Class: RGeo::CoordSys::Proj4

Inherits:
Object
  • Object
show all
Defined in:
lib/rgeo/coord_sys/proj4.rb,
ext/proj4_c_impl/main.c

Overview

This is a Ruby wrapper around a Proj4 coordinate system. It represents a single geographic coordinate system, which may be a flat projection, a geocentric (3-dimensional) coordinate system, or a geographic (latitude-longitude) coordinate system.

Generally, these are used to define the projection for a Feature::Factory. You can then convert between coordinate systems by casting geometries between such factories using the :project option. You may also use this object directly to perform low-level coordinate transformations.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

._create(str, uses_radians) ⇒ Object 



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# File 'ext/proj4_c_impl/main.c', line 260

static VALUE cmethod_proj4_create(VALUE klass, VALUE str, VALUE uses_radians)
{
  VALUE result;
  RGeo_Proj4Data* data;

  result = Qnil;
  Check_Type(str, T_STRING);
  data = ALLOC(RGeo_Proj4Data);
  if (data) {
    data->pj = pj_init_plus(RSTRING_PTR(str));
    data->original_str = str;
    data->uses_radians = RTEST(uses_radians) ? 1 : 0;
    result = Data_Wrap_Struct(klass, mark_proj4_func, destroy_proj4_func, data);
  }
  return result;
}

._proj_version ⇒ Object 



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# File 'ext/proj4_c_impl/main.c', line 222

static VALUE cmethod_proj4_version(VALUE module)
{
  return INT2NUM(PJ_VERSION);
}

._transform_coords(from, to, x, y, z) ⇒ Object 



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# File 'ext/proj4_c_impl/main.c', line 228

static VALUE cmethod_proj4_transform(VALUE module, VALUE from, VALUE to, VALUE x, VALUE y, VALUE z)
{
  VALUE result;
  projPJ from_pj;
  projPJ to_pj;
  double xval, yval, zval;
  int err;

  result = Qnil;
  from_pj = RGEO_PROJ4_DATA_PTR(from)->pj;
  to_pj = RGEO_PROJ4_DATA_PTR(to)->pj;
  if (from_pj && to_pj) {
    xval = rb_num2dbl(x);
    yval = rb_num2dbl(y);
    zval = 0.0;
    if (!NIL_P(z)) {
      zval = rb_num2dbl(z);
    }
    err = pj_transform(from_pj, to_pj, 1, 1, &xval, &yval, NIL_P(z) ? NULL : &zval);
    if (!err && xval != HUGE_VAL && yval != HUGE_VAL && (NIL_P(z) || zval != HUGE_VAL)) {
      result = rb_ary_new2(NIL_P(z) ? 2 : 3);
      rb_ary_push(result, rb_float_new(xval));
      rb_ary_push(result, rb_float_new(yval));
      if (!NIL_P(z)) {
        rb_ary_push(result, rb_float_new(zval));
      }
    }
  }
  return result;
}

.create(defn_, opts_ = {}) ⇒ Object

Create a new Proj4 object, given a definition, which may be either a string or a hash. Returns nil if the given definition is invalid or Proj4 is not supported.

Recognized options include:

:radians

If set to true, then this proj4 will represent geographic (latitude/longitude) coordinates in radians rather than degrees. If this is a geographic coordinate system, then its units will be in radians. If this is a projected coordinate system, then its units will be unchanged, but any geographic coordinate system obtained using get_geographic will use radians as its units. If this is a geocentric or other type of coordinate system, this has no effect. Default is false. (That is all coordinates are in degrees by default.)



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# File 'lib/rgeo/coord_sys/proj4.rb', line 171

def create(defn_, opts_ = {})
  result_ = nil
  if supported?
    if defn_.is_a?(::Hash)
      defn_ = defn_.map { |k_, v_| v_ ? "+#{k_}=#{v_}" : "+#{k_}" }.join(" ")
    end
    unless defn_ =~ /^\s*\+/
      defn_ = defn_.sub(/^(\s*)/, '\1+').gsub(/(\s+)([^+\s])/, '\1+\2')
    end
    result_ = _create(defn_, opts_[:radians])
    result_ = nil unless result_._valid?
  end
  result_
end

.new(defn_, opts_ = {}) ⇒ Object

Create a new Proj4 object, given a definition, which may be either a string or a hash. Raises Error::UnsupportedOperation if the given definition is invalid or Proj4 is not supported.

