Support for selecting directory using dialog

include/nanogui/common.h

@@ -274,6 +274,15 @@ extern NANOGUI_EXPORT std::string
 file_dialog(const std::vector<std::pair<std::string, std::string>> &filetypes,
             bool save);
 
+/**
+* \brief Open a native directory dialog.
+*
+*
+* \param saved_path
+*     Optional parameter to specify a directory that the dialog should start in.
+*/
+    extern NANOGUI_EXPORT std::string
+    directory_dialog(std::string saved_path = "");
 
 /**
  * \brief Check for the availability of displays with 10-bit color and/or

src/common.cpp

@@ -16,6 +16,7 @@
 #  define NOMINMAX 1
 #  endif
 #  include <windows.h>
+#  include <shlobj.h>
 #endif
 
 #include <nanogui/opengl.h>
@@ -441,6 +442,67 @@ std::vector<std::string> file_dialog(const std::vector<std::pair<std::string, st
 }
 #endif
 
+#if !defined(__APPLE__)
+    #if !defined(_WIN32)
+        //linux
+        std::string directory_dialog(const std::string save_dir){
+            static const int DIRECTORY_DIALOG_MAX_BUFFER = 16384;
+            char buffer[DIRECTORY_DIALOG_MAX_BUFFER];
+            buffer[0] = '\0';
+
+            std::string cmd = "zenity --file-selection --directory ";
+            if(save_dir.length() > 0 ){
+                cmd += "--filename="+save_dir;
+            }
+
+            FILE *output = popen(cmd.c_str(), "r");
+            if (output == nullptr)
+                throw std::runtime_error("popen() failed -- could not launch zenity!");
+            while (fgets(buffer, DIRECTORY_DIALOG_MAX_BUFFER, output) != NULL);
+            pclose(output);
+            std::string path(buffer);
+
+            path.erase(std::remove(path.begin(), path.end(), '\n'), path.end());
+
+            return path;
+
+        };
+    #else
+
+
+        std::string directory_dialog(const std::string saved_path){
+            TCHAR path[MAX_PATH];
+
+            const char * path_param = saved_path.c_str();
+
+            BROWSEINFO browseInfo = { 0 };
+            browseInfo.lpszTitle  = ("Select directory");
+            browseInfo.ulFlags    = BIF_RETURNONLYFSDIRS | BIF_NEWDIALOGSTYLE | BIF_EDITBOX | BIF_BROWSEINCLUDEURLS;
+            browseInfo.lParam     = (LPARAM) path_param;
+
+            LPITEMIDLIST pidl = SHBrowseForFolder ( &browseInfo );
+
+            if( pidl == 0 ){
+                return "";
+            }else{
+                //get path
+                SHGetPathFromIDList ( pidl, path );
+
+                //free memory
+                IMalloc * imalloc = 0;
+
+                if ( SUCCEEDED( SHGetMalloc ( &imalloc )) ){
+                    imalloc->Free(pidl);
+                    imalloc->Release();
+                }
+
+                return path;
+            }
+        }
+
+    #endif
+#endif
+
 static void (*object_inc_ref_py)(PyObject *) noexcept = nullptr;
 static void (*object_dec_ref_py)(PyObject *) noexcept = nullptr;
 

src/darwin.mm

@@ -56,6 +56,24 @@ @interface NSScreen (ForwardDeclare)
     return result;
 }
 
+std::string directory_dialog(const std::string saved_path) {
+    NSOpenPanel *openDlg = [NSOpenPanel openPanel];
+
+    if(saved_path.length() > 0 ){
+        std::string urlString = "folder"+saved_path;
+        [openDlg setDirectoryURL: [NSURL URLWithString: [NSString stringWithUTF8String: urlString.c_str()]]];
+    }
+    [openDlg setCanChooseFiles:NO];
+    [openDlg setCanChooseDirectories:YES];
+    [openDlg setAllowsMultipleSelection:NO];
+
+    if ([openDlg runModal] == NSModalResponseOK) {
+        NSURL* url = [openDlg URL];
+        return ((char*) [[url path] UTF8String]);
+    }
+    return "";
+}
+
 void chdir_to_bundle_parent() {
     NSString *path = [[[NSBundle mainBundle] bundlePath] stringByDeletingLastPathComponent];
     chdir([path fileSystemRepresentation]);

src/python/main.cpp

@@ -111,6 +111,7 @@ NB_MODULE(nanogui_ext, m_) {
               bool)) &
               nanogui::file_dialog,
           D(file_dialog, 2));
+    m.def("directory_dialog", &nanogui::directory_dialog);
 #if defined(__APPLE__)
         m.def("chdir_to_bundle_parent", &nanogui::chdir_to_bundle_parent);
     #endif