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POLimit Scrolling on offline maps, in Android
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copied!<p>I got these piece of codes or patches from osmdroid, and I decided to ask for your help guys because i don't have the enough knowledge to combine these codes to come up with on a solution on my problem, Scrolling limit on an offline map. I searched across the web, and modified tutorials. Honestly I tried to modify these codes but i have not found any progress. Basically I have an offline map from mapnik, and a few overlays. I don't know where to properly place these set of codes. Your ideas and modification will be a great help and also helps me keep going with my project and I guess your answers will definitely help others with the same problem as mine in the future. I know this is to much. Thank you sirs for your time, and God Bless.</p> <pre><code>public void onCreate(Bundle savedInstanceState) { ... ... m_mapView = (MapView) findViewById(R.id.mapview); m_mapView.setTileSource(TileSourceFactory.MAPNIK); } </code></pre> <p>First: BoundingBox</p> <pre><code>BoundingBoxE6 bbox = new BoundingBoxE6(9.37398, 123.33761, 9.23948, 123.25035); this.setScrollableAreaLimit(bbox); </code></pre> <p>Second: LimitScrollToGeographicArea.patch</p> <pre><code>Index: MapView.java =================================================================== --- MapView.java (revision 944) +++ MapView.java (working copy) @@ -103,6 +103,8 @@ protected MapListener mListener; + protected Rect mScrollableAreaLimit; + // for speed (avoiding allocations) private final Matrix mMatrix = new Matrix(); private final MapTileProviderBase mTileProvider; @@ -505,6 +507,36 @@ mMapOverlay.setUseDataConnection(aMode); } + /** + * Set the map to limit it's scrollable view to the specified BoundingBoxE6. Note that, like + * North/South bounds limiting, this allows an overscroll of half the screen size. This means + * each border can be scrolled to the center of the screen. + * + * @param boundingBox + * A lat/long bounding box to limit scrolling to, or null to remove any scrolling + * limitations + */ + public void setScrollableAreaLimit(BoundingBoxE6 boundingBox) { + final int worldSize_2 = TileSystem.MapSize(MapViewConstants.MAXIMUM_ZOOMLEVEL) / 2; + + // Clear scrollable area limit if null passed. + if (boundingBox == null) { + mScrollableAreaLimit = null; + return; + } + + // Get NW/upper-left + final Point upperLeft = TileSystem.LatLongToPixelXY(boundingBox.getLatNorthE6() / 1E6, + boundingBox.getLonWestE6() / 1E6, MapViewConstants.MAXIMUM_ZOOMLEVEL, null); + upperLeft.offset(-worldSize_2, -worldSize_2); + + // Get SE/lower-right + final Point lowerRight = TileSystem.LatLongToPixelXY(boundingBox.getLatSouthE6() / 1E6, + boundingBox.getLonEastE6() / 1E6, MapViewConstants.MAXIMUM_ZOOMLEVEL, null); + lowerRight.offset(-worldSize_2, -worldSize_2); + mScrollableAreaLimit = new Rect(upperLeft.x, upperLeft.y, lowerRight.x, lowerRight.y); + } + // =========================================================== // Methods from SuperClass/Interfaces // =========================================================== @@ -772,10 +804,26 @@ //I am confused with these codes below, where should I declare it? Int x, y in the onCreate method? x += (worldSize_2 * 2); while (x > worldSize_2) x -= (worldSize_2 * 2); - while (y < -worldSize_2) - y += (worldSize_2 * 2); - while (y > worldSize_2) - y -= (worldSize_2 * 2); + if (y < -worldSize_2) + y = -worldSize_2; + if (y > worldSize_2) + y = worldSize_2; + + if (mScrollableAreaLimit != null) { + final int zoomDiff = MapViewConstants.MAXIMUM_ZOOMLEVEL - getZoomLevel(); + final int minX = mScrollableAreaLimit.left >> zoomDiff; + final int minY = mScrollableAreaLimit.top >> zoomDiff; + final int maxX = mScrollableAreaLimit.right >> zoomDiff; + final int maxY = mScrollableAreaLimit.bottom >> zoomDiff; + if (x < minX) + x = minX; + else if (x > maxX) + x = maxX; + if (y < minY) + y = minY; + else if (y > maxY) + y = maxY; + } super.scrollTo(x, y); // do callback on listener </code></pre> <p>Another one:</p> <pre><code> scrollToMethod public void scrollTo(int x, int y) { int curZoomLevel = mZoomLevel; final int worldSize_2 = TileSystem.MapSize(curZoomLevel) / 2; Log.v("HELP", "Scrolling to X=" + x + " Y=" + y + " ZL=" + curZoomLevel + " - WW="+worldSize_2); while (x < -worldSize_2) x += (worldSize_2 * 2); while (x > worldSize_2) x -= (worldSize_2 * 2); if (y < -worldSize_2) y = -worldSize_2; if (y > worldSize_2) y = worldSize_2; if (mScrollableAreaLimit != null) { int targetZoomLevel = getZoomLevel(); final int zoomDiff = MapViewConstants.MAXIMUM_ZOOMLEVEL - targetZoomLevel; //final int zoomDiff = MapViewConstants.MAXIMUM_ZOOMLEVEL - mZoomLevel; final int minX = mScrollableAreaLimit.left >> zoomDiff; final int minY = mScrollableAreaLimit.top >> zoomDiff; final int maxX = mScrollableAreaLimit.right >> zoomDiff; final int maxY = mScrollableAreaLimit.bottom >> zoomDiff; Log.v("HELP", "Limit: minX=" + minX + " maxX=" + maxX + " minY=" + minY + " maxY=" + maxY + " ZL=" + curZoomLevel + " ZLTarget="+ targetZoomLevel + " ZD="+zoomDiff); if (x < minX) { Log.v("HELP", "!!! X=" + x + " minX=" + minX + " CORRECTION:" + (minX-x)); x = minX; } else if (x > maxX) { Log.v("HELP", "!!! X=" + x + " maxX=" + maxX + " CORRECTION:" + (maxX-x)); x = maxX; } if (y < minY) { Log.v("HELP", "!!! Y=" + y + " minY=" + minY + " CORRECTION:" + (minY-y)); y = minY; } else if (y > maxY) { Log.v("HELP", "!!! Y=" + y + " maxY=" + maxY + " CORRECTION:" + (maxY-y)); y = maxY; } } super.scrollTo(x, y); // do callback on listener if (mListener != null) { final ScrollEvent event = new ScrollEvent(this, x, y); mListener.onScroll(event); } } </code></pre>

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