Android 2.1实现屏幕不同方向旋转

http://www.linuxidc.com/Linux/2011-08/40119.htm

最近调g-sensor的过程中发现Android2.1在设置界面横竖屏幕旋转时只有两个方向，而且板子横着时显示竖屏，竖着时显示横屏（前一版硬件可没这个问题，看来是硬件工程师将g-sensor模块贴片方向改变）。

为了解决横竖颠倒的问题，干脆用最简单的方法：在g-sensor驱动中在input_report_abs()函数上报前将x、y轴交换，z轴不变。

1.short temp;

1.temp = x;

2.x = y;

3.y = temp;

4.input_report_abs(mma_abs_dev, ABS_X, x);

5.input_report_abs(mma_abs_dev, ABS_Y, y);

6.input_report_abs(mma_abs_dev, ABS_Z, z);

7.input_report_abs(mma_abs_dev, ABS_RX, tilt);

8.input_sync(mma_abs_dev);

横竖颠倒解决了，但只有两个方向旋转（0度、90度），我可是需要四个方向啊，研究了下framework代码，发现Android是支持四个方向的，分别是：ROTATION_0、ROTATION_90、ROTATION_180、ROTATION_270，在板子上试了下Android2.2发现有3个方向，而Android2.1只有2个，既然是版本的问题，那就直接修改框架层代码，找了半天终于发现只要修改文件frameworks/base/core/java/android/view/WindowOrientationListener.java

修改代码：

1.public void onSensorChanged(SensorEvent event) {

1. float[] values = event.values;

2. float X = values[_DATA_X];

3. float Y = values[_DATA_Y];

4. float Z = values[_DATA_Z];

5. float OneEightyOverPi = 57.29577957855f;

6. float gravity = (float) Math.sqrt(X*X+Y*Y+Z*Z);

7. float zyangle = (float)Math.asin(Z/gravity)*OneEightyOverPi;

8. int rotation = -1;

9. if ((zyangle <= PIVOT_UPPER) && (zyangle >= PIVOT_LOWER)) {

10. // Check orientation only if the phone is flat enough

11. // Don't trust the angle if the magnitude is small compared to the y value

1. float angle = (float)Math.atan2(Y, -X) * OneEightyOverPi;

13. int orientation = 90 - (int)Math.round(angle);

14. // normalize to 0 - 359 range

1. while (orientation >= 360) {

16. orientation -= 360;

17. }

18. while (orientation < 0) {

19. orientation += 360;

20. }

21. // Orientation values between LANDSCAPE_LOWER and PL_LOWER

22. // are considered landscape.

23. // Ignore orientation values between 0 and LANDSCAPE_LOWER

24. // For orientation values between LP_UPPER and PL_LOWER,

25. // the threshold gets set linearly around PIVOT.

26. /*

1. if ((orientation >= PL_LOWER) && (orientation <= LP_UPPER)) {

2. float threshold;

3. float delta = zyangle - PIVOT;

4. if (mSensorRotation == Surface.ROTATION_90) {

5. if (delta < 0) {

6. // Delta is negative

7. threshold = LP_LOWER - (LP_LF_LOWER * delta);

8. } else {

9. threshold = LP_LOWER + (LP_LF_UPPER * delta);

10. }

11. rotation = (orientation >= threshold) ? Surface.ROTATION_0 : Surface.ROTATION_90;

12. } else {

13. if (delta < 0) {

14. // Delta is negative

15. threshold = PL_UPPER+(PL_LF_LOWER * delta);

16. } else {

17. threshold = PL_UPPER-(PL_LF_UPPER * delta);

18. }

19. rotation = (orientation <= threshold) ? Surface.ROTATION_90: Surface.ROTATION_0;

20. }

21. } else if ((orientation >= LANDSCAPE_LOWER) && (orientation < LP_LOWER)) {

22. rotation = Surface.ROTATION_90;

23. } else if ((orientation >= PL_UPPER) || (orientation <= PORTRAIT_LOWER)) {

24. rotation = Surface.ROTATION_0;

25. }

26. */

27. if(orientation > 325 || orientation <= 45){

28. rotation = Surface.ROTATION_0;

29. }else if(orientation > 45 && orientation <= 135){

30. rotation = Surface.ROTATION_270;

31. }else if(orientation > 135 && orientation < 225){

32. rotation = Surface.ROTATION_180;

33. }else {

34. rotation = Surface.ROTATION_90;

35. }

36. if ((rotation != -1) && (rotation != mSensorRotation)) {

37. mSensorRotation = rotation;

38. onOrientationChanged(mSensorRotation);

39. }

40. }

41. }

哈哈，四个方向旋转都可以了！