Recognized options include:

:radians

If set to true, then this proj4 will represent geographic (latitude/longitude) coordinates in radians rather than degrees. If this is a geographic coordinate system, then its units will be in radians. If this is a projected coordinate system, then its units will be unchanged, but any geographic coordinate system obtained using get_geographic will use radians as its units. If this is a geocentric or other type of coordinate system, this has no effect. Default is false. (That is all coordinates are in degrees by default.)



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# File 'lib/rgeo/coord_sys/proj4.rb', line 203

def new(defn_, opts_ = {})
  result_ = create(defn_, opts_)
  unless result_
    raise Error::UnsupportedOperation, "Proj4 not supported in this installation"
  end
  result_
end

.supported? ⇒ Boolean

Returns true if Proj4 is supported in this installation. If this returns false, the other methods such as create will not work.

Returns:

  • (Boolean) 


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# File 'lib/rgeo/coord_sys/proj4.rb', line 144

def supported?
  respond_to?(:_create)
end

.transform(from_proj_, from_geometry_, to_proj_, to_factory_) ⇒ Object

Low-level geometry transform method. Transforms the given geometry between the given two projections. The resulting geometry is constructed using the to_factory. Any projections associated with the factories themselves are ignored.



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# File 'lib/rgeo/coord_sys/proj4.rb', line 235

def transform(from_proj_, from_geometry_, to_proj_, to_factory_)
  case from_geometry_
  when Feature::Point
    transform_point(from_proj_, from_geometry_, to_proj_, to_factory_)
  when Feature::Line
    to_factory_.line(from_geometry_.points.map { |p_| transform_point(from_proj_, p_, to_proj_, to_factory_) })
  when Feature::LinearRing
    transform_linear_ring(from_proj_, from_geometry_, to_proj_, to_factory_)
  when Feature::LineString
    to_factory_.line_string(from_geometry_.points.map { |p_| transform_point(from_proj_, p_, to_proj_, to_factory_) })
  when Feature::Polygon
    transform_polygon(from_proj_, from_geometry_, to_proj_, to_factory_)
  when Feature::MultiPoint
    to_factory_.multi_point(from_geometry_.map { |p_| transform_point(from_proj_, p_, to_proj_, to_factory_) })
  when Feature::MultiLineString
    to_factory_.multi_line_string(from_geometry_.map { |g_| transform(from_proj_, g_, to_proj_, to_factory_) })
  when Feature::MultiPolygon
    to_factory_.multi_polygon(from_geometry_.map { |p_| transform_polygon(from_proj_, p_, to_proj_, to_factory_) })
  when Feature::GeometryCollection
    to_factory_.collection(from_geometry_.map { |g_| transform(from_proj_, g_, to_proj_, to_factory_) })
  end
end

.transform_coords(from_proj_, to_proj_, x_, y_, z_ = nil) ⇒ Object

Low-level coordinate transform method. Transforms the given coordinate (x, y, [z]) from one proj4 coordinate system to another. Returns an array with either two or three elements.



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# File 'lib/rgeo/coord_sys/proj4.rb', line 216

def transform_coords(from_proj_, to_proj_, x_, y_, z_ = nil)
  if !from_proj_._radians? && from_proj_._geographic?
    x_ *= ImplHelper::Math::RADIANS_PER_DEGREE
    y_ *= ImplHelper::Math::RADIANS_PER_DEGREE
  end
  result_ = _transform_coords(from_proj_, to_proj_, x_, y_, z_)
  if result_ && !to_proj_._radians? && to_proj_._geographic?
    result_[0] *= ImplHelper::Math::DEGREES_PER_RADIAN
    result_[1] *= ImplHelper::Math::DEGREES_PER_RADIAN
  end
  result_
end

.version ⇒ Object

Returns the Proj library version as an integer (example: 493). TODO: return as string of the format “x.y.z”.



