Hi,
I'm porting a lib to Python-3.
This code works with Python-2
------------------------------------------------------
const std::string Image::getExifThumbnailData()
{
Exiv2::DataBuf buffer = _getExifThumbnail()->copy();
// Copy the data buffer in a string.
// First allocate the memory for the whole string...
std::string data = std::string(buffer.size_, ' ');
// ... then fill it with the raw data.
for(unsigned int i = 0; i < buffer.size_; ++i)
{
data[i] = buffer.pData_[i];
}
return data;
-----------------------------------------------------
The object Exiv2::DataBuf contain the pixel's values of an image
[R,G,B,R,G,B,...]
It is described here (1)
With Python-3 I get this error:
buf_ = self._metadata._image._getExifThumbnailData()
TypeError: No to_python (by-value) converter found for C++ type:
std::vector<char, std::allocator<char> >
Then, I've made some tests with memoryView, like this:
-----------------------------------------------------
boost::python::object Image::getExifThumbnailData()
{
Exiv2::DataBuf buffer = _getExifThumbnail()->copy();
Py_ssize_t size = buffer.size_;
Py_buffer py_buffer;
PyObject exporter;
int res = PyBuffer_FillInfo(&py_buffer, &exporter, &buffer.pData_,
size,
true, PyBUF_CONTIG_RO);
if (res == -1) {
PyErr_Print();
exit(EXIT_FAILURE);
}
boost::python::object memoryView(boost::python::handle<>
(PyMemoryView_FromMemory
(&exporter, size, PyBUF_READ)));
return memoryView;
}
----------------------------------------------------
But that doesn't compile.
src/exiv2wrapper.cpp: In member function ‘boost::python::api::object
exiv2wrapper::Image::getExifThumbnailData()’:
src/exiv2wrapper.cpp:504:65: error: cannot convert ‘PyObject* {aka
_object*}’ to ‘char*’ for argument ‘1’ to ‘PyObject*
PyMemoryView_FromMemory(char*, Py_ssize_t, int)’
(&exporter, size, PyBUF_READ)));
(1) DataBuf: http://www.exiv2.org/doc/classExiv2_1_1DataBuf.html
Regards,
Vincent
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