StarOfBethlehemLayer.java

// Copyright 2010 Google Inc.
//
// 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.android.stardroid.layers;

import android.content.res.Resources;
import android.util.Log;

import com.google.android.stardroid.R;
import com.google.android.stardroid.base.TimeConstants;
import com.google.android.stardroid.control.AstronomerModel;
import com.google.android.stardroid.renderer.RendererObjectManager.UpdateType;
import com.google.android.stardroid.source.AbstractAstronomicalSource;
import com.google.android.stardroid.source.AstronomicalSource;
import com.google.android.stardroid.source.ImageSource;
import com.google.android.stardroid.source.Sources;
import com.google.android.stardroid.source.impl.ImageSourceImpl;
import com.google.android.stardroid.units.GeocentricCoordinates;
import com.google.android.stardroid.units.Vector3;
import com.google.android.stardroid.util.MiscUtil;

import java.util.ArrayList;
import java.util.Calendar;
import java.util.EnumSet;
import java.util.List;

/**
 * A {@link Layer} specially for Christmas.
 *
 * @author John Taylor
 */

public class StarOfBethlehemLayer extends AbstractSourceLayer {
  public static final String TAG = MiscUtil.getTag(StarOfBethlehemLayer.class);
  private final AstronomerModel model;

  public StarOfBethlehemLayer(AstronomerModel model, Resources resources) {
    super(resources, true);
    this.model = model;
  }

  @Override
  protected void initializeAstroSources(ArrayList<AstronomicalSource> sources) {
    sources.add(new StarOfBethlehemSource(model, getResources()));
  }

  @Override
  public int getLayerDepthOrder() {
    return 40;
  }

  // TODO(brent): Remove this.
  @Override
  public String getPreferenceId() {
    return "source_provider.0";
  }

  @Override
  public String getLayerName() {
    return "Easter Egg";
  }

  @Override
  protected int getLayerNameId() {
    return R.string.show_stars_pref;
  }

  private static class StarOfBethlehemSource extends AbstractAstronomicalSource {
    private static final Vector3 UP = new Vector3(0.0f, 1.0f, 0.0f);
    private static final long UPDATE_FREQ_MS = 1L * TimeConstants.MILLISECONDS_PER_MINUTE;
    private static final float SCALE_FACTOR = 0.03f;

    private final List<ImageSource> imageSources = new ArrayList<ImageSource>();
    private final AstronomerModel model;

    private long lastUpdateTimeMs = 0L;
    private GeocentricCoordinates coords;
    private ImageSourceImpl theImage;

    public StarOfBethlehemSource(AstronomerModel model, Resources resources) {
      this.model = model;
      coords = new GeocentricCoordinates(1, 0, 0);
      // star_off2 is a 1pxX1px image that should be invisible.
      // We'd prefer not to show any image except on the Christmas dates, but there
      // appears to be a bug in the renderer in that new images added later don't get
      // picked up, even if we return UpdateType.Reset.
      theImage = new ImageSourceImpl(coords, resources, R.drawable.blank, UP, SCALE_FACTOR);
      imageSources.add(theImage);
    }

    private void updateStar() {
      this.lastUpdateTimeMs = model.getTime().getTime();
      // We will only show the star if it's Christmas Eve.
      Calendar calendar = Calendar.getInstance();
      calendar.setTimeInMillis(model.getTime().getTime());
      theImage.setUpVector(UP);
      // TODO(johntaylor): consider varying the sizes by scaling factor as time progresses.
      if ((calendar.get(Calendar.MONTH) == Calendar.DECEMBER)
            && (calendar.get(Calendar.DAY_OF_MONTH) == 25)) {
        Log.d(TAG, "Showing Easter Egg");
        theImage.setImageId(R.drawable.star_of_b);
        GeocentricCoordinates zenith = model.getZenith();
        GeocentricCoordinates east = model.getEast();
        coords.assign((zenith.x + 2 * east.x) / 3,
                      (zenith.y + 2 * east.y) / 3,
                      (zenith.z + 2 * east.z) / 3);
        theImage.setUpVector(zenith);
      } else {
        theImage.setImageId(R.drawable.blank);
      }
    }

    @Override
    public Sources initialize() {
      updateStar();
      return this;
    }

    @Override
    public EnumSet<UpdateType> update() {
      EnumSet<UpdateType> updateTypes = EnumSet.noneOf(UpdateType.class);
      if (Math.abs(model.getTime().getTime() - lastUpdateTimeMs) > UPDATE_FREQ_MS) {
        updateStar();
        updateTypes.add(UpdateType.UpdateImages);
        updateTypes.add(UpdateType.UpdatePositions);
      }
      return updateTypes;
    }

    @Override
    public List<? extends ImageSource> getImages() {
      return imageSources;
    }
  }
}