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## Copyright (C) 2017-2022 Philip Nienhuis
##
## This program is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program. If not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {} {@var{gml} =} gmlread (@var{fname}, @var{dots})
## Read a .gml (Geographic Markup Language) file.
##
## gmlread only reads coordinates, no attributes.
##
## Required input argument @var{fname} is the name of a .gml file. If
## no other arguments are specified all features in the entire .gml file
## will be read.
##
## The following optional property/value pairs (all case-insensitive)
## can be specified to select only some feature types and/or features
## limited to a certain area:
##
## @itemize
## @item "FeatureType"
## (Just one "f" will do) Only read a certain feature type; the value
## can be one of "Points", "LineStrings" or "Polygons" (only the first
## three characters matter). Multiple feature types can be selected by
## specifying multiple FeatureType property/value pairs.
## @end item
##
## @item BoundingBox
## (just one "b" suffices) Only read features that lie entirely within
## a coordinate rectangle specified as a 2x2 matrix containing [minX minY;
## maxX maxY].
## @end item
## @end itemize
##
## In addition verbose output can be obtained by specifying the following
## property/value pair:
##
## @itemize
## @item Debug
## (a "d" will do) followed by a numeric value of 1 (or true) specifies
## verbose output; a numeric value of 0 (or false) suppresses verbose output.
## @end item
## @end itemize
##
## The output of gmlread comprises a struct containing up to three
## mapstructs (MultiPoint and/or Polyline and/or Polygon mapstructs),
## depending on optional featuretype selection.
##
## @seealso{shaperead}
## @end deftypefn
## Author: Philip Nienhuis <prnienhuis@users.sf.net>
## Created: 2017-03-06
function [gml] = gmlread (fname, varargin)
## FIXME Input validation
fid = fopen (fname, "r");
if (fid < 0)
error ("gmlread: file %s not found.\n", fname);
endif
## Process [property, value] options
idx = pol = [];
dbug = feat = ipt = iln = ipg = 0;
for ii=1:2:numel (varargin)
if (ischar (varargin{ii}) && numel (varargin{ii}) > 0 && mod (numel (varargin), 2) == 0)
switch lower (varargin{ii})(1)
case "f"
## Feature type. Keep track of whether this option was entered
feat = 1;
if (ischar (varargin{ii+1}))
switch lower (varargin{ii+1})(1:3)
case "poi"
ipt = 1;
case "lin"
iln = 1;
case "pol"
ipg = 1;
otherwise
error ("gmlread: unknown FeatureType '%s'", varargin{ii+1});
endswitch
else
error ("gmlread: illegal value for argument %d\n", ii+1);
endif
case "b"
## Bounding box
bbox = varargin{ii+1};
if (! isnumeric (idx) && size (bbox, 1) != 2 && size (bbox, 2) != 2)
error ("gmlread: numeric 2x2 matrix expected for arg.# %d\n", ii+1);
else
pol = [bbox(1, 1), bbox(2, 1), bbox(2, 1), bbox(1, 1), bbox(1, 1); ...
bbox(1, 2), bbox(1, 2), bbox(2, 2), bbox(2, 2), bbox(1, 2)];
endif
case ("d")
## Debug
dbug = varargin{ii+1} == 1;
otherwise
warning ("gmlread: unknown option '%s' - ignored\n", varargin{ii});
endswitch
else
error ("gmlread: wrong [property, value] options list");
endif
endfor
if (! feat)
ipt = iln = ipg = 1;
endif
if (dbug)
printf ("Reading %s ... ", fname);
endif
xml = fread (fid, 1000, "char=>char")';
## Skip header lines/-nodes
hdls = cell2mat (regexp (xml, '(<\?.*?\?>)|(<!.*?>)', "tokenExtents"));
spos = hdls(end);
