/// <summary>
/// Callback method for the handling of messages to be sent to/from the folder browser dialog.
/// </summary>
/// <param name="hwnd"></param>
/// <param name="msg"></param>
/// <param name="lParam"></param>
/// <param name="lpData"></param>
/// <returns></returns>
private int FolderBrowserDialog_BrowseCallbackProc(IntPtr hwnd, int msg, IntPtr lParam, IntPtr lpData)
{
switch (msg)
{
case NativeWindowCommon.BFFM_INITIALIZED:
// We get in here when the dialog is first displayed. If an initial directory
// has been specified we will make this the selection now, and also make sure
// that directory is expanded.
if (this.selectedPath.Length != 0)
{
NativeWindowCommon.SendMessage(hwnd, NativeWindowCommon.BFFM_SETSELECTIONW, 1, this.selectedPath);
}
break;
case NativeWindowCommon.BFFM_SELCHANGED:
{
IntPtr pidl = lParam;
if (pidl != IntPtr.Zero)
{
StringBuilder sb = new StringBuilder(MAX_PATH * Marshal.SystemDefaultCharSize);
bool flag = NativeWindowCommon.SHGetPathFromIDList(pidl, sb);
NativeWindowCommon.SendMessage(hwnd, NativeWindowCommon.BFFM_ENABLEOK, 0, flag ? 1 : 0);
}
if (!doneScrolling)
{
IntPtr hbrowse = NativeWindowCommon.FindWindowEx(hwnd, IntPtr.Zero, "SHBrowseForFolder ShellNameSpace Control", null);
IntPtr htree = NativeWindowCommon.FindWindowEx(hbrowse, IntPtr.Zero, "SysTreeView32", null);
IntPtr htis = NativeHeader.SendMessage(htree, NativeWindowCommon.TVM_GETNEXTITEM, NativeWindowCommon.TVGN_CARET, IntPtr.Zero);
IntPtr htir = NativeHeader.SendMessage(htree, NativeWindowCommon.TVM_GETNEXTITEM, NativeWindowCommon.TVGN_ROOT, IntPtr.Zero);
IntPtr htic = NativeHeader.SendMessage(htree, NativeWindowCommon.TVM_GETNEXTITEM, NativeWindowCommon.TVGN_CHILD, htir);
//we actually go into the BFFM_SELCHANGED case three times when the dialog is first shown, and it's only on the third one that we actually scroll,
//since before this htic is always zero, so you need to cope with this
//- i.e. don't set 'doneScrolling' flag until htic has been non - zero(or until you've gone into the BFFM_SELCHANGED three times).
if ((int)htic != 0)
{
doneScrolling = true;
//The only solution I've found that works consistently is to send a TVM_ENSUREVISIBLE to the tree, using TVM_GETNEXTITEM/TVGN_CARET, from BFFM_SELCHANGED.
//That works. Every time.
NativeHeader.SendMessage(htree, NativeWindowCommon.TVM_ENSUREVISIBLE, 0, htis);
//Active the tree view control window inside the folder browser dialog to set the focus on it.
NativeWindowCommon.SendMessage(htree, NativeWindowCommon.WM_ACTIVATE, 1, 0);
}
}
}
break;
}
return(0);
}
/// <summary>
/// Shows the folder browser dialog box with the specified owner window.
/// </summary>
protected override bool RunDialog(IntPtr hWndOwner)
{
IntPtr pidlRoot = IntPtr.Zero;
bool flag = false;
// Get the IDL for the specific startLocation. e.g. Environment.SpecialFolder.Desktop
NativeWindowCommon.SHGetSpecialFolderLocation(hWndOwner, (int)this.rootFolder, ref pidlRoot);
if (pidlRoot == IntPtr.Zero)
{
// Get the IDL for the default startLocation.
NativeWindowCommon.SHGetSpecialFolderLocation(hWndOwner, 0, ref pidlRoot);
if (pidlRoot == IntPtr.Zero)
{
throw new InvalidOperationException();
}
}
int flags = GetFlags();
if ((flags & (int)NativeWindowCommon.BffStyles.NewDialogStyle) != 0)
{
if (System.Threading.ApartmentState.MTA == Application.OleRequired())
{
flags = flags & (~(int)NativeWindowCommon.BffStyles.NewDialogStyle);
}
}
IntPtr pidl = IntPtr.Zero;
IntPtr hglobal = IntPtr.Zero;
try
{
hglobal = Marshal.AllocHGlobal((int)(MAX_PATH * Marshal.SystemDefaultCharSize));
this.callback = new NativeWindowCommon.BrowseCallbackProc(this.FolderBrowserDialog_BrowseCallbackProc);
NativeWindowCommon.BROWSEINFO lpbi = new NativeWindowCommon.BROWSEINFO
{
pidlRoot = pidlRoot,
hwndOwner = hWndOwner,
pszDisplayName = hglobal,
lpszTitle = this.descriptionText,
ulFlags = flags,
lpfn = this.callback,
lParam = IntPtr.Zero,
iImage = 0
};
// Show the dialog.
pidl = NativeWindowCommon.SHBrowseForFolder(ref lpbi);
if (pidl != IntPtr.Zero)
{
// Retrieve the path from the IDList.
StringBuilder sb = new StringBuilder(MAX_PATH * Marshal.SystemDefaultCharSize);
NativeWindowCommon.SHGetPathFromIDList(pidl, sb);
this.selectedPathNeedsCheck = true;
this.selectedPath = sb.ToString();
flag = true;
}
}
finally
{
NativeWindowCommon.IMalloc malloc = GetSHMalloc();
//Free the memory allocated for getting the ID list for the specific startLocation.
malloc.Free(pidlRoot);
if (pidl != IntPtr.Zero)
{
//Free the memory allocated for getting the ID list for the showing the SHBrowseForFolder.
malloc.Free(pidl);
}
// Free the buffer you've allocated on the global heap.
if (hglobal != IntPtr.Zero)
{
Marshal.FreeHGlobal(hglobal);
}
//Reset the callback function to null.
this.callback = null;
}
return(flag);
}