private async Task<bool> NavigateCore(
Type sourcePageType, object parameter, NavigationMode navigationMode)
{
_isNavigating = true;
this.CanNavigate = false;
this.CanGoBack = false;
this.CanGoForward = false;
this.IsHitTestVisible = false;
// Make sure we run on UI thread
if (!Dispatcher.HasThreadAccess)
{
Task<bool> navigateCoreTask = null;
await Dispatcher.RunAsync(
CoreDispatcherPriority.High,
() => navigateCoreTask = NavigateCore(sourcePageType, parameter, navigationMode));
return await navigateCoreTask;
}
try
{
await _waitForApplyTemplateTaskSource.Task;
await this.WaitForLoadedAsync();
AlternativePage currentPage = null;
#region OnNavigatingFrom part
if (_currentPagePresenter != null)
{
currentPage = (AlternativePage)_currentPagePresenter.Content;
var cancelArgs =
new AlternativeNavigatingCancelEventArgs(
navigationMode,
sourcePageType);
await this.OnNavigating(cancelArgs);
if (!cancelArgs.Cancel)
{
await currentPage.OnNavigatingFromInternal(cancelArgs);
}
if (cancelArgs.Cancel)
{
return false;
}
}
#endregion
#region Initializing new page instance part
var je = new JournalEntry { SourcePageType = sourcePageType, Parameter = parameter };
AlternativePage newPage;
ContentPresenter newPagePresenter;
if (_preloadedPageCache.ContainsKey(je))
{
newPagePresenter = _preloadedPageCache[je];
newPage = (AlternativePage)newPagePresenter.Content;
_preloadedPageCache.Remove(je);
}
else
{
newPage = _frameCache.Get(je.SourcePageType);
if (newPage == null)
{
throw new InvalidOperationException(
"Pages used in AlternativeFrame need to be of AlternativePage type.");
}
newPage.Frame = this;
newPagePresenter = new ContentPresenter { Style = PagePresenterStyle };
newPagePresenter.Content = newPage;
_pagePresentersPanel.Children.Add(newPagePresenter);
}
newPagePresenter.Opacity = 0.005;
await UnloadAllPreloaded();
#endregion
#region OnNavigatingTo part
var args = new AlternativeNavigationEventArgs(
newPage.Content, navigationMode, je.Parameter, je.SourcePageType);
await newPage.OnNavigatingToInternal(args);
#endregion
#region Journal Bookeeping part
switch (navigationMode)
{
case NavigationMode.New:
this.ForwardStack.Clear();
if (this.CurrentJournalEntry != null)
{
this.BackStack.Push(this.CurrentJournalEntry);
}
break;
case NavigationMode.Forward:
this.ForwardStack.Pop();
if (this.CurrentJournalEntry != null)
{
this.BackStack.Push(this.CurrentJournalEntry);
}
break;
case NavigationMode.Back:
this.BackStack.Pop();
if (this.CurrentJournalEntry != null)
{
this.ForwardStack.Push(this.CurrentJournalEntry);
}
break;
}
this.CurrentJournalEntry = je;
#endregion
#region OnNavigated~() calls
await this.OnNavigated(args);
if (currentPage != null)
{
await currentPage.OnNavigatedFromInternal(args);
}
await newPage.OnNavigatedToInternal(args);
#endregion
#region Transition part
await newPagePresenter.WaitForLoadedAsync();
await newPagePresenter.WaitForNonZeroSizeAsync();
if (this.ShouldWaitForImagesToLoad == true &&
newPage.ShouldWaitForImagesToLoad != false ||
newPage.ShouldWaitForImagesToLoad == true &&
this.ShouldWaitForImagesToLoad != false)
{
await newPage.WaitForImagesToLoad(WaitForImagesToLoadTimeout);
}
newPagePresenter.Opacity = 1.0;
if (navigationMode == NavigationMode.Back)
{
await TransitionBackward(
currentPage,
newPage,
_currentPagePresenter,
newPagePresenter);
}
else
{
await TransitionForward(
currentPage,
newPage,
_currentPagePresenter,
newPagePresenter);
}
if (_currentPagePresenter != null)
{
_pagePresentersPanel.Children.Remove(_currentPagePresenter);
_frameCache.Store(currentPage);
}
_currentPagePresenter = newPagePresenter;
#endregion
return true;
}
finally
{
this.IsHitTestVisible = true;
_isNavigating = false;
this.CanNavigate = true;
this.CanGoBack = this.BackStack.Count > 0;
this.CanGoForward = this.ForwardStack.Count > 0;
//DC.TraceLocalized(GetNavigationState());
}
}
/// <summary>
/// Unloads the preloaded page of a given type and parameter.
/// </summary>
/// <remarks>
/// A page might have been preloaded in the anticipation of the user navigating to it,
/// then a state change might invalidate or reduce the possibility of a navigation request and
/// it might be worth unloading the preloaded page to release resources that it consumed.
/// The preloaded page will be released or cached depending on its NavigationCacheMode property.
/// </remarks>
/// <param name="sourcePageType">Type of the source page.</param>
/// <param name="parameter">The parameter.</param>
/// <returns></returns>
public async Task UnloadPreloaded(Type sourcePageType, object parameter)
{
var je = new JournalEntry { SourcePageType = sourcePageType, Parameter = parameter };
if (!_preloadedPageCache.ContainsKey(je))
{
return;
}
var cp = _preloadedPageCache[je];
var page = (AlternativePage)cp.Content;
await page.UnloadPreloadedInternal();
_frameCache.Store(page);
_pagePresentersPanel.Children.Remove(cp);
_preloadedPageCache.Remove(je);
}
private void AppendEntryToNavigationStateString(StringBuilder sb, JournalEntry journalEntry)
{
var pageTypeString = journalEntry.SourcePageType.AssemblyQualifiedName;
sb.AppendFormat(",{0},{1}", pageTypeString.Length, pageTypeString);
if (journalEntry.Parameter == null)
{
sb.Append(",0");
return;
}
var valueString = journalEntry.Parameter.ToString();
if (journalEntry.Parameter is byte)
{
AddParameterToNavigationStateString(sb, 1, valueString);
return;
}
if (journalEntry.Parameter is Int16)
{
AddParameterToNavigationStateString(sb, 2, valueString);
return;
}
if (journalEntry.Parameter is UInt16)
{
AddParameterToNavigationStateString(sb, 3, valueString);
return;
}
if (journalEntry.Parameter is Int32)
{
AddParameterToNavigationStateString(sb, 4, valueString);
return;
}
if (journalEntry.Parameter is UInt32)
{
AddParameterToNavigationStateString(sb, 5, valueString);
return;
}
if (journalEntry.Parameter is Int64)
{
AddParameterToNavigationStateString(sb, 6, valueString);
return;
}
if (journalEntry.Parameter is UInt64)
{
AddParameterToNavigationStateString(sb, 7, valueString);
return;
}
if (journalEntry.Parameter is Single)
{
AddParameterToNavigationStateString(sb, 8, valueString);
return;
}
if (journalEntry.Parameter is Double)
{
AddParameterToNavigationStateString(sb, 9, valueString);
return;
}
if (journalEntry.Parameter is Char)
{
AddParameterToNavigationStateString(sb, 10, valueString);
return;
}
if (journalEntry.Parameter is Boolean)
{
AddParameterToNavigationStateString(sb, 11, valueString);
return;
}
if (journalEntry.Parameter is String)
{
AddParameterToNavigationStateString(sb, 12, valueString);
}
}
/// <summary>
/// Preloads a page of the specified source page type.
/// </summary>
/// <remarks>
/// Allows to preload a page before user navigates to it, so if it does get navigated to - shows up quickly.
/// If another page gets navigated to - the preloaded page will be released or cached depending on its NavigationCacheMode property.
