Question

嗨瞄准工作n Android应用程序使用相机预览检测页码。在我从OnPreviewFrame收到框架后，我使用opencv进行实时图像处理以找到页码位置。现在我的问题是如何在表面上绘制矩形视图？

Answer 1

使用此代码

PreviewDemo.java

public class PreviewDemo extends Activity implements OnClickListener {

private SurfaceView preview = null;
private SurfaceHolder previewHolder = null;
private Camera camera = null;
private boolean inPreview = false;
ImageView image;
Bitmap bmp, itembmp;
static Bitmap mutableBitmap;
PointF start = new PointF();
PointF mid = new PointF();
float oldDist = 1f;
File imageFileName = null;
File imageFileFolder = null;
private MediaScannerConnection msConn;
Display d;
int screenhgt, screenwdh;
ProgressDialog dialog;



@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.preview);

    image = (ImageView) findViewById(R.id.image);
    preview = (SurfaceView) findViewById(R.id.surface);

    previewHolder = preview.getHolder();
    previewHolder.addCallback(surfaceCallback);
    previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    previewHolder.setFixedSize(getWindow().getWindowManager()
        .getDefaultDisplay().getWidth(), getWindow().getWindowManager()
        .getDefaultDisplay().getHeight());


}


@Override
public void onResume() {
    super.onResume();
    camera = Camera.open();
}

@Override
public void onPause() {
    if (inPreview) {
        camera.stopPreview();
    }

    camera.release();
    camera = null;
    inPreview = false;
    super.onPause();
}

private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters) {
    Camera.Size result = null;
    for (Camera.Size size: parameters.getSupportedPreviewSizes()) {
        if (size.width <= width && size.height <= height) {
            if (result == null) {
                result = size;
            } else {
                int resultArea = result.width * result.height;
                int newArea = size.width * size.height;
                if (newArea > resultArea) {
                    result = size;
                }
            }
        }
    }
    return (result);
}

SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() {
    public void surfaceCreated(SurfaceHolder holder) {
        try {
            camera.setPreviewDisplay(previewHolder);
        } catch (Throwable t) {
            Log.e("PreviewDemo-surfaceCallback",
                "Exception in setPreviewDisplay()", t);
            Toast.makeText(PreviewDemo.this, t.getMessage(), Toast.LENGTH_LONG)
                .show();
        }
    }

    public void surfaceChanged(SurfaceHolder holder,
    int format, int width,
    int height) {
        Camera.Parameters parameters = camera.getParameters();
        Camera.Size size = getBestPreviewSize(width, height,
        parameters);

        if (size != null) {
            parameters.setPreviewSize(size.width, size.height);
            camera.setParameters(parameters);
            camera.startPreview();
            inPreview = true;
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // no-op
    }
};


Camera.PictureCallback photoCallback = new Camera.PictureCallback() {
    public void onPictureTaken(final byte[] data, final Camera camera) {
        dialog = ProgressDialog.show(PreviewDemo.this, "", "Saving Photo");
        new Thread() {
            public void run() {
                try {
                    Thread.sleep(1000);
                } catch (Exception ex) {}
                onPictureTake(data, camera);
            }
        }.start();
    }
};



public void onPictureTake(byte[] data, Camera camera) {

    bmp = BitmapFactory.decodeByteArray(data, 0, data.length);
    mutableBitmap = bmp.copy(Bitmap.Config.ARGB_8888, true);
    savePhoto(mutableBitmap);
    dialog.dismiss();
}



class SavePhotoTask extends AsyncTask < byte[], String, String > {@Override
    protected String doInBackground(byte[]...jpeg) {
        File photo = new File(Environment.getExternalStorageDirectory(), "photo.jpg");
        if (photo.exists()) {
            photo.delete();
        }
        try {
            FileOutputStream fos = new FileOutputStream(photo.getPath());
            fos.write(jpeg[0]);
            fos.close();
        } catch (java.io.IOException e) {
            Log.e("PictureDemo", "Exception in photoCallback", e);
        }
        return (null);
    }
}


public void savePhoto(Bitmap bmp) {
    imageFileFolder = new File(Environment.getExternalStorageDirectory(), "Rotate");
    imageFileFolder.mkdir();
    FileOutputStream out = null;
    Calendar c = Calendar.getInstance();
    String date = fromInt(c.get(Calendar.MONTH)) + fromInt(c.get(Calendar.DAY_OF_MONTH)) + fromInt(c.get(Calendar.YEAR)) + fromInt(c.get(Calendar.HOUR_OF_DAY)) + fromInt(c.get(Calendar.MINUTE)) + fromInt(c.get(Calendar.SECOND));
    imageFileName = new File(imageFileFolder, date.toString() + ".jpg");
    try {
        out = new FileOutputStream(imageFileName);
        bmp.compress(Bitmap.CompressFormat.JPEG, 100, out);
        out.flush();
        out.close();
        scanPhoto(imageFileName.toString());
        out = null;
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public String fromInt(int val) {
    return String.valueOf(val);
}

public void scanPhoto(final String imageFileName) {
    msConn = new MediaScannerConnection(PreviewDemo.this, new MediaScannerConnectionClient() {
        public void onMediaScannerConnected() {
            msConn.scanFile(imageFileName, null);
            Log.i("msClient obj  in Photo Utility", "connection established");
        }
        public void onScanCompleted(String path, Uri uri) {
            msConn.disconnect();
            Log.i("msClient obj in Photo Utility", "scan completed");
        }
    });
    msConn.connect();
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_MENU && event.getRepeatCount() == 0) {
        onBack();
    }
    return super.onKeyDown(keyCode, event);
}

public void onBack() {
    Log.e("onBack :", "yes");
    camera.takePicture(null, null, photoCallback);
    inPreview = false;
}

@Override
public void onClick(View v) {
}
}

Preview.xml

<RelativeLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">

 <android.view.SurfaceView
 android:id="@+id/surface"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent" />
</RelativeLayout>

还添加权限

如何在相机预览上绘制矩形？

1 个答案: