How to read map tile images from database stored locally into google earth plugin using just javascript/html5?

Question

I have an SQLite database with coordinates and tiled up map data/images that I can use to calculate corresponding LatLonBox elements for a GroundOverlay in a KMZ/KML for the Google Earth plugin. I can do the necessary query to determine what images go where on the plugin (aka I can create the GroundOverlay bounds correctly).

Problem: This is just an example use case, I'm not actually planning on using an OSM map tile - Let's say I downloaded this image:
OSM map tile http://otile1.mqcdn.com/tiles/1.0.0/osm/7/41/79.png

from -> http://otile1.mqcdn.com/tiles/1.0.0/osm/7/41/79.png

and put it into an sqlite database.

Let's say I then calculated the LatLonBox for that image and made a kml file via javascript:

var groundOverlay = ge.createGroundOverlay('');
groundOverlay.setIcon(ge.createIcon(''))
groundOverlay.getIcon().setHref("http://otile1.mqcdn.com/tiles/1.0.0/osm/7/41/79.png");
groundOverlay.setLatLonBox(ge.createLatLonBox(''));

var center = ge.getView().copyAsLookAt(ge.ALTITUDE_RELATIVE_TO_GROUND);
var north = -38.822591;
var south = -40.979898;
var east = -61.875;
var west = -64.6875;
var rotation = 0;
var latLonBox = groundOverlay.getLatLonBox();
latLonBox.setBox(north, south, east, west, rotation);

ge.getFeatures().appendChild(groundOverlay);

Example KML file:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
  <GroundOverlay>
    <name> 00</name>
    <Icon>
      <href>http://otile1.mqcdn.com/tiles/1.0.0/osm/7/41/79.png</href>
      <drawOrder>0</drawOrder>
    </Icon>
    <LatLonBox>
      <north>-38.822591</north>
      <south>-40.979898</south>
      <east>-61.875</east>
      <west>-64.6875</west>
      <rotation>0.0</rotation>
    </LatLonBox>
  </GroundOverlay>
</kml>

Except instead of the href element pointing to http://otile1.mqcdn.com/tiles/1.0.0/osm/7/41/79.png, I want it to point to the image in my database. It doesn't have to directly point to the image in the database, I can use javascript to get the specific image(s) of interest, but once I have the image data I am lost on what to do.

So I can access the sqlite database with the image of interest in it on my local filesystem via javascript/html5 and parse an almost complete KML file (missing the href element because I don't know how to get the correct href element).

Once I'm at this point, I don't know where to go. How would I display that image on the google earth plugin or is it even possible without hosting it on a server? Is it possible to use javascript to serve up those images (aka act like a server in the browser to link the images in the database to a specific href that can be referenced in a kml document)?

The third element from the answer here makes me think it MIGHT be possible, but since it wasn't tried and it was aimed at serving up a KML file rather than the href element inside the KML file, I have no idea if it even applies.

Can this be done solely with javascript or must the images be hosted somehow/somewhere?

Answer 1

"Can this be done solely with javascript or must the images be hosted..."

Yes, they must be hosted either locally or remotely, how can you possible serve them if they aren't?

The Kml <href> element must contain a link to a local or remote file that is accessible via HTTP or HTTPS.

"Is it possible to use javascript to serve up those images"

No, JavaScript is a client side language -it doesn't have access to the networking layer or local file system - it can't 'serve' anything.

You could always just set up a local server to do this, Windows comes with IIS built in for example.

It is fine to have the <href> element point to a local file via http, e.g. http://localhost/whatever.kml, https://127.0.0.1/images/foo.jpg, etc.