1 //*********************************************************
3 // Copyright (c) Microsoft. All rights reserved.
4 // THIS CODE IS PROVIDED *AS IS* WITHOUT WARRANTY OF
5 // ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY
6 // IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR
7 // PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.
9 //*********************************************************
12 #include "LayoutAwarePage.h"
13 #include "SuspensionManager.h"
15 using namespace SDKSample::Common;
17 using namespace Platform;
18 using namespace Platform::Collections;
19 using namespace Windows::Foundation;
20 using namespace Windows::Foundation::Collections;
21 using namespace Windows::System;
22 using namespace Windows::UI::Core;
23 using namespace Windows::UI::ViewManagement;
24 using namespace Windows::UI::Xaml;
25 using namespace Windows::UI::Xaml::Controls;
26 using namespace Windows::UI::Xaml::Interop;
27 using namespace Windows::UI::Xaml::Navigation;
30 /// Initializes a new instance of the <see cref="LayoutAwarePage"/> class.
32 LayoutAwarePage::LayoutAwarePage()
34 if (Windows::ApplicationModel::DesignMode::DesignModeEnabled)
39 // Create an empty default view model
40 DefaultViewModel = ref new Map<String^, Object^>(std::less<String^>());
42 // When this page is part of the visual tree make two changes:
43 // 1) Map application view state to visual state for the page
44 // 2) Handle keyboard and mouse navigation requests
45 Loaded += ref new RoutedEventHandler(this, &LayoutAwarePage::OnLoaded);
47 // Undo the same changes when the page is no longer visible
48 Unloaded += ref new RoutedEventHandler(this, &LayoutAwarePage::OnUnloaded);
51 static DependencyProperty^ _defaultViewModelProperty =
52 DependencyProperty::Register("DefaultViewModel",
53 TypeName(IObservableMap<String^, Object^>::typeid), TypeName(LayoutAwarePage::typeid), nullptr);
56 /// Identifies the <see cref="DefaultViewModel"/> dependency property.
58 DependencyProperty^ LayoutAwarePage::DefaultViewModelProperty::get()
60 return _defaultViewModelProperty;
64 /// Gets an implementation of <see cref="IObservableMap<String, Object>"/> designed to be
65 /// used as a trivial view model.
67 IObservableMap<String^, Object^>^ LayoutAwarePage::DefaultViewModel::get()
69 return safe_cast<IObservableMap<String^, Object^>^>(GetValue(DefaultViewModelProperty));
73 /// Sets an implementation of <see cref="IObservableMap<String, Object>"/> designed to be
74 /// used as a trivial view model.
76 void LayoutAwarePage::DefaultViewModel::set(IObservableMap<String^, Object^>^ value)
78 SetValue(DefaultViewModelProperty, value);
82 /// Invoked when the page is part of the visual tree
84 /// <param name="sender">Instance that triggered the event.</param>
85 /// <param name="e">Event data describing the conditions that led to the event.</param>
86 void LayoutAwarePage::OnLoaded(Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
88 this->StartLayoutUpdates(sender, e);
90 // Keyboard and mouse navigation only apply when occupying the entire window
91 if (this->ActualHeight == Window::Current->Bounds.Height &&
92 this->ActualWidth == Window::Current->Bounds.Width)
94 // Listen to the window directly so focus isn't required
95 _acceleratorKeyEventToken = Window::Current->CoreWindow->Dispatcher->AcceleratorKeyActivated +=
96 ref new TypedEventHandler<CoreDispatcher^, AcceleratorKeyEventArgs^>(this,
97 &LayoutAwarePage::CoreDispatcher_AcceleratorKeyActivated);
98 _pointerPressedEventToken = Window::Current->CoreWindow->PointerPressed +=
99 ref new TypedEventHandler<CoreWindow^, PointerEventArgs^>(this,
100 &LayoutAwarePage::CoreWindow_PointerPressed);
101 _navigationShortcutsRegistered = true;
106 /// Invoked when the page is removed from visual tree
108 /// <param name="sender">Instance that triggered the event.</param>
109 /// <param name="e">Event data describing the conditions that led to the event.</param>
110 void LayoutAwarePage::OnUnloaded(Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
112 if (_navigationShortcutsRegistered)
114 Window::Current->CoreWindow->Dispatcher->AcceleratorKeyActivated -= _acceleratorKeyEventToken;
115 Window::Current->CoreWindow->PointerPressed -= _pointerPressedEventToken;
116 _navigationShortcutsRegistered = false;
118 StopLayoutUpdates(sender, e);
121 #pragma region Navigation support
124 /// Invoked as an event handler to navigate backward in the page's associated <see cref="Frame"/>
125 /// until it reaches the top of the navigation stack.
