libraries/pyshapelib/shapelibmodule.c

#include "pyshapelib_common.h"

/* --- SHPObject ----------------------------------------------------------------------------------------------------- */

typedef struct
{
        PyObject_HEAD
        SHPObject* shpObject;
}
SHPObjectObject;

enum {
        vtXY,
        vtXYM,
        vtXYZM,
        vtInvalid
} VertexType;

int determine_vertex_type(int shape_type, int* has_z, int* has_m)
{
        switch (shape_type)
        {
        case SHPT_POINT:
        case SHPT_ARC:
        case SHPT_POLYGON:
        case SHPT_MULTIPOINT:
                if (has_z) *has_z = 0;
                if (has_m) *has_m = 0;
                return vtXY;
        case SHPT_POINTM:
        case SHPT_ARCM:
        case SHPT_POLYGONM:
        case SHPT_MULTIPOINTM:
                if (has_z) *has_z = 0;
                if (has_m) *has_m = 1;
        case SHPT_POINTZ:
        case SHPT_ARCZ:
        case SHPT_POLYGONZ:
        case SHPT_MULTIPOINTZ:
        case SHPT_MULTIPATCH:
                if (has_z) *has_z = 1;
                if (has_m) *has_m = 1;
                return vtXYZM;
        default:
                if (has_z) *has_z = 0;
                if (has_m) *has_m = 0;
                return vtInvalid;
        }
}
        
/* allocator
 */
static PyObject* shpobject_new(PyTypeObject* type, PyObject* args, PyObject* kwds)
{
        SHPObjectObject* self;  
        self = (SHPObjectObject*) type->tp_alloc(type, 0);
        self->shpObject = NULL;
        return (PyObject*) self;
}

/* deallocator
 */
static void shpobject_dealloc(SHPObjectObject* self)
{
        SHPDestroyObject(self->shpObject);
        self->shpObject = NULL;
        self->ob_type->tp_free((PyObject*)self);
}

/* The constructor of SHPObject. parts is a list of lists of tuples
* describing the parts and their vertices just likethe output of the
* vertices() method. part_type_list is the list of part-types and may
* be NULL. For the meaning of the part-types and their default value
* see the Shaplib documentation.
*/
static int shpobject_init(SHPObjectObject* self, PyObject* args, PyObject* kwds)
{
        int type;
        int id;
        PyObject* parts = NULL; 
        PyObject* part_type_list = NULL;
        
        int num_parts;
        int num_vertices;
        int part_start;
        
        double* xs = NULL;
        double* ys = NULL;
        double* zs = NULL;
        double* ms = NULL;
        int* part_starts = NULL;
        int* part_types = NULL;
        
        PyObject* part;
        int vertex_type;
        int has_z;
        int has_m;
        
        int i;
        int ok, return_code = -1;
        
        /* first, unpack parameters */
        if (kwds != NULL && PyDict_Size(kwds) > 0)
        {
                PyErr_Format(PyExc_TypeError, "shapelib.SHPObject.__init__ takes no keyword arguments");
                return -1;
        }
        if (!PyArg_ParseTuple(args, "iiO|O:__init__", &type, &id, &parts, &part_type_list)) return -1;

        /* check parts */
        if (!PySequence_Check(parts))
        {
                PyErr_SetString(PyExc_TypeError, "parts is not a sequence");
                return -1;
        }
        num_parts = PySequence_Length(parts);
        if (num_parts < 0)
        {
                PyErr_SetString(PyExc_TypeError, "cannot determine length of parts");
                return -1;
        }
        
        /* parts and part_types have to have the same lengths */
        if (part_type_list == Py_None)
        {
                Py_DECREF(part_type_list);
                part_type_list = NULL;
        }
        if (part_type_list)
        {
                if (!PySequence_Check(parts))
                {
                        PyErr_SetString(PyExc_TypeError, "part_type_list is not a sequence");
                        return -1;
                }
                if (PySequence_Length(part_type_list) != num_parts)
                {
                        PyErr_SetString(PyExc_TypeError, "parts and part_types have to have the same lengths");
                        return -1;
                }
        }

