File picker

A file browser that ships with the framework: a places sidebar on the left, a Name / Date Modified / Size / Kind table on the right, a toolbar with history arrows and a filter field, and a status row with the item count and a key legend.

It is registered by AddArlecchino under the route Routes.FilePicker, so nothing has to be wired up.

Asking for a path

private readonly ArlecchinoState _state;

_state.FilePicker = new FilePickerRequest(
    Title: "Pick a folder",
    PickFolder: true,
    InitialPath: Environment.CurrentDirectory,
    ReturnView: ViewKind.Default,
    OnPicked: path => _state.Output = $"picked: {path}");

return Routes.FilePicker;

Fill ArlecchinoState.FilePicker, then navigate to Routes.FilePicker — the view reads the request in its constructor. Navigating there without a request opens a folder picker rooted at the drive list that returns to ViewRoute.None.

Member	Meaning
Title	Shown in the toolbar
PickFolder	true picks directories, false picks files
InitialPath	Where browsing starts: a folder is opened, a file is opened in the folder that holds it and starts under the cursor, and a path that no longer exists starts at the drive list
ReturnView	Route navigated to after a pick or a cancel
OnPicked	Called with the chosen path before returning
Places	Extra sidebar entries, listed above the standard favorites
FileFilter	Predicate over the full path; files that fail it are not listed

_state.FilePicker = new FilePickerRequest(
    "Pick a save",
    PickFolder: false,
    start,
    ViewKind.Default,
    Load)
{
    Places = [new FilePickerPlace("Game saves", savesPath, "▪")],
    FileFilter = static path => path.EndsWith(".sav", StringComparison.OrdinalIgnoreCase),
};

The request is cleared on pick and on cancel, and ArlecchinoState.PickerLastFolder is set to the folder the picker ended in — pass it as the next InitialPath to resume where the user left off.

Sidebar

Above the standard entries come the request's own Places. Then Favorites — Desktop, Documents, Downloads, Pictures, Music, Videos, each skipped when the folder does not exist — and Locations: the home folder, This computer, and every ready drive. Section headers are not selectable.

Keys

Key	In the list	In the sidebar
↑ ↓	Move the selection	Move between places
PgUp PgDn Home End	Jump ten rows / to the ends	—
→	Enter the selected folder	Focus the list
←	Go to the parent folder, or focus the sidebar when already at the drive list	—
Enter	Open a folder; pick a file when picking files	Go to the place and focus the list
Ctrl+Enter	Pick the current folder when picking folders	—
Tab	Switch panes	Switch panes
Backspace	Shorten the filter, or go up when it is empty	—
any character	Appends to the filter	—
Esc	Cancel and return to ReturnView	Cancel

Typed characters go through KeyText, so filtering works on a non-latin layout — see Keyboard.

Text

Every label, column header, size, date and kind string is a delegate on ArlecchinoStrings.FilePicker, including the defaults that format 12.3 MB, Today at 9:41 and ZIP archive. See Localization.