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

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：

 public CameraBridgeViewBase(Context context, int cameraId) {
        super(context);
        mCameraIndex = cameraId;
        getHolder().addCallback(this);
        mMaxWidth = MAX_UNSPECIFIED;
        mMaxHeight = MAX_UNSPECIFIED;
        windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    }

    public CameraBridgeViewBase(Context context, AttributeSet attrs) {
        super(context, attrs);

        int count = attrs.getAttributeCount();
        Log.d(TAG, "Attr count: " + Integer.valueOf(count));

        TypedArray styledAttrs = getContext().obtainStyledAttributes(attrs, R.styleable.CameraBridgeViewBase);
        if (styledAttrs.getBoolean(R.styleable.CameraBridgeViewBase_show_fps, false))
            enableFpsMeter();

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

        getHolder().addCallback(this);
        mMaxWidth = MAX_UNSPECIFIED;
        mMaxHeight = MAX_UNSPECIFIED;
        windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        styledAttrs.recycle();
    }

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

  protected void deliverAndDrawFrame(CvCameraViewFrame frame) {
        Mat modified;

        if (mListener != null) {
            modified = mListener.onCameraFrame(frame);
        } else {
            modified = frame.rgba();
        }

        boolean bmpValid = true;
        if (modified != null) {
            try {
                Utils.matToBitmap(modified, mCacheBitmap);
            } catch (Exception e) {
                Log.e(TAG, "Mat type: " + modified);
                Log.e(TAG, "Bitmap type: " + mCacheBitmap.getWidth() + "*" + mCacheBitmap.getHeight());
                Log.e(TAG, "Utils.matToBitmap() throws an exception: " + e.getMessage());
                bmpValid = false;
            }
        }

        if (bmpValid && mCacheBitmap != null) {
            Canvas canvas = getHolder().lockCanvas();
            if (canvas != null) {
                canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);
                int rotation = windowManager.getDefaultDisplay().getRotation();
                int degrees = 0;
                // config degrees as you need
                switch (rotation) {
                    case Surface.ROTATION_0:
                        degrees = 90;
                        break;
                    case Surface.ROTATION_90:
                        degrees = 0;
                        break;
                    case Surface.ROTATION_180:
                        degrees = 270;
                        break;
                    case Surface.ROTATION_270:
                        degrees = 180;
                        break;
                }

                Matrix matrix = new Matrix();
                matrix.postRotate(degrees);
                Bitmap outputBitmap = Bitmap.createBitmap(mCacheBitmap, 0, 0, mCacheBitmap.getWidth(), mCacheBitmap.getHeight(), matrix, true);

                if (outputBitmap.getWidth() <= canvas.getWidth()) {
                    mScale = getRatio(outputBitmap.getWidth(), outputBitmap.getHeight(), canvas.getWidth(), canvas.getHeight());
                } else {
                    mScale = getRatio(canvas.getWidth(), canvas.getHeight(), outputBitmap.getWidth(), outputBitmap.getHeight());
                }

                if (mScale != 0) {
                    canvas.scale(mScale, mScale, 0, 0);
                }
                Log.d(TAG, "mStretch value: " + mScale);

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

                if (mFpsMeter != null) {
                    mFpsMeter.measure();
                    mFpsMeter.draw(canvas, 20, 30);
                }
                getHolder().unlockCanvasAndPost(canvas);

            }
        }
    }

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

 private float getRatio(int widthSource, int heightSource, int widthTarget, int heightTarget) {
        if (widthTarget <= heightTarget) {
            return (float) heightTarget / (float) heightSource;
        } else {
            return (float) widthTarget / (float) widthSource;
        }
    }

看到这里你也许已经明白了，核心代码是如下这些：

int rotation = windowManager.getDefaultDisplay().getRotation();
                int degrees = 0;
                // config degrees as you need
                switch (rotation) {
                    case Surface.ROTATION_0:
                        degrees = 90;
                        break;
                    case Surface.ROTATION_90:
                        degrees = 0;
                        break;
                    case Surface.ROTATION_180:
                        degrees = 270;
                        break;
                    case Surface.ROTATION_270:
                        degrees = 180;
                        break;
                }

                Matrix matrix = new Matrix();
                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。