Subversion Repositories Projects

# Calculate tile characteristics given a bounding box of coordinates and a zoom...

# Author. John D. Coryat 01/2008...

# USNaviguide LLC.

# Published under Apache 2.0 license.

# Adapted from: Google Maps API Javascript...

##

# In order to correctly locate objects of interest on a Custom Map Overlay Google Maps, 

# the characteristics of each tile to build are required.

##

# Google_Tiles                                  # Calculate all tiles for a bounding box and zoom

# Google_Tile_Factors                           # Calculate the factors needed ( Zoom, Tilesize )

# Google_Tile_Calc                              # Calculate a single tile features from a tile name and zoom

# Google_Tile_to_Pix                            # Calculate tile name to pixel

# Google_Coord_to_Pix                           # Calculate coordinate to Pixel

# Google_Pix_to_Tile                            # Calculate a tile name from a pixel location and zoom

# Google_Pix_to_Coordinate                      # Calculate a coordinate from Pixel

require 5.003 ;

package libgemaps;

use strict ;

use Math::Trig ;

BEGIN {

 use Exporter ;

 use vars qw ( $VERSION @ISA @EXPORT) ;

 $VERSION       = 1.0 ;

 @ISA           = qw ( Exporter ) ;

 @EXPORT        = qw (

 Google_Tiles

 Google_Tile_Factors

 Google_Tile_Calc

 Google_Tile_to_Pix

 Google_Coord_to_Pix

 Google_Pix_to_Tile

 Google_Pix_to_Coordinate

 ) ;

}

#

# Call as: <array of Hashes> = &Google_Tiles(<LatitudeS>, <LongitudeW>, <LatitudeN>, <LongitudeE>, <Zoom>, [<option: tileSize>], [<option: Partial/Whole>]) ;

# Partial/Whole option: (Default: Partial)

#       Partial: Include the edge to create partial tiles

#       Whole: Include only tiles that are contained by the bounds

#

#          Returned Array Specifications:

#            Each element is a reference to a Hash:

#              NAMEY - Tile Name y

#              NAMEX - Tile Name x

#              PYS - Pixel South

#              PXW - Pixel West

#              PYN - Pixel North

#              PXE - Pixel East

#              LATS - South Latitude

#              LNGW - West Longitude

#              LATN - North Latitude

#              LNGE - East Longitude

#

#          Note: X is width, Y is height...

#

sub Google_Tiles

{

 my $latS       = shift ;

 my $lngW       = shift ;

 my $latN       = shift ;

 my $lngE       = shift ;

 my $zoom       = shift ;

 my $tileSize   = shift ;

 my $parwho     = shift ;

 my $ty         = 0 ;

 my $tx         = 0 ;

 my @ret        = ( ) ;

 my %first      = ( ) ;                         # First Results Hash

 my %last       = ( ) ;                         # Last Results Hash

 my $value      = &Google_Tile_Factors($zoom, $tileSize) ; # Calculate Tile Factors

 if (!defined($parwho) or !$parwho)

 {

  $parwho = 'Partial' ;

 }

 # NW: Convert Coordinates to Pixels...

 ($first{'NORTH'},$first{'WEST'}) = &Google_Coord_to_Pix( $value, $latN, $lngW ) ;

 # Convert Pixels to Tile Name...

 ($first{'NAMEY'},$first{'NAMEX'}) = &PixtoTileName( $value, $first{'NORTH'}, $first{'WEST'}, 'N', 'W', $parwho ) ;

 # SE: Convert Coordinates to Pixels...

 ($last{'SOUTH'},$last{'EAST'}) = &Google_Coord_to_Pix( $value, $latS, $lngE ) ;

 # Convert Pixels to Tile Name...

 ($last{'NAMEY'},$last{'NAMEX'}) = &PixtoTileName( $value, $last{'SOUTH'}, $last{'EAST'}, 'S', 'E', $parwho ) ;

 # Calculate tile values for all tiles...

 if ( $first{'NAMEX'} > $last{'NAMEX'} )                        # Across the date line

