/// <include file='doc\FolderBrowserDialog.uex' path='docs/doc[@for="FolderBrowserDialog.RunDialog"]/*' />
/// <devdoc>
/// Implements running of a folder browser dialog.
/// </devdoc>
protected override bool RunDialog(IntPtr hWndOwner)
{
IntPtr pidlRoot = IntPtr.Zero;
bool returnValue = false;
UnsafeNativeMethods.Shell32.SHGetSpecialFolderLocation(hWndOwner, (int)rootFolder, ref pidlRoot);
if (pidlRoot == IntPtr.Zero)
{
UnsafeNativeMethods.Shell32.SHGetSpecialFolderLocation(hWndOwner, NativeMethods.CSIDL_DESKTOP, ref pidlRoot);
if (pidlRoot == IntPtr.Zero)
{
throw new InvalidOperationException(SR.GetString(SR.FolderBrowserDialogNoRootFolder));
}
}
int mergedOptions = unchecked ((int)(long)UnsafeNativeMethods.BrowseInfos.NewDialogStyle);
if (!showNewFolderButton)
{
mergedOptions += unchecked ((int)(long)UnsafeNativeMethods.BrowseInfos.HideNewFolderButton);
}
// The SHBrowserForFolder dialog is OLE/COM based, and documented as only being safe to use under the STA
// threading model if the BIF_NEWDIALOGSTYLE flag has been requested (which we always do in mergedOptions
// above). So make sure OLE is initialized, and throw an exception if caller attempts to invoke dialog
// under the MTA threading model (...dialog does appear under MTA, but is totally non-functional).
if (Control.CheckForIllegalCrossThreadCalls && Application.OleRequired() != System.Threading.ApartmentState.STA)
{
throw new System.Threading.ThreadStateException(SR.GetString(SR.DebuggingExceptionOnly, SR.GetString(SR.ThreadMustBeSTA)));
}
IntPtr pidlRet = IntPtr.Zero;
IntPtr pszDisplayName = IntPtr.Zero;
IntPtr pszSelectedPath = IntPtr.Zero;
try
{
// Construct a BROWSEINFO
UnsafeNativeMethods.BROWSEINFO bi = new UnsafeNativeMethods.BROWSEINFO();
pszDisplayName = Marshal.AllocHGlobal(NativeMethods.MAX_PATH * Marshal.SystemDefaultCharSize);
pszSelectedPath = Marshal.AllocHGlobal((NativeMethods.MAX_PATH + 1) * Marshal.SystemDefaultCharSize);
this.callback = new UnsafeNativeMethods.BrowseCallbackProc(this.FolderBrowserDialog_BrowseCallbackProc);
bi.pidlRoot = pidlRoot;
bi.hwndOwner = hWndOwner;
bi.pszDisplayName = pszDisplayName;
bi.lpszTitle = descriptionText;
bi.ulFlags = mergedOptions;
bi.lpfn = callback;
bi.lParam = IntPtr.Zero;
bi.iImage = 0;
// And show the dialog
pidlRet = UnsafeNativeMethods.Shell32.SHBrowseForFolder(bi);
if (pidlRet != IntPtr.Zero)
{
// Then retrieve the path from the IDList
UnsafeNativeMethods.Shell32.SHGetPathFromIDListLongPath(pidlRet, ref pszSelectedPath);
// set the flag to True before selectedPath is set to
// assure security check and avoid bogus race condition
selectedPathNeedsCheck = true;
// Convert to a string
selectedPath = Marshal.PtrToStringAuto(pszSelectedPath);
returnValue = true;
}
}
finally
{
UnsafeNativeMethods.CoTaskMemFree(pidlRoot);
if (pidlRet != IntPtr.Zero)
{
UnsafeNativeMethods.CoTaskMemFree(pidlRet);
}
// Then free all the stuff we've allocated or the SH API gave us
if (pszSelectedPath != IntPtr.Zero)
{
Marshal.FreeHGlobal(pszSelectedPath);
}
if (pszDisplayName != IntPtr.Zero)
{
Marshal.FreeHGlobal(pszDisplayName);
}
this.callback = null;
}
return(returnValue);
}