swen100 / phpng-proj

A php extension for proj.4

phpng-proj6+

A php extension to be usable with PHP7+ and next generation of libProj (6+).

Installation

see INSTALL.md

API Functions

Basic API

resource proj_create(string definition); Create a Proj resource coordinate system object from the projection definition suitable for use with proj_create_crs_to_crs_from_pj(). Be aware: the definitions used for proj_create have then to be in form of "EPSG:xxx"!

resource proj_create_crs_to_crs(string srcCrs, string tgtCrs); Create a Proj resource coordinate system object from the source SRID and target SRID.

resource proj_create_crs_to_crs_from_pj(resource srcPj, resource tgtPj); Create a Proj resource coordinate system object from the source PROJ and target PROJ.

resource proj_area_create(); Create an area of use. Such an area of use is to be passed to proj_create_crs_to_crs() to specify the area of use for the choice of relevant coordinate operations.

void proj_area_set_bbox(resource area, float west_lon_degree, float south_lat_degree, float east_lon_degree, float north_lat_degree); Set the bounding box of the area of use. In the case of an area of use crossing the antimeridian (longitude +/- 180 degrees), west_lon_degree will be greater than east_lon_degree. Lon is in range of -180 to 180 degrees and lat is in range of -90 to 90 degrees.

array proj_transform_point(resource pj, mixed x, mixed y, mixed z); Transform the x/y/z points from the previously set coordinate systems (source, target) within projection. x, y and z can be double, int or a numeric string.

array proj_transform_string(resource pj, string xyz); Transform the x/y[/z] string from the previously set coordinate systems (source, target) within projection.

array proj_transform_array(resource pj, array xyz); Transform the x/y[/z] array from the previously set coordinate systems (source, target) within projection. The array can contain strings with x,y,z-values or also an array with x,y[,z]-values where x, y and z can be of type double, int or numeric string.

void proj_destroy(resource pj); Frees all resources associated with pj.

Advanced Functions

boolean proj_is_latlong(resource pj); Returns true if the output coordinate system is geographic (proj=latlong).

boolean proj_is_geocent(resource pj); Returns true if the output coordinate system is geocentric (proj=geocent).

string proj_get_def(resource pj); Returns the PROJ initialization string suitable for use with proj_create() that would produce this coordinate system, but with the definition expanded as much as possible (for instance +init= and +datum= definitions).

array proj_get_pj_info(resource pj); Returns an array with multiple informations about the projection object:

• id (short ID of the operation the PJ object is based on, that is, what comes after the +proj= in a proj-string, e.g. “merc”.)
• definition (long description of the operation the PJ object is based on, e.g. “Mercator Cyl, Sph&Ell lat_ts=”.)
• description (the proj-string that was used to create the PJ object with, e.g. “+proj=merc +lat_0=24 +lon_0=53 +ellps=WGS84”.)
• accuracy (expected accuracy of the transformation. -1 if unknown.)
• has_inverse (1 if an inverse mapping of the defined operation exists, otherwise 0.)

Environment Functions

string proj_get_errno_string(int); Returns the error text associated with the passed in error code.

int proj_get_errno(resource pj); Returns an integer value that can be used for the proj_errno_string(int) function.

array proj_get_info(); Returns an array with informations about the current PROJ library.

string proj_get_release(); Returns an internal string describing the release version.

array proj_list_units(); Returns an array of globally defined distance units.

array proj_list_ellps(); Returns an array of globally defined ellipsoids.

Code examples

<?php  
	$proj_wgs84 = "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
	$proj_merc = "+proj=merc +a=6378137 +b=6378137 +units=m +k=1.0 +nadgrids=@null +no_defs";
        $PROJ = proj_create_crs_to_crs($proj_wgs84, $proj_merc);
?>

example 1:

Transforming variables with x and y [and z] values.

<?php  
	if ($PROJ !== false) {  
	    $x = 11;
	    $y = 51;
	    $transformed = proj_transform_point($PROJ, $x, $y);
	    print 'latitude: '.$transformed['x'].'<br />';
	    print 'longitude: '.$transformed['y'].'<br />';
	}
?>

Output:

	latitude: 1224514.398726
	longitude: 6621293.7227402

example 2:

Transforming a string containing x,y[,z]-values.

<?php  
	if ($PROJ !== false) {
	    $coords = "11 51,11.5 51.5 20";
	    $transformed = proj_transform_string($PROJ, $coords);
	    print_r($transformed);
	}
?>

Output:

	Array
        (
            [0] => Array
                (
                    [x] => 1224514.398726
                    [y] => 6621293.7227402
                    [z] => 0
                )

            [1] => Array
                (
                    [x] => 1280174.1441226
                    [y] => 6710219.0832207
                    [z] => 20
                )

        )

example 3:

Transforming an array containing x,y[,z]-values as strings.

<?php  
	if ($PROJ !== false) {
	    $coords = ["11 51", "11.5 51.5 20"];
	    $transformed = proj_transform_array( $PROJ, $coords );
	    print_r($transformed);
	}
?>

Output:

	Array
	(
	    [0] => Array
	        (
	            [x] => 1224514.398726
	            [y] => 6621293.7227402
	            [z] => 0
	        )
	
	    [1] => Array
	        (
	            [x] => 1280174.1441226
	            [y] => 6710219.0832207
	            [z] => 20
	        )
	
	)

example 4:

Transforming an array containing x,y[,z]-values as arrays.

<?php  
	if ($PROJ !== false) {  
	    $coords = [[11, 51], [11.5, 51.5, 20]];
	    $transformed = proj_transform_array( $PROJ, $coords );
	    print_r($transformed);
	}
?>

Output:

	Array
	(
	    [0] => Array
	        (
	            [x] => 1224514.398726
	            [y] => 6621293.7227402
	            [z] => 0
	        )
	
	    [1] => Array
	        (
	            [x] => 1280174.1441226
	            [y] => 6710219.0832207
	            [z] => 20
	        )
	
	)