 {

  for ( $ty = $first{'NAMEY'} ; $ty <= $last{'NAMEY'} ; $ty++ )

  {

   for ( $tx = $first{'NAMEX'} ; $tx <= $$value{'max'} ; $tx++ )

   {

    push( @ret, {&Google_Tile_Calc( $value, $ty, $tx)} ) ;

   }

   for ( $tx = 0 ; $tx <= $last{'NAMEX'} ; $tx++ )

   {

    push( @ret, {&Google_Tile_Calc( $value, $ty, $tx)} ) ;

   }

  }

 } else

 {

  for ( $ty = $first{'NAMEY'} ; $ty <= $last{'NAMEY'} ; $ty++ )

  {

   for ( $tx = $first{'NAMEX'} ; $tx <= $last{'NAMEX'} ; $tx++ )

   {

    push( @ret, {&Google_Tile_Calc( $value, $ty, $tx)} ) ;

   }

  }

 }

 $ret[0]{'NORTH'} = $first{'NORTH'} ;

 $ret[0]{'WEST'} = $first{'WEST'} ;

 $ret[$#ret]{'SOUTH'} = $last{'SOUTH'} ;

 $ret[$#ret]{'EAST'} = $last{'EAST'} ;

 return ( @ret ) ;

}

# Calculate Tile Factors...

sub Google_Tile_Factors

{

 my $zoom       = shift ;

 my $tileSize   = shift ;

 my %value      = ( ) ;

 # Validate and correct input parameters...

 if ( !defined($zoom) or $zoom < 0 )

 {

  $zoom = 0 ;

 }

 if ( !defined($tileSize) or !$tileSize )

 {

  $tileSize     = 256 ;

 }

 # Calculate Values...

 $value{'zoom'} = $zoom ;

 $value{'PI'}   = 3.1415926536 ;

 $value{'bc'}   = 2 * $value{'PI'} ;

 $value{'Wa'}   = $value{'PI'} / 180 ;

 $value{'cp'}   = 2 ** ($value{'zoom'} + 8) ;

 $value{'max'}  = (2 ** $value{'zoom'}) - 1 ;           # Maximum Tile Number

 $value{'pixLngDeg'}= $value{'cp'} / 360;

 $value{'pixLngRad'}= $value{'cp'} / $value{'bc'} ;

 $value{'bmO'}  = $value{'cp'} / 2 ;

 $value{'tileSize'} = $tileSize ;

 return \%value ;

}

# Calculate tile values from Name...

sub Google_Tile_Calc

{

 my %result     = ( ) ;

 my $value      = shift ;

 $result{'NAMEY'} = shift ;

 $result{'NAMEX'} = shift ;

 # Convert Tile Name to Pixels...

 ($result{'PYN'},$result{'PXW'}) = &Google_Tile_to_Pix( $value, $result{'NAMEY'}, $result{'NAMEX'} ) ;

 # Convert Pixels to Coordinates (Upper Left Corner)...

 ($result{'LATN'},$result{'LNGW'}) = &Google_Pix_to_Coordinate( $value, $result{'PYN'}, $result{'PXW'} ) ;

 $result{'PYS'} = $result{'PYN'} + 255 ;

 $result{'PXE'} = $result{'PXW'} + 255 ;

 # Convert Pixels to Coordinates (Lower Right Corner)...

 ($result{'LATS'},$result{'LNGE'}) = &Google_Pix_to_Coordinate( $value, $result{'PYS'}, $result{'PXE'} ) ;

 return %result ;

}

# Calculate a tile name from a pixel location and zoom...

sub Google_Pix_to_Tile

{

 my $value      = shift ;

 my $ty         = shift ;

 my $tx         = shift ;

 # Convert Pixels to Tile Name...

 ($ty,$tx) = &PixtoTileName( $value, $ty, $tx, 'N', 'W', 'Partial' ) ;

 return ( $ty,$tx ) ;

}

# Translate a coordinate to a pixel location...

sub Google_Coord_to_Pix

{

 my $value      = shift ;

 my $lat        = shift ;

 my $lng        = shift ;

 my @d          = ( ) ;

 my $e          = 0 ;

 $d[1] = sprintf("%0.0f", $$value{'bmO'} + $lng * $$value{'pixLngDeg'} ) ;

 $e = sin($lat * $$value{'Wa'}) ;

 if( $e > 0.99999 )

 {

  $e = 0.99999 ;

 }

 if( $e < -0.99999 )

 {

  $e = -0.99999 ;

 }

 $d[0] = sprintf("%0.0f", $$value{'bmO'} + 0.5 * log((1 + $e) / (1 - $e)) * (-1) * $$value{'pixLngRad'} ) ;

 return (@d) ;

}

# Translate a pixel location to a tile name...

sub PixtoTileName

{

 my $value      = shift ;

 my $y          = shift ;

 my $x          = shift ;

 my $yd         = shift ;                               # Y Direction: N or S

 my $xd         = shift ;                               # X Direction: W or E

 my $parwho     = shift ;                               # Partial / Whole

 my $yn         = 0 ;                                   # Y Name

 my $xn         = 0 ;                                   # X Name

 $yn = int( $y / $$value{'tileSize'} ) ;                # Round Down

 $xn = int( $x / $$value{'tileSize'} ) ;                # Round Down

 if ( $parwho ne 'Partial' )

 {

  if ( $yd eq 'N' )

  {

   $yn++ ;

  } else

  {

   $yn-- ;

  }

  if ( $xd eq 'W' )

  {

   $xn++ ;

  } else

  {

   $xn-- ;

  }

 }

 # Make sure tile numbers are sane...

 if ( $yn > $$value{'max'} )

 {

  $yn = $$value{'max'} ;

 } elsif ( $yn < 0 )

 {

  $yn = 0 ;

 }

 if ( $xn > $$value{'max'} )

 {

  $xn = $$value{'max'} ;

 } elsif ( $xn < 0 )

 {

  $xn = 0 ;

 }

 return( $yn, $xn ) ;

}

# Translate a tile name to a pixel location...

sub Google_Tile_to_Pix

{

 my $value      = shift ;

 my $y          = shift ;

 my $x          = shift ;

 return( (sprintf("%0.0f", $y * $$value{'tileSize'} ), sprintf("%0.0f", $x * $$value{'tileSize'} )) ) ;

}

# Translate a pixel location to a coordinate...

sub Google_Pix_to_Coordinate

{

 my $value      = shift ;

 my $y          = shift ;

 my $x          = shift ;

 my @d          = ( ) ;

 my $e          = (($y - $$value{'bmO'}) / $$value{'pixLngRad'}) * (-1) ;

 $d[1]  = sprintf("%0.6f",($x - $$value{'bmO'}) / $$value{'pixLngDeg'}) ;

 $d[0]  = sprintf("%0.6f", (2 * atan(exp($e)) - $$value{'PI'} / 2) / $$value{'Wa'}) ;

 return (@d);

}

1;

__END__

=head1 SYNOPSIS

#!/usr/bin/perl -w

# Test Program:

# Google Tile Calculator Test Program...

# Author. John D. Coryat 01/2008 USNaviguide LLC

use strict;

use USNaviguide_Google_Tiles ;

my $latS        = 34.177442 ;

my $lngW        = -91.318359 ;

my $latN        = 35.797300 ;

my $lngE        = -88.681641 ;

my $zoom        = 8 ;

my $x           = '' ;

my %tile        = ( ) ;

my $i           = 0 ;

my @d = &Google_Tiles($latS, $lngW, $latN, $lngE, $zoom,0,'Whole');

print "Total: " . scalar(@d) . "\n" ;

for ( $i = 0; $i <= $#d; $i++ )

{

 print "Tile # $i Y: $d[$i]{'NAMEY'} X: $d[$i]{'NAMEX'}\n" ;

 %tile = %{$d[$i]} ;

 foreach $x (sort keys %tile)

 {

  print "\t$x: $tile{$x}\n" ;

 }

}

=cut