3

End goal is to be able to access a pouchdb of map tiles on phone off-line that has been synced from remote couchdb of map tiles. This will all be wrapped in Cordova.

  • Using ol3, I currently can pull the tiles from couchdb
  • Couchdb is synced with local pouchdb

Here is my working code for couchdb:

var bc_orm_trails_couchdbLayerXYZ = new ol.layer.Tile({
    source: new ol.source.XYZ({
        url: "http://127.0.0.1:5984/trail_tiles_nw/NWoriginMercator-{z}-{x}-{y}/tile"
    })
});

Using PouchDB-3.0.6, how do I request the tiles for the layer in ol3?

References:

Using tileUrlFunction to provide url to ol.source.XYZ:

var bc_orm_trails_pouchdbLayerXYZ = new ol.layer.Tile({
    source: new ol.source.XYZ({
        tileUrlFunction: (function (tileCoord, projection) {
            var deferred = new $.Deferred();
            //var docId = "NWoriginMercator-" + tileCoord.z + "-" + tileCoord.y + "-" + tileCoord.x;
            var docId = ["NWoriginMercator", tileCoord.z, tileCoord.y, tileCoord.x].join('-');
            db.getAttachment(docId, 'tile.png', function(err, response) {
                if (err && err.error == 'not_found') {
                    return;
                } else {
                    var blob = response;
                    var imgURL = URL.createObjectURL(blob);
                    deferred.resolve(imgURL);
                    URL.revokeObjectURL(imgURL);
                }
            });
            return deferred;
        })
    })
});

Error is:

GET http://localhost:8081/xxxxxxxxxx.cordova.app/www/[object%20Object] 404 (Not Found)
  • Revised code and included new error msg. Any input or questions appreciated. – user2898616 Oct 21 '14 at 2:13
2

Angus from OL3-dev group helped me on this. See: https://groups.google.com/forum/#!topic/ol3-dev/gd2OXsrKBTk

Here is the adapted code that finally worked.

var bc_orm_trails_pouchdbLayerXYZ = new ol.layer.Tile({
    extent: BC,
    source: new ol.source.XYZ({
        //adapted from: http://jsfiddle.net/gussy/LCNWC/
        tileLoadFunction: function (imageTile, src) {
            pouchTilesDB.getAttachment(src, 'tile', function (err, res) {
                if (err && err.error == 'not_found') return;
                if(!res) return;
                    imageTile.getImage().src = window.URL.createObjectURL(res);
            });
        },
        tileUrlFunction: function (coordinate, projection) {
            if (coordinate === null) return undefined;
            // OSM NW origin style URL
            var z = coordinate[0];
            var x = coordinate[1];
            var y = coordinate[2];
            var imgURL = ["NWoriginMercator", z, x, y].join('-');
            return imgURL;
        }
    })
});

Note: final issue I missed to make it work was: "attachment: true" for inline attachments when syncing to remote couchdb.

function pouchTilesDBSync() {
var opts = {
    //live: true,
    batch_size: 100,
    attachments: true
};
pouchTilesDB.replicate.from(remoteCouchdb, opts, syncError);
//var syncDom = document.getElementById('sync-wrapper');
//syncDom.setAttribute('data-sync-state', 'syncing');
}

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