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# File 'lib/rgeo/coord_sys/proj4.rb', line 150

def version
  _proj_version
end

Instance Method Details

#_canonical_str ⇒ Object 



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# File 'ext/proj4_c_impl/main.c', line 169

static VALUE method_proj4_canonical_str(VALUE self)
{
  VALUE result;
  projPJ pj;
  char* str;

  result = Qnil;
  pj = RGEO_PROJ4_DATA_PTR(self)->pj;
  if (pj) {
    str = pj_get_def(pj, 0);
    if (str) {
      result = rb_str_new2(str);
      pj_dalloc(str);
    }
  }
  return result;
}

#_geocentric? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'ext/proj4_c_impl/main.c', line 202

static VALUE method_proj4_is_geocentric(VALUE self)
{
  VALUE result;
  projPJ pj;

  result = Qnil;
  pj = RGEO_PROJ4_DATA_PTR(self)->pj;
  if (pj) {
    result = pj_is_geocent(pj) ? Qtrue : Qfalse;
  }
  return result;
}

#_geographic? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'ext/proj4_c_impl/main.c', line 188

static VALUE method_proj4_is_geographic(VALUE self)
{
  VALUE result;
  projPJ pj;

  result = Qnil;
  pj = RGEO_PROJ4_DATA_PTR(self)->pj;
  if (pj) {
    result = pj_is_latlong(pj) ? Qtrue : Qfalse;
  }
  return result;
}

#_get_geographic ⇒ Object 



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# File 'ext/proj4_c_impl/main.c', line 138

static VALUE method_proj4_get_geographic(VALUE self)
{
  VALUE result;
  RGeo_Proj4Data* new_data;
  RGeo_Proj4Data* self_data;

  result = Qnil;
  new_data = ALLOC(RGeo_Proj4Data);
  if (new_data) {
    self_data = RGEO_PROJ4_DATA_PTR(self);
    new_data->pj = pj_latlong_from_proj(self_data->pj);
    new_data->original_str = Qnil;
    new_data->uses_radians = self_data->uses_radians;
    result = Data_Wrap_Struct(CLASS_OF(self), mark_proj4_func, destroy_proj4_func, new_data);
  }
  return result;
}

#_original_str ⇒ Object 



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# File 'ext/proj4_c_impl/main.c', line 157

static VALUE method_proj4_original_str(VALUE self)
{
  return RGEO_PROJ4_DATA_PTR(self)->original_str;
}

#_radians? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'ext/proj4_c_impl/main.c', line 163

static VALUE method_proj4_uses_radians(VALUE self)
{
  return RGEO_PROJ4_DATA_PTR(self)->uses_radians ? Qtrue : Qfalse;
}

#_set_value(str, uses_radians) ⇒ Object 



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# File 'ext/proj4_c_impl/main.c', line 113

static VALUE method_proj4_set_value(VALUE self, VALUE str, VALUE uses_radians)
{
  RGeo_Proj4Data* self_data;
  projPJ pj;

  Check_Type(str, T_STRING);

  // Clear out any existing value
  self_data = RGEO_PROJ4_DATA_PTR(self);
  pj = self_data->pj;
  if (pj) {
    pj_free(pj);
    self_data->pj = NULL;
    self_data->original_str = Qnil;
  }

  // Set new data
  self_data->pj = pj_init_plus(RSTRING_PTR(str));
  self_data->original_str = str;
  self_data->uses_radians = RTEST(uses_radians) ? 1 : 0;

  return self;
}

#_valid? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'ext/proj4_c_impl/main.c', line 216

static VALUE method_proj4_is_valid(VALUE self)
{
  return RGEO_PROJ4_DATA_PTR(self)->pj ? Qtrue : Qfalse;
}

#canonical_hash ⇒ Object

Returns the “canonical” hash definition for this coordinate system, as reported by Proj4. This may be slightly different from the definition used to construct this object.



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# File 'lib/rgeo/coord_sys/proj4.rb', line 92

def canonical_hash
  unless defined?(@canonical_hash)
    @canonical_hash = {}
    canonical_str.strip.split(/\s+/).each do |elem_|
      @canonical_hash[Regexp.last_match(1)] = Regexp.last_match(3) if elem_ =~ /^\+(\w+)(=(\S+))?$/
    end
  end
  @canonical_hash
end

#canonical_str ⇒ Object

Returns the “canonical” string definition for this coordinate system, as reported by Proj4. This may be slightly different from the definition used to construct this object.



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# File 'lib/rgeo/coord_sys/proj4.rb', line 78

def canonical_str
  unless defined?(@canonical_str)
    @canonical_str = _canonical_str
    if @canonical_str.respond_to?(:force_encoding)
      @canonical_str.force_encoding("US-ASCII")
    end
  end
  @canonical_str
end

#encode_with(coder_) ⇒ Object

Psych support



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# File 'lib/rgeo/coord_sys/proj4.rb', line 61

def encode_with(coder_) # :nodoc:
  coder_["proj4"] = original_str || canonical_str
  coder_["radians"] = radians?
end

#eql?(rhs_) ⇒ Boolean Also known as: ==

Returns true if this Proj4 is equivalent to the given Proj4.

