qt5 based implementation

note: this is not integrated into the build - I have no idea of premake in combination with qt
but I still hope it can serve as a reference

src/nfd_qt.cpp

@@ -0,0 +1,155 @@
+/*
+ Native File Dialog
+
+ http://www.frogtoss.com/labs
+ */
+
+#include <stdio.h>
+#include <assert.h>
+#include <string.h>
+#include <QApplication>
+#include <QFileDialog>
+#include "nfd_common.h"
+
+const char NOPATH_MSG[] = "The selected path is out of memory.";
+const char NOMEM_MSG[] = "Out of memory.";
+
+static void AddFiltersToDialog( QFileDialog &dialog, const char *filterList )
+{
+    if ( !filterList )
+    {
+        return;
+    }
+    QStringList filterStringList;
+
+    QStringList filters = QString( filterList ).split( ';' );
+    QListIterator<QString> iter( filters );
+    while ( iter.hasNext() )
+    {
+        const QString& filterEntry = iter.next();
+        const QStringList& wildcards = filterEntry.split( ',' );
+        QListIterator<QString> iterWildcards( wildcards );
+        QString filterString;
+        while ( iterWildcards.hasNext() )
+        {
+            filterString.append( "*." ).append(iterWildcards.next());
+            if ( iterWildcards.hasNext() )
+            {
+                filterString.append( ' ' );
+            }
+        }
+        filterStringList << filterString;
+    }
+
+    filterStringList << "Any files (*)";
+    dialog.setNameFilters( filterStringList );
+}
+
+static nfdresult_t NFD_QTOpenDialog(QFileDialog::AcceptMode acceptMode, QFileDialog::FileMode fileMode,
+        const char *filterList, const nfdchar_t *defaultPath, nfdchar_t **outPath, nfdpathset_t *outPaths) {
+    int argc = 0;
+    QApplication app( argc, nullptr );
+
+    QFileDialog dialog;
+    dialog.setAcceptMode( acceptMode );
+    dialog.setFileMode( fileMode );
+    dialog.setWindowFlags( Qt::WindowStaysOnTopHint );
+    dialog.setWindowModality( Qt::ApplicationModal );
+    AddFiltersToDialog( dialog, filterList );
+
+    if ( defaultPath )
+    {
+        dialog.setDirectory( defaultPath );
+    }
+
+    nfdresult_t result = NFD_CANCEL;
+    if (dialog.exec()) {
+        const QStringList& selectedFiles = dialog.selectedFiles();
+        if ( selectedFiles.empty() )
+        {
+            result = NFD_CANCEL;
+        }
+        else if ( outPath )
+        {
+            const QString& entry = selectedFiles.at( 0 );
+            const size_t len = entry.size();
+            const QByteArray& ba = entry.toLatin1();
+            const char *cstr = ba.data();
+            *outPath = (nfdchar_t*)NFDi_Malloc( len + 1 );
+            memcpy( *outPath, cstr, len + 1 );
+            if ( !*outPath )
+            {
+                NFDi_SetError( NOPATH_MSG );
+                result = NFD_ERROR;
+            }
+            else
+            {
+                result = NFD_OKAY;
+            }
+        }
+        else if ( outPaths )
+        {
+            outPaths->count = (size_t) selectedFiles.size();
+            outPaths->indices = (size_t *)NFDi_Malloc( sizeof( size_t ) * outPaths->count );
+            if ( !outPaths->indices )
+            {
+                NFDi_SetError( NOMEM_MSG );
+                result = NFD_ERROR;
+            }
+            else
+            {
+                size_t bufSize = 0;
+                QListIterator<QString> iter( selectedFiles );
+                while ( iter.hasNext() )
+                {
+                    const QString& entry = iter.next();
+                    bufSize += entry.size() + 1;
+                }
+
+                outPaths->buf = (nfdchar_t *)NFDi_Malloc( sizeof( nfdchar_t ) * bufSize );
+
+                nfdchar_t *p_buf = outPaths->buf;
+                iter = QListIterator<QString>( selectedFiles );
+                int count = 0;
+                while ( iter.hasNext() )
+                {
+                    const QString& entry = iter.next();
+                    const QByteArray& ba = entry.toLatin1();
+                    const char *cstr = ba.data();
+                    nfdchar_t *path = (nfdchar_t*) (cstr);
+                    size_t byteLen = entry.size() + 1;
+                    memcpy( p_buf, path, byteLen );
+                    const ptrdiff_t index = p_buf - outPaths->buf;
+                    assert(index >= 0);
+                    outPaths->indices[count] = (size_t) index;
+
+                    p_buf += byteLen;
+                    ++count;
+                }
+                result = NFD_OKAY;
+            }
+        }
+    }
+    app.quit();
+    return result;
+}
+
+nfdresult_t NFD_OpenDialog( const char *filterList, const nfdchar_t *defaultPath, nfdchar_t **outPath )
+{
+    return NFD_QTOpenDialog(QFileDialog::AcceptOpen, QFileDialog::ExistingFile, filterList, defaultPath, outPath, nullptr);
+}
+
+nfdresult_t NFD_OpenDialogMultiple( const nfdchar_t *filterList, const nfdchar_t *defaultPath, nfdpathset_t *outPaths )
+{
+    return NFD_QTOpenDialog(QFileDialog::AcceptOpen, QFileDialog::ExistingFiles, filterList, defaultPath, nullptr, outPaths);
+}
+
+nfdresult_t NFD_SaveDialog( const nfdchar_t *filterList, const nfdchar_t *defaultPath, nfdchar_t **outPath )
+{
+    return NFD_QTOpenDialog(QFileDialog::AcceptSave, QFileDialog::AnyFile, filterList, defaultPath, outPath, nullptr);
+}
+
+nfdresult_t NFD_PickFolder( const nfdchar_t *defaultPath, nfdchar_t **outPath )
+{
+    return NFD_QTOpenDialog(QFileDialog::AcceptOpen, QFileDialog::Directory, nullptr, defaultPath, outPath, nullptr);
+}