OpenCV on Android 開發(fā) （3）豎屏預(yù)覽圖像自動旋轉(zhuǎn)問題解決

在之前的例子里遇到了個(gè)讓我頭疼的小問題，豎屏?xí)rCamera的預(yù)覽圖像總是會左旋90度并且不能全屏。

總之很丑很丑。。。

方法一

經(jīng)過我的研究，網(wǎng)上有很多解決的方法，主要都是通過修改CameraBridgeViewBase.java這個(gè)庫文件實(shí)現(xiàn)的，該庫文件在你的工程\openCVLibrary340\java\org.openv\android文件夾下，如圖



我嘗試了其中的一種方法，在CameraBridgeViewBase.java中找到protected void deliverAndDrawFrame(CvCameraViewFrame frame) 這個(gè)方法
將其中的代碼修改如下：

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);

                /*                
                //原來的方法
                if (BuildConfig.DEBUG)
                    Log.d(TAG, "mStretch value: " + mScale);

                if (mScale != 0) {
                    canvas.drawBitmap(mCacheBitmap, new Rect(0,0,mCacheBitmap.getWidth(), mCacheBitmap.getHeight()),
                         new Rect((int)((canvas.getWidth() - mScale*mCacheBitmap.getWidth()) / 2),
                         (int)((canvas.getHeight() - mScale*mCacheBitmap.getHeight()) / 2),
                         (int)((canvas.getWidth() - mScale*mCacheBitmap.getWidth()) / 2 + mScale*mCacheBitmap.getWidth()),
                         (int)((canvas.getHeight() - mScale*mCacheBitmap.getHeight()) / 2 + mScale*mCacheBitmap.getHeight())), null);
                } else {
                     canvas.drawBitmap(mCacheBitmap, new Rect(0,0,mCacheBitmap.getWidth(), mCacheBitmap.getHeight()),
                         new Rect((canvas.getWidth() - mCacheBitmap.getWidth()) / 2,
                         (canvas.getHeight() - mCacheBitmap.getHeight()) / 2,
                         (canvas.getWidth() - mCacheBitmap.getWidth()) / 2 + mCacheBitmap.getWidth(),
                         (canvas.getHeight() - mCacheBitmap.getHeight()) / 2 + mCacheBitmap.getHeight()), null);
                }
                */



                //修改預(yù)覽旋轉(zhuǎn)90度問題
                canvas.rotate(90, 0, 0);
                float scalew = canvas.getWidth() / (float)mCacheBitmap.getHeight();
                float scaleh = canvas.getHeight() / (float)mCacheBitmap.getHeight();
                if (scaleh > scalew) {
                    scalew = scaleh;
                }
                if (scalew !=0 ) {
                    canvas.scale(scalew, scalew, 0, 0);
                }
                canvas.drawBitmap(mCacheBitmap, 0, -mCacheBitmap.getHeight(), null);
                //修改預(yù)覽旋轉(zhuǎn)90度問題end
     

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

該方法是能解決此問題，但是圖像被放的很大，分辨率很低，豎屏?xí)r也仍然檢測不到人臉。

方法二

直接調(diào)用opencv的庫函數(shù)方法，先定義三個(gè)全局變量，并且修改onCameraViewStarted（）函數(shù)和onCameraFrame（）函數(shù)

Mat mRgba;
Mat mRgbaF;
Mat mRgbaT;

public void onCameraViewStarted(int width, int height) {

        mRgba = new Mat(height, width, CvType.CV_8UC4);
        mRgbaF = new Mat(height, width, CvType.CV_8UC4);
        mRgbaT = new Mat(width, width, CvType.CV_8UC4);
    }

@Override
    public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {

        /**
         * // TODO Auto-generated method stub
         mRgba = inputFrame.rgba();
         // Rotate mRgba 90 degrees
         Core.transpose(mRgba, mRgbaT);
         Imgproc.resize(mRgbaT, mRgbaF, mRgbaF.size(), 0, 0, 0);
         Core.flip(mRgbaF, mRgba, 1);
         */
        mRgba = inputFrame.rgba();

        switch (mOpenCvCameraView.getDisplay().getRotation()) {
            case Surface.ROTATION_0: // Vertical portrait
                Core.transpose(mRgba, mRgbaT);
                Imgproc.resize(mRgbaT, mRgbaF, mRgbaF.size(), 0,0, 0);
                Core.flip(mRgbaF, mRgba, 1);
                break;
            case Surface.ROTATION_90: // 90° anti-clockwise
                break;
            case Surface.ROTATION_180: // Vertical anti-portrait
                Core.transpose(mRgba, mRgbaT);
                Imgproc.resize(mRgbaT, mRgbaF, mRgbaF.size(), 0,0, 0);
                Core.flip(mRgbaF, mRgba, 0);
                break;
            case Surface.ROTATION_270: // 90° clockwise
                Imgproc.resize(mRgba, mRgbaF, mRgbaF.size(), 0,0, 0);
                Core.flip(mRgbaF, mRgba, -1);
                break;
            default:
        }
        return mRgba;
    }

