folderBrowseDialog hangs application

M

magicRoot

Newcomer
Joined
Jan 19, 2009
Messages
7
Hi,
I programming a windows forms application with visualC++ 2008 Express Edition. I have a button event that triggers a folderBrowseDialog component to open. When the user chooses a folder, the dialog closes and the application hangs indefinitely.

Heres the code

Code: 
button2_Click(System::Object^  sender, System::EventArgs^  e) {
                 System::Threading::Thread^ temp = gcnew System::Threading::Thread( gcnew System::Threading::ThreadStart(this, &FormApp::Form1::folderDialog));
                 temp->SetApartmentState(System::Threading::ApartmentState::STA);
                 temp->Start();
             temp->Join();
         }

private: void folderDialog(){            
            ////create and show a directory dialog box
            folderBrowserDialog1 = gcnew FolderBrowserDialog();
            //folderBrowser->RootFolder = Environment::SpecialFolder::MyComputer;
            //// save the current directory
            String^ currentDirectory = System::IO::Directory::GetCurrentDirectory();

            ////show the dialog
            System::Windows::Forms::DialogResult result = folderBrowserDialog1->ShowDialog();

            if(result == System::Windows::Forms::DialogResult::OK){
                folderName = folderBrowserDialog1->SelectedPath;
                    
                //enable the preview button
                button3->Enabled = true;
            }

            
         }

When I comment out temp->Join(), the app does not hang but if I do that, the folderBrowseDialog can be pushed behind the main application, which is what I dont want. I want the folderBrowseDialog to be in front until the user chooses a folder or exits the dialog. How can I stop the application hang? Thanks
 
Last edited:
I don't know c++ at all, but have a few questions.
Why are you making button1 create a new thread? Why not just call folderDialog() directly from button1?

I suspect the reason the FBD shows behind the form is because it's being called from a non-UI thread (illegal cross-threading).

If you need to have the code execute from a background thread, then use delegates to display the FBD.
 
calling showDialog() within button2_Click() brings up other issues; primarily, the folderBrowserDialog does not display properly, the filesystem tree is missing and all that is displayed in the dialog are buttons. I have read in other forums about that issue but no solutions given have worked in my code. This is the what I have resulted to so far. How would I go about using delegates? I have not worked with that mechanism much and would it solve my problem stated above? Thanks
 
I solved problem, here it is in case some of you run into the same bump

Code: 
button2_Click(System::Object^  sender, System::EventArgs^  e) {

				// save the current directory
				String^ currentDirectory = System::IO::Directory::GetCurrentDirectory();
				
				//create a new thread that will display the foloderBrowserDialog
				// this is done to give the folderBrowserDialog freedom
				System::Threading::Thread^ temp = gcnew System::Threading::Thread( gcnew System::Threading::ThreadStart(this, &App::Form1::folderDialog));
				temp->SetApartmentState(System::Threading::ApartmentState::STA);
				temp->Start();
				temp->Join();

				if(folderBrowserDialog1->SelectedPath != ""){

					folderName = folderBrowserDialog1->SelectedPath;

	
				 }
				// switch back to the working directory
				System::IO::Directory::SetCurrentDirectory(currentDirectory);
		 }

 // thread function for the folder browser
private: void folderDialog(){
			//configure the dialog
			folderBrowserDialog1->SelectedPath = "";


			//show the dialog
			System::Windows::Forms::DialogResult result = folderBrowserDialog1->ShowDialog();
		 }
 
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