path.c

/*
 * The Python Imaging Library.
 *
 * 2D path utilities
 *
 * history:
 * 1996-11-04 fl   Added to PIL (incomplete)
 * 1996-11-05 fl   Added sequence semantics
 * 1997-02-28 fl   Fixed getbbox
 * 1997-06-12 fl   Added id attribute
 * 1997-06-14 fl   Added slicing and setitem
 * 1998-12-29 fl   Improved sequence handling (from Richard Jones)
 * 1999-01-10 fl   Fixed IndexError test for 1.5 (from Fred Drake)
 * 2000-10-12 fl   Added special cases for tuples and lists
 * 2002-10-27 fl   Added clipping boilerplate
 * 2004-09-19 fl   Added tolist(flat) variant
 * 2005-05-06 fl   Added buffer interface support to path constructor
 *
 * notes:
 * FIXME: fill in remaining slots in the sequence api
 *
 * Copyright (c) 1997-2005 by Secret Labs AB
 * Copyright (c) 1997-2005 by Fredrik Lundh
 *
 * See the README file for information on usage and redistribution.
 */


#include "Python.h"

#include <math.h>

#if PY_VERSION_HEX < 0x01060000
#define PyObject_New PyObject_NEW
#define PyObject_Del PyMem_DEL
#endif

#if PY_VERSION_HEX < 0x02050000
#define Py_ssize_t int
#define lenfunc inquiry
#define ssizeargfunc intargfunc
#define ssizessizeargfunc intintargfunc
#define ssizeobjargproc intobjargproc
#define ssizessizeobjargproc intintobjargproc
#endif

#include "py3.h"

/* compatibility wrappers (defined in _imaging.c) */
extern int PyImaging_CheckBuffer(PyObject* buffer);
extern int PyImaging_ReadBuffer(PyObject* buffer, const void** ptr);

/* -------------------------------------------------------------------- */
/* Class                                                                */
/* -------------------------------------------------------------------- */

typedef struct {
    PyObject_HEAD
    Py_ssize_t count;
    double *xy;
    int index; /* temporary use, e.g. in decimate */
} PyPathObject;

staticforward PyTypeObject PyPathType;

static double*
alloc_array(Py_ssize_t count)
{
    double* xy;
    if (count < 0) {
        PyErr_NoMemory();
        return NULL;
    }
    xy = malloc(2 * count * sizeof(double) + 1);
    if (!xy)
        PyErr_NoMemory();
    return xy;
}

static PyPathObject*
path_new(Py_ssize_t count, double* xy, int duplicate)
{
    PyPathObject *path;

    if (duplicate) {
        /* duplicate path */
        double* p = alloc_array(count);
        if (!p)
            return NULL;
        memcpy(p, xy, count * 2 * sizeof(double));
        xy = p;
    }

    path = PyObject_New(PyPathObject, &PyPathType);
    if (path == NULL)
        return NULL;

    path->count = count;
    path->xy = xy;

    return path;
}

static void
path_dealloc(PyPathObject* path)
{
    free(path->xy);
    PyObject_Del(path);
}

/* -------------------------------------------------------------------- */
/* Helpers                                                              */
/* -------------------------------------------------------------------- */

#ifdef PY3
#define PyPath_Check(op) (Py_TYPE(op) == &PyPathType)
#else
#define PyPath_Check(op) ((op)->ob_type == &PyPathType)
#endif

int
PyPath_Flatten(PyObject* data, double **pxy)
{
    int i, j, n;
    double *xy;

    if (PyPath_Check(data)) {
    /* This was another path object. */
    PyPathObject *path = (PyPathObject*) data;
        xy = alloc_array(path->count);
    if (!xy)
        return -1;
    memcpy(xy, path->xy, 2 * path->count * sizeof(double));
    *pxy = xy;
    return path->count;
    }
    
    if (PyImaging_CheckBuffer(data)) {
        /* Assume the buffer contains floats */
        float* ptr;
        int n = PyImaging_ReadBuffer(data, (const void**) &ptr);
        n /= 2 * sizeof(float);
        xy = alloc_array(n);
        if (!xy)
            return -1;
        for (i = 0; i < n+n; i++)
            xy[i] = ptr[i];
        *pxy = xy;
        return n;
    }

    if (!PySequence_Check(data)) {
    PyErr_SetString(PyExc_TypeError, "argument must be sequence");
    return -1;
    }

    j = 0;
    n = PyObject_Length(data);
    /* Just in case __len__ breaks (or doesn't exist) */
    if (PyErr_Occurred())
        return -1;

    /* Allocate for worst case */
    xy = alloc_array(n);
    if (!xy)
    return -1;