## Start with outer content node
fseek (fid, spos+1, "bof");
xml = fread (fid, Inf, "char=>char")';
fclose (fid);
## Parse xml int 5xN cell array
ptrn = '<gml:((Point|LineString|Polygon)) .*?<gml:(coordinates|posList|pos).*?srsDimension="(\d)".*?>([\d\. ]*?)</gml:(coordinates|posList|pos)>';
feats = reshape (cell2mat (regexp (xml, ptrn, "tokens")), 5, []);
if (ipt)
if (dbug)
printf ("\nSearching Points ... ");
endif
ipt = find (strcmp (feats(1, :), "Point"));
if (dbug)
printf ("%d found.\n", numel (ipt));
endif
else
ipt = [];
endif
if (iln)
if (dbug)
printf ("Searching LineStrings ... ");
endif
iln = find (strcmp (feats(1, :), "LineString"));
if (dbug)
printf ("%d found.\n", numel (iln));
endif
else
iln = [];
endif
if (ipg)
if (dbug)
printf ("Searching Polygons ... ");
endif
ipg = find (strcmp (feats(1, :), "Polygon"));
if (dbug)
printf ("%d found.\n", numel (ipg));
endif
else
ipg = [];
endif
if (dbug)
printf ("Converting ....\n", numel (ipg));
endif
## Points
if (! isempty (ipt))
gmlpt = repmat (struct ("Geometry", "Multipoint", "X", NaN (1, 10), "Y",
NaN (1, 10), "BoundingBox", NaN (2, 2)), numel (ipt), 1);
jpt = 0;
for ii=1:numel (ipt)
if (dbug)
printf ("%d of %d Points ....\r", ii, numel (ipt));
endif
[xy, cnt] = sscanf (feats{4, ipt(ii)}, "%f");
dimsn = str2double (feats{3, ipt(ii)});
xy = reshape (xy, dimsn, []);
if (isempty (pol) || bbox <= 0 || all (inpolygon (xy(1, :), xy(2, :), pol(1, :), pol(2, :))))
++jpt;
gmlpt(jpt).X = xy(1, :);
gmlpt(jpt).Y = xy(2, :);
gmlpt(jpt).BoundingBox = [min(xy(1, :)), min(xy(2, :)); max(xy(1, :)), max(xy(2, :))];
if (dimsn >= 3)
gmlpt(jpt).Z = xy(3, :);
gmlpt(jpt).BoundingBox = [gmlpt(jpt).BoundingBox, [min(xy(3, :)); max(xy(3, :))]];
endif
endif
endfor
if (dbug)
printf ("\n");
endif
gml.Points = gmlpt(1:jpt);
endif
## LineStrings
if (! isempty (iln))
jpt = 0;
gmlpl = repmat (struct ("Geometry", "Polyline", "X", NaN (1, 15), "Y",
NaN (1, 15), "BoundingBox", NaN (2, 2)), numel (iln), 1);
for ii=1:numel (iln)
if (dbug)
printf ("%d of %d LineStrings ....\r", ii, numel (iln));
endif
[xy, cnt] = sscanf (feats{4, iln(ii)}, "%f");
dimsn = str2double (feats{3, iln(ii)});
xy = reshape (xy, dimsn, []);
if (isempty (pol) || all (inpolygon (xy(1, :), xy(2, :), pol(1, :), pol(2, :))))
++jpt;
gmlpl(jpt).X = xy(1, :);
gmlpl(jpt).Y = xy(2, :);
gmlpl(jpt).BoundingBox = [min(xy(1, :)), min(xy(2, :)); max(xy(1, :)), max(xy(2, :))];
if (dimsn >= 3)
gmlpl(jpt).Z = xy(3, :);
gmlpl(jpt).BoundingBox = [gmlpl(jpt).BoundingBox, [min(xy(3, :)); max(xy(3, :))]];
endif
endif
endfor
if (dbug)
printf ("\n");
endif
gml.Polylines = gmlpl(1:jpt);
endif
## Polygons
if (! isempty (ipg))
jpt = 0;
gmlpg = repmat (struct ("Geometry", "Polygon", "X", NaN (1, 20), "Y",
NaN (1, 20), "BoundingBox", NaN (2, 2)), numel (ipg), 1);
for ii=1:numel (ipg)
if (dbug)
printf ("%d of %d Polygons ....\r", ii, numel (ipg));
endif
[xy, cnt] = sscanf (feats{4, ipg(ii)}, "%f");
dimsn = str2double (feats{3, ipg(ii)});
xy = reshape (xy, dimsn, []);
if (isempty (pol) || all (inpolygon (xy(1, :), xy(2, :), pol(1, :), pol(2, :))))
++jpt;
gmlpg(jpt).X = xy(1, :);
gmlpg(jpt).Y = xy(2, :);
gmlpg(jpt).BoundingBox = [min(xy(1, :)), min(xy(2, :)); max(xy(1, :)), max(xy(2, :))];
if (dimsn >= 3)
gmlpg(jpt).Z = xy(3, :);
gmlpg(jpt).BoundingBox = [gmlpg(jpt).BoundingBox, [min(xy(3, :)); max(xy(3, :))]];
endif
endif
endfor
if (dbug)
printf ("\n");
endif
gml.Polygons = gmlpg(1:jpt);
endif
endfunction
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