vtm/vtm-android/src/org/oscim/android/MapPreferences.java

package org.oscim.android;

import org.oscim.core.MapPosition;
import org.oscim.map.Map;

import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;

public class MapPreferences {
	private static final String KEY_LATITUDE = "latitude";
	private static final String KEY_LONGITUDE = "longitude";
	private static final String KEY_SCALE = "scale";

	private final String PREFERENCES_FILE;
	Context ctx;

	public MapPreferences(String name, Context ctx) {
		this.ctx = ctx;
		this.PREFERENCES_FILE = name;
	}

	private void putDouble(Editor editor, String key, double value) {
		editor.putLong(key, Double.doubleToLongBits(value));
	}

	private double getDouble(SharedPreferences prefs, String key) {
		return Double.longBitsToDouble(prefs.getLong(key, 0));
	}

	public void save(Map map) {
		save(map.getMapPosition());
	}

	public void save(MapPosition pos) {
		Editor editor = ctx.getSharedPreferences(PREFERENCES_FILE,
		                                         Activity.MODE_PRIVATE).edit();
		editor.clear();
		putDouble(editor, KEY_LATITUDE, pos.y);
		putDouble(editor, KEY_LONGITUDE, pos.x);
		putDouble(editor, KEY_SCALE, pos.scale);
		putDouble(editor, KEY_LATITUDE, pos.y);
		editor.commit();
	}

	private static boolean containsViewport(SharedPreferences prefs) {
		return prefs.contains(KEY_LATITUDE)
		        && prefs.contains(KEY_LONGITUDE)
		        && prefs.contains(KEY_SCALE);
	}

	public boolean load(Map map) {
		MapPosition pos = map.getMapPosition();
		if (load(pos)) {
			map.setMapPosition(pos);
			return true;
		}
		return false;
	}

	public boolean load(MapPosition pos) {
		SharedPreferences prefs = ctx.getSharedPreferences(PREFERENCES_FILE,
		                                                   Activity.MODE_PRIVATE);

		if (containsViewport(prefs)) {
			pos.x = getDouble(prefs, KEY_LONGITUDE);
			pos.y = getDouble(prefs, KEY_LATITUDE);
			pos.scale = getDouble(prefs, KEY_SCALE);
			return true;
		}
		return false;
	}
}