關于android2.3調試g-sensor

由于工作上的需要，特地寫了這麼一份關于調試g-sensor的内容.

1.首先确定你要調試的裝置的螢幕的橫豎屏如何設定。

在代碼中我們主要的流程如下：

os 啟動後 ：

WindowManagerService.java中ENABLE_SCREEN

–>performEnableScreen（）

–>mPolicy.enableScreenAfterBoot()/setRotation()

–>setRotationUnchecked()

–>PhoneWindowManager.java中的rotationForOrientationLw（）

–>Surface.setOrientation()

基本上流程就是如上，隻要稍微跟蹤一下就可以了。

下面大概對上面主要code進行注釋說明：

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//下面的方法主要用于判斷螢幕是否需要進行一個新的旋轉 public boolean setRotationUncheckedLocked( int rotation,  int animFlags) { boolean changed; //rotation從外面傳入目前的rotation以及animFlags 最後的标簽 //如果rotation等于系統第一次啟動則rotation指派為mRequestedRotation此時為0 if (rotation == WindowManagerPolicy.USE_LAST_ROTATION) { rotation = mRequestedRotation; } else { mRequestedRotation = rotation; mLastRotationFlags = animFlags; } if (DEBUG_ORIENTATION) Slog.v(TAG,  "Overwriting rotation value from " + rotation); //此時的rotation為老的rotation，下面通過mPolicy.rotationForOrientationLw（）進行擷取新的rotation rotation = mPolicy.rotationForOrientationLw(mForcedAppOrientation, mRotation, mDisplayEnabled); if (DEBUG_ORIENTATION) Slog.v(TAG,  "new rotation is set to " + rotation); changed = mDisplayEnabled && mRotation != rotation; //如果擷取新的rotation與舊的rotation一樣則不做改變 //否則進入下面函數進行調整 if (changed) { if (DEBUG_ORIENTATION) Slog.v(TAG, "Rotation changed to " + rotation + " from " + mRotation + " (forceApp=" + mForcedAppOrientation + ", req=" + mRequestedRotation + ")" ); mRotation = rotation; mWindowsFreezingScreen = true ; mH.removeMessages(H.WINDOW_FREEZE_TIMEOUT); mH.sendMessageDelayed(mH.obtainMessage(H.WINDOW_FREEZE_TIMEOUT), 2000 ); mWaitingForConfig = true ; mLayoutNeeded = true ; startFreezingDisplayLocked(); Slog.i(TAG, "Setting rotation to " + rotation +  ", animFlags=" + animFlags); mInputManager.setDisplayOrientation( , rotation); if (mDisplayEnabled) { //Surface.setOrientation(）這裡将進行調整Orientation Surface.setOrientation( , rotation, animFlags); } for ( int i=mWindows.size()- 1 ; i>= ; i--) { WindowState w = mWindows.get(i); if (w.mSurface !=  null ) { w.mOrientationChanging = true ; } } for ( int i=mRotationWatchers.size()- 1 ; i>= ; i--) { try { mRotationWatchers.get(i).onRotationChanged(rotation); } catch (RemoteException e) { } } } //end if changed return changed; }

下面在對rotationForOrientationLw（）進行解析一下：

在setRotationUncheckedLocked（）中的 mPolicy.rotationForOrientationLw()如是：

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public int rotationForOrientationLw( int orientation,  int lastRotation, boolean displayEnabled) { if (mPortraitRotation <  ) { // Initialize the rotation angles for each orientation once. Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE)) .getDefaultDisplay(); //這裡的d.getWidth() 和 d.getHeight()得到的是實體螢幕的寬高。 //平闆跟手機不一樣。平闆的寬比高大 //（0度時位于//landscape模式，右轉90度進入porit模式）， //而手機是高比寬大（0度是位于porit模式，右轉90度進入landscape模式）。 //是以下面我做的是對平闆的修改 if (d.getWidth() > d.getHeight()) { //mPortraitRotation = Surface.ROTATION_90; mPortraitRotation = Surface.ROTATION_270; mLandscapeRotation = Surface.ROTATION_0; //mUpsideDownRotation = Surface.ROTATION_270; mUpsideDownRotation = Surface.ROTATION_90; mSeascapeRotation = Surface.ROTATION_180; } else { mPortraitRotation = Surface.ROTATION_0; //mLandscapeRotation = Surface.ROTATION_90; mLandscapeRotation = Surface.ROTATION_270; mUpsideDownRotation = Surface.ROTATION_180; //mSeascapeRotation = Surface.ROTATION_270; mSeascapeRotation = Surface.ROTATION_90; } } ...... }

2.如果g-sensor在旋轉上有不旋轉的方向或者方向不是很靈敏，則我們從下面進行分析：

主要流程如下：

–>WindowOrientationListener.java中的onSensorChanged（）

–>computeNewOrientation()

–>filterOrientation()

–>calculateNewRotation()

calculateNewRotation()

–>mOrientationListener.onOrientationChanged()

PhoneWindowManager.java 中的onOrientationChanged()

–>mWindowManager.setRotation()

首先在android中的x，y，z定義如下摘自http://developer.android.com/reference/android/hardware/SensorEvent.html ：

Class Overview

This class represents a Sensor event and holds informations such as the sensor’s type, the time-stamp, accuracy and of course the sensor’s data.

