟随系统方向，于是进行了标红处的代码添加，最终运行测试，OK，测试通过！！

PS: 横屏好像还有点问题，后面再细查。

PMS:frameworks/base/services/core/java/com/android/server/wm/WindowManagerService.java

WMS:frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java

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