blender-archive/source/blender/python/intern/bpy_utils_units.c

/*
 * 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 2
 * 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, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

/** \file
 * \ingroup pythonintern
 *
 * This file defines a singleton py object accessed via 'bpy.utils.units',
 * which exposes various data and functions useful in units handling.
 */

/* Future-proof, See https://docs.python.org/3/c-api/arg.html#strings-and-buffers */
#define PY_SSIZE_T_CLEAN

#include <Python.h>
#include <structmember.h>

#include "BLI_string.h"
#include "BLI_utildefines.h"

#include "bpy_utils_units.h"

#include "../generic/py_capi_utils.h"

#include "BKE_unit.h"

/***** C-defined systems and types *****/

static PyTypeObject BPyUnitsSystemsType;
static PyTypeObject BPyUnitsCategoriesType;

/* XXX Maybe better as externs of BKE_unit.h ? */
static const char *bpyunits_usystem_items[] = {
    "NONE",
    "METRIC",
    "IMPERIAL",
    NULL,
};

static const char *bpyunits_ucategorie_items[] = {
    "NONE",
    "LENGTH",
    "AREA",
    "VOLUME",
    "MASS",
    "ROTATION",
    "TIME",
    "VELOCITY",
    "ACCELERATION",
    "CAMERA",
    "POWER",
    NULL,
};

/**
 * These fields are just empty placeholders, actual values get set in initializations functions.
 * This allows us to avoid many handwriting, and above all,
 * to keep all systems/categories definition stuff in ``BKE_unit.h``.
 */
static PyStructSequence_Field bpyunits_systems_fields[ARRAY_SIZE(bpyunits_usystem_items)];
static PyStructSequence_Field bpyunits_categories_fields[ARRAY_SIZE(bpyunits_ucategorie_items)];

static PyStructSequence_Desc bpyunits_systems_desc = {
    "bpy.utils.units.systems",                                /* name */
    "This named tuple contains all pre-defined unit systems", /* doc */
    bpyunits_systems_fields,                                  /* fields */
    ARRAY_SIZE(bpyunits_systems_fields) - 1,
};
static PyStructSequence_Desc bpyunits_categories_desc = {
    "bpy.utils.units.categories",                           /* name */
    "This named tuple contains all pre-defined unit names", /* doc */
    bpyunits_categories_fields,                             /* fields */
    ARRAY_SIZE(bpyunits_categories_fields) - 1,
};

/**
 * Simple utility function to initialize #PyStructSequence_Desc
 */
static PyObject *py_structseq_from_strings(PyTypeObject *py_type,
                                           PyStructSequence_Desc *py_sseq_desc,
                                           const char **str_items)
{
  PyObject *py_struct_seq;
  int pos = 0;

  const char **str_iter;
  PyStructSequence_Field *desc;

  /* initialize array */
  /* We really populate the contexts' fields here! */
  for (str_iter = str_items, desc = py_sseq_desc->fields; *str_iter; str_iter++, desc++) {
    desc->name = (char *)*str_iter;
    desc->doc = NULL;
  }
  /* end sentinel */
  desc->name = desc->doc = NULL;

  PyStructSequence_InitType(py_type, py_sseq_desc);

  /* initialize pytype */
  py_struct_seq = PyStructSequence_New(py_type);
  BLI_assert(py_struct_seq != NULL);

  for (str_iter = str_items; *str_iter; str_iter++) {
    PyStructSequence_SET_ITEM(py_struct_seq, pos++, PyUnicode_FromString((*str_iter)));
  }

  return py_struct_seq;
}

static bool bpyunits_validate(const char *usys_str, const char *ucat_str, int *r_usys, int *r_ucat)
{
  *r_usys = BLI_str_index_in_array(usys_str, bpyunits_usystem_items);
  if (*r_usys < 0) {
    PyErr_Format(PyExc_ValueError, "Unknown unit system specified: %.200s.", usys_str);
    return false;
  }

