在android4.2sdk上，机器默认是横屏，横屏下camera位于机器右上角，安装竖屏APK后，APK旋转180度，需要将camera位置朝下使用。
这一点不符合消费者使用习惯，需要在竖屏APK的情况下，camera位置朝上。 强制改变屏幕启动的方向，我是改的out目录下的build.prop中的ro.sf.hwrotation=90//270，不过这样改，重力感应和camera，开机logo都要翻转方向
由此引出以下开机logo的修改，原生态的logo是ppm格式的，如何修改ppm格式呢，从网上查到的信息是通过代码
具体方法如下
1. pngtopnm logo_linux_clut224.png > logo_linux_clut224.pnm
2. pnmquant 224 logo_linux_clut224.pnm > logo_linux_clut224.pnm
3.pnmtoplainpnm logo_linux_clut224.pnm > logo_linux_clut224.ppm

要删除logo_linux_clut224.clogo_linux_clut224.o 文件，重新编译内核，
注意编译完内核后，也要将上层编译下在打包，不然第一次烧录和recovery时，logo还会出现原来的现象

以下为转载部分
如何改变android默认的横竖屏，修改源码一个地方就可以了。



[java] view plain copy print ?

1. public int rotationForOrientationLw(int orientation, int lastRotation,
2. boolean displayEnabled) {
4. if (mPortraitRotation < 0) {
5. // Initialize the rotation angles for each orientation once.
6. Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))
7. .getDefaultDisplay();
8. if (d.getWidth() > d.getHeight()) {
9. mPortraitRotation = Surface.ROTATION_90;
10. mLandscapeRotation = Surface.ROTATION_0;
11. mUpsideDownRotation = Surface.ROTATION_270;
12. mSeascapeRotation = Surface.ROTATION_180;
13. } else {
14. mPortraitRotation = Surface.ROTATION_0;
15. mLandscapeRotation = Surface.ROTATION_90;
16. mUpsideDownRotation = Surface.ROTATION_180;
17. mSeascapeRotation = Surface.ROTATION_270;
18. }
19. }
21. {
22. Log.i(TAG, "MediaPlayer.is not PlayingVideo");
23. synchronized (mLock) {
24. switch (orientation) {
25. case ActivityInfo.SCREEN_ORIENTATION_PORTRAIT:
26. //always return portrait if orientation set to portrait
27. //return mPortraitRotation;
28. return mUpsideDownRotation;
29. case ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE:
30. //always return landscape if orientation set to landscape
31. return mLandscapeRotation;
32. case ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT:
33. //always return portrait if orientation set to portrait
34. //return mUpsideDownRotation;
35. return mPortraitRotation;
36. case ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE:
37. //always return seascape if orientation set to reverse landscape
38. return mSeascapeRotation;
39. case ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE:
40. //return either landscape rotation based on the sensor
41. mOrientationListener.setAllow180Rotation(
42. isLandscapeOrSeascape(Surface.ROTATION_180));
43. return getCurrentLandscapeRotation(lastRotation);
44. case ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT:
45. mOrientationListener.setAllow180Rotation(
46. !isLandscapeOrSeascape(Surface.ROTATION_180));
47. return getCurrentPortraitRotation(lastRotation);
48. }
50. mOrientationListener.setAllow180Rotation(
51. orientation == ActivityInfo.SCREEN_ORIENTATION_FULL_SENSOR
52. || orientation == ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
54. // case for nosensor meaning ignore sensor and consider only lid
55. // or orientation sensor disabled
56. //or case.unspecified
57. if (mLidOpen) {
58. return mLidOpenRotation;
59. } else if (mDockMode == Intent.EXTRA_DOCK_STATE_CAR && mCarDockRotation >= 0) {
60. return mCarDockRotation;
61. } else if (mDockMode == Intent.EXTRA_DOCK_STATE_DESK && mDeskDockRotation >= 0) {
62. return mDeskDockRotation;
63. } else {
64. if (useSensorForOrientationLp(orientation)) {
65. return mOrientationListener.getCurrentRotation(lastRotation);
66. }
67. return Surface.ROTATION_0;
68. }
69. }
70. }
71. }

