function openlayers_get_resolutions in Openlayers 6.2

Same name and namespace in other branches

1. 7.2 openlayers.module \openlayers_get_resolutions()

Get resolution given projection

Returns a default set of resolutions for standard TMS, WMS, etc servers serving up common projections. Layers supporting less common projections and resolutions can easily define custom resolutions arrays.

Parameters

$projection: String specifying which projection this should take, like 900913.

$zoom_start: Integer of first zoom level, default 0.

$zoom_end: Integer of last zoom level, default FALSE.

Return value

Array of resolutions.

10 calls to openlayers_get_resolutions()

openlayers_layer_type_google::options_init in includes/layer_types/google.inc

Provide initial values for options.

openlayers_layer_type_maptiler::options_form in includes/layer_types/maptiler.inc

Options form which generates layers

openlayers_layer_type_maptiler::options_init in includes/layer_types/maptiler.inc

Provide initial values for options.

openlayers_layer_type_osm::options_form in includes/layer_types/osm.inc

Options form which generates layers

openlayers_layer_type_osm::options_init in includes/layer_types/osm.inc

Provide initial values for options.

... See full list

File

./openlayers.module, line 794

Main OpenLayers API File

Code

function openlayers_get_resolutions($projection, $zoom_start = 0, $zoom_end = FALSE) {
  switch ($projection) {
    case '900913':

      // 16 zoom levels, taken from
      // openlayers.org TMS map
      $res = array(
        156543.0339,
        78271.51695,
        39135.758475,
        19567.8792375,
        9783.939618750001,
        4891.969809375,
        2445.9849046875,
        1222.99245234375,
        611.496226171875,
        305.7481130859375,
        152.87405654296876,
        76.43702827148438,
        38.21851413574219,
        19.109257067871095,
        9.554628533935547,
        4.777314266967774,
        2.388657133483887,
        1.1943285667419434,
        0.5971642833709717,
      );
      break;
    case '4326':

      // 16 zoom levels, taken from
      // openlayers.org default WMS map
      $res = array(
        0.703125,
        0.3515625,
        0.17578125,
        0.087890625,
        0.0439453125,
        0.02197265625,
        0.010986328125,
        0.0054931640625,
        0.00274658203125,
        0.001373291015625,
        0.0006866455078125,
        0.00034332275390625,
        0.000171661376953125,
        8.58306884765625E-5,
        4.291534423828125E-5,
        2.1457672119140625E-5,
      );
      break;
    default:
      $res = array();
      break;
  }
  $length = $zoom_end == FALSE ? NULL : $zoom_end - $zoom_start;

  // By default this will not actually clip the array
  $resolutions = array_slice($res, $zoom_start, $length);
  return $resolutions;
}