        /* determine how many vertices there are altogether */
        num_vertices = 0;
        for (i = 0; i < num_parts; ++i)
        {
                PyObject* part = PySequence_ITEM(parts, i);
                if (!PySequence_Check(part))
                {
                        PyErr_SetString(PyExc_TypeError, "at least one item in parts is not a sequence");
                        Py_DECREF(part);
                        return -1;
                }
                num_vertices += PySequence_Length(part);
                Py_DECREF(part);
        }
        
        
        vertex_type = determine_vertex_type(type, &has_z, &has_m);

        /* allocate the memory for the various arrays and check for memory errors */
        xs = malloc(num_vertices * sizeof(double));
        ys = malloc(num_vertices * sizeof(double));
        zs = has_z ? malloc(num_vertices * sizeof(double)) : NULL;
        ms = has_m ? malloc(num_vertices * sizeof(double)) : NULL;
        part_starts = malloc(num_parts * sizeof(int));
        part_types = part_type_list ? malloc(num_parts * sizeof(int)) : 0;

        if (!xs || !ys || (has_z && !zs) || (has_m && !ms) || !part_starts || (part_type_list && !part_types))
        {
                PyErr_NoMemory();
                goto exit;
        }

        /* convert the part types */
        if (part_type_list)
        {
                for (i = 0; i < num_parts; i++)
                {
                        PyObject* otype = PySequence_ITEM(part_type_list, i);
                        part_types[i] = PyInt_AsLong(otype);
                        Py_DECREF(otype);
                        if (part_types[i] < 0)
                        {
                                PyErr_SetString(PyExc_TypeError, "at least one item in part_type_list is not an integer or is negative");
                                goto exit;
                        }
                }
        }

        /* convert the list of parts */
        part_start = 0;
        for (i = 0; i < num_parts; ++i)
        {
                int j, length;
                
                part = PySequence_ITEM(parts, i);
                length = PySequence_Length(part);
                if (length < 0) goto exit;
                part_starts[i] = part_start;

                for (j = 0; j < length; ++j)
                {
                        PyObject* vertex = PySequence_ITEM(part, j);
                        switch (vertex_type)
                        {
                        case vtXY:
                                ok = PyArg_ParseTuple(vertex, "dd:__init__", xs + part_start + j, ys + part_start + j);
                                break;
                        case vtXYM:
                                ok = PyArg_ParseTuple(vertex, "ddd:__init__", xs + part_start + j, ys + part_start + j, ms + part_start + j);
                                break;
                        case vtXYZM:
                                ms[part_start + j] = 0.;
                                ok = PyArg_ParseTuple(vertex, "ddd|d:__init__", xs + part_start + j, ys + part_start + j, zs + part_start + j,
                                        ms + part_start + j);
                                break;
                        }
                        Py_DECREF(vertex);
                        if (!ok)
                        {
                                PyErr_SetString(PyExc_TypeError, "at least one vertex is of the wrong format");
                                goto exit;
                        }
                }
                Py_DECREF(part);
                part = NULL;
                part_start += length;
        }

        self->shpObject = SHPCreateObject(type, id, num_parts, part_starts, part_types, num_vertices, xs, ys, zs, ms);
        return_code = 0;
        
exit:
        Py_XDECREF(part);
        free(xs);
        free(ys);
        free(zs);
        free(ms);
        free(part_starts);
        free(part_types);
        return return_code;
}

/*
* The extents() method of SHPObject.
*
* Return the extents as a tuple of two 4-element lists with the min.
* and max. values of x, y, z, m.
*/
static PyObject* shpobject_extents(SHPObjectObject* self)
{
        SHPObject* object = self->shpObject;
        return Py_BuildValue("(dddd)(dddd)",
                        object->dfXMin, object->dfYMin, object->dfZMin, object->dfMMin, 
                        object->dfXMax, object->dfYMax, object->dfZMax, object->dfMMax);
}