/// </remarks>
/// <param name="sourcePageType">Type of the source page.</param>
/// <param name="parameter">The parameter.</param>
/// <returns></returns>
public async Task<bool> Preload(Type sourcePageType, object parameter)
{
var je = new JournalEntry { SourcePageType = sourcePageType, Parameter = parameter };
if (_preloadedPageCache.ContainsKey(je))
{
return true;
}
var cp = new ContentPresenter { Style = PagePresenterStyle };
var newPage = _frameCache.Get(sourcePageType);
Debug.Assert(newPage != null, "Pages used in AlternativeFrame need to be of AlternativePage type.");
if (newPage == null)
{
return false;
}
newPage.Frame = this;
cp.Content = newPage;
cp.Opacity = 0.005;
Canvas.SetZIndex(cp, int.MinValue);
_pagePresentersPanel.Children.Insert(0, cp);
_preloadedPageCache.Add(je, cp);
await newPage.PreloadInternal(parameter);
cp.Opacity = 0;
return true;
}
public async Task<bool> Navigate(Type sourcePageType, object parameter)
{
if (_isNavigating)
{
throw new InvalidOperationException("Navigation already in progress.");
}
_isNavigating = true;
this.CanNavigate = false;
this.CanGoBack = false;
try
{
await this.WaitForLoadedAsync();
AlternativePage currentPage = null;
if (_currentPagePresenter != null)
{
currentPage = (AlternativePage)_currentPagePresenter.Content;
var cancelArgs =
new AlternativeNavigatingCancelEventArgs(
NavigationMode.New,
sourcePageType);
await currentPage.OnNavigatingFromInternal(cancelArgs);
if (cancelArgs.Cancel)
{
return false;
}
}
var je = new JournalEntry {Type = sourcePageType, Parameter = parameter};
AlternativePage newPage;
ContentPresenter newPagePresenter;
if (_preloadedPageCache.ContainsKey(je))
{
newPagePresenter = _preloadedPageCache[je];
newPage = (AlternativePage)newPagePresenter.Content;
_preloadedPageCache.Remove(je);
}
else
{
newPage = (AlternativePage)Activator.CreateInstance(je.Type);
newPage.Frame = this;
newPagePresenter = new ContentPresenter {Style = PagePresenterStyle};
newPagePresenter.Content = newPage;
_pagePresentersPanel.Children.Add(newPagePresenter);
}
newPagePresenter.Opacity = 0.005;
// TODO: await?
UnloadPreloadedPages();
var args = new AlternativeNavigationEventArgs(
newPage.Content, NavigationMode.New, je.Parameter, je.Type);
await newPage.OnNavigatingToInternal(args);
await newPagePresenter.WaitForLoadedAsync();
await newPagePresenter.WaitForNonZeroSizeAsync();
if (this.ShouldWaitForImagesToLoad == true && newPage.ShouldWaitForImagesToLoad != false ||
newPage.ShouldWaitForImagesToLoad == true && this.ShouldWaitForImagesToLoad != false)
{
await newPage.WaitForImagesToLoad();
}
newPagePresenter.Opacity = 1.0;
if (this.PageTransition != null)
{
await this.PageTransition.TransitionForward(_currentPagePresenter, newPagePresenter);
}
this.BackStack.Push(je);
if (currentPage != null)
{
await currentPage.OnNavigatedFromInternal(args);
_pagePresentersPanel.Children.Remove(_currentPagePresenter);
}
_currentPagePresenter = newPagePresenter;
await newPage.OnNavigatedToInternal(args);
return true;
}
finally
{
_isNavigating = false;
this.CanNavigate = true;
this.CanGoBack = this.BackStack.Count > 1;
}
}
// Allows to preload a page before user navigates to it, so if it does get navigated to - it is quick.