127 /// <param name="sender">Instance that triggered the event.</param>
128 /// <param name="e">Event data describing the conditions that led to the event.</param>
129 void LayoutAwarePage::GoHome(Object^ sender, RoutedEventArgs^ e)
131 (void) sender; // Unused parameter
132 (void) e; // Unused parameter
134 // Use the navigation frame to return to the topmost page
135 if (Frame != nullptr)
137 while (Frame->CanGoBack)
145 /// Invoked as an event handler to navigate backward in the navigation stack
146 /// associated with this page's <see cref="Frame"/>.
148 /// <param name="sender">Instance that triggered the event.</param>
149 /// <param name="e">Event data describing the conditions that led to the event.</param>
150 void LayoutAwarePage::GoBack(Object^ sender, RoutedEventArgs^ e)
152 (void) sender; // Unused parameter
153 (void) e; // Unused parameter
155 // Use the navigation frame to return to the previous page
156 if (Frame != nullptr && Frame->CanGoBack)
163 /// Invoked as an event handler to navigate forward in the navigation stack
164 /// associated with this page's <see cref="Frame"/>.
166 /// <param name="sender">Instance that triggered the event.</param>
167 /// <param name="e">Event data describing the conditions that led to the event.</param>
168 void LayoutAwarePage::GoForward(Object^ sender, RoutedEventArgs^ e)
170 (void) sender; // Unused parameter
171 (void) e; // Unused parameter
173 // Use the navigation frame to advance to the next page
174 if (Frame != nullptr && Frame->CanGoForward)
181 /// Invoked on every keystroke, including system keys such as Alt key combinations, when
182 /// this page is active and occupies the entire window. Used to detect keyboard navigation
183 /// between pages even when the page itself doesn't have focus.
185 /// <param name="sender">Instance that triggered the event.</param>
186 /// <param name="args">Event data describing the conditions that led to the event.</param>
187 void LayoutAwarePage::CoreDispatcher_AcceleratorKeyActivated(CoreDispatcher^ sender, AcceleratorKeyEventArgs^ args)
189 auto virtualKey = args->VirtualKey;
191 // Only investigate further when Left, Right, or the dedicated Previous or Next keys
193 if ((args->EventType == CoreAcceleratorKeyEventType::SystemKeyDown ||
194 args->EventType == CoreAcceleratorKeyEventType::KeyDown) &&
195 (virtualKey == VirtualKey::Left || virtualKey == VirtualKey::Right ||
196 (int)virtualKey == 166 || (int)virtualKey == 167))
198 auto coreWindow = Window::Current->CoreWindow;
199 auto downState = Windows::UI::Core::CoreVirtualKeyStates::Down;
200 bool menuKey = (coreWindow->GetKeyState(VirtualKey::Menu) & downState) == downState;
201 bool controlKey = (coreWindow->GetKeyState(VirtualKey::Control) & downState) == downState;
202 bool shiftKey = (coreWindow->GetKeyState(VirtualKey::Shift) & downState) == downState;
203 bool noModifiers = !menuKey && !controlKey && !shiftKey;
204 bool onlyAlt = menuKey && !controlKey && !shiftKey;
206 if (((int)virtualKey == 166 && noModifiers) ||
207 (virtualKey == VirtualKey::Left && onlyAlt))
209 // When the previous key or Alt+Left are pressed navigate back
210 args->Handled = true;
211 GoBack(this, ref new RoutedEventArgs());
213 else if (((int)virtualKey == 167 && noModifiers) ||
214 (virtualKey == VirtualKey::Right && onlyAlt))
216 // When the next key or Alt+Right are pressed navigate forward
217 args->Handled = true;
218 GoForward(this, ref new RoutedEventArgs());
224 /// Invoked on every mouse click, touch screen tap, or equivalent interaction when this
225 /// page is active and occupies the entire window. Used to detect browser-style next and
226 /// previous mouse button clicks to navigate between pages.
228 /// <param name="sender">Instance that triggered the event.</param>
229 /// <param name="args">Event data describing the conditions that led to the event.</param>
230 void LayoutAwarePage::CoreWindow_PointerPressed(CoreWindow^ sender, PointerEventArgs^ args)
232 auto properties = args->CurrentPoint->Properties;
234 // Ignore button chords with the left, right, and middle buttons
235 if (properties->IsLeftButtonPressed || properties->IsRightButtonPressed ||
236 properties->IsMiddleButtonPressed) return;
238 // If back or foward are pressed (but not both) navigate appropriately
239 bool backPressed = properties->IsXButton1Pressed;
240 bool forwardPressed = properties->IsXButton2Pressed;
241 if (backPressed ^ forwardPressed)
243 args->Handled = true;
244 if (backPressed) GoBack(this, ref new RoutedEventArgs());
245 if (forwardPressed) GoForward(this, ref new RoutedEventArgs());
251 #pragma region Visual state switching
254 /// Invoked as an event handler, typically on the <see cref="Loaded"/> event of a
255 /// <see cref="Control"/> within the page, to indicate that the sender should start receiving
256 /// visual state management changes that correspond to application view state changes.
258 /// <param name="sender">Instance of <see cref="Control"/> that supports visual state management
259 /// corresponding to view states.</param>
260 /// <param name="e">Event data that describes how the request was made.</param>
261 /// <remarks>The current view state will immediately be used to set the corresponding visual state
262 /// when layout updates are requested. A corresponding <see cref="Unloaded"/> event handler
263 /// connected to <see cref="StopLayoutUpdates"/> is strongly encouraged. Instances of
264 /// <see cref="LayoutAwarePage"/> automatically invoke these handlers in their Loaded and Unloaded
265 /// events.</remarks>
266 /// <seealso cref="DetermineVisualState"/>
267 /// <seealso cref="InvalidateVisualState"/>
268 void LayoutAwarePage::StartLayoutUpdates(Object^ sender, RoutedEventArgs^ e)
270 (void) e; // Unused parameter
272 auto control = safe_cast<Control^>(sender);
273 if (_layoutAwareControls == nullptr)
275 // Start listening to view state changes when there are controls interested in updates
276 _layoutAwareControls = ref new Vector<Control^>();
277 _windowSizeEventToken = Window::Current->SizeChanged += ref new WindowSizeChangedEventHandler(this, &LayoutAwarePage::WindowSizeChanged);
279 // Page receives notifications for children. Protect the page until we stopped layout updates for all controls.
282 _layoutAwareControls->Append(control);
284 // Set the initial visual state of the control
285 VisualStateManager::GoToState(control, DetermineVisualState(ApplicationView::Value), false);
288 void LayoutAwarePage::WindowSizeChanged(Object^ sender, Windows::UI::Core::WindowSizeChangedEventArgs^ e)
290 (void) sender; // Unused parameter
291 (void) e; // Unused parameter
293 InvalidateVisualState();
297 /// Invoked as an event handler, typically on the <see cref="Unloaded"/> event of a
298 /// <see cref="Control"/>, to indicate that the sender should start receiving visual state
299 /// management changes that correspond to application view state changes.
301 /// <param name="sender">Instance of <see cref="Control"/> that supports visual state management
302 /// corresponding to view states.</param>
303 /// <param name="e">Event data that describes how the request was made.</param>
304 /// <remarks>The current view state will immediately be used to set the corresponding visual state
305 /// when layout updates are requested.</remarks>
306 /// <seealso cref="StartLayoutUpdates"/>
307 void LayoutAwarePage::StopLayoutUpdates(Object^ sender, RoutedEventArgs^ e)
309 (void) e; // Unused parameter
311 auto control = safe_cast<Control^>(sender);
313 if (_layoutAwareControls != nullptr && _layoutAwareControls->IndexOf(control, &index))
315 _layoutAwareControls->RemoveAt(index);
316 if (_layoutAwareControls->Size == 0)
318 // Stop listening to view state changes when no controls are interested in updates
319 Window::Current->SizeChanged -= _windowSizeEventToken;
320 _layoutAwareControls = nullptr;
321 // Last control has received the Unload notification.
328 /// Translates <see cref="ApplicationViewState"/> values into strings for visual state management
329 /// within the page. The default implementation uses the names of enum values. Subclasses may
330 /// override this method to control the mapping scheme used.
332 /// <param name="viewState">View state for which a visual state is desired.</param>
333 /// <returns>Visual state name used to drive the <see cref="VisualStateManager"/></returns>
334 /// <seealso cref="InvalidateVisualState"/>
335 String^ LayoutAwarePage::DetermineVisualState(ApplicationViewState viewState)
339 case ApplicationViewState::Filled:
341 case ApplicationViewState::Snapped:
343 case ApplicationViewState::FullScreenPortrait:
344 return "FullScreenPortrait";
345 case ApplicationViewState::FullScreenLandscape:
347 return "FullScreenLandscape";
352 /// Updates all controls that are listening for visual state changes with the correct visual
356 /// Typically used in conjunction with overriding <see cref="DetermineVisualState"/> to
357 /// signal that a different value may be returned even though the view state has not changed.
359 void LayoutAwarePage::InvalidateVisualState()
361 if (_layoutAwareControls != nullptr)
363 String^ visualState = DetermineVisualState(ApplicationView::Value);
364 auto controlIterator = _layoutAwareControls->First();
365 while (controlIterator->HasCurrent)
367 auto control = controlIterator->Current;
368 VisualStateManager::GoToState(control, visualState, false);
369 controlIterator->MoveNext();
376 #pragma region Process lifetime management
379 /// Invoked when this page is about to be displayed in a Frame.
381 /// <param name="e">Event data that describes how this page was reached. The Parameter
382 /// property provides the group to be displayed.</param>
383 void LayoutAwarePage::OnNavigatedTo(NavigationEventArgs^ e)
385 // Returning to a cached page through navigation shouldn't trigger state loading
386 if (_pageKey != nullptr) return;
388 auto frameState = SuspensionManager::SessionStateForFrame(Frame);
389 _pageKey = "Page-" + Frame->BackStackDepth;
391 if (e->NavigationMode == NavigationMode::New)
393 // Clear existing state for forward navigation when adding a new page to the
395 auto nextPageKey = _pageKey;
396 int nextPageIndex = Frame->BackStackDepth;
397 while (frameState->HasKey(nextPageKey))
399 frameState->Remove(nextPageKey);
401 nextPageKey = "Page-" + nextPageIndex;
404 // Pass the navigation parameter to the new page
405 LoadState(e->Parameter, nullptr);
409 // Pass the navigation parameter and preserved page state to the page, using
410 // the same strategy for loading suspended state and recreating pages discarded
412 LoadState(e->Parameter, safe_cast<IMap<String^, Object^>^>(frameState->Lookup(_pageKey)));
417 /// Invoked when this page will no longer be displayed in a Frame.
419 /// <param name="e">Event data that describes how this page was reached. The Parameter
420 /// property provides the group to be displayed.</param>
421 void LayoutAwarePage::OnNavigatedFrom(NavigationEventArgs^ e)
423 auto frameState = SuspensionManager::SessionStateForFrame(Frame);
424 auto pageState = ref new Map<String^, Object^>();
425 SaveState(pageState);
426 frameState->Insert(_pageKey, pageState);
430 /// Populates the page with content passed during navigation. Any saved state is also
431 /// provided when recreating a page from a prior session.
433 /// <param name="navigationParameter">The parameter value passed to
434 /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested.
436 /// <param name="pageState">A map of state preserved by this page during an earlier
437 /// session. This will be null the first time a page is visited.</param>
438 void LayoutAwarePage::LoadState(Object^ navigationParameter, IMap<String^, Object^>^ pageState)
443 /// Preserves state associated with this page in case the application is suspended or the
444 /// page is discarded from the navigation cache. Values must conform to the serialization
445 /// requirements of <see cref="SuspensionManager.SessionState"/>.
447 /// <param name="pageState">An empty map to be populated with serializable state.</param>
448 void LayoutAwarePage::SaveState(IMap<String^, Object^>^ pageState)