/*
* The vertices() method of SHPObject.
*
* Return the x and y coords of the vertices as a list of lists of
* tuples.
*/

static PyObject* build_vertex_list(SHPObject *object, int index, int length, int vertex_type);

static PyObject* shpobject_vertices(SHPObjectObject* self)
{
        PyObject *result = NULL;
        PyObject *part = NULL;
        int part_idx, vertex_idx;
        int length = 0;
        int vertex_type;
        
        SHPObject* object = self->shpObject;
        vertex_type = determine_vertex_type(object->nSHPType, NULL, NULL);

        if (object->nParts > 0)
        {
                /* A multipart shape. Usual for SHPT_ARC and SHPT_POLYGON */
        
                result = PyList_New(object->nParts);
                if (!result)
                        return NULL;

                for (part_idx = 0, vertex_idx = 0; part_idx < object->nParts; part_idx++)
                {
                        if (part_idx < object->nParts - 1)
                                length = (object->panPartStart[part_idx + 1]
                                        - object->panPartStart[part_idx]);
                        else
                                length = object->nVertices - object->panPartStart[part_idx];
                        
                        part = build_vertex_list(object, vertex_idx, length, vertex_type);
                        if (!part) goto fail;

                        if (PyList_SetItem(result, part_idx, part) < 0) goto fail;

                        vertex_idx += length;
                }
        }
        else
        {
                /* only one part. usual for SHPT_POINT */
                result = build_vertex_list(object, 0, object->nVertices, vertex_type);
        }

        return result;

fail:
        Py_XDECREF(part);
        Py_DECREF(result);
        return NULL;
}


/* Return the length coordinates of the shape object starting at vertex
* index as a Python-list of tuples. Helper function for
* SHPObject_vertices.
*/
static PyObject* build_vertex_list(SHPObject *object, int index, int length, int vertex_type)
{
        int i;
        PyObject * list;
        PyObject * vertex = NULL;

        list = PyList_New(length);
        if (!list)
                return NULL;

        for (i = 0; i < length; i++, index++)
        {
                switch (vertex_type)
                {
                case vtXY:
                        vertex = Py_BuildValue("dd", object->padfX[index], object->padfY[index]);
                        break;                  
                case vtXYM:
                        vertex = Py_BuildValue("ddd", object->padfX[index], object->padfY[index], 
                                object->padfM[index]);
                case vtXYZM:
                        vertex = Py_BuildValue("dddd", object->padfX[index], object->padfY[index], 
                                object->padfZ[index], object->padfM[index]);
                        break;                  
                default:
                        goto fail;
                }

                if (!vertex || PyList_SetItem(list, i, vertex) < 0) goto fail;
        }
        
        return list;

fail:
        Py_DECREF(list);
        return NULL;
}


static PyObject* shpobject_part_types(SHPObjectObject* self)
{
        int i;
        PyObject* result = NULL;
        SHPObject* object = self->shpObject;
        
        if (object->nParts == 0 || object->panPartType == 0)
        {
                Py_RETURN_NONE;
        }
        
        result = PyTuple_New(object->nParts);
        if (!result) return NULL;
        
        for (i = 0; i < object->nParts; ++i)
        {
                /* PyTuple_SetItem steals a reference */
                PyObject* part_type = PyInt_FromLong((long)object->panPartType[i]);
                if (!part_type || PyTuple_SetItem(result, i, part_type) < 0) goto fail;
        }       
        return result;
        
fail:
        Py_DECREF(result);
        return NULL;
}


static PyObject* shpobject_type(SHPObjectObject* self, void* closure)
{
        return PyInt_FromLong(self->shpObject->nSHPType);
}


static PyObject* shpobject_id(SHPObjectObject* self, void* closure)
{
        return PyInt_FromLong(self->shpObject->nShapeId);
}