這樣就能實(shí)現(xiàn)豎屏顯示了，并且橫豎屏能隨意切換，但是在我的測試?yán)镓Q屏?xí)r存在圖像被壓縮不能全屏的問題，比例為橫屏的比例，理論上如果在 case Surface.ROTATION_0: // Vertical portrait下做替換如下：

Imgproc.resize(mRgbaT, mRgbaF, mRgbaF.size(), 0,0, 0);
Imgproc.resize(mRgbaT, mRgbaF, mRgbaT.size(), 0,0, 0);
Imgproc.resize(mRgba, mRgba, mRgbaT.size(),0,0,0);
Core.flip(mRgbaF, mRgba, 1);

應(yīng)該能解決圖像比例不對的問題，但是測試發(fā)現(xiàn)，一直是黑屏并沒有顯示23333具體原因不明。。。
所以這個(gè)方法的達(dá)不到我想要的效果，不知道有沒有同志能有更好的改法，能不改opencv庫文件，來解決這個(gè)比例的問題。

方法三

我通過查閱opencv android sdk 給出的sample 發(fā)現(xiàn)了一個(gè)解決這個(gè)問題的新思路。核心思想就是鎖定app的方向旋轉(zhuǎn)，將其固定為Landscape，即水平模式
通過修改AndroidMainifest.xml來實(shí)現(xiàn)，無需修改CameraBridgeViewBase.java這個(gè)庫文件

重點(diǎn)

給AndroidMainifest.xml里的<application標(biāo)簽添加如下代碼android:theme="@android:style/Theme.NoTitleBar.Fullscreen"
給<activity標(biāo)簽添加android:screenOrientation="landscape"
即把AndroidMainifest.xml修改為

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.aaa.facedetection1_0">
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" android:required="false" />
    <uses-feature android:name="android.hardware.camera.autofocus" android:required="false" />
    <uses-feature android:name="android.hardware.camera.front" android:required="false" />
    <uses-feature android:name="android.hardware.camera.front.autofocus" android:required="false" />
    <application
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:theme="@android:style/Theme.NoTitleBar.Fullscreen">
        <activity android:name=".MainActivity"
            android:screenOrientation="landscape">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

這樣就能鎖定橫屏并且全屏顯示了
另外附上MainActivity.java代碼和activity_main.xml
activity_main.xml為

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/relative"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context="com.example.aaa.facedetection1_0.MainActivity">
    <org.opencv.android.JavaCameraView
        android:id="@+id/openCvCameraView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:visibility="gone"
        app:camera_id="any"
        app:show_fps="true"
        />

</RelativeLayout>

MainActivity.java

package com.example.aaa.facedetection1_0;

import android.app.Activity;
import android.content.Context;
import android.content.res.Configuration;
import android.graphics.Camera;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.RelativeLayout;
import android.widget.TextView;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.JavaCameraView;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfRect;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.imgproc.Imgproc;
import org.opencv.objdetect.CascadeClassifier;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import static com.example.aaa.facedetection1_0.R.id.openCvCameraView;

public class MainActivity extends Activity implements CameraBridgeViewBase.CvCameraViewListener{

    private CameraBridgeViewBase openCvCameraView;
    private CascadeClassifier cascadeClassifier;
    private Mat grayscaleImage;
    private int absoluteFaceSize;

    public static int CAMERA_FRONT = 0;
    public static int CAMERA_BACK = 1;
    private  int camera_scene = CAMERA_BACK;

    private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
        @Override
        public void onManagerConnected(int status){
            switch (status){
                case LoaderCallbackInterface.SUCCESS:
                    initializeOpenCVDependencies();
                    break;
                default:
                    super.onManagerConnected(status);
                    break;
            }
        }
    };

    private void initializeOpenCVDependencies(){
        try{
            InputStream is = getResources().openRawResource(R.raw.lbpcascade_frontalface);
            File casadeDir = getDir("cascade", Context.MODE_PRIVATE);
            File mCascadeFile = new File(casadeDir,"lbpcascade_frontalface.xml");
            FileOutputStream os = new FileOutputStream(mCascadeFile);

            byte[] buffer = new byte[4096];
            int bytesRead;
            while ((bytesRead = is.read(buffer)) != -1){
                os.write(buffer, 0, bytesRead);
            }
            is.close();
            os.close();

            cascadeClassifier = new CascadeClassifier(mCascadeFile.getAbsolutePath());

        } catch (Exception e) {
            Log.e("OpenCVActivity","Error Loading casade",e);
        }

        openCvCameraView.enableView();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        setContentView(R.layout.activity_main);

        final RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.relative);

        openCvCameraView = new JavaCameraView(this, CameraBridgeViewBase.CAMERA_ID_BACK)      
        openCvCameraView.setCvCameraViewListener(this);
        

        final Button button = new Button(MainActivity.this);

        button.setText("切換攝像頭");

