Lee ♫ Goddard > Image-Maps-Plot-FromLatLong-0.12 > Image::Maps::Plot::FromLatLong



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Image::Maps::Plot::FromLatLong - plots points on Mercator Projection world/regional map


        use Image::Maps::Plot::FromLatLong;

        # Get ready
        $m = new Image::Maps::Plot::FromLatLong (
                MAP=>"THE WORLD",
                PATH=>"C:/out.html",    # Extension is irrelevant

        # Now, Create an HTML page with images:
        # Or just the image
        # Or get a reference to an image blob:

        # Create HTML pages of all maps in the db, with index
        my $m = new Image::Maps::Plot::FromLatLong(

        # Add a map
        $Image::Maps::Plot::FromLatLong::MAPS{"LONDON AREA"} = {
                FILE => 'C:\PhotoWebServer\Perl\site\lib\Image\Maps\Plot\london_bourghs.jpg',
                DIM      => [650,640],
                SPOTSIZE => 5,
                ANCHOR_PIXELS => [447,397],             # Greenwich on the pixel map
                ANCHOR_LATLON => [51.466,0],    # Greenwich lat/lon
                ANCHOR_NAME       => 'Greenwich',
                ANCHOR_PLACE  => 'Observatory',
                ONEMILE         => 19.5,                        # 1 km = .6 miles  (10km=180px = 10miles=108px)

        # Add a user to the db
        $m->load_db (".earth.dat");
        $m->add_entry ('Ike Elben Goddard','Hungary','H-1165');
        $m->save_db (".aliyah.dat");

        # Create map content on the fly:
        $maker = new Image::Maps::Plot::FromLatLong(
                MAP     => "THE WORLD",
                PATH    => "/Two.foo",
                DBFILE  => undef,
                LOCATIONS => {
                  'Lee' => {
                         'LAT' => '51.592423',
                         'PLACE' => '#ffff44',
                         'LON' => '-0.171996'
                  'Lee Again' => {
                        'PLACE' => '#ffff77',
                        'LAT' => 46,
                        'LON' => 16



Plots points defined by latitude/longitude on JPEG Mercator Projection maps, optionally creating an HTML page with image map to display the image.



        WWW::MapBlast 0.02
        Image::Thumbnail 0.011


In addition to this file, the distribution uses the included files for default settings: they should be placed in the same directory as the module itself only if you wish to use default settings.





Returns an object in this class.

Accepts arguments in a hash, where keys/values are as follows:


Either THE WORLD, THE UK, A BAD MAP OF LONDON, or any other key to the %MAPS hash defined elsewhere, and documented below.


The path at which to save - will use the filename you supply, but please include an extension, coz I'm lazy. You will receive a .jpg and .html file in return.


Name of the configuration/db file - defaults to .earth.dat, which comes with the distribution: set to undef if you do not wish to use the default (perhaps because you are using the LOCATIONS field to supply a 'database' - see the next item).


Optional: a reference to a hash that will add and replace items in the module's content 'database'. Format of the hash referred to should be:

        $LOCATIONS = {
            'This key is a printable proper name' => {
        'LAT' => 11111111,      # Latitude value, or 11111111 if unknown
            'PLACE' => 'An Image;:Magick Colour Name or printable descriptor of the location',
            'LON' => 11111111   # Longitude value, or 11111111 if unknown

If PLACE fields are supplied as hex colour names (# prefix) then their values will not be printed.

Note that if you supply this field without supplying the DBFILE with a value of undef, you will inherit the default location 'database'.


If supplied, will be prefixed to the value of the IMG src attribute in HTML pages generated.


Set if you want rabbit (Amos: that's London-speak for talk) to STDERR.


Text output onto the image. Defaults to 'Created on <date> by <package>.';


Title text to include on the image (in bold) and as the content of the HTML page's TITLE element: is appended with the name of the map. This defaults to London.pm, where this module originates.


Font for the above: absolute path or something Image Magick can find.


Set if you wish the map's anchor point to be included in the output.


Filename prefix - added to the start of all files output except the db file. Default is m_.


If set, will assume the 'place' sub-keys in locations hash are colour values for spots printed.


Border and fill colours: if not set, SPOTCOLOUR will set them both.


Formatted inline CSS to go within a STYLE type='text/css' block in the header.


If defined, added at the end of the page.

METHOD create_html ^

Creates an image and an HTML page.

Requires that the PATH field be set (see CONSTRUCTOR).

METHOD create_imagefile ^

Creates just an image file.