/* return a string that can be feeded to eval() to reconstruct the object,
 * assuming a proper context
 */
static PyObject* shpobject_repr(SHPObjectObject* self)
{
        PyObject* format = NULL;
        PyObject* args = NULL;
        PyObject* result = NULL;
        
        format = PyString_FromString("shapelib.SHPObject(%i, %i, %s, %s)");
        if (!format) return NULL;

        args = Py_BuildValue("iiNN", 
                self->shpObject->nSHPType, 
                self->shpObject->nShapeId,
                shpobject_vertices(self), 
                shpobject_part_types(self));
        if (!args) 
        {
                Py_DECREF(format);
                return NULL;
        }
        
        result = PyString_Format(format, args);
        Py_DECREF(args);
        Py_DECREF(format);
        return result;
}


static struct PyMethodDef shpobject_methods[] = 
{
        {"extents", (PyCFunction)shpobject_extents, METH_NOARGS, 
                "extents()\n"
                "returns ((x_min, y_min, z_min, m_min), (x_max, y_max, z_max, m_max)), the 4D bounding box of the SHPObject"},
        {"vertices", (PyCFunction)shpobject_vertices, METH_NOARGS, 
                "vertices()\n"
                "returns [[(x, y, ...), ...], ...], a list of object parts, where each part is again a list of vertices.\n"
                "each vertex is a tuple of two to four doubles, depending on the object type."},
        {"part_types", (PyCFunction)shpobject_part_types, METH_NOARGS, 
                "part_types()\n"
                "returns a tuple of integers, each integer indicating the type of the corresponding part in vertices()"},
        {NULL}
};

static struct PyGetSetDef shpobject_getsetters[] = 
{
        {"type", (getter)shpobject_type, NULL, "type of the object (read-only)" },
        {"id", (getter)shpobject_id, NULL, "id of the object (read-only)" },
        {NULL}
};

static PyTypeObject SHPObjectType = PYSHAPELIB_DEFINE_TYPE(SHPObjectObject, shpobject, "shapelib.SHPObject", 0);


/* --- ShapeFile ----------------------------------------------------------------------------------------------------- */

typedef struct
{
        PyObject_HEAD
        SHPHandle handle;
}
ShapeFileObject;

/* allocator 
 */
static PyObject* shapefile_new(PyTypeObject* type, PyObject* args, PyObject* kwds)
{
        ShapeFileObject* self;  
        self = (ShapeFileObject*) type->tp_alloc(type, 0);
        self->handle = NULL;
        return (PyObject*) self;
}

/* destructor
*/
static void shapefile_dealloc(ShapeFileObject* self)
{
        SHPClose(self->handle);
        self->ob_type->tp_free((PyObject*)self);
}

/* constructor
 */
static int shapefile_init(ShapeFileObject* self, PyObject* args, PyObject* kwds)
{
        char* file;
        char* mode = "rb";
        if (kwds != NULL && PyDict_Size(kwds) > 0)
        {
                PyErr_Format(PyExc_TypeError, "shapelib.ShapeFile.__init__ takes no keyword arguments");
                return -1;
        }
        if (!PyArg_ParseTuple(args, "et|s:__init__", Py_FileSystemDefaultEncoding, &file, &mode)) return -1;
        
        self->handle = SHPOpen(file, mode);
        return self->handle ? 0 : -1;
}

static PyObject* shapefile_close(ShapeFileObject* self)
{
        SHPClose(self->handle);
        self->handle = NULL;
        Py_RETURN_NONE;
}

static PyObject* shapefile_info(ShapeFileObject* self)
{
        SHPHandle handle = self->handle;
        return Py_BuildValue("ii(dddd)(dddd)",
                        handle->nRecords, handle->nShapeType,
                        handle->adBoundsMin[0], handle->adBoundsMin[1], handle->adBoundsMin[2], handle->adBoundsMin[3],
                        handle->adBoundsMax[0], handle->adBoundsMax[1], handle->adBoundsMax[2], handle->adBoundsMax[3]);
}

static PyObject* shapefile_read_object(ShapeFileObject* self, PyObject* args)
{
        int index;
        SHPObject* object;
        SHPObjectObject* result;
        