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v){
                if (camera_scene == CAMERA_FRONT) {
                    relativeLayout.removeAllViews();
                    openCvCameraView.disableView();
                    openCvCameraView = null;
                    cascadeClassifier = null;

                    openCvCameraView = new JavaCameraView(MainActivity.this, CameraBridgeViewBase.CAMERA_ID_BACK);
                    openCvCameraView.setCvCameraViewListener(MainActivity.this);
                    openCvCameraView.setCameraIndex(CameraBridgeViewBase.CAMERA_ID_BACK);

                    camera_scene = CAMERA_BACK;

                    relativeLayout.addView(openCvCameraView);
                    relativeLayout.addView(button);

                    initializeOpenCVDependencies();
                } else {
                    relativeLayout.removeAllViews();
                    openCvCameraView.disableView();
                    openCvCameraView = null;
                    cascadeClassifier = null;

                    openCvCameraView = new JavaCameraView(MainActivity.this, CameraBridgeViewBase.CAMERA_ID_FRONT);
                    openCvCameraView.setCvCameraViewListener(MainActivity.this);
                    openCvCameraView.setCameraIndex(CameraBridgeViewBase.CAMERA_ID_FRONT);

                    camera_scene = CAMERA_FRONT;

                    relativeLayout.addView(openCvCameraView);
                    relativeLayout.addView(button);

                    initializeOpenCVDependencies();
                }
            }
        });

        relativeLayout.addView(openCvCameraView);
        relativeLayout.addView(button);

        if (camera_scene == CAMERA_FRONT) {
            openCvCameraView.setCameraIndex(CameraBridgeViewBase.CAMERA_ID_FRONT);

        } else if (camera_scene == CAMERA_BACK) {
            openCvCameraView.setCameraIndex(CameraBridgeViewBase.CAMERA_ID_BACK);

        }


    }

    @Override
    public void onCameraViewStarted(int width, int height){
        grayscaleImage = new Mat(height, width, CvType.CV_8UC4);

        absoluteFaceSize = (int)(height * 0.2);

    }

    @Override
    public void onCameraViewStopped(){

    }

    @Override
    public Mat onCameraFrame(Mat aInputFrame){

        Imgproc.cvtColor(aInputFrame, grayscaleImage, Imgproc.COLOR_RGBA2RGB);

      
        //使前置的圖像也是正的
        if (camera_scene == CAMERA_FRONT) {
            Core.flip(aInputFrame, aInputFrame, 1);
            Core.flip(grayscaleImage, grayscaleImage, 1);
        }


        MatOfRect faces = new MatOfRect();

        if (cascadeClassifier != null){
            cascadeClassifier.detectMultiScale(grayscaleImage,faces,1.1,2,2,new Size(absoluteFaceSize,absoluteFaceSize),new Size());
        }

        Rect[] faceArray = faces.toArray();
        for (int i = 0; i < faceArray.length; i++)

            Imgproc.rectangle(aInputFrame, faceArray[i].tl(), faceArray[i].br(), new Scalar(0, 255, 0, 255), 1);

        return aInputFrame;
    }

    @Override
    public void onResume(){
        super.onResume();
        if (!OpenCVLoader.initDebug()){
            OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_4_0, this, mLoaderCallback);

        } else {
            mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
        }
    }
}

添加了切換前后置攝像頭的功能

注意，因?yàn)樵谝狝ndroidMainifest.xml里要使用android:theme="@android:style/Theme.NoTitleBar.Fullscreen"這個(gè)主題，需要我們繼承Activity這個(gè)類而不是之前一直默認(rèn)使用的AppCompatActivity，即.java文件開始應(yīng)該為
public class MainActivity extends Activity implements CameraBridgeViewBase.CvCameraViewListener{

否則程序無法運(yùn)行，一打開就閃退

后置豎屏


后置橫屏



前置橫屏


可以發(fā)現(xiàn)這個(gè)方法還是有問題的，因?yàn)槭侵苯渔i定橫屏的，豎屏?xí)r狀態(tài)欄和按鈕不會旋轉(zhuǎn)至豎屏，并且仍然是只有在橫屏下人臉識別才能正常運(yùn)行，這個(gè)可能是因?yàn)閛pencv這個(gè)sdk寫的時(shí)候時(shí)是默認(rèn)橫屏圖像才是正的吧

附上一個(gè)類似問題解決答案的來源
https://stackoverflow.com/questions/14816166/rotate-camera-preview-to-portrait-android-opencv-camera

看來還得好好的啃android開發(fā)和opencv的知識去，畢竟也是半路上的車，遭不住?。。?！要學(xué)習(xí)的東西好多。。。
總不能一直做調(diào)參俠吧23333

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