How to open a windows file open or save dialog without crashing Unity?

Questions & Answers
1

I want to open a file dialog on windows to open a file with. This is my current code:

var openFileDialog : System.Windows.Forms.OpenFileDialog = new System.Windows.Forms.OpenFileDialog();
openFileDialog.InitialDirectory = Application.dataPath;
openFileDialog.Filter = "text files (*.txt)|*.txt";
openFileDialog.FilterIndex = 2;
openFileDialog.RestoreDirectory = false;
openFileDialog.ShowDialog();

It actually works fine after building my project and kinda okay, when executing it the first time from within Unity, but with the following message in the log:

IsD3D9DeviceLost() || g_D3DInsideScene System.Windows.Forms.XplatUIWin32:Win32GetMessage(MSG&, IntPtr, Int32, Int32) System.Windows.Forms.XplatUIWin32:Win32GetMessage(MSG&, IntPtr, Int32, Int32) System.Windows.Forms.XplatUIWin32:GetMessage(MSG&, IntPtr, Int32, Int32, Boolean) System.Windows.Forms.XplatUIWin32:GetMessage(Object, MSG&, IntPtr, Int32, Int32) System.Windows.Forms.XplatUI:GetMessage(Object, MSG&, IntPtr, Int32, Int32) System.Windows.Forms.Application:RunLoop(Boolean, ApplicationContext) System.Windows.Forms.Form:ShowDialog(IWin32Window) System.Windows.Forms.CommonDialog:ShowDialog(IWin32Window) System.Windows.Forms.CommonDialog:ShowDialog()

The dialog shows up, I can choose my file and open it. If I now leave Unity and am moving a bit through my folder structure using the explorer, I usually get the standart win 7 message that Unity doesnt react anymore. If I dont do this, but open another dialog, I get tons of error messages and in the end the same windows message. The error messages I get then look like this (as popup windows):

Oops: Could not register the window class, win32 error 0

Sometimes the form shows up a second time and everything works as the first time, but then after the third time opening the dialog Unity crashes.

It would be great if anyone could tell me what I am doing wrong and maybe how to solve it :) Thanks.

3

Assuming you are using the script for the editor...

Take a look at the EditorUtility class' OpenFilePanel instead of using .NET functionality that might intervene with Unity's processes.

2

make sure to use mono's windows.forms.dll and not the .net one. it should works with both but test it. there is another way to use a C++ dll and call the open dialog and return the result in a dll function call.

4

The best thing to do is code a plugin that does this now that all versions of Unity support plugins. You can easily make this multi-platform for all computer OSes by using defines and setting the correct dll/bundle to load.

I’ve just made a plugin for OSX and it works great. Just make sure you build a universal bundle if you plan on making your game run on a 32bit machine.