Android开发使用OpenCv中JavaCameraView预览图左旋90度问题

转自：https://blog.youkuaiyun.com/yd_yandong/article/details/52698696

本文参考地址：http://stackoverflow.com/questions/14816166/rotate-camera-preview-to-portrait-android-opencv-camera点击打开链接

至于预览图左旋90的问题不再贴图了

下面说一下解决办法：

我使用的开发工是Android Studio 2.2

如果你导入了OpenCv的SDK，请继续阅读，其他请立即关闭本博客。

首先找到CameraBridgeViewBase这个类：添加全局变量

private WindowManager windowManager;

接下来是构造方法中对windowManager初始化：

1. public CameraBridgeViewBase(Context context, int cameraId) {

2. super(context);

3. mCameraIndex = cameraId;

4. getHolder().addCallback(this);

5. mMaxWidth = MAX_UNSPECIFIED;

6. mMaxHeight = MAX_UNSPECIFIED;

7. windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);

8. }

9.  

10. public CameraBridgeViewBase(Context context, AttributeSet attrs) {

11. super(context, attrs);

12.  

13. int count = attrs.getAttributeCount();

14. Log.d(TAG, "Attr count: " + Integer.valueOf(count));

15.  

16. TypedArray styledAttrs = getContext().obtainStyledAttributes(attrs, R.styleable.CameraBridgeViewBase);

17. if (styledAttrs.getBoolean(R.styleable.CameraBridgeViewBase_show_fps, false))

18. enableFpsMeter();

19.  

20. mCameraIndex = styledAttrs.getInt(R.styleable.CameraBridgeViewBase_camera_id, -1);

21.  

22. getHolder().addCallback(this);

23. mMaxWidth = MAX_UNSPECIFIED;

24. mMaxHeight = MAX_UNSPECIFIED;

25. windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);

26. styledAttrs.recycle();

27. }

接下来把deliverAndDrawFrame(CvCameraViewFrame frame)方法替换为下面的代码：

1. protected void deliverAndDrawFrame(CvCameraViewFrame frame) {

2. Mat modified;

3.  

4. if (mListener != null) {

5. modified = mListener.onCameraFrame(frame);

6. } else {

7. modified = frame.rgba();

8. }

9.  

10. boolean bmpValid = true;

11. if (modified != null) {

12. try {

13. Utils.matToBitmap(modified, mCacheBitmap);

14. } catch (Exception e) {

15. Log.e(TAG, "Mat type: " + modified);

16. Log.e(TAG, "Bitmap type: " + mCacheBitmap.getWidth() + "*" + mCacheBitmap.getHeight());

17. Log.e(TAG, "Utils.matToBitmap() throws an exception: " + e.getMessage());

18. bmpValid = false;

19. }

20. }

21.  

22. if (bmpValid && mCacheBitmap != null) {

23. Canvas canvas = getHolder().lockCanvas();

24. if (canvas != null) {

25. canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);

26. int rotation = windowManager.getDefaultDisplay().getRotation();

27. int degrees = 0;

28. // config degrees as you need

29. switch (rotation) {

30. case Surface.ROTATION_0:

31. degrees = 90;

32. break;

33. case Surface.ROTATION_90:

34. degrees = 0;

35. break;

36. case Surface.ROTATION_180:

37. degrees = 270;

38. break;

39. case Surface.ROTATION_270:

40. degrees = 180;

41. break;

42. }

43.  

44. Matrix matrix = new Matrix();

45. matrix.postRotate(degrees);

46. Bitmap outputBitmap = Bitmap.createBitmap(mCacheBitmap, 0, 0, mCacheBitmap.getWidth(), mCacheBitmap.getHeight(), matrix, true);

47.  

48. if (outputBitmap.getWidth() <= canvas.getWidth()) {

49. mScale = getRatio(outputBitmap.getWidth(), outputBitmap.getHeight(), canvas.getWidth(), canvas.getHeight());

50. } else {

51. mScale = getRatio(canvas.getWidth(), canvas.getHeight(), outputBitmap.getWidth(), outputBitmap.getHeight());

52. }

53.  

54. if (mScale != 0) {

55. canvas.scale(mScale, mScale, 0, 0);

56. }

57. Log.d(TAG, "mStretch value: " + mScale);

58.  

59. canvas.drawBitmap(outputBitmap, 0, 0, null);

60.  

61. if (mFpsMeter != null) {

62. mFpsMeter.measure();

63. mFpsMeter.draw(canvas, 20, 30);

64. }

65. getHolder().unlockCanvasAndPost(canvas);

66.  

67. }

68. }

69. }

上面还引用了getRatio(int widthSource, int heightSource, int widthTarget, int heightTarget)方法：

1. private float getRatio(int widthSource, int heightSource, int widthTarget, int heightTarget) {

2. if (widthTarget <= heightTarget) {

3. return (float) heightTarget / (float) heightSource;

4. } else {

5. return (float) widthTarget / (float) widthSource;

6. }

7. }

看到这里你也许已经明白了，核心代码是如下这些：

1. int rotation = windowManager.getDefaultDisplay().getRotation();

2. int degrees = 0;

3. // config degrees as you need

4. switch (rotation) {

5. case Surface.ROTATION_0:

6. degrees = 90;

7. break;

8. case Surface.ROTATION_90:

9. degrees = 0;

10. break;

11. case Surface.ROTATION_180:

12. degrees = 270;

13. break;

14. case Surface.ROTATION_270:

15. degrees = 180;

16. break;

17. }

18.  

19. Matrix matrix = new Matrix();

20. matrix.postRotate(degrees);

其实就是更改Rotation参数。
下面看一下效果：

现在可能又出现了一个问题:图像预览界面不能全屏，如图：画红色线条部分为黑色边框。