qr_scanner/src/com/google/zxing/client/android/camera/CameraConfigurationManager.java

/*
 * Copyright (C) 2010 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.camera;

import android.content.Context;
import android.content.SharedPreferences;
import android.graphics.Point;
import android.hardware.Camera;
import android.preference.PreferenceManager;
import android.util.Log;
import android.view.Display;
import android.view.WindowManager;

import java.util.Collection;

/**
 * A class which deals with reading, parsing, and setting the camera parameters which are used to
 * configure the camera hardware.
 */
final class CameraConfigurationManager {

  private static final String TAG = "CameraConfiguration";
  private static final int MIN_PREVIEW_PIXELS = 320 * 240; // small screen
  private static final int MAX_PREVIEW_PIXELS = 800 * 480; // large/HD screen

  private final Context context;
  private Point screenResolution;
  private Point cameraResolution;

  CameraConfigurationManager(Context context) {
    this.context = context;
  }

  /**
   * Reads, one time, values from the camera that are needed by the app.
   */
  void initFromCameraParameters(Camera camera) {
    Camera.Parameters parameters = camera.getParameters();
    WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    Display display = manager.getDefaultDisplay();
    int width = display.getWidth();
    int height = display.getHeight();
    // We're landscape-only, and have apparently seen issues with display thinking it's portrait 
    // when waking from sleep. If it's not landscape, assume it's mistaken and reverse them:
    if (width < height) {
      Log.i(TAG, "Display reports portrait orientation; assuming this is incorrect");
      int temp = width;
      width = height;
      height = temp;
    }
    screenResolution = new Point(width, height);
    Log.i(TAG, "Screen resolution: " + screenResolution);
    cameraResolution = findBestPreviewSizeValue(parameters, screenResolution, false);
    Log.i(TAG, "Camera resolution: " + cameraResolution);
  }

  void setDesiredCameraParameters(Camera camera) {
    Camera.Parameters parameters = camera.getParameters();

    if (parameters == null) {
      Log.w(TAG, "Device error: no camera parameters are available. Proceeding without configuration.");
      return;
    }

    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);

    initializeTorch(parameters, prefs);
    String focusMode = findSettableValue(parameters.getSupportedFocusModes(),
                                         Camera.Parameters.FOCUS_MODE_AUTO,
                                         Camera.Parameters.FOCUS_MODE_MACRO);
    if (focusMode != null) {
      parameters.setFocusMode(focusMode);
    }

    parameters.setPreviewSize(cameraResolution.x, cameraResolution.y);
    camera.setParameters(parameters);
  }

  Point getCameraResolution() {
    return cameraResolution;
  }

  Point getScreenResolution() {
    return screenResolution;
  }

  void setTorch(Camera camera, boolean newSetting) {
    Camera.Parameters parameters = camera.getParameters();
    doSetTorch(parameters, newSetting);
    camera.setParameters(parameters);
    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
    boolean currentSetting = false; // prefs.getBoolean(PreferencesActivity.KEY_FRONT_LIGHT, false);
//    if (currentSetting != newSetting) {
//      SharedPreferences.Editor editor = prefs.edit();
//      editor.putBoolean(PreferencesActivity.KEY_FRONT_LIGHT, newSetting);
//      editor.commit();
//    }
  }

  private static void initializeTorch(Camera.Parameters parameters, SharedPreferences prefs) {
    boolean currentSetting = false;// prefs.getBoolean(PreferencesActivity.KEY_FRONT_LIGHT, false);
    doSetTorch(parameters, currentSetting);
  }

  private static void doSetTorch(Camera.Parameters parameters, boolean newSetting) {
    String flashMode;
    if (newSetting) {
      flashMode = findSettableValue(parameters.getSupportedFlashModes(),
                                    Camera.Parameters.FLASH_MODE_TORCH,
                                    Camera.Parameters.FLASH_MODE_ON);
    } else {
      flashMode = findSettableValue(parameters.getSupportedFlashModes(),
                                    Camera.Parameters.FLASH_MODE_OFF);
    }
    if (flashMode != null) {
      parameters.setFlashMode(flashMode);
    }
  }

  private static Point findBestPreviewSizeValue(Camera.Parameters parameters,
                                                Point screenResolution,
                                                boolean portrait) {
    Point bestSize = null;
    int diff = Integer.MAX_VALUE;
    for (Camera.Size supportedPreviewSize : parameters.getSupportedPreviewSizes()) {
      int pixels = supportedPreviewSize.height * supportedPreviewSize.width;
      if (pixels < MIN_PREVIEW_PIXELS || pixels > MAX_PREVIEW_PIXELS) {
        continue;
      }
      int supportedWidth = portrait ? supportedPreviewSize.height : supportedPreviewSize.width;
      int supportedHeight = portrait ? supportedPreviewSize.width : supportedPreviewSize.height;
      int newDiff = Math.abs(screenResolution.x * supportedHeight - supportedWidth * screenResolution.y);
      if (newDiff == 0) {
        bestSize = new Point(supportedWidth, supportedHeight);
        break;
      }
      if (newDiff < diff) {
        bestSize = new Point(supportedWidth, supportedHeight);
        diff = newDiff;
      }
    }
    if (bestSize == null) {
      Camera.Size defaultSize = parameters.getPreviewSize();
      bestSize = new Point(defaultSize.width, defaultSize.height);
    }
    return bestSize;
  }

  private static String findSettableValue(Collection<String> supportedValues,
                                          String... desiredValues) {
    Log.i(TAG, "Supported values: " + supportedValues);
    String result = null;
    if (supportedValues != null) {
      for (String desiredValue : desiredValues) {
        if (supportedValues.contains(desiredValue)) {
          result = desiredValue;
          break;
        }
      }
    }
    Log.i(TAG, "Settable value: " + result);
    return result;
  }

}