  *r_ucat = BLI_str_index_in_array(ucat_str, bpyunits_ucategorie_items);
  if (*r_ucat < 0) {
    PyErr_Format(PyExc_ValueError, "Unknown unit category specified: %.200s.", ucat_str);
    return false;
  }

  if (!bUnit_IsValid(*r_usys, *r_ucat)) {
    PyErr_Format(PyExc_ValueError,
                 "%.200s / %.200s unit system/category combination is not valid.",
                 usys_str,
                 ucat_str);
    return false;
  }

  return true;
}

PyDoc_STRVAR(
    bpyunits_to_value_doc,
    ".. method:: to_value(unit_system, unit_category, str_input, str_ref_unit=None)\n"
    "\n"
    "   Convert a given input string into a float value.\n"
    "\n"
    "   :arg unit_system: The unit system, from :attr:`bpy.utils.units.systems`.\n"
    "   :type unit_system: string\n"
    "   :arg unit_category: The category of data we are converting (length, area, rotation, "
    "etc.),\n"
    "      from :attr:`bpy.utils.units.categories`.\n"
    "   :type unit_category: string\n"
    "   :arg str_input: The string to convert to a float value.\n"
    "   :type str_input: string\n"
    "   :arg str_ref_unit: A reference string from which to extract a default unit, if none is "
    "found in ``str_input``.\n"
    "   :type str_ref_unit: string or None\n"
    "   :return: The converted/interpreted value.\n"
    "   :rtype: float\n"
    "   :raises ValueError: if conversion fails to generate a valid python float value.\n");
static PyObject *bpyunits_to_value(PyObject *UNUSED(self), PyObject *args, PyObject *kw)
{
  char *usys_str = NULL, *ucat_str = NULL, *inpt = NULL, *uref = NULL;
  const float scale = 1.0f;

  char *str;
  Py_ssize_t str_len;
  double result;
  int usys, ucat;
  PyObject *ret;

  static const char *_keywords[] = {
      "unit_system",
      "unit_category",
      "str_input",
      "str_ref_unit",
      NULL,
  };
  static _PyArg_Parser _parser = {"sss#|z:to_value", _keywords, 0};
  if (!_PyArg_ParseTupleAndKeywordsFast(
          args, kw, &_parser, &usys_str, &ucat_str, &inpt, &str_len, &uref)) {
    return NULL;
  }

  if (!bpyunits_validate(usys_str, ucat_str, &usys, &ucat)) {
    return NULL;
  }

  str_len = str_len * 2 + 64;
  str = PyMem_MALLOC(sizeof(*str) * (size_t)str_len);
  BLI_strncpy(str, inpt, (size_t)str_len);

  bUnit_ReplaceString(str, (int)str_len, uref, scale, usys, ucat);

  if (!PyC_RunString_AsNumber(NULL, str, "<bpy_units_api>", &result)) {
    if (PyErr_Occurred()) {
      PyErr_Print();
      PyErr_Clear();
    }

    PyErr_Format(
        PyExc_ValueError, "'%.200s' (converted as '%s') could not be evaluated.", inpt, str);
    ret = NULL;
  }
  else {
    ret = PyFloat_FromDouble(result);
  }

  PyMem_FREE(str);
  return ret;
}

PyDoc_STRVAR(bpyunits_to_string_doc,
             ".. method:: to_string(unit_system, unit_category, value, precision=3, "
             "split_unit=False, compatible_unit=False)\n"
             "\n"
             "   Convert a given input float value into a string with units.\n"
             "\n"
             "   :arg unit_system: The unit system, from :attr:`bpy.utils.units.systems`.\n"
             "   :type unit_system: string\n"
             "   :arg unit_category: The category of data we are converting (length, area, "
             "rotation, etc.),\n"
             "      from :attr:`bpy.utils.units.categories`.\n"
             "   :type unit_category: string\n"
             "   :arg value: The value to convert to a string.\n"
             "   :type value: float\n"
             "   :arg precision: Number of digits after the comma.\n"
             "   :type precision: int\n"
             "   :arg split_unit: Whether to use several units if needed (1m1cm), or always only "
             "one (1.01m).\n"
             "   :type split_unit: bool\n"
             "   :arg compatible_unit: Whether to use keyboard-friendly units (1m2) or nicer "
             "utf-8 ones (1m²).\n"
             "   :type compatible_unit: bool\n"
             "   :return: The converted string.\n"
             "   :rtype: str\n"
             "   :raises ValueError: if conversion fails to generate a valid python string.\n");
static PyObject *bpyunits_to_string(PyObject *UNUSED(self), PyObject *args, PyObject *kw)
{
  char *usys_str = NULL, *ucat_str = NULL;
  double value = 0.0;
  int precision = 3;
  bool split_unit = false, compatible_unit = false;