    /* Copy table to path array */
    if (PyList_Check(data)) {
        for (i = 0; i < n; i++) {
            double x, y;
            PyObject *op = PyList_GET_ITEM(data, i);
            if (PyFloat_Check(op))
        xy[j++] = PyFloat_AS_DOUBLE(op);
            else if (PyInt_Check(op))
        xy[j++] = (float) PyInt_AS_LONG(op);
            else if (PyNumber_Check(op))
                xy[j++] = PyFloat_AsDouble(op);
            else if (PyArg_ParseTuple(op, "dd", &x, &y)) {
                xy[j++] = x;
                xy[j++] = y;
            } else {
                free(xy);
                return -1;
            }
        }
    } else if (PyTuple_Check(data)) {
        for (i = 0; i < n; i++) {
            double x, y;
            PyObject *op = PyTuple_GET_ITEM(data, i);
            if (PyFloat_Check(op))
        xy[j++] = PyFloat_AS_DOUBLE(op);
            else if (PyInt_Check(op))
        xy[j++] = (float) PyInt_AS_LONG(op);
            else if (PyNumber_Check(op))
                xy[j++] = PyFloat_AsDouble(op);
            else if (PyArg_ParseTuple(op, "dd", &x, &y)) {
                xy[j++] = x;
                xy[j++] = y;
            } else {
                free(xy);
                return -1;
            }
        }
    } else {
        for (i = 0; i < n; i++) {
            double x, y;
            PyObject *op = PySequence_GetItem(data, i);
            if (!op) {
                /* treat IndexError as end of sequence */
                if (PyErr_Occurred() &&
                    PyErr_ExceptionMatches(PyExc_IndexError)) {
                    PyErr_Clear();
                    break;
                } else {
                    free(xy);
                    return -1;
                }
            }
            if (PyFloat_Check(op))
        xy[j++] = PyFloat_AS_DOUBLE(op);
            else if (PyInt_Check(op))
        xy[j++] = (float) PyInt_AS_LONG(op);
            else if (PyNumber_Check(op))
                xy[j++] = PyFloat_AsDouble(op);
            else if (PyArg_ParseTuple(op, "dd", &x, &y)) {
                xy[j++] = x;
                xy[j++] = y;
            } else {
                Py_DECREF(op);
                free(xy);
                return -1;
            }
            Py_DECREF(op);
        }
    }

    if (j & 1) {
    PyErr_SetString(PyExc_ValueError, "wrong number of coordinates");
    free(xy);
    return -1;
    }

    *pxy = xy;
    return j/2;
}


/* -------------------------------------------------------------------- */
/* Factories                                                            */
/* -------------------------------------------------------------------- */

PyObject*
PyPath_Create(PyObject* self, PyObject* args)
{
    PyObject* data;
    Py_ssize_t count;
    double *xy;

    if (PyArg_ParseTuple(args, "i:Path", &count)) {

        /* number of vertices */
        xy = alloc_array(count);
        if (!xy)
            return NULL;

    } else {

        /* sequence or other path */
        PyErr_Clear();
        if (!PyArg_ParseTuple(args, "O", &data))
            return NULL;

        count = PyPath_Flatten(data, &xy);
        if (count < 0)
            return NULL;
    }

    return (PyObject*) path_new(count, xy, 0);
}


/* -------------------------------------------------------------------- */
/* Methods                                */
/* -------------------------------------------------------------------- */

static PyObject*
path_compact(PyPathObject* self, PyObject* args)
{
    /* Simple-minded method to shorten path.  A point is removed if
       the city block distance to the previous point is less than the
       given distance */
    int i, j;
    double *xy;

    double cityblock = 2.0;

    if (!PyArg_ParseTuple(args, "|d:compact", &cityblock))
        return NULL;

    xy = self->xy;

    /* remove bogus vertices */
    for (i = j = 1; i < self->count; i++) {
    if (fabs(xy[j+j-2]-xy[i+i]) + fabs(xy[j+j-1]-xy[i+i+1]) >= cityblock) {
        xy[j+j] = xy[i+i];
        xy[j+j+1] = xy[i+i+1];
        j++;
    }
    }

    i = self->count - j;
    self->count = j;

    /* shrink coordinate array */
    self->xy = realloc(self->xy, 2 * self->count * sizeof(double));

    return Py_BuildValue("i", i); /* number of removed vertices */
}

static PyObject*
path_clip_polygon(PyPathObject* self, PyObject* args)
{
    /* Clip path representing a single polygon */
    PyErr_SetString(PyExc_RuntimeError, "not yet implemented");
    return NULL;
}

static PyObject*
path_clip_polyline(PyPathObject* self, PyObject* args)
{
    /* Clip path representing a single polyline (outline) */
    PyErr_SetString(PyExc_RuntimeError, "not yet implemented");
    return NULL;
}