Definition of the coordinate system used by the SensorEvent API.

The coordinate-system is defined relative to the screen of the phone in its default orientation. The axes are not swapped when the device’s screen orientation changes.

The X axis is horizontal and points to the right, the Y axis is vertical and points up and the Z axis points towards the outside of the front face of the screen. In this system, coordinates behind the screen have negative Z values.

Sensors coordinate-system diagram.

Note: This coordinate system is different from the one used in the Android 2D APIs where the origin is in the top-left corner.

frameworks/base/core/java/android/view/WindowOrientationListener.java

WindowOrientationListener.java 是一個abstract class，它主要是把從gsensor擷取到的資料轉化為orientation.

每次sensor有進行改變時都會調用到以下函數進行計算Orientation。

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public void onSensorChanged(SensorEvent event) { // the vector given in the SensorEvent points straight up (towards the sky) under ideal // conditions (the phone is not accelerating).  i'll call this upVector elsewhere. float x = event.values[_DATA_X]; float y = event.values[_DATA_Y]; float z = event.values[_DATA_Z]; float magnitude = vectorMagnitude(x, y, z); float deviation = Math.abs(magnitude - SensorManager.STANDARD_GRAVITY); handleAccelerationDistrust(deviation); // only filter tilt when we're accelerating float alpha =  1 ; if (mAccelerationDistrust >  ) { alpha = ACCELERATING_LOWPASS_ALPHA; } float newTiltAngle = tiltAngle(z, magnitude); mTiltAngle = lowpassFilter(newTiltAngle, mTiltAngle, alpha); float absoluteTilt = Math.abs(mTiltAngle); checkFullyTilted(absoluteTilt); if (mTiltDistrust >  ) { return ; // when fully tilted, ignore orientation entirely } //下面通過x,y計算得到新的OrientationAngle，計算方法如下 //        private float computeNewOrientation(float x, float y) { //           float orientationAngle = (float) -Math.atan2(-x, y) * RADIANS_TO_DEGREES; // atan2 returns [-180, 180]; normalize to [0, 360] //            if (orientationAngle < 0) { //               orientationAngle += 360; //            } //            return orientationAngle; //        } float newOrientationAngle = computeNewOrientation(x, y); //通過下面函數計算出Orientation的值。 filterOrientation(absoluteTilt, newOrientationAngle); calculateNewRotation(mOrientationAngle, absoluteTilt); }

