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Use pybind11 in ttconv module #25253

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Mar 30, 2023
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6 changes: 3 additions & 3 deletions setupext.py
Original file line number Diff line number Diff line change
Expand Up @@ -468,15 +468,15 @@ def get_extensions(self):
cxx_std=11)
yield ext
# ttconv
ext = Extension(
ext = Pybind11Extension(
"matplotlib._ttconv", [
"src/_ttconv.cpp",
"extern/ttconv/pprdrv_tt.cpp",
"extern/ttconv/pprdrv_tt2.cpp",
"extern/ttconv/ttutil.cpp",
],
include_dirs=["extern"])
add_numpy_flags(ext)
include_dirs=["extern"],
cxx_std=11)
yield ext


Expand Down
169 changes: 36 additions & 133 deletions src/_ttconv.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -5,157 +5,80 @@

Python wrapper for TrueType conversion library in ../ttconv.
*/
#define PY_SSIZE_T_CLEAN
#include "mplutils.h"

#include <Python.h>
#include <pybind11/pybind11.h>
#include "ttconv/pprdrv.h"
#include "py_exceptions.h"
#include <vector>
#include <cassert>

namespace py = pybind11;

/**
* An implementation of TTStreamWriter that writes to a Python
* file-like object.
*/
class PythonFileWriter : public TTStreamWriter
{
PyObject *_write_method;
py::function _write_method;

public:
PythonFileWriter()
{
_write_method = NULL;
}

~PythonFileWriter()
{
Py_XDECREF(_write_method);
}

void set(PyObject *write_method)
{
Py_XDECREF(_write_method);
_write_method = write_method;
Py_XINCREF(_write_method);
}
PythonFileWriter(py::object& file_object)
: _write_method(file_object.attr("write")) {}

virtual void write(const char *a)
{
PyObject *result = NULL;
if (_write_method) {
PyObject *decoded = NULL;
decoded = PyUnicode_DecodeLatin1(a, strlen(a), "");
if (decoded == NULL) {
throw py::exception();
}
result = PyObject_CallFunctionObjArgs(_write_method, decoded, NULL);
Py_DECREF(decoded);
if (!result) {
throw py::exception();
}
Py_DECREF(result);
PyObject* decoded = PyUnicode_DecodeLatin1(a, strlen(a), "");
if (decoded == NULL) {
throw py::error_already_set();
}
_write_method(py::handle(decoded));
Py_DECREF(decoded);
}
};

int fileobject_to_PythonFileWriter(PyObject *object, void *address)
static void convert_ttf_to_ps(
const char *filename,
py::object &output,
int fonttype,
py::iterable* glyph_ids)
{
PythonFileWriter *file_writer = (PythonFileWriter *)address;
PythonFileWriter output_(output);

PyObject *write_method = PyObject_GetAttrString(object, "write");
if (write_method == NULL || !PyCallable_Check(write_method)) {
PyErr_SetString(PyExc_TypeError, "Expected a file-like object with a write method.");
return 0;
}

file_writer->set(write_method);
Py_DECREF(write_method);

return 1;
}

int pyiterable_to_vector_int(PyObject *object, void *address)
{
std::vector<int> *result = (std::vector<int> *)address;

PyObject *iterator = PyObject_GetIter(object);
if (!iterator) {
return 0;
}

PyObject *item;
while ((item = PyIter_Next(iterator))) {
long value = PyLong_AsLong(item);
Py_DECREF(item);
if (value == -1 && PyErr_Occurred()) {
return 0;
std::vector<int> glyph_ids_;
if (glyph_ids) {
for (py::handle glyph_id: *glyph_ids) {
glyph_ids_.push_back(glyph_id.cast<int>());
}
result->push_back((int)value);
}

Py_DECREF(iterator);

return 1;
}

static PyObject *convert_ttf_to_ps(PyObject *self, PyObject *args, PyObject *kwds)
{
const char *filename;
PythonFileWriter output;
int fonttype;
std::vector<int> glyph_ids;

static const char *kwlist[] = { "filename", "output", "fonttype", "glyph_ids", NULL };
if (!PyArg_ParseTupleAndKeywords(args,
kwds,
"yO&i|O&:convert_ttf_to_ps",
(char **)kwlist,
&filename,
fileobject_to_PythonFileWriter,
&output,
&fonttype,
pyiterable_to_vector_int,
&glyph_ids)) {
return NULL;
}

if (fonttype != 3 && fonttype != 42) {
PyErr_SetString(PyExc_ValueError,
"fonttype must be either 3 (raw Postscript) or 42 "
"(embedded Truetype)");
return NULL;
throw py::value_error(
"fonttype must be either 3 (raw Postscript) or 42 (embedded Truetype)");
}

try
{
insert_ttfont(filename, output, (font_type_enum)fonttype, glyph_ids);
insert_ttfont(filename, output_, static_cast<font_type_enum>(fonttype), glyph_ids_);
}
catch (TTException &e)
{
PyErr_SetString(PyExc_RuntimeError, e.getMessage());
return NULL;
}
catch (const py::exception &)
{
return NULL;
throw std::runtime_error(e.getMessage());
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I am concerned that we don't exercise this line in the test suite as it would be good to confirm that TTExceptions propagate through pybind11 as expected. But given that we've evidently never had such a test it doesn't have to be done here, it can be punted to "future work".

}
catch (...)
{
PyErr_SetString(PyExc_RuntimeError, "Unknown C++ exception");
return NULL;
throw std::runtime_error("Unknown C++ exception");
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This catch all isn't really needed as pybind11 catches C++ exceptions and converts them to Python ones. But I like the approach that support for pybind11 should happen with minimal changes to C++ code so it is fine to leave it as it is.

}

Py_INCREF(Py_None);
return Py_None;
}

static PyMethodDef ttconv_methods[] =
{
{
"convert_ttf_to_ps", (PyCFunction)convert_ttf_to_ps, METH_VARARGS | METH_KEYWORDS,
"convert_ttf_to_ps(filename, output, fonttype, glyph_ids)\n"
"\n"
PYBIND11_MODULE(_ttconv, m) {
m.doc() = "Module to handle converting and subsetting TrueType "
"fonts to Postscript Type 3, Postscript Type 42 and "
"Pdf Type 3 fonts.";
m.def("convert_ttf_to_ps", &convert_ttf_to_ps,
py::arg("filename"),
py::arg("output"),
py::arg("fonttype"),
py::arg("glyph_ids") = py::none(),
"Converts the Truetype font into a Type 3 or Type 42 Postscript font, "
"optionally subsetting the font to only the desired set of characters.\n"
"\n"
Expand All @@ -169,25 +92,5 @@ static PyMethodDef ttconv_methods[] =
"subsetting to a Type 3 font. If glyph_ids is not provided or is None, "
"then all glyphs will be included. If any of the glyphs specified are "
"composite glyphs, then the component glyphs will also be included."
},
{0, 0, 0, 0} /* Sentinel */
};

static const char *module_docstring =
"Module to handle converting and subsetting TrueType "
"fonts to Postscript Type 3, Postscript Type 42 and "
"Pdf Type 3 fonts.";

static PyModuleDef ttconv_module = {
PyModuleDef_HEAD_INIT,
"ttconv",
module_docstring,
-1,
ttconv_methods,
};

PyMODINIT_FUNC
PyInit__ttconv(void)
{
return PyModule_Create(&ttconv_module);
);
}