static PyObject*
path_getbbox(PyPathObject* self, PyObject* args)
{
    /* Find bounding box */
    int i;
    double *xy;
    double x0, y0, x1, y1;

    if (!PyArg_ParseTuple(args, ":getbbox"))
        return NULL;

    xy = self->xy;

    x0 = x1 = xy[0];
    y0 = y1 = xy[1];

    for (i = 1; i < self->count; i++) {
    if (xy[i+i] < x0)
        x0 = xy[i+i];
    if (xy[i+i] > x1)
        x1 = xy[i+i];
    if (xy[i+i+1] < y0)
        y0 = xy[i+i+1];
    if (xy[i+i+1] > y1)
        y1 = xy[i+i+1];
    }

    return Py_BuildValue("dddd", x0, y0, x1, y1);
}

static PyObject*
path_getitem(PyPathObject* self, Py_ssize_t i)
{   
    if (i < 0)
        i = self->count + i;
    if (i < 0 || i >= self->count) {
        PyErr_SetString(PyExc_IndexError, "path index out of range");
        return NULL;
    }

    return Py_BuildValue("dd", self->xy[i+i], self->xy[i+i+1]);
}

static PyObject*
path_getslice(PyPathObject* self, Py_ssize_t ilow, Py_ssize_t ihigh)
{
    /* adjust arguments */
    if (ilow < 0)
        ilow = 0;
    else if (ilow >= self->count)
        ilow = self->count;
    if (ihigh < 0)
        ihigh = 0;
    if (ihigh < ilow)
        ihigh = ilow;
    else if (ihigh > self->count)
        ihigh = self->count;
    
    return (PyObject*) path_new(ihigh - ilow, self->xy + ilow * 2, 1);
}

static Py_ssize_t
path_len(PyPathObject* self)
{
    return self->count;
}

static PyObject*
path_map(PyPathObject* self, PyObject* args)
{
    /* Map coordinate set through function */
    int i;
    double *xy;
    PyObject* function;

    if (!PyArg_ParseTuple(args, "O:map", &function))
        return NULL;

    xy = self->xy;

    /* apply function to coordinate set */
    for (i = 0; i < self->count; i++) {
    double x = xy[i+i];
    double y = xy[i+i+1];
    PyObject* item = PyObject_CallFunction(function, "dd", x, y);
    if (!item || !PyArg_ParseTuple(item, "dd", &x, &y)) {
        Py_XDECREF(item);
        return NULL;
    }
    xy[i+i] = x;
    xy[i+i+1] = y;
    Py_DECREF(item);
    }

    Py_INCREF(Py_None);
    return Py_None;
}

static int
path_setitem(PyPathObject* self, int i, PyObject* op)
{
    double* xy;

    if (i < 0 || i >= self->count) {
        PyErr_SetString(PyExc_IndexError,
                        "path assignment index out of range");
        return -1;
    }

    if (op == NULL) {
        PyErr_SetString(PyExc_TypeError,
                        "cannot delete from path");
        return -1;
    }

    xy = &self->xy[i+i];

    if (!PyArg_ParseTuple(op, "dd", &xy[0], &xy[1]))
        return -1;

    return 0;
}

static PyObject*
path_tolist(PyPathObject* self, PyObject* args)
{
    PyObject *list;
    int i;

    int flat = 0;
    if (!PyArg_ParseTuple(args, "|i:tolist", &flat))
        return NULL;

    if (flat) {
        list = PyList_New(self->count*2);
        for (i = 0; i < self->count*2; i++) {
            PyObject* item;
            item = PyFloat_FromDouble(self->xy[i]);
            if (!item)
                goto error;
            PyList_SetItem(list, i, item);
        }
    } else {
        list = PyList_New(self->count);
        for (i = 0; i < self->count; i++) {
            PyObject* item;
            item = Py_BuildValue("dd", self->xy[i+i], self->xy[i+i+1]);
            if (!item)
                goto error;
            PyList_SetItem(list, i, item);
        }
    }

    return list;

error:
    Py_DECREF(list);
    return NULL;
}

static PyObject*
path_transform(PyPathObject* self, PyObject* args)
{
    /* Apply affine transform to coordinate set */
    int i;
    double *xy;
    double a, b, c, d, e, f;

    double wrap = 0.0;

    if (!PyArg_ParseTuple(args, "(dddddd)|d:transform",
              &a, &b, &c, &d, &e, &f,
              &wrap))
        return NULL;

    xy = self->xy;

    /* transform the coordinate set */
    if (b == 0.0 && d == 0.0)
    /* scaling */
    for (i = 0; i < self->count; i++) {
        xy[i+i]   = a*xy[i+i]+c;
        xy[i+i+1] = e*xy[i+i+1]+f;
    }
    else
    /* affine transform */
    for (i = 0; i < self->count; i++) {
        double x = xy[i+i];
        double y = xy[i+i+1];
        xy[i+i]   = a*x+b*y+c;
        xy[i+i+1] = d*x+e*y+f;
    }