public async Task Preload(Type sourcePageType, object parameter)
{
var je = new JournalEntry {Type = sourcePageType, Parameter = parameter};
if (_preloadedPageCache.ContainsKey(je))
{
return;
}
var cp = new ContentPresenter {Style = PagePresenterStyle};
var newPage = (AlternativePage)Activator.CreateInstance(sourcePageType);
newPage.Frame = this;
cp.Content = newPage;
cp.Opacity = 0.005;
Canvas.SetZIndex(cp, int.MinValue);
_pagePresentersPanel.Children.Insert(0, cp);
_preloadedPageCache.Add(je, cp);
await newPage.PreloadInternal(parameter);
}
private void AppendEntryToNavigationStateString(StringBuilder sb, JournalEntry journalEntry)
{
var pageTypeString = journalEntry.SourcePageType.AssemblyQualifiedName;
sb.AppendFormat(",{0},{1}", pageTypeString.Length, pageTypeString);
if (journalEntry.Parameter == null)
{
sb.Append(",0");
return;
}
var valueString = journalEntry.Parameter.ToString();
if (journalEntry.Parameter is byte)
{
AddParameterToNavigationStateString(sb, 1, valueString);
return;
}
if (journalEntry.Parameter is Int16)
{
AddParameterToNavigationStateString(sb, 2, valueString);
return;
}
if (journalEntry.Parameter is UInt16)
{
AddParameterToNavigationStateString(sb, 3, valueString);
return;
}
if (journalEntry.Parameter is Int32)
{
AddParameterToNavigationStateString(sb, 4, valueString);
return;
}
if (journalEntry.Parameter is UInt32)
{
AddParameterToNavigationStateString(sb, 5, valueString);
return;
}
if (journalEntry.Parameter is Int64)
{
AddParameterToNavigationStateString(sb, 6, valueString);
return;
}
if (journalEntry.Parameter is UInt64)
{
AddParameterToNavigationStateString(sb, 7, valueString);
return;
}
if (journalEntry.Parameter is Single)
{
AddParameterToNavigationStateString(sb, 8, valueString);
return;
}
if (journalEntry.Parameter is Double)
{
AddParameterToNavigationStateString(sb, 9, valueString);
return;
}
if (journalEntry.Parameter is Char)
{
AddParameterToNavigationStateString(sb, 10, valueString);
return;
}
if (journalEntry.Parameter is Boolean)
{
AddParameterToNavigationStateString(sb, 11, valueString);
return;
}
if (journalEntry.Parameter is String)
{
AddParameterToNavigationStateString(sb, 12, valueString);
return;
}
if (journalEntry.Parameter is Guid)
{
AddParameterToNavigationStateString(sb, 16, valueString);
}
}
private async Task <bool> NavigateCoreAsync(
Type sourcePageType, object parameter, NavigationMode navigationMode)
{
_isNavigating = true;
this.CanNavigate = false;
this.CanGoBack = false;
this.CanGoForward = false;
this.IsHitTestVisible = false;
// Make sure we run on UI thread
if (!Dispatcher.HasThreadAccess)
{
Task <bool> navigateCoreTask = null;
await Dispatcher.RunAsync(
CoreDispatcherPriority.High,
() => navigateCoreTask = this.NavigateCoreAsync(sourcePageType, parameter, navigationMode));
return(await navigateCoreTask);
}
try
{
await _waitForApplyTemplateTaskSource.Task;
await this.WaitForLoadedAsync();
AlternativePage currentPage = null;
#region OnNavigatingFrom part
if (_currentPagePresenter != null)
{
currentPage = (AlternativePage)_currentPagePresenter.Content;
var cancelArgs =
new AlternativeNavigatingCancelEventArgs(
navigationMode,
sourcePageType);
await this.OnNavigatingAsync(cancelArgs);
if (!cancelArgs.Cancel)
{
await currentPage.OnNavigatingFromInternalAsync(cancelArgs);
}
if (cancelArgs.Cancel)
{
return(false);
}
}
#endregion
#region Initializing new page instance part
var je = new JournalEntry {
SourcePageType = sourcePageType, Parameter = parameter
};
AlternativePage newPage;
ContentPresenter newPagePresenter;
if (_preloadedPageCache.ContainsKey(je))
{
newPagePresenter = _preloadedPageCache[je];
newPage = (AlternativePage)newPagePresenter.Content;
_preloadedPageCache.Remove(je);
}
else
{
newPage = _frameCache.Get(je.SourcePageType);
if (newPage == null)
{
throw new InvalidOperationException(
"Pages used in AlternativeFrame need to be of AlternativePage type.");
}
newPage.Frame = this;
newPagePresenter = new ContentPresenter {
Style = PagePresenterStyle
};
newPagePresenter.Content = newPage;
_pagePresentersPanel.Children.Add(newPagePresenter);
}
newPagePresenter.Opacity = 0.005;
await UnloadAllPreloadedAsync();
#endregion
#region OnNavigatingTo part
var args = new AlternativeNavigationEventArgs(
newPage.Content, navigationMode, je.Parameter, je.SourcePageType);
await newPage.OnNavigatingToInternalAsync(args);
#endregion
#region Journal Bookeeping part
switch (navigationMode)
{
case NavigationMode.New:
this.ForwardStack.Clear();
if (this.CurrentJournalEntry != null)
{
this.BackStack.Push(this.CurrentJournalEntry);
}
break;
case NavigationMode.Forward:
this.ForwardStack.Pop();
if (this.CurrentJournalEