blob: ebab171f267c0a94fa304386eeb837bd8d796b0b [file] [log] [blame]
// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// @dart = 2.9
part of swarmlib;
/// The base class for UI state that intends to support browser history.
abstract class UIState {
/// The event listener we hook to the window's "popstate" event.
/// This event is triggered by the back button or by the first page load.
StreamSubscription _historyTracking;
void startHistoryTracking() {
bool firstEvent = true;
var handler = EventBatch.wrap((event) {
String state = window.location.hash;
if (state.startsWith('#')) {
// TODO(jimhug): Support default argument on substring.
state = state.substring(1, state.length);
if (firstEvent && state != '') {
// TODO(jmesserly): When loading a bookmark or refreshing, we replace
// the app state with a clean app state so the back button works. It
// would be better to support jumping to the previous story.
// We'd need to do some history manipulation here and some fixes to
// the views for this.
window.history.replaceState(null, document.title, '#');
} else if (state != '') {
firstEvent = false;
_historyTracking = window.onPopState.listen(handler);
void stopHistoryTracking() {
if (_historyTracking != null) {
/// Pushes a state onto the browser history stack */
void pushToHistory() {
if (_historyTracking == null) {
throw 'history tracking not started';
String state = jsonEncode(toHistory());
// TODO(jmesserly): [state] should be an Object, and we should pass it to
// the state parameter instead of as a #hash URL. Right now we're working
// around b/4582542.
window.history.pushState(null, document.title, '${document.title}#$state');
/// Serialize the state to a form suitable for storing in browser history.
Map<String, String> toHistory();
/// Load the UI state from the given [values].
void loadFromHistory(Map<String, String> values);