    /* special treatment of geographical map data */
    if (wrap != 0.0)
    for (i = 0; i < self->count; i++)
        xy[i+i] = fmod(xy[i+i], wrap);

    Py_INCREF(Py_None);
    return Py_None;
}

static struct PyMethodDef methods[] = {
    {"getbbox", (PyCFunction)path_getbbox, 1},
    {"tolist", (PyCFunction)path_tolist, 1},
    {"clip_polygon", (PyCFunction)path_clip_polygon, 1},
    {"clip_polyline", (PyCFunction)path_clip_polyline, 1},
    {"compact", (PyCFunction)path_compact, 1},
    {"map", (PyCFunction)path_map, 1},
    {"transform", (PyCFunction)path_transform, 1},
    {NULL, NULL} /* sentinel */
};

static PyObject*  
path_getattr(PyPathObject* self, char* name)
{
    PyObject* res;

#ifdef PY3
    res = PyObject_GenericGetAttr((PyObject *)self,
                                  PyUnicode_FromString(name));
#else
    res = Py_FindMethod(methods, (PyObject*) self, name);
#endif

    if (res)
        return res;

    PyErr_Clear();

    if (strcmp(name, "id") == 0)
        return Py_BuildValue("n", (Py_ssize_t) self->xy);

    PyErr_SetString(PyExc_AttributeError, name);
    return NULL;
}

static PyObject* 
path_subscript(PyPathObject* self, PyObject* item) {
    if (PyIndex_Check(item)) {
        Py_ssize_t i;
        i = PyNumber_AsSsize_t(item, PyExc_IndexError);
        if (i == -1 && PyErr_Occurred())
            return NULL;
        return path_getitem(self, i);
    }
    if (PySlice_Check(item)) {
        int len = 4;
        Py_ssize_t start, stop, step, slicelength;

        if (PySlice_GetIndicesEx((PyObject*)item, len, &start, &stop, &step, &slicelength) < 0)
            return NULL;

        if (slicelength <= 0) {
            double *xy = alloc_array(0);
            return (PyObject*) path_new(0, xy, 0);
        }
        else if (step == 1) {
            return path_getslice(self, start, stop);
        }
        else {
            PyErr_SetString(PyExc_TypeError, "slice steps not supported");
            return NULL;
        }
    }
    else {
        PyErr_Format(PyExc_TypeError,
                     "Path indices must be integers, not %.200s",
#ifdef PY3
                     Py_TYPE(&item)->tp_name);
#else
                     item->ob_type->tp_name);
#endif
        return NULL;
    }
}


static PySequenceMethods path_as_sequence = {
    (lenfunc)path_len,                /*sq_length*/
    (binaryfunc)0,                    /*sq_concat*/
    (ssizeargfunc)0,                  /*sq_repeat*/
    (ssizeargfunc)path_getitem,       /*sq_item*/
    (ssizessizeargfunc)path_getslice, /*sq_slice*/
    (ssizeobjargproc)path_setitem,    /*sq_ass_item*/
    (ssizessizeobjargproc)0,          /*sq_ass_slice*/
};

static PyMappingMethods path_as_mapping = {
    (lenfunc)path_len,
    (binaryfunc)path_subscript,
    NULL
};

#ifdef PY3
static PyTypeObject PyPathType = {
    PyVarObject_HEAD_INIT(0,0)
#else
statichere PyTypeObject PyPathType = {
    PyObject_HEAD_INIT(NULL)
    0,                              /*ob_size*/
#endif
    "Path",                         /*tp_name*/
    sizeof(PyPathObject),           /*tp_size*/
    0,                              /*tp_itemsize*/
    /* methods */
    (destructor)path_dealloc,       /*tp_dealloc*/
    0,                              /*tp_print*/
    (getattrfunc)path_getattr,      /*tp_getattr*/
    0,                              /*tp_setattr*/
    0,                              /*tp_compare*/
    0,                              /*tp_repr*/
    0,                              /*tp_as_number */
    &path_as_sequence,              /*tp_as_sequence */
    &path_as_mapping,               /*tp_as_mapping */
    0,                              /*tp_hash*/
    0,                              /* tp_call */
    0,                              /* tp_str */
    0,                              /* tp_getattro */
    0,                              /* tp_setattro */
    0,                              /* tp_as_buffer */
    0,                              /* tp_flags */
    0,                              /* tp_doc */
    0,                              /* tp_traverse */
    0,                              /* tp_clear */
    0,                              /* tp_richcompare */
    0,                              /* tp_weaklistoffset */
    0,                              /* tp_iter */
    0,                              /* tp_iternext */
    methods,                        /* tp_methods */
};