        if (!PyArg_ParseTuple(args, "i:read_object", &index)) return NULL;
        
        object = SHPReadObject(self->handle, index);    
        if (!object)
        {
                PyErr_SetString(PyExc_RuntimeError, "failed to read object");
                return NULL;
        }
        
        result = PyObject_New(SHPObjectObject, &SHPObjectType);
        if (!result)
        {
                return PyErr_NoMemory();
        }
        
        result->shpObject = object;
        return (PyObject*) result;
}

static PyObject* shapefile_write_object(ShapeFileObject* self, PyObject* args)
{
        int index, result;
        PyObject* object;
        
        if (!PyArg_ParseTuple(args, "iO:write_object", &index, &object)) return NULL;
        
        if (!PyObject_IsInstance(object, (PyObject*)&SHPObjectType))
        {
                PyErr_SetString(PyExc_TypeError, "object is not a SHPObject");
                return NULL;
        }
        
        result = SHPWriteObject(self->handle, index, ((SHPObjectObject*)object)->shpObject);
        if (result < 0)
        {
                PyErr_SetString(PyExc_RuntimeError, "failed to write object");
                return NULL;
        }
        return PyInt_FromLong((long)result);
}

static PyObject* shapefile_cobject(ShapeFileObject* self)
{
        return PyCObject_FromVoidPtr(self->handle, NULL);
}

static PyObject* shapefile_repr(ShapeFileObject* self)
{
        /* TODO: it would be nice to do something like "shapelib.ShapeFile(filename, mode)" instead */
        return PyString_FromFormat("<shapelib.ShapeFile object at %p>", self->handle);
}

static struct PyMethodDef shapefile_methods[] = 
{
        {"close", (PyCFunction)shapefile_close, METH_NOARGS, 
                "close()\n"
                "close the shape file" },
        {"info", (PyCFunction)shapefile_info, METH_NOARGS,
                "info()\n"
                "returns (num_shapes, type, (x_min, y_min, z_min, m_min), (x_max, y_max, z_max, m_max)) with:\n"
                "-num_shapes: the number of the objects in the file\n"
                "-type: the type of the shape file (SHPT_POINT, SHPT_POLYGON, ...)\n"
                "-(x_min, y_min, z_min, m_min), (x_max, y_max, z_max, m_max): 4D bounding box of the data in the shape file" },
        {"read_object", (PyCFunction)shapefile_read_object, METH_VARARGS, 
                "read_object(id)\n"
                "Return object indexed by id" },
        {"write_object", (PyCFunction)shapefile_write_object, METH_VARARGS, 
                "write_object(id, object)\n"
                "Write an object at index id.\n"
                "If id == -1, the object is appended at the end of the shape file"},
        {"cobject", (PyCFunction)shapefile_cobject, METH_NOARGS, 
                "cobject()\n"
                "Return the shapelib SHPHandle as a Python CObject"},
        {NULL}
};

static struct PyGetSetDef shapefile_getsetters[] = 
{
        {NULL}
};

static PyTypeObject ShapeFileType = PYSHAPELIB_DEFINE_TYPE(ShapeFileObject, shapefile, "shapelib.ShapeFile", 0);

/* --- shapelib ------------------------------------------------------------------------------------------------------ */

static PyObject* shapelib_open(PyObject* module, PyObject* args)
{
        return PyObject_CallObject((PyObject*)&ShapeFileType, args);
}

static PyObject* shapelib_create(PyObject* module, PyObject* args)
{
        char* file;
        int type;
        ShapeFileObject* result;
        
        if (!PyArg_ParseTuple(args, "eti:create", Py_FileSystemDefaultEncoding, &file, &type)) return NULL;
        
        result = PyObject_New(ShapeFileObject, &ShapeFileType);
        if (!result)
        {
                return PyErr_NoMemory();
        }
        
        result->handle = SHPCreate(file, type);
        if (!result->handle)
        {
                PyObject_Del((PyObject*)result);
                PyErr_SetString(PyExc_RuntimeError, "Failed to create ShapeFile");
                return NULL;
        }
        
        return (PyObject*) result;
}
        
static PyShapeLibAPI shapelib_the_api = 
{
        SHPReadObject,
        SHPDestroyObject,
        SHPCreateTree,
        SHPDestroyTree,
        SHPTreeFindLikelyShapes
};

static PyObject* shapelib_c_api(PyObject* module) 
{
        return PyCObject_FromVoidPtr(&shapelib_the_api, NULL);
}

static PyObject* shapelib_type_name(PyObject* module, PyObject* args)
{
        int type;
        if (!PyArg_ParseTuple(args, "i:type_name", &type)) return NULL;
        return PyString_FromString(SHPTypeName(type));
}

static PyObject* shapelib_part_type_name(PyObject* module, PyObject* args)
{
        int type;
        if (!PyArg_ParseTuple(args, "i:part_type_name", &type)) return NULL;
        return PyString_FromString(SHPPartTypeName(type));
}

static struct PyMethodDef shapelib_methods[] = 
{
        {"open", (PyCFunction)shapelib_open, METH_VARARGS, 
                "open(filename [, mode='rb'])\n"
                "open a ShapeFile" },
        {"create", (PyCFunction)shapelib_create, METH_VARARGS, 
                "create(filename, type)\n"
                "create a ShapeFile of a certain type (one of SHPT_POINT, SHPT_POLYGON)" },
        {"c_api", (PyCFunction)shapelib_c_api, METH_NOARGS, 
                "c_api()\n"
                "get C API of shapelib" },
        {"type_name", (PyCFunction)shapelib_type_name, METH_VARARGS, 
                "type_name(type)\n"
                "return type as string" },
        {"part_type_name", (PyCFunction)shapelib_part_type_name, METH_VARARGS, 
                "part_type_name(part_type)\n"
                "return part type as string" },
        {NULL}
};

PyMODINIT_FUNC initshapelib(void)
{
        PyObject* module = Py_InitModule("shapelib", shapelib_methods);
        if (!module) return;
        
        PYSHAPELIB_ADD_TYPE(SHPObjectType, "SHPObject");
        PYSHAPELIB_ADD_TYPE(ShapeFileType, "ShapeFile");
        
        PYSHAPELIB_ADD_CONSTANT(SHPT_NULL);
        PYSHAPELIB_ADD_CONSTANT(SHPT_POINT);
        PYSHAPELIB_ADD_CONSTANT(SHPT_ARC);
        PYSHAPELIB_ADD_CONSTANT(SHPT_POLYGON);
        PYSHAPELIB_ADD_CONSTANT(SHPT_MULTIPOINT);
        PYSHAPELIB_ADD_CONSTANT(SHPT_POINTZ);
        PYSHAPELIB_ADD_CONSTANT(SHPT_ARCZ);
        PYSHAPELIB_ADD_CONSTANT(SHPT_POLYGONZ);
        PYSHAPELIB_ADD_CONSTANT(SHPT_MULTIPOINTZ);
        PYSHAPELIB_ADD_CONSTANT(SHPT_POINTM);
        PYSHAPELIB_ADD_CONSTANT(SHPT_ARCM);
        PYSHAPELIB_ADD_CONSTANT(SHPT_POLYGONM);
        PYSHAPELIB_ADD_CONSTANT(SHPT_MULTIPOINTM);
        PYSHAPELIB_ADD_CONSTANT(SHPT_MULTIPATCH);
        PYSHAPELIB_ADD_CONSTANT(SHPP_TRISTRIP);
        PYSHAPELIB_ADD_CONSTANT(SHPP_TRIFAN);
        PYSHAPELIB_ADD_CONSTANT(SHPP_OUTERRING);
        PYSHAPELIB_ADD_CONSTANT(SHPP_INNERRING);
        PYSHAPELIB_ADD_CONSTANT(SHPP_FIRSTRING);
        PYSHAPELIB_ADD_CONSTANT(SHPP_RING);
}

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