public int rotationForOrientationLw(int orientation, int lastRotation, boolean displayEnabled) {if (mPortraitRotation < 0) { // Initialize the rotation angles for each orientation once. Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE)) .getDefaultDisplay(); if (d.getWidth() > d.getHeight()) { mPortraitRotation = Surface.ROTATION_90; mLandscapeRotation = Surface.ROTATION_0; mUpsideDownRotation = Surface.ROTATION_270; mSeascapeRotation = Surface.ROTATION_180; } else { mPortraitRotation = Surface.ROTATION_0; mLandscapeRotation = Surface.ROTATION_90; mUpsideDownRotation = Surface.ROTATION_180; mSeascapeRotation = Surface.ROTATION_270; } }{ Log.i(TAG, "MediaPlayer.is not PlayingVideo"); synchronized (mLock) { switch (orientation) { case ActivityInfo.SCREEN_ORIENTATION_PORTRAIT: //always return portrait if orientation set to portrait //return mPortraitRotation; return mUpsideDownRotation; case ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE: //always return landscape if orientation set to landscape return mLandscapeRotation; case ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT: //always return portrait if orientation set to portrait //return mUpsideDownRotation; return mPortraitRotation; case ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE: //always return seascape if orientation set to reverse landscape return mSeascapeRotation; case ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE: //return either landscape rotation based on the sensor mOrientationListener.setAllow180Rotation( isLandscapeOrSeascape(Surface.ROTATION_180)); return getCurrentLandscapeRotation(lastRotation); case ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT: mOrientationListener.setAllow180Rotation( !isLandscapeOrSeascape(Surface.ROTATION_180)); return getCurrentPortraitRotation(lastRotation); }mOrientationListener.setAllow180Rotation( orientation == ActivityInfo.SCREEN_ORIENTATION_FULL_SENSOR || orientation == ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED); // case for nosensor meaning ignore sensor and consider only lid // or orientation sensor disabled //or case.unspecified if (mLidOpen) { return mLidOpenRotation; } else if (mDockMode == Intent.EXTRA_DOCK_STATE_CAR && mCarDockRotation >= 0) { return mCarDockRotation; } else if (mDockMode == Intent.EXTRA_DOCK_STATE_DESK && mDeskDockRotation >= 0) { return mDeskDockRotation; } else { if (useSensorForOrientationLp(orientation)) { return mOrientationListener.getCurrentRotation(lastRotation); } return Surface.ROTATION_0; } } } }

修改上面倒数一行代码把return Surface.ROTATION_0改为你要的方向，记得这个要和上面的匹配，宽高不同，Surface.ROTATION_0也不同。因为代码开头就有

[java] view plain copy print ?

1. if (mPortraitRotation < 0) {
2. // Initialize the rotation angles for each orientation once.
3. Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))
4. .getDefaultDisplay();
5. if (d.getWidth() > d.getHeight()) {
6. mPortraitRotation = Surface.ROTATION_90;
7. mLandscapeRotation = Surface.ROTATION_0;
8. mUpsideDownRotation = Surface.ROTATION_270;
9. mSeascapeRotation = Surface.ROTATION_180;
10. } else {
11. mPortraitRotation = Surface.ROTATION_0;
12. mLandscapeRotation = Surface.ROTATION_90;
13. mUpsideDownRotation = Surface.ROTATION_180;
14. mSeascapeRotation = Surface.ROTATION_270;
15. }
16. }

if (mPortraitRotation < 0) { // Initialize the rotation angles for each orientation once. Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE)) .getDefaultDisplay(); if (d.getWidth() > d.getHeight()) { mPortraitRotation = Surface.ROTATION_90; mLandscapeRotation = Surface.ROTATION_0; mUpsideDownRotation = Surface.ROTATION_270; mSeascapeRotation = Surface.ROTATION_180; } else { mPortraitRotation = Surface.ROTATION_0; mLandscapeRotation = Surface.ROTATION_90; mUpsideDownRotation = Surface.ROTATION_180; mSeascapeRotation = Surface.ROTATION_270; } }

【android如何改变系统默认横竖屏方向】

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