這裡對calculateNewRotation進行分析前必須先對SensorEventListenerImpl類中的一些變量先進行解釋：

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private static final int [][][] THRESHOLDS =  new int [][][] { {{ 60 , 180 }, { 180 , 300 }}, {{ , 30 }, { 195 , 315 }, { 315 , 360 }}, {{ , 45 }, { 45 , 165 }, { 330 , 360 }}, // Handle situation where we are currently doing 180 rotation // but that is no longer allowed. {{ , 45 }, { 45 , 135 }, { 135 , 225 }, { 225 , 315 }, { 315 , 360 }}, }; // See THRESHOLDS private static final int [][] ROTATE_TO =  new int [][] { {ROTATION_90, ROTATION_270}, {ROTATION_0, ROTATION_270, ROTATION_0}, {ROTATION_0, ROTATION_90, ROTATION_0}, {ROTATION_0, ROTATION_90, ROTATION_0, ROTATION_270, ROTATION_0}, }; private static final int [][][] THRESHOLDS_WITH_180 =  new int [][][] { {{ 60 , 165 }, { 165 , 195 }, { 195 , 300 }}, {{ , 30 }, { 165 , 195 }, { 195 , 315 }, { 315 , 360 }}, {{ , 45 }, { 45 , 165 }, { 165 , 195 }, { 330 , 360 }}, {{ , 45 }, { 45 , 135 }, { 225 , 315 }, { 315 , 360 }}, }; private static final int [][] ROTATE_TO_WITH_180 =  new int [][] { {ROTATION_90, ROTATION_180, ROTATION_270}, {ROTATION_0, ROTATION_180, ROTATION_90, ROTATION_0}, {ROTATION_0, ROTATION_270, ROTATION_180, ROTATION_0}, {ROTATION_0, ROTATION_90, ROTATION_270, ROTATION_0}, }; //當裝置平放，螢幕朝正上方。以下四個常量分别代表： private static final int ROTATION_0 =  ; //初始情況。橫/豎屏與一開始設定有關 private static final int ROTATION_90 =  1 ; //右側翻起側立時，螢幕會旋轉到這個方向。 private static final int ROTATION_270 =  2 ; //左側翻起度側立時，螢幕會旋轉到這個方向。 private static final int ROTATION_180 =  3 ; //螢幕底部側立時，螢幕會旋轉到這個方向 //如上則 // {ROTATION_90, ROTATION_180, ROTATION_270} //對應落在的範圍為 {{60, 165}, {165, 195}, {195, 300}} //{ROTATION_0, ROTATION_180, ROTATION_90, ROTATION_0} //對應落在的範圍為 {{0, 30}, {165, 195}, {195, 315}, {315, 360}} //{ROTATION_0, ROTATION_270, ROTATION_180, ROTATION_0} //對應落在的範圍為 {{0, 45}, {45, 165}, {165, 195}, {330, 360}} //{ROTATION_0, ROTATION_90, ROTATION_270, ROTATION_0} //對應落在的範圍為{{0, 45}, {45, 135}, {225, 315}, {315, 360}} //是以如果需要微調的話隻要修改對應的範圍既可 //目前螢幕旋轉方向為ROTATION_0時，取int[][] threshold=THRESHOLDS_WITH_180[0]; //此時的範圍為：{{60, 165}, {165, 195}, {195, 300}} //目前螢幕旋轉方向為ROTATION_90時，取int[][] threshold=THRESHOLDS_WITH_180[1]; //此時的範圍為：{{0, 30}, {165, 195}, {195, 315}, {315, 360}} //目前螢幕旋轉方向為ROTATION_270時，取int[][] threshold=THRESHOLDS_WITH_180[2]; //此時的範圍為：{{0, 45}, {45, 165}, {165, 195}, {330, 360}} //目前螢幕旋轉方向為ROTATION_180時，取int[][] threshold=THRESHOLDS_WITH_180[3]; //此時的範圍為：{{0, 45}, {45, 135}, {225, 315}, {315, 360}} //例如目前我們的位置為ROTATION_90那麼此時我們的THRESHOLDS_WITH_180就 //為{{0, 30}, {165, 195}, {195, 315}, {315, 360}} //，然後通過filterOrientation計算出的orientation值落在了第2個元素圍内，則到ROTATE_TO_WITH_180找到對應的值， //這裡為ROTATION_180，則此時把方向選裝到ROTATION_180

對上面的變量稍微了解後對下面的分析就很簡單了。

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private void calculateNewRotation( float orientation,  float tiltAngle) { //這裡的orientation，tiltAngle，mRotation為gsensor擷取到的最新的資料 if (localLOGV) Log.i(TAG, orientation +  ", " + tiltAngle +  ", " + mRotation); //是否允許180度旋轉，這裡定義的其實就是變成了360度旋轉了， //如果mAllow180Rotation為false時，上面的變量中使用的為THRESHOLDS以及ROTATE_TO //如果為ture則為THRESHOLDS_WITH_180與ROTATE_TO_WITH_180 final boolean allow180Rotation = mAllow180Rotation; int thresholdRanges[][] = allow180Rotation ? THRESHOLDS_WITH_180[mRotation] : THRESHOLDS[mRotation]; int row = - 1 ; for ( int i =  ; i < thresholdRanges.length; i++) { if (orientation >= thresholdRanges[i][ ] && orientation < thresholdRanges[i][ 1 ]) { row = i; break ; } } if (row == - 1 ) return ;  // no matching transition int rotation = allow180Rotation ? ROTATE_TO_WITH_180[mRotation][row] : ROTATE_TO[mRotation][row]; if (tiltAngle > MAX_TRANSITION_TILT[rotation]) { // tilted too far flat to go to this rotation return ; } if (localLOGV) Log.i(TAG,  "orientation " + orientation +  " gives new rotation = " + rotation); mRotation = rotation; //這裡通過WindowOrientationListener監聽調用onOrientationChanged中的setRotation進而旋轉界面 mOrientationListener.onOrientationChanged(INTERNAL_TO_SURFACE_ROTATION[mRotation]); }

onOrientationChanged（）的實作在PhoneWindowManager.java 中，如下：

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class MyOrientationListener  extends WindowOrientationListener { MyOrientationListener(Context context) { super (context); } @Override public void onOrientationChanged( int rotation) { // Send updates based on orientation value if (localLOGV) Log.v(TAG,  "onOrientationChanged, rotation changed to " +rotation); try { mWindowManager.setRotation(rotation, false , mFancyRotationAnimation); SystemProperties.set( "service.screen.rotation" , "" +rotation); } catch (RemoteException e) { // Ignore } } }

基本上整個流程到此結束。

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文章出處：http://www.code007.org/

作者：Code007