How to take picture with camera using ARCore

问题:

ARCore camera doesn't seem to support takePicture. https://developers.google.com/ar/reference/java/com/google/ar/core/Camera

Anyone know how I can take pictures with ARCore?

回答1:

I am assuming you mean a picture of what the camera is seeing and the AR objects. At a high level you need to get permission to write to external storage to save the picture, copy the frame from OpenGL and then save it as a png (for example). Here are the specifics:

Add the WRITE_EXTERNAL_STORAGE permission to the AndroidManifest.xml

   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Then change CameraPermissionHelper to iterate over both the CAMERA and WRITE_EXTERNAL_STORAGE permissions to make sure they are granted

 private static final String REQUIRED_PERMISSIONS[] = {
          Manifest.permission.WRITE_EXTERNAL_STORAGE,
          Manifest.permission.CAMERA
  };

  /**
   * Check to see we have the necessary permissions for this app.
   */
  public static boolean hasCameraPermission(Activity activity) {
    for (String p : REQUIRED_PERMISSIONS) {
      if (ContextCompat.checkSelfPermission(activity, p) !=
            PackageManager.PERMISSION_GRANTED) {
        return false;
      }
    }
    return true;
  }

  /**
   * Check to see we have the necessary permissions for this app,
   *   and ask for them if we don't.
   */
  public static void requestCameraPermission(Activity activity) {
    ActivityCompat.requestPermissions(activity, REQUIRED_PERMISSIONS,
            CAMERA_PERMISSION_CODE);
  }

  /**
   * Check to see if we need to show the rationale for this permission.
   */
  public static boolean shouldShowRequestPermissionRationale(Activity activity) {
    for (String p : REQUIRED_PERMISSIONS) {
      if (ActivityCompat.shouldShowRequestPermissionRationale(activity, p)) {
        return true;
      }
    }
    return false;
  }

Next, add a couple fields to HelloARActivity to keep track of the dimensions of the frame and boolean to indicate when to save the picture.

 private int mWidth;
 private int mHeight;
 private  boolean capturePicture = false;

Set the width and height in onSurfaceChanged()

 public void onSurfaceChanged(GL10 gl, int width, int height) {
     mDisplayRotationHelper.onSurfaceChanged(width, height);
     GLES20.glViewport(0, 0, width, height);
     mWidth = width;
     mHeight = height;
 }

At the bottom of onDrawFrame(), add a check for the capture flag. This should be done after all the other drawing happens.

         if (capturePicture) {
             capturePicture = false;
             SavePicture();
         }

Then add the onClick method for a button to take the picture, and the actual code to save the image:

  public void onSavePicture(View view) {
    // Here just a set a flag so we can copy
    // the image from the onDrawFrame() method.
    // This is required for OpenGL so we are on the rendering thread.
    this.capturePicture = true;
  }

  /**
   * Call from the GLThread to save a picture of the current frame.
   */
  public void SavePicture() throws IOException {
    int pixelData[] = new int[mWidth * mHeight];

    // Read the pixels from the current GL frame.
    IntBuffer buf = IntBuffer.wrap(pixelData);
    buf.position(0);
    GLES20.glReadPixels(0, 0, mWidth, mHeight,
            GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, buf);

    // Create a file in the Pictures/HelloAR album.
    final File out = new File(Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_PICTURES) + "/HelloAR", "Img" +
            Long.toHexString(System.currentTimeMillis()) + ".png");

    // Make sure the directory exists
    if (!out.getParentFile().exists()) {
      out.getParentFile().mkdirs();
    }

    // Convert the pixel data from RGBA to what Android wants, ARGB.
    int bitmapData[] = new int[pixelData.length];
    for (int i = 0; i < mHeight; i++) {
      for (int j = 0; j < mWidth; j++) {
        int p = pixelData[i * mWidth + j];
        int b = (p & 0x00ff0000) >> 16;
        int r = (p & 0x000000ff) << 16;
        int ga = p & 0xff00ff00;
        bitmapData[(mHeight - i - 1) * mWidth + j] = ga | r | b;
      }
    }
    // Create a bitmap.
    Bitmap bmp = Bitmap.createBitmap(bitmapData,
                     mWidth, mHeight, Bitmap.Config.ARGB_8888);

    // Write it to disk.
    FileOutputStream fos = new FileOutputStream(out);
    bmp.compress(Bitmap.CompressFormat.PNG, 100, fos);
    fos.flush();
    fos.close();
    runOnUiThread(new Runnable() {
      @Override
      public void run() {
        showSnackbarMessage("Wrote " + out.getName(), false);
      }
    });
  }

Last step is to add the button to the end of activity_main.xml layout

<Button
    android:id="@+id/fboRecord_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/surfaceview"
    android:layout_alignTop="@+id/surfaceview"
    android:onClick="onSavePicture"
    android:text="Snap"
    tools:ignore="OnClick"/>

回答2:

Acquiring the image buffer

In the latest ARCore SDK, we get access to the image buffer via public class Frame. Below is the sample code which gives us access to the image buffer.

private void onSceneUpdate(FrameTime frameTime) {
    try {
        Frame currentFrame = sceneView.getArFrame();
        Image currentImage = currentFrame.acquireCameraImage();
        int imageFormat = currentImage.getFormat();
        if (imageFormat == ImageFormat.YUV_420_888) {
            Log.d("ImageFormat", "Image format is YUV_420_888");
        }
}

onSceneUpdate() will be called for every update if you register it to setOnUpdateListener() callback. Image will be in YUV_420_888 format, but it will have full Field of view of native high resolution camera.

