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/*=========================================================================
Program: Visualization Toolkit
Module: PyVTKExtras.cxx
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
#include "PyVTKExtras.h"
#include "vtkPythonCompatibility.h"
#include "PyVTKMutableObject.h"
// Silence warning like
// "dereferencing type-punned pointer will break strict-aliasing rules"
// it happens because this kind of expression: (long *)&ptr
#if defined(__GNUC__)
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif
//--------------------------------------------------------------------
// Helper function for the buffer_shared() check: get the pointer and
// size (in bytes) of the buffer of the provided object. A return
// value of zero indicates that an exception was raised.
static void *buffer_pointer_and_size(PyObject *o, Py_ssize_t *size)
{
void *ptr = NULL;
#if PY_VERSION_HEX >= 0x02060000
// New buffer protocol
Py_buffer view = VTK_PYBUFFER_INITIALIZER;
if (PyObject_CheckBuffer(o))
{
// Check for a simple buffer
if (PyObject_GetBuffer(o, &view, PyBUF_SIMPLE) == -1)
{
// Check for a C or Fortran contiguous buffer
PyErr_Clear();
if (PyObject_GetBuffer(o, &view, PyBUF_STRIDES) == -1)
{
return NULL;
}
}
ptr = view.buf;
*size = view.len;
PyBuffer_Release(&view);
if (ptr)
{
return ptr;
}
}
#endif
#ifndef VTK_PY3K
// Old buffer protocol
PyBufferProcs *b = Py_TYPE(o)->tp_as_buffer;
if (b && b->bf_getreadbuffer && b->bf_getsegcount)
{
if (b->bf_getsegcount(o, NULL) == 1)
{
*size = b->bf_getreadbuffer(o, 0, &ptr);
if (ptr)
{
return ptr;
}
}
else
{
PyErr_SetString(PyExc_TypeError, "buffer must be single-segment");
return NULL;
}
}
#endif
PyErr_SetString(PyExc_TypeError,
"object does not have a readable buffer");
return NULL;
}
//--------------------------------------------------------------------
static PyObject *PyVTKExtras_buffer_shared(PyObject *, PyObject *args)
{
PyObject *ob[2] = { NULL, NULL };
if (PyArg_UnpackTuple(args, "buffer_shared", 2, 2, &ob[0], &ob[1]))
{
void *ptr[2] = { NULL, NULL };
Py_ssize_t size[2] = { 0, 0 };
for (int i = 0; i < 2; i++)
{
ptr[i] = buffer_pointer_and_size(ob[i], &size[i]);
if (!ptr[i])
{
break;
}
}
// check if the pointers and memory size are equal
if (ptr[0] && ptr[1])
{
if (ptr[0] == ptr[1] && size[0] == size[1])
{
Py_RETURN_TRUE;
}
else
{
Py_RETURN_FALSE;
}
}
}
return NULL;
}
//--------------------------------------------------------------------
static PyMethodDef PyVTKExtras_Methods[] = {
{"buffer_shared", PyVTKExtras_buffer_shared, METH_VARARGS,
"Check if two objects share the same buffer, meaning that they"
" point to the same block of memory. An TypeError exception will"
" be raised if either of the objects does not provide a buffer."},
{NULL, NULL, 0, NULL}
};
//--------------------------------------------------------------------
// Exported method called by vtkCommonCorePythonInit
void PyVTKAddFile_PyVTKExtras(PyObject *dict)
{
PyObject *o = (PyObject *)&PyVTKMutableObject_Type;
if (o && PyDict_SetItemString(dict, "mutable", o) != 0)
{
Py_DECREF(o);
}
for (PyMethodDef *meth = PyVTKExtras_Methods;
meth->ml_name != NULL;
meth++)
{
// Third argument would be the module object, but all we have is
// the module's dict, and it's safe to set it to NULL.
o = PyCFunction_NewEx(meth, NULL, NULL);
if (o && PyDict_SetItemString(dict, meth->ml_name, o) != 0)
{
Py_DECREF(o);
}
}
}
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