Fortran 2003 interface to the shapelib http://shapelib.maptools.org/ library. More...

Data Types
interface	dbfreadattribute
	Interface to SUBROUTINEs for reading dbf attributes. More...

interface	dbfwriteattribute
	Interface to FUNCTIONs for setting dbf attributes. More...

type	shpfileobject
	Object describing a shapefile dataset. More...

type	shpobject
	Object describing the geometrical properties of a shape. More...

Functions/Subroutines
type(shpfileobject) function, public	shpopen (pszshapefile, pszaccess)
	It tries to open the files composing a shapefile dataset. More...

logical function, public	shpfileisnull (hshp)
	It returns .TRUE. More...

logical function, public	dbffileisnull (hshp)
	It returns .TRUE. More...

type(shpfileobject) function, public	shpcreate (pszshapefile, nshapetype)
	It creates a new, empty set of files composing a shapefile dataset. More...

subroutine, public	shpgetinfo (hshp, nentities, shapetype, minbound, maxbound, dbffieldcount, dbfrecordcount)
	It gets information about the shapefile database, including dbf. More...

type(shpobject) function, target, public	shpreadobject (hshp, ishape)
	It reads a single shape from a shapefile. More...

logical function, public	shpisnull (psobject)
	It returns .TRUE. More...

subroutine, public	shpclose (hshp)
	It closes all the files associated with the shapefile dataset. More...

type(shpobject) function, target, public	shpcreatesimpleobject (nshptype, nvertices, padfx, padfy, padfz)
	It creates a new shape object, simple version. More...

type(shpobject) function, target, public	shpcreateobject (nshptype, ishape, nparts, panpartstart, panparttype, nvertices, padfx, padfy, padfz, padfm)
	It creates a new shape object, full version. More...

subroutine, public	shpcomputeextents (psobject)
	It recomputes the extents of a shape. More...

integer function, public	shpwriteobject (hshp, ishape, psobject)
	It writes a shape object to a file. More...

subroutine, public	shpdestroyobject (psobject)
	It destroys a shape object for subsequent reuse or when not used anymore. More...

integer function, public	dbfgetfieldindex (hshp, pszfieldname)
	It returns the index of the field matching the name. More...

integer function, public	dbfgetfieldinfo (hshp, ifield, pszfieldname, pnwidth, pndecimals)
	It returns information about a dbf field. More...

integer function, public	dbfaddfield (hshp, pszfieldname, etype, nwidth, ndecimals)
	It adds a new field to an existing dataset. More...

logical function, public	dbfisattributenull (hshp, ishape, ifield)
	It returns .TRUE. More...

character(len=1) function, public	dbfgetnativefieldtype (hshp, ifield)
	It returns the dbf type code of the requested field. More...

Variables
integer, parameter, public	shpt_null = 0
	Series of constants for specifying type of new shape datasets with shpcreate, null shape. More...

integer, parameter, public	shpt_point = 1
	points More...

integer, parameter, public	shpt_arc = 3
	arcs (Polylines, possible in parts) More...

integer, parameter, public	shpt_polygon = 5
	polygons (possible in parts) More...

integer, parameter, public	shpt_multipoint = 8
	multiPoint (related points) More...

integer, parameter, public	shpt_pointz = 11
	3D (+ measure) points More...

integer, parameter, public	shpt_arcz = 13
	3D (+ measure) arcs More...

integer, parameter, public	shpt_polygonz = 15
	3D (+ measure) polygons More...

integer, parameter, public	shpt_multipointz = 18
	3D (+ measure) multiPoint More...

integer, parameter, public	shpt_pointm = 21
	2D + measure points More...

integer, parameter, public	shpt_arcm = 23
	2D + measure arcs More...

integer, parameter, public	shpt_polygonm = 25
	2D + measure polygons More...

integer, parameter, public	shpt_multipointm = 28
	2D + measure multiPoint More...

integer, parameter, public	shpt_multipatch = 31
	complex (TIN-like) with Z, and Measure More...

integer, parameter, public	ftstring = 0
	Series of constants for specifying dbf field type, fixed length string field. More...

integer, parameter, public	ftinteger = 1
	numeric field with no decimals More...

integer, parameter, public	ftdouble = 2
	numeric field with decimals More...

integer, parameter, public	ftlogical = 3
	LOGICAL field. More...

integer, parameter, public	ftinvalid = 4
	not a recognised field TYPE More...

Detailed Description

Fortran 2003 interface to the shapelib http://shapelib.maptools.org/ library.

This module defines an API which reflects the original shapelib C API with some modifications:

shpopen, shpcreate and shpclose functions act also on .dbf files
shpgetinfo accesses also .dbf information
the DBFRead*Attribute and DBWrite*Attribute are converted into two f90 interfaces called dbfreadattribute and dbwriteattribute respectively.

The module defines two derived types: shpfileobject associated to a shapefile dataset, and shpobject associated to a single shape within a dataset. Access to database (.dbf) information is done by accessing the file object only.

For an example of application of the shapelib module, please refer to the following test program, which creates a shapefile and successively reads it:

!    Copyright 2011 Davide Cesari <dcesari69 at gmail dot com>
!
!    This file is part of FortranGIS.
!
!    FortranGIS is free software: you can redistribute it and/or modify
!    it under the terms of the GNU Lesser General Public License as
!    published by the Free Software Foundation, either version 3 of the
!    License, or (at your option) any later version.
!
!    FortranGIS 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
!    Lesser General Public License for more details.
!
!    You should have received a copy of the GNU Lesser General Public
!    License along with FortranGIS.  If not, see
!    <http://www.gnu.org/licenses/>.
PROGRAM shapelib_test
use,INTRINSIC :: iso_c_binding
USE shapelib
IMPLICIT NONE
INTEGER,PARAMETER :: lencharattr=40, nshp=4, tshp=shpt_polygonz
TYPE(shpfileobject) :: shphandle
TYPE(shpobject) :: shpobj
INTEGER :: i, j
CHARACTER(len=1024) :: filename
INTEGER :: nshpr, tshpr, nfield, nrec, nd
REAL(kind=c_double) :: minbound(4), maxbound(4)
CHARACTER(len=lencharattr) :: charattrr
INTEGER :: intattrr
REAL(kind=c_double) :: doubleattrr
!CALL getarg(1,filename)
!IF (filename == '') THEN
!  PRINT'(A)','Usage: shape_test <shp_file>'
!  STOP
!ENDIF
filename = 'testshape'
! ==== How to create a shapefile ====
! create a new shapefile object with data of type tshp (polygon)
! and associate it to a file, filename does not include extension
shphandle = shpcreate(trim(filename), tshp)
! error check
IF (shpfileisnull(shphandle) .OR. dbffileisnull(shphandle)) THEN
  print*,'Error opening ',trim(filename),' for writing'
  stop 1
ENDIF
! add 3 dbf field, of type character, integer and double respectively
j = dbfaddfield(shphandle, 'name', ftstring, lencharattr, 0)
IF (j /= 0) THEN
  print*,'Error in dbfaddfield',0,j
  stop 1
ENDIF
j = dbfaddfield(shphandle, 'number', ftinteger, 10, 0)
IF (j /= 1) THEN
  print*,'Error in dbfaddfield',1,j
  stop 1
ENDIF
j = dbfaddfield(shphandle, 'size', ftdouble, 30, 20)
IF (j /= 2) THEN
  print*,'Error in dbfaddfield',2,j
  stop 1
ENDIF
! add nshp shapes, of different lengths
DO i = 0, nshp - 1
  print*,'Creating shape',i
! create a shape object with the "simple" method
! for each shape 3 components are added x, y, z
! the type of shape has to be repeated here
! makesimpleshp() is an utility function returning an array
  shpobj = shpcreatesimpleobject(tshp, &
   SIZE(makesimpleshp(i, 0)), &
   makesimpleshp(i, 0), &
   makesimpleshp(i, 1), &
   makesimpleshp(i, 2))
! write the shape object to the shapefile object as i-th element
! -1 = append
  j = shpwriteobject(shphandle, -1, shpobj)
  IF (j /= i) THEN
    print*,'Error in shpwriteobject',i,j
    stop 1
  ENDIF
! destroy the shape object to avoid memory leaks
  CALL shpdestroyobject(shpobj)
! write the 3 dbf attributes of different types for the i-th shape
! object to the shapefile object
! makechardbf(), makeintdbf() and makedoubledbf() are utility functions
! returning an attribute of the proper type
  j = dbfwriteattribute(shphandle, i, 0, makechardbf(i))
  IF (j /= 1) THEN
    print*,'Error in dbfwriteattribute, char',j
    stop 1
  ENDIF
  j = dbfwriteattribute(shphandle, i, 1, makeintdbf(i))
  IF (j /= 1) THEN
    print*,'Error in dbfwriteattribute, int',j
    stop 1
  ENDIF
  j = dbfwriteattribute(shphandle, i, 2, makedoubledbf(i))
  IF (j /= 1) THEN
    print*,'Warning in dbfwriteattribute, double',j
  ENDIF
ENDDO
! close the shapefile object
CALL shpclose(shphandle)
! ==== How to read a shapefile ====
! open an exixting shapefile and associate it to a shapefile object
! filename does not include extension
shphandle = shpopen(trim(filename), 'rb')
! error check
IF (shpfileisnull(shphandle) .OR. dbffileisnull(shphandle)) THEN
  print*,'Error opening ',trim(filename),' for reading'
  stop 1
ENDIF
! get general information about the shapefile object
CALL shpgetinfo(shphandle, nshpr, tshpr, minbound, maxbound, nfield, nrec)
IF (nshpr /= nshp) THEN
  print*,'Error in shpgetinfo, wrong number of shapes',nshp,nshpr
  stop 1
ENDIF
IF (tshpr /= tshp) THEN
  print*,'Error in shpgetinfo, wrong type of shapes',tshp,tshpr
  stop 1
ENDIF
IF (nfield /= 3) THEN
  print*,'Error in shpgetinfo, wrong number of fields',3,nfield
  stop 1
ENDIF
IF (nrec /= nshp) THEN
  print*,'Error in shpgetinfo, wrong number of records',nshp,nrec
  stop 1
ENDIF
! read the nshp shapes
DO i = 0, nshp - 1
  print*,'Checking shape',i
! read the i-th shape from the shapefile object and obtain a shape object
  shpobj = shpreadobject(shphandle, i)
! error check
  IF (shpisnull(shpobj)) THEN
    print*,'Error in shpreadobject',i
    stop 1
  ENDIF
! now access all the components of the shape object
! number of vertices
  IF (shpobj%nvertices /= SIZE(makesimpleshp(i,0))) THEN
    print*,'Error in shpreadobject, wrong number of vertices',i,&
     SIZE(makesimpleshp(i,0)),shpobj%nvertices
    stop 1
  ENDIF
! x shape data
  IF (any(shpobj%padfx(:) /= makesimpleshp(i,0))) THEN
    print*,'Error in shpreadobject, discrepancies in x',i
    print*,makesimpleshp(i,0)
    print*,shpobj%padfx(:)
    stop 1
  ENDIF
! y shape data
  IF (any(shpobj%padfy(:) /= makesimpleshp(i,1))) THEN
    print*,'Error in shpreadobject, discrepancies in y',i
    print*,makesimpleshp(i,1)
    print*,shpobj%padfy(:)
    stop 1
  ENDIF
! z shape data
  IF (any(shpobj%padfz(:) /= makesimpleshp(i,2))) THEN
    print*,'Error in shpreadobject, discrepancies in z',i
    print*,makesimpleshp(i,2)
    print*,shpobj%padfz(:)
    stop 1
  ENDIF
! destroy the shape object to avoid memory leaks
! notice that for accessing dbf attributes the shape object is not required
  CALL shpdestroyobject(shpobj)
! get the dbf attributes for the i-th shape in the shapefile object
! first field (character)
  CALL dbfreadattribute(shphandle, i, 0, charattrr)
  IF (charattrr /= makechardbf(i)) THEN
    print*,'Error in dbfreadattribute, discrepancies in char'
    print*,makechardbf(i)
    print*,charattrr
    stop 1
  ENDIF
! second field (integer)
  CALL dbfreadattribute(shphandle, i, 1, intattrr)
  IF (intattrr /= makeintdbf(i)) THEN
    print*,'Error in dbfreadattribute, discrepancies in int'
    print*,makeintdbf(i)
    print*,intattrr
    stop 1
  ENDIF
! third field (double)
  CALL dbfreadattribute(shphandle, i, 2, doubleattrr)
  IF (doubleattrr /= makedoubledbf(i)) THEN
! here discreapancies are tolerated
    print*,'Warning in dbfreadattribute, discrepancies in double'
    print*,makedoubledbf(i)
    print*,doubleattrr
  ENDIF
ENDDO
! close the shapefile object
CALL shpclose(shphandle)
CONTAINS
! Functions for generating predictable shp and dbf values
FUNCTION makesimpleshp(nshp, ncoord) RESULT(shp)
INTEGER,INTENT(in) :: nshp, ncoord
REAL(kind=c_double) :: shp(nshp+2)
INTEGER :: i
shp(:) = (/(-100.0_c_double + &
 10.0_c_double*i + 100.0_c_double*nshp + 1000.0_c_double*ncoord, &
 i=1, SIZE(shp))/)
END FUNCTION makesimpleshp
FUNCTION makechardbf(nshp) RESULT(dbf)
INTEGER,INTENT(in) :: nshp
CHARACTER(len=lencharattr) :: dbf
INTEGER :: i
DO i = 1, len(dbf)
  dbf(i:i) = char(32 + mod(i+2*nshp,32))
ENDDO
END FUNCTION makechardbf
FUNCTION makeintdbf(nshp) RESULT(dbf)
INTEGER,INTENT(in) :: nshp
INTEGER :: dbf
dbf = -118 + 47*nshp
END FUNCTION makeintdbf
FUNCTION makedoubledbf(nshp) RESULT(dbf)
INTEGER,INTENT(in) :: nshp
REAL(kind=c_double) :: dbf
dbf = -5.894823e+12_c_double + 8.4827943e+11*nshp
END FUNCTION makedoubledbf
END PROGRAM shapelib_test

Data Types

Functions/Subroutines

Variables

Detailed Description