Note: this tests for equivalence by comparing only the hash definitions of the Proj4 objects, and returning true if those definitions are equivalent. In some cases, this may still return false even if the actual coordinate systems are identical, since there are sometimes multiple ways to express a given coordinate system.

Returns:

  • (Boolean) 


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# File 'lib/rgeo/coord_sys/proj4.rb', line 44

def eql?(rhs_)
  rhs_.class == self.class && rhs_.canonical_hash == canonical_hash && rhs_._radians? == _radians?
end

#geocentric? ⇒ Boolean

Returns true if this Proj4 object is a geocentric (3dz) coordinate system.

Returns:

  • (Boolean) 


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# File 'lib/rgeo/coord_sys/proj4.rb', line 120

def geocentric?
  _geocentric?
end

#geographic? ⇒ Boolean

Returns true if this Proj4 object is a geographic (lat-long) coordinate system.

Returns:

  • (Boolean) 


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# File 'lib/rgeo/coord_sys/proj4.rb', line 113

def geographic?
  _geographic?
end

#get_geographic ⇒ Object

Get the geographic (unprojected lat-long) coordinate system corresponding to this coordinate system; i.e. the one that uses the same ellipsoid and datum.



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# File 'lib/rgeo/coord_sys/proj4.rb', line 135

def get_geographic
  _get_geographic
end

#hash ⇒ Object

:nodoc:



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# File 'lib/rgeo/coord_sys/proj4.rb', line 31

def hash  # :nodoc:
  @hash ||= canonical_hash.hash
end

#init_with(coder_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/coord_sys/proj4.rb', line 66

def init_with(coder_) # :nodoc:
  if coder_.type == :scalar
    _set_value(coder_.scalar, false)
  else
    _set_value(coder_["proj4"], coder_["radians"])
  end
end

#initialize_copy(orig) ⇒ Object 



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# File 'ext/proj4_c_impl/main.c', line 80

static VALUE method_proj4_initialize_copy(VALUE self, VALUE orig)
{
  RGeo_Proj4Data* self_data;
  projPJ pj;
  RGeo_Proj4Data* orig_data;
  char* str;

  // Clear out any existing value
  self_data = RGEO_PROJ4_DATA_PTR(self);
  pj = self_data->pj;
  if (pj) {
    pj_free(pj);
    self_data->pj = NULL;
    self_data->original_str = Qnil;
  }

  // Copy value from orig
  orig_data = RGEO_PROJ4_DATA_PTR(orig);
  if (!NIL_P(orig_data->original_str)) {
    self_data->pj = pj_init_plus(RSTRING_PTR(orig_data->original_str));
  }
  else {
    str = pj_get_def(orig_data->pj, 0);
    self_data->pj = pj_init_plus(str);
    pj_dalloc(str);
  }
  self_data->original_str = orig_data->original_str;
  self_data->uses_radians = orig_data->uses_radians;

  return self;
}

#inspect ⇒ Object

:nodoc:



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# File 'lib/rgeo/coord_sys/proj4.rb', line 23

def inspect # :nodoc:
  "#<#{self.class}:0x#{object_id.to_s(16)} #{canonical_str.inspect}>"
end

#marshal_dump ⇒ Object

Marshal support



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# File 'lib/rgeo/coord_sys/proj4.rb', line 51

def marshal_dump # :nodoc:
  { "rad" => radians?, "str" => original_str || canonical_str }
end

#marshal_load(data_) ⇒ Object

:nodoc:



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# File 'lib/rgeo/coord_sys/proj4.rb', line 55

def marshal_load(data_) # :nodoc:
  _set_value(data_["str"], data_["rad"])
end

#original_str ⇒ Object

Returns the string definition originally used to construct this object. Returns nil if this object wasn’t created by a string definition; i.e. if it was created using get_geographic.



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# File 'lib/rgeo/coord_sys/proj4.rb', line 106

def original_str
  _original_str
end

#radians? ⇒ Boolean

Returns true if this Proj4 object uses radians rather than degrees if it is a geographic coordinate system.

Returns:

  • (Boolean) 


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# File 'lib/rgeo/coord_sys/proj4.rb', line 127

def radians?
  _radians?
end

#to_s ⇒ Object

:nodoc:



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# File 'lib/rgeo/coord_sys/proj4.rb', line 27

def to_s  # :nodoc:
  canonical_str
end