FileSystem API-based cache for Kothic-JS - v.0.02

kothic-leaflet.js

window.requestFileSystem  = window.requestFileSystem || window.webkitRequestFileSystem;
BlobBuilder = window.MozBlobBuilder || window.WebKitBlobBuilder || window.BlobBuilder;

Object.size = function(obj) {
    var size = 0, key;
    for (key in obj) {
        if (obj.hasOwnProperty(key)) size++;
    }
    return size;
};

if (typeof(window.requestFileSystem) != 'undefined')
{
  // window.requestFileSystem(TEMPORARY, 1024 * 1024 * 128, onInitFs, errorHandler);
  window.requestFileSystem(0, 1024 * 1024 * 128, onInitFs, errorHandler);
}

function onInitFs(fs_) {
  window.fs = fs_;
}

function errorHandler(e) {
  var msg = '';

  switch (e.code) {
    case FileError.QUOTA_EXCEEDED_ERR:
      msg = 'QUOTA_EXCEEDED_ERR';
      break;
    case FileError.NOT_FOUND_ERR:
      msg = 'NOT_FOUND_ERR';
      break;
    case FileError.SECURITY_ERR:
      msg = 'SECURITY_ERR';
      break;
    case FileError.INVALID_MODIFICATION_ERR:
      msg = 'INVALID_MODIFICATION_ERR';
      break;
    case FileError.INVALID_STATE_ERR:
      msg = 'INVALID_STATE_ERR';
      break;
    default:
      msg = 'Unknown Error';
      break;
  };

  console.log('Error: ' + msg);
}

L.TileLayer.Kothic = L.TileLayer.Canvas.extend({
	options: {
		tileSize: 256 * 4,
		zoomOffset: 2,
		minZoom: 2,
		maxZoom: 22,
		updateWhenIdle: true,
		unloadInvisibleTiles: true,
		attribution: 'Map data &copy; 2011 OpenStreetMap contributors, Rendering by <a href="http://github.com/kothic/kothic-js">Kothic JS</a>',
		async: true,
		buffered: true
	},
	
	initialize: function(options) {
		L.Util.setOptions(this, options);
		
		this._canvases = {};
		this._debugMessages = [];
		
		var layer = this;
		
		window.onKothicDataResponse = L.Util.bind(this._onKothicDataResponse, this);
	},

    saveToCache: function(canvas, zoom, x, y)
    {
        if ((typeof(fs) != 'undefined') && (typeof(window.requestFileSystem) != 'undefined'))
        {
            // we now have correct filesystem object to use for cache            

            fs.root.getFile(x + '_' + y + '_' + zoom + '.txt', {create: true}, function(fileEntry) {

            console.log('saving to cache: '+fileEntry.fullPath);

            // Create a FileWriter object for our FileEntry.
            fileEntry.createWriter(function(fileWriter) {

              fileWriter.seek(0); // Start write position at EOF.

              var bb = new BlobBuilder(); // Note: window.WebKitBlobBuilder in Chrome 12.
              bb.append(canvas.toDataURL("image/png"));

              fileWriter.write(bb.getBlob('text/plain'));

              bb = null;

              console.log('saved to cache: '+fileEntry.fullPath);

            }, errorHandler);

          }, errorHandler);

        }
    },
	
	_onKothicDataResponse: function(data, zoom, x, y) {

		var key = [zoom, x, y].join('/'),
			canvas = this._canvases[key],
			buffered = this.options.buffered,
			zoomOffset = this.options.zoomOffset,
			layer = this;

		function onRenderComplete(debugInfo) {

            layer.saveToCache(canvas, zoom, x, y);

			// TODO move this logic outside
			// var debugStr = layer.getDebugStr(debugInfo, x, y, zoom);
			// layer._debugMessages.push(debugStr);
            // temporary disable debug messages

			layer.tileDrawn(canvas);
		}
		
		Kothic.render(canvas, data, zoom + zoomOffset, layer._additionalStyle, onRenderComplete, buffered);

		delete this._canvases[key];
	},
	
	getDebugStr: function(debugInfo, x, y, zoom) {
		return '<b>tile ' + x + ':' + y + ':' + zoom + '</b><br />' +
			'<table><tr><td>' + debugInfo.layersStyled + ' ms</td><td>layers styled</td></tr>' +
			'<tr><td>' + debugInfo.mapRendered + ' ms</td><td>map rendered</td></tr>' +
			'<tr><td>' + debugInfo.iconsAndTextRendered + ' ms</td><td>icons/text rendered</td></tr>' +
			'<tr><td>' + debugInfo.total + ' ms</td><td>total</td></tr></table>';
	},
	
	getDebugMessages: function() {
		return this._debugMessages;
	},
	
	drawTile: function(canvas, tilePoint, zoom) {

        console.log('!!! '+Object.size(this._canvases));

		var zoomOffset = this.options.zoomOffset,
			key = [(zoom - zoomOffset), tilePoint.x, tilePoint.y].join('/'),
			path = '/' + [tilePoint.x, tilePoint.y, (zoom - zoomOffset)].join('_') + '.txt';

        console.log('seeking cache for: '+path);
		
        var url = 'http://2g0.ru/map/kothic/tileprxy.php?z=' + (zoom - zoomOffset) + '&x=' + tilePoint.x + '&y=' + tilePoint.y;
        var layer = this;

        if ((typeof(fs) != 'undefined') && (typeof(window.requestFileSystem) != 'undefined'))
        {
            fs.root.getFile(path, {}, function(fileEntry) {

                fileEntry.file(function(file) {
                    var reader = new FileReader();

                    reader.onloadend = function(e) {

                        var cached_img = new Image();
                        cached_img.src = this.result;

                        cached_img.onload = function () {
                            canvas.getContext('2d').drawImage(cached_img, 0, 0);
    	           		    layer.tileDrawn(canvas);

                            console.log('shown from cache: '+path);
                        }
                    };

                    reader.readAsText(file);
                }, function(e) {
                                    layer._canvases[key] = canvas;
                                    layer._loadScript(url);
                                    errorHandler(e);
                                    console.log('requesting from server: '+path);
                               } );

            }, function(e) {
                                layer._canvases[key] = canvas;
                                layer._loadScript(url);
                                errorHandler(e);
                                console.log('requesting from server: '+path);
                           } );
        } else {
            layer._canvases[key] = canvas;
            layer._loadScript(url);
        }
    },
	
	setAdditionalStyle: function(fn) {
		this._additionalStyle = fn;
		
		// TODO implement layer.redraw() in Leaflet
		if (this._map && this._map._container) {
			this._reset();
			this._update();
		}
	},
	
	_loadScript: function(url) {
		var script = document.createElement('script');
		script.src = url;
		script.charset = 'utf-8';
		document.getElementsByTagName('head')[0].appendChild(script);
	}
});