path: root/src/com/google/zxing/client/android/CameraManager.java

/*
 * Copyright (C) 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.zxing.client.android;

import com.google.zxing.ResultPoint;

import android.content.Context;
import android.graphics.PixelFormat;
import android.graphics.Point;
import android.graphics.Rect;
import android.hardware.Camera;
import android.os.Build;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Display;
import android.view.SurfaceHolder;
import android.view.WindowManager;

import java.io.IOException;
import java.util.regex.Pattern;

/**
 * This object wraps the Camera service object and expects to be the only one talking to it. The
 * implementation encapsulates the steps needed to take preview-sized images, which are used for
 * both preview and decoding.
 *
 * @author dswitkin@google.com (Daniel Switkin)
 */
final class CameraManager {

  private static final String TAG = "CameraManager";

  private static final int MIN_FRAME_WIDTH = 240;
  private static final int MIN_FRAME_HEIGHT = 240;
  private static final int MAX_FRAME_WIDTH = 480;
  private static final int MAX_FRAME_HEIGHT = 360;

  private static final int TARGET_PREVIEW_WIDTH = 320;
  private static final int TARGET_PREVIEW_HEIGHT = 240;

  private static final Pattern COMMA_PATTERN = Pattern.compile(",");

  private static CameraManager cameraManager;

  private Camera camera;
  private final Context context;
  private Point screenResolution;
  private Point cameraResolution;
  private Rect framingRect;
  private Handler previewHandler;
  private int previewMessage;
  private Handler autoFocusHandler;
  private int autoFocusMessage;
  private boolean initialized;
  private boolean previewing;
  private int previewFormat;
  private String previewFormatString;
  private boolean useOneShotPreviewCallback;

  /**
   * Preview frames are delivered here, which we pass on to the registered handler. Make sure to
   * clear the handler so it will only receive one message.
   */
  private final Camera.PreviewCallback previewCallback = new Camera.PreviewCallback() {
    public void onPreviewFrame(byte[] data, Camera camera) {
      if (!useOneShotPreviewCallback) {
        camera.setPreviewCallback(null);
      }
      if (previewHandler != null) {
        Message message = previewHandler.obtainMessage(previewMessage, cameraResolution.x,
            cameraResolution.y, data);
        message.sendToTarget();
        previewHandler = null;
      }
    }
  };

  /**
   * Autofocus callbacks arrive here, and are dispatched to the Handler which requested them.
   */
  private final Camera.AutoFocusCallback autoFocusCallback = new Camera.AutoFocusCallback() {
    public void onAutoFocus(boolean success, Camera camera) {
      if (autoFocusHandler != null) {
        Message message = autoFocusHandler.obtainMessage(autoFocusMessage, success);
        // Simulate continuous autofocus by sending a focus request every 1.5 seconds.
        autoFocusHandler.sendMessageDelayed(message, 1500L);
        autoFocusHandler = null;
      }
    }
  };

  /**
   * Initializes this static object with the Context of the calling Activity.
   *
   * @param context The Activity which wants to use the camera.
   */
  public static void init(Context context) {
    if (cameraManager == null) {
      cameraManager = new CameraManager(context);
    }
  }

  /**
   * Gets the CameraManager singleton instance.
   *
   * @return A reference to the CameraManager singleton.
   */
  public static CameraManager get() {
    return cameraManager;
  }

  private CameraManager(Context context) {
    this.context = context;
    camera = null;
    initialized = false;
    previewing = false;

    // Camera.setOneShotPreviewCallback() has a race condition in Cupcake, so we use the older
    // Camera.setPreviewCallback() on 1.5 and earlier. For Donut and later, we need to use
    // the more efficient one shot callback, as the older one can swamp the system and cause it
    // to run out of memory. We can't use SDK_INT because it was introduced in the Donut SDK.
    useOneShotPreviewCallback = Integer.parseInt(Build.VERSION.SDK) > Build.VERSION_CODES.CUPCAKE;
  }

  /**
   * Opens the camera driver and initializes the hardware parameters.
   *
   * @param holder The surface object which the camera will draw preview frames into.
   * @throws IOException Indicates the camera driver failed to open.
   */
  public void openDriver(SurfaceHolder holder) throws IOException {
    if (camera == null) {
      camera = Camera.open();
      if (camera == null) {
        throw new IOException();
      }
      camera.setPreviewDisplay(holder);

      if (!initialized) {
        initialized = true;
        getScreenResolution();
      }

      setCameraParameters();
    }
  }

  /**
   * Closes the camera driver if still in use.
   */
  public void closeDriver() {
    if (camera != null) {
      camera.release();
      camera = null;
    }
  }

  /**
   * Asks the camera hardware to begin drawing preview frames to the screen.
   */
  public void startPreview() {
    if (camera != null && !previewing) {
      camera.startPreview();
      previewing = true;
    }
  }

  /**
   * Tells the camera to stop drawing preview frames.
   */
  public void stopPreview() {
    if (camera != null && previewing) {
      if (!useOneShotPreviewCallback) {
        camera.setPreviewCallback(null);
      }
      camera.stopPreview();
      previewHandler = null;
      autoFocusHandler = null;
      previewing = false;
    }
  }

  /**
   * A single preview frame will be returned to the handler supplied. The data will arrive as byte[]
   * in the message.obj field, with width and height encoded as message.arg1 and message.arg2,
   * respectively.
   *
   * @param handler The handler to send the message to.
   * @param message The what field of the message to be sent.
   */
  public void requestPreviewFrame(Handler handler, int message) {
    if (camera != null && previewing) {
      previewHandler = handler;
      previewMessage = message;
      if (useOneShotPreviewCallback) {
        camera.setOneShotPreviewCallback(previewCallback);
      } else {
        camera.setPreviewCallback(previewCallback);
      }
    }
  }

  /**
   * Asks the camera hardware to perform an autofocus.
   *
   * @param handler The Handler to notify when the autofocus completes.
   * @param message The message to deliver.
   */
  public void requestAutoFocus(Handler handler, int message) {
    if (camera != null && previewing) {
      autoFocusHandler = handler;
      autoFocusMessage = message;
      camera.autoFocus(autoFocusCallback);
    }
  }

  /**
   * Calculates the framing rect which the UI should draw to show the user where to place the
   * barcode. This target helps with alignment as well as forces the user to hold the device
   * far enough away to ensure the image will be in focus.
   *
   * @return The rectangle to draw on screen in window coordinates.
   */
  public Rect getFramingRect() {
    if (framingRect == null) {
      if (camera == null) {
        return null;
      }
      int width = cameraResolution.x * 3 / 4;
      if (width < MIN_FRAME_WIDTH) {
        width = MIN_FRAME_WIDTH;
      } else if (width > MAX_FRAME_WIDTH) {
        width = MAX_FRAME_WIDTH;
      }
      int height = cameraResolution.y * 3 / 4;
      if (height < MIN_FRAME_HEIGHT) {
        height = MIN_FRAME_HEIGHT;
      } else if (height > MAX_FRAME_HEIGHT) {
        height = MAX_FRAME_HEIGHT;
      }
      int leftOffset = (cameraResolution.x - width) / 2;
      int topOffset = (cameraResolution.y - height) / 2;
      framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
      Log.v(TAG, "Calculated framing rect: " + framingRect);
    }
    return framingRect;
  }

  /**
   * Converts the result points from still resolution coordinates to screen coordinates.
   *
   * @param points The points returned by the Reader subclass through Result.getResultPoints().
   * @return An array of Points scaled to the size of the framing rect and offset appropriately
   *         so they can be drawn in screen coordinates.
   */
  public Point[] convertResultPoints(ResultPoint[] points) {
    Rect frame = getFramingRect();
    int count = points.length;
    Point[] output = new Point[count];
    for (int x = 0; x < count; x++) {
      output[x] = new Point();
      output[x].x = frame.left + (int) (points[x].getX() + 0.5f);
      output[x].y = frame.top + (int) (points[x].getY() + 0.5f);
    }
    return output;
  }

  /**
   * A factory method to build the appropriate LuminanceSource object based on the format
   * of the preview buffers, as described by Camera.Parameters.
   *
   * @param data A preview frame.
   * @param width The width of the image.
   * @param height The height of the image.
   * @return A PlanarYUVLuminanceSource instance.
   */
  public PlanarYUVLuminanceSource buildLuminanceSource(byte[] data, int width, int height) {
    Rect rect = getFramingRect();
    switch (previewFormat) {
      // This is the standard Android format which all devices are REQUIRED to support.
      // In theory, it's the only one we should ever care about.
      case PixelFormat.YCbCr_420_SP:
      // This format has never been seen in the wild, but is compatible as we only care
      // about the Y channel, so allow it.
      case PixelFormat.YCbCr_422_SP:
        return new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top,
            rect.width(), rect.height());
      default:
        // The Samsung Moment incorrectly uses this variant instead of the 'sp' version.
        // Fortunately, it too has all the Y data up front, so we can read it.
        if ("yuv420p".equals(previewFormatString)) {
          return new PlanarYUVLuminanceSource(data, width, height, rect.left, rect.top,
            rect.width(), rect.height());
        }
    }
    throw new IllegalArgumentException("Unsupported picture format: " +
        previewFormat + '/' + previewFormatString);
  }

  /**
   * Sets the camera up to take preview images which are used for both preview and decoding.
   * We detect the preview format here so that buildLuminanceSource() can build an appropriate
   * LuminanceSource subclass. In the future we may want to force YUV420SP as it's the smallest,
   * and the planar Y can be used for barcode scanning without a copy in some cases.
   */
  private void setCameraParameters() {
    Camera.Parameters parameters = camera.getParameters();
    previewFormat = parameters.getPreviewFormat();
    previewFormatString = parameters.get("preview-format");
    Log.v(TAG, "Default preview format: " + previewFormat + '/' + previewFormatString);

    cameraResolution = getCameraResolution(parameters);
    Log.v(TAG, "Setting preview size: " + cameraResolution.x + ", " + cameraResolution.y);
    parameters.setPreviewSize(cameraResolution.x, cameraResolution.y);

    // FIXME: This is a hack to turn the flash off on the Samsung Galaxy.
    parameters.set("flash-value", 2);

    // This is the standard setting to turn the flash off that all devices should honor.
    parameters.set("flash-mode", "off");

    // Set zoom to 2x if available. This helps encourage the user to pull back.
    // Some devices like the Behold have a zoom parameter
    parameters.set("zoom", "2.0");
    // Most devices, like the Hero, appear to expose this zoom parameter.
    // (I think) This means 2.0x
    parameters.set("taking-picture-zoom", "20");

    camera.setParameters(parameters);
  }

  private Point getScreenResolution() {
    if (screenResolution == null) {
      WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
      Display display = manager.getDefaultDisplay();
      screenResolution = new Point(display.getWidth(), display.getHeight());
    }
    return screenResolution;
  }

  private Point getCameraResolution(Camera.Parameters parameters) {

    String previewSizeValueString = parameters.get("preview-size-values");
    // saw this on Xperia
    if (previewSizeValueString == null) {
      previewSizeValueString = parameters.get("preview-size-value");
    }
    Point cameraResolution = null;
    if (previewSizeValueString != null) {
      Log.v(TAG, "preview-size parameter: " + previewSizeValueString);
      cameraResolution = findBestPreviewSizeValue(previewSizeValueString);
    }

    if (cameraResolution == null) {
      Camera.Size cameraPreviewSize = parameters.getPreviewSize();
      if (cameraPreviewSize != null) {
        Log.v(TAG, "Default preview size: " + cameraPreviewSize.width + ", " + cameraPreviewSize.height);
        cameraResolution = new Point(cameraPreviewSize.width, cameraPreviewSize.height);
      }
    }

    if (cameraResolution == null) {
      cameraResolution = new Point(screenResolution.x, screenResolution.y);
    }

    // Ensure that the camera resolution is a multiple of 8, as the screen may not be.
    cameraResolution.x = (cameraResolution.x >> 3) << 3;
    cameraResolution.y = (cameraResolution.y >> 3) << 3;

    return cameraResolution;
  }

  private static Point findBestPreviewSizeValue(String previewSizeValueString) {
    int bestX = 0;
    int bestY = 0;
    int diff = Integer.MAX_VALUE;
    for (String previewSize : COMMA_PATTERN.split(previewSizeValueString)) {

      previewSize = previewSize.trim();
      int dimPosition = previewSize.indexOf('x');
      if (dimPosition < 0) {
        Log.w(TAG, "Bad preview-size");
        continue;
      }

      int newX;
      int newY;
      try {
        newX = Integer.parseInt(previewSize.substring(0, dimPosition));
        newY = Integer.parseInt(previewSize.substring(dimPosition + 1));
      } catch (NumberFormatException nfe) {
        Log.w(TAG, "Bad preview-size");
        continue;
      }

      int newDiff = Math.abs(newX - TARGET_PREVIEW_WIDTH) + Math.abs(newY - TARGET_PREVIEW_HEIGHT);
      if (newDiff == 0) {
        bestX = newX;
        bestY = newY;
        break;
      } else if (newDiff < diff) {
        bestX = newX;
        bestY = newY;
        diff = newDiff;
      }

    }

    if (bestX > 0 && bestY > 0) {
      return new Point(bestX, bestY);
    }
    return null;
  }

}