  int usys, ucat;

  static const char *_keywords[] = {
      "unit_system",
      "unit_category",
      "value",
      "precision",
      "split_unit",
      "compatible_unit",
      NULL,
  };
  static _PyArg_Parser _parser = {"ssd|iO&O&:to_string", _keywords, 0};
  if (!_PyArg_ParseTupleAndKeywordsFast(args,
                                        kw,
                                        &_parser,
                                        &usys_str,
                                        &ucat_str,
                                        &value,
                                        &precision,
                                        PyC_ParseBool,
                                        &split_unit,
                                        PyC_ParseBool,
                                        &compatible_unit)) {
    return NULL;
  }

  if (!bpyunits_validate(usys_str, ucat_str, &usys, &ucat)) {
    return NULL;
  }

  {
    /* Maximum expected length of string result:
     * - Number itself: precision + decimal dot + up to four 'above dot' digits.
     * - Unit: up to ten chars
     *   (six currently, let's be conservative, also because we use some utf8 chars).
     * This can be repeated twice (e.g. 1m20cm), and we add ten more spare chars
     * (spaces, trailing '\0'...).
     * So in practice, 64 should be more than enough.
     */
    char buf1[64], buf2[64], *str;
    PyObject *result;

    bUnit_AsString(buf1, sizeof(buf1), value, precision, usys, ucat, (bool)split_unit, false);

    if (compatible_unit) {
      bUnit_ToUnitAltName(buf2, sizeof(buf2), buf1, usys, ucat);
      str = buf2;
    }
    else {
      str = buf1;
    }

    result = PyUnicode_FromString(str);

    return result;
  }
}

static PyMethodDef bpyunits_methods[] = {
    {"to_value",
     (PyCFunction)bpyunits_to_value,
     METH_VARARGS | METH_KEYWORDS,
     bpyunits_to_value_doc},
    {"to_string",
     (PyCFunction)bpyunits_to_string,
     METH_VARARGS | METH_KEYWORDS,
     bpyunits_to_string_doc},
    {NULL, NULL, 0, NULL},
};

PyDoc_STRVAR(bpyunits_doc, "This module contains some data/methods regarding units handling.");

static struct PyModuleDef bpyunits_module = {
    PyModuleDef_HEAD_INIT,
    "bpy.utils.units",
    bpyunits_doc,
    -1, /* multiple "initialization" just copies the module dict. */
    bpyunits_methods,
    NULL,
    NULL,
    NULL,
    NULL,
};

PyObject *BPY_utils_units(void)
{
  PyObject *submodule, *item;

  submodule = PyModule_Create(&bpyunits_module);
  PyDict_SetItemString(PyImport_GetModuleDict(), bpyunits_module.m_name, submodule);

  /* Finalize our unit systems and types structseq definitions! */

  /* bpy.utils.units.system */
  item = py_structseq_from_strings(
      &BPyUnitsSystemsType, &bpyunits_systems_desc, bpyunits_usystem_items);
  PyModule_AddObject(submodule, "systems", item); /* steals ref */

  /* bpy.utils.units.categories */
  item = py_structseq_from_strings(
      &BPyUnitsCategoriesType, &bpyunits_categories_desc, bpyunits_ucategorie_items);
  PyModule_AddObject(submodule, "categories", item); /* steals ref */

  return submodule;
}