HI all,

I'm having some trouble figuring out how to do this one.

Assimp gives me a string, containing all the file extensions it can handle.

I found some code to tokenize strings on SO and wrapped it in a function.

The format of the string that is used to initialise the accepted extensions list for the OPENFILENAME structure is as follows:

L"All\0*.*\0Text\*.txt\0"

And so I'm trying to recreate that programatically. Which is a nightmare, as I'm trying to stick '\0' in the middle of a string.

// Get a vector of extensions supported by Assimp ( assimp exts string, tokenise by ';' )
std::vector<std::string> exts = Scatterbrain::Split(extsAccepted.c_str(), ';');
	
//create a string with a bunch of '\0' s in it, if possible
std::string extsList="";
for(size_t i = 0; i < exts.size(); i++)
	extsList.append(exts[i] + '\0');
	
// contains the first extension.
CString pwszExts(extsList.c_str());

// Initialize OPENFILENAME
ZeroMemory(&ofn, sizeof(ofn));

ofn.lpstrFilter = (LPCWSTR)pwszExts; // This one
...

// Display the Open dialog box. 
if( GetOpenFileName(&ofn) == TRUE ) 
{
...

Okay - I see one bug already: the dialog is going to say 'extension_a extension_b', instead of 'ext_name_a ext_a', but I'm happy to add blank spaces for names.

how is the generation of a string

L"Hello\0World\0How\0Are\0You\0'

done?

Thanks in advance

how is the generation of a string

L"Hello\0World\0How\0Are\0You\0'

done?

std::wstring ext;
ext.reserve(str.length()+1);

std::transform(str.begin(),str.end(),back_inserter(ext),[](char t) -> wchar_t {
	return t == ';' ? 0 : t;
});
ext.push_back(0); // (This is necessary to indicate where the array of strings end)

wchar_t* buf = ext.c_str(); // An extra null terminator should be appended here.

// str = "Hello;World;How;Are;You"
// buf = L"Hello\0World\0How\0Are\0You\0\0"

What is this lambda magic?

[](char t)->wchar_t

Is that it? It's not the replacing that I'm struggling with, it's the char ->wchar_t.. and there is the char->wchar_t

I'm going to try basically an empty lambda, meanwhile, whats with the extra push_back(0)'s? are those important (i.e. the real null terminator of the returned exts wstring?

struct ReplaceAndWiden {
	char to_find;
	wchar_t to_replace;
	
	ReplaceAndWiden(char f, wchar_t r) : to_find(f), to_replace(r) {
	}

	wchar_t operator() (char t) const {
		return t == to_find ? to_replace : (wchar_t)t;
	}
};

std::transform( str.begin(), str.end(), back_inserter(ext), ReplaceAndWiden(';',0) );

I bailed on my split fn, all that CString jazz.. now I have this beautiful code:

std::string App::DoOpenFileDialog(std::string extsAccepted)
{
	std::string fName;
	OPENFILENAME ofn;       // common dialog box structure
	char szFile[260];       // buffer for file name

	std::wstring wextsList;
	std::transform(extsAccepted.begin(), extsAccepted.end(), back_inserter(wextsList), [](char t)->wchar_t {
		return t==';' ? '\0' : t;
	});

	// Initialize OPENFILENAME
	ZeroMemory(&ofn, sizeof(ofn));
	ofn.lStructSize = sizeof(ofn);
	ofn.hwndOwner = m_hWnd;
	ofn.lpstrFile = (LPWSTR)szFile;
	ofn.lpstrFile[0] = '\0';
	ofn.nMaxFile = sizeof(szFile);
	ofn.lpstrFilter = (LPCWSTR)wextsList.c_str();
	ofn.nFilterIndex = 1;
	ofn.lpstrFileTitle = NULL;
	ofn.nMaxFileTitle = 0;
	ofn.lpstrInitialDir = NULL;
	ofn.Flags = OFN_PATHMUSTEXIST | OFN_FILEMUSTEXIST;

	// Display the Open dialog box. 

	if( GetOpenFileName(&ofn) == TRUE ) 
	{	

..Problem is, it's missing every other file format - this is something I saw before while straying through the realms of doing it a char at a time in a for loop, and also while using a CString..

PS: D'oh! I've got Unicode set in my project settings (VS 2012), so that should make things easier?
PPS: I just saw your reply - I've used lambdas before, just appreciating the sly-as-hell widening, just implicit. Must use lambdas much more.Loving that one, using it, thank you

Crap - I just added the extra null terminator.

Okay..

Everything seems to be working with the lambda. The reason I have half the file formats visible in the dialog is to do with the OPENFILENAME and the GetOpenFileName() function

http://msdn.microsoft.com/en-gb/library/windows/desktop/ms646829(v=vs.85).aspx#open_file

I think I need a name for each format.. "Model" will do.

Hello people above std::string seems to work fine - I think (it appears) Assimp provides an overload - pretty sure I've seen it documented.

I don't think that's actually going to do the right thing if there's anything other than US ASCII in the original string.

Indeed. I'm happy to assume Assimp don't bother with language packs. PS That all sounds like a lot of effort - have you seen that lambda?!

Bregma is correct, Assimp's aiString is UTF-8. Therefore, a temporary buffer and mbstowcs are needed for proper UTF-8 handling.

That will probably not be a correct conversion either, as mbstowcs expects the multibyte string to be in the system native multibyte encoding, which on Windows probably never is UTF-8.

You probably want something like this for a correct conversion:

#include <codecvt>
...
std::wstring_convert<std::codecvt_utf8<wchar_t>> wc;
std::wstring converted_str = wc.from_bytes(utf8str);