Requires that the PATH field be set (see CONSTRUCTOR).

METHOD create_blob ^

Creates an image and return a reference to it's BLOB.

Requires that the PATH field be set (see CONSTRUCTOR).

METHOD all (base_path,base_url,title, blurb) ^

A method that produces all available maps, and an index page with thumbnails.

It accepts four arguments, a path at which files can be built, a filename prefix (see "new"), a title, and blurb to add beneath the list of hyperlinks to the maps.

If no base path is supplied, the PATH field is used.

An index page will be produced, linking to the following files for each map:

m_MAPNAME.jpg m_MAPNAME_t.jpg m_MAPNAME.html

where MAPNAME is ... the name of the map. The m_ prefix is held in the instance variable FNPREFIX. You may also wish to look at and adjust the instance variable CREATIONTXT.

METHOD load_db ^

A method that loads a "database" hash from the specified path.

Returns a true value on success, undef on failure.

METHOD save_db ^

A method that saves the currently loaded "database" hash to the filename specified as the only arguemnt.

Note tha tyou may want to load a db before saving.

Returns nothing, but does die on failure.

METHOD add_entry ^

A method that accepts: $name, $latitude, $longitude, maybe $place_or_colour

If an entry already exists for $name, will return undef unless the global scalar $ADDENTRY is set to it's default value of MULTIPLE, in which case $name will be appended with the time.

Does not save them to file - you must do that manually ("METHOD save_db"), but note that you may wish to load the db before adding to it and saving.

Incidentaly returns a reference to the new key.

See also "ADDING MAPS".

&remove_entry ^

A subroutine, not a method, that accepts the name field of the entry in the db, and returns 1 on success, undef if no such entry exists.


A future version may allow you to pass map data to the constructor. In the meantime, adding maps is not in itself a big deal, perl-wise. Add a new key to the %MAPS hash, with the value of an anonymous hash with the content listed below.


scalar file name of Mercator Projection map.


anon array of dimensions of map in pixels [x,y]. You could create DIM on the fly using Image::Magick, but there's probably no point, as you're almost certainly going to have to edit the map to align it with longitude and latitude (if you find a stock of public-domain maps that are already aligned, please drop the author a line).


scalar number for the size of the map-marker spots, in pixels


anon array of the pixel location of the arbitrary anchor pont [x,y]


anon array of the latitude/longitude of the arbitrary anchor pont [x,y]


scalar name of the anchor, when marked on map


scalar place name of the anchor, when marked on map


scalar representation of 1 mile in pixels


After http://www.mapblast.com/myblast/helpFaq.mb#2:

Zero degrees latitude is the equator, with the North pole at 90 degrees latitude and the South pole at -90 degrees latitude. one degree is approximately 69 miles. Greenwich, England is at 51.466 degrees north of the equator.

Zero degrees longitude goes through Greenwich, England. Again, Each 69 miles from this meridian represents approximately 1 degree of longitude. East/West is plus/minus respectively.

Actually, latitude and longitude vary depending upon the degree in hand: see The Compton Encyclopdedia for more information.


The exmaple map, london_postcodes.jpg, is inaccurate.

Whilst degrees of latitude are accurate to two decimal places, Degrees of longitude are taken to be 69 miles: this isn't quite right - see "NOTES ON LATITUDE AND LONGITUDE". This will be adjusted in a later version.

All images must be JPEGs - PNG or other support could easily be added.



Corrected a slight mis-positioning of points.

Replaced GD with Image::Magick as I was seeing terrible JPEG output with GD.

Replaced support for non-maintained Image::GD::Thumbnail with Image::Thumbnail; evaluate a require of this at run time rather than using the apparently still shakey pragmas.

Added methods to create just images and to return references to image blobs.


Don't remember.


Clean IMG path and double-header bugs


Added more documentation; escaping of href text


Added thumbnail images to index page


perl(1); Image::Magick (http://www.ImageMagick.org); File::Basename; Acme::Pony; Data::Dumper; WWW::MapBlast; Image::Thumbnail


Thanks to the London.pm group for their test data and insipration, to Leon for his patience with all that mess on the list, to Philip Newton for his frankly amazing knowledge of international postcodes.

Thanks also to the CIA, About.com, The University of Texas, and The Ordnance Survey for their public-domain maps.


Lee Goddard <lgoddard -at- cpan -point- org>


Copyright (C) Lee Goddard, 2001. All Rights Reserved.

This module is supplied and may be used under the same terms as Perl itself.

The public domain maps provided with this distribution are the property of their respective copyright holders.

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