Articles Tricks And Hacks
Tricks And Hacks
GIS Mapping with PHP; Part Two - Page 4
by: Simon Moss
|
February 9, 2004
The import script is made up of two functions, LoadMIF and GetPolyString.
<?php
function LoadMIF($file)
{
//Loads MIF file into a set of arrays.
//Open the file
$hfile = fopen("$file", "r");
$polygons = array();
$in_data = false;
// Read through the file until we hit the end
while (!feof($hfile))
{
$line = strtoupper(fgets($hfile, 1024));
// You could do this with reg. expressions. I hate them. So there.
// The DATA tag tells us we have got past the header info
// and are into the vector data proper.
if(substr($line,0,4)=="DATA")
{
$in_data=true;
}
else if($in_data)
{
// Are we a LINE? NB we don't plot these in this article.
if(substr($line,0,4)=="LINE")
{
$array = explode(" ",$line);
$poly_info = array();
$poly_info["min_long"] = $long =
trim($array[1]);
$poly_info["min_lat"] = $lat = trim($array[2]);
$poly_info["max_long"] = $long_to
= trim($array[3]);
$poly_info["max_lat"] = $lat_to =
trim($array[4]);
$poly_info["vector_type"] = 1;
$poly_info["poly_count"] = 2;
$poly_info["poly_string"] = "$long
$lat $long_to $lat_to";
}
// Are we a PLINE ( poly-line: A hollow polygon )
else if(substr($line,0,5)=="PLINE")
{
$array = explode(" ",$line);
// Get all the points in this polygon
// The first word on the line always stores
// the number of points in the polygon
$poly_info = GetPolyString($hfile,$array[1]);
$poly_info["vector_type"] = 2;
}
// Are we a region ( a filled polygon )
else if(substr($line,0,6)=="REGION")
{
$line = fgets($hfile,
1024);
// Again, get all the points in this polygon
// The first line always stores the number of points in the polygon
$poly_info =
GetPolyString($hfile,$line);
$poly_info["vector_type"] = 3;
}
if(isset($poly_info))
{
$polygons[] = $poly_info;
unset($poly_info);
}
}
}
fclose($hfile);
return $polygons;
}
function GetPolyString($hfile,$poly_count)
{
$ret_vector = array();
$ret_vector["min_long"] = 9999999;
$ret_vector["min_lat"] = 9999999;
$ret_vector["max_long"] = -9999999;
$ret_vector["max_lat"] = -9999999;
$ret_vector["poly_string"] = "";
$ret_vector["poly_count"] = $poly_count;
// Loop though the coordinates
// Each line contains the long. and lats. coordinates
// delimited by a space.
for($i=0;$i<$ret_vector->poly_count;$i++)
{
$line = fgets($hfile, 1024);
$array = explode(" ",$line);
$long = $array[0];
$lat = $array[1];
$ret_vector["min_long"] = min($long,$ret_vector["min_long"]);
$ret_vector["min_lat"] = min($lat ,$ret_vector["min_lat"]);
$ret_vector["max_long"] = max($long,$ret_vector["max_long"]);
$ret_vector["max_lat"] = max($lat ,$ret_vector["max_lat"]);
if(!empty($ret_vector["poly_line"]))$ret_vector["poly_line"] .= " ";
$ret_vector["poly_line"] .= "$long $lat";
}
return $ret_vector;
}
?>
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