Writing the acquired image buffer to a file Following implementation converts YUV buffer to compressed JPEG byte array

private static byte[] NV21toJPEG(byte[] nv21, int width, int height) {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    YuvImage yuv = new YuvImage(nv21, ImageFormat.NV21, width, height, null);
    yuv.compressToJpeg(new Rect(0, 0, width, height), 100, out);
    return out.toByteArray();
}

public static void WriteImageInformation(Image image, String path) {
    byte[] data = null;
    data = NV21toJPEG(YUV_420_888toNV21(image),
                image.getWidth(), image.getHeight());
    BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(path));                       
    bos.write(data);
    bos.flush();
    bos.close();
}

private static byte[] YUV_420_888toNV21(Image image) {
    byte[] nv21;
    ByteBuffer yBuffer = image.getPlanes()[0].getBuffer();
    ByteBuffer uBuffer = image.getPlanes()[1].getBuffer();
    ByteBuffer vBuffer = image.getPlanes()[2].getBuffer();

    int ySize = yBuffer.remaining();
    int uSize = uBuffer.remaining();
    int vSize = vBuffer.remaining();

    nv21 = new byte[ySize + uSize + vSize];

    //U and V are swapped
    yBuffer.get(nv21, 0, ySize);
    vBuffer.get(nv21, ySize, vSize);
    uBuffer.get(nv21, ySize + vSize, uSize);

    return nv21;
}

回答3:

Sorry for answering late.You can use code to click picture in ARCore:

private String generateFilename() {
    String date =
            new SimpleDateFormat("yyyyMMddHHmmss", java.util.Locale.getDefault()).format(new Date());
    return Environment.getExternalStoragePublicDirectory(
            Environment.DIRECTORY_PICTURES) + File.separator + "Sceneform/" + date + "_screenshot.jpg";
}

private void saveBitmapToDisk(Bitmap bitmap, String filename) throws IOException {

    File out = new File(filename);
    if (!out.getParentFile().exists()) {
        out.getParentFile().mkdirs();
    }
    try (FileOutputStream outputStream = new FileOutputStream(filename);
         ByteArrayOutputStream outputData = new ByteArrayOutputStream()) {
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, outputData);
        outputData.writeTo(outputStream);
        outputStream.flush();
        outputStream.close();
    } catch (IOException ex) {
        throw new IOException("Failed to save bitmap to disk", ex);
    }
}

private void takePhoto() {
    final String filename = generateFilename();
    /*ArSceneView view = fragment.getArSceneView();*/
    mSurfaceView = findViewById(R.id.surfaceview);
    // Create a bitmap the size of the scene view.
    final Bitmap bitmap = Bitmap.createBitmap(mSurfaceView.getWidth(), mSurfaceView.getHeight(),
            Bitmap.Config.ARGB_8888);

    // Create a handler thread to offload the processing of the image.
    final HandlerThread handlerThread = new HandlerThread("PixelCopier");
    handlerThread.start();
    // Make the request to copy.
    PixelCopy.request(mSurfaceView, bitmap, (copyResult) -> {
        if (copyResult == PixelCopy.SUCCESS) {
            try {
                saveBitmapToDisk(bitmap, filename);
            } catch (IOException e) {
                Toast toast = Toast.makeText(DrawAR.this, e.toString(),
                        Toast.LENGTH_LONG);
                toast.show();
                return;
            }
            Snackbar snackbar = Snackbar.make(findViewById(android.R.id.content),
                    "Photo saved", Snackbar.LENGTH_LONG);
            snackbar.setAction("Open in Photos", v -> {
                File photoFile = new File(filename);

                Uri photoURI = FileProvider.getUriForFile(DrawAR.this,
                        DrawAR.this.getPackageName() + ".ar.codelab.name.provider",
                        photoFile);
                Intent intent = new Intent(Intent.ACTION_VIEW, photoURI);
                intent.setDataAndType(photoURI, "image/*");
                intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
                startActivity(intent);

            });
            snackbar.show();
        } else {
            Log.d("DrawAR", "Failed to copyPixels: " + copyResult);
            Toast toast = Toast.makeText(DrawAR.this,
                    "Failed to copyPixels: " + copyResult, Toast.LENGTH_LONG);
            toast.show();
        }
        handlerThread.quitSafely();
    }, new Handler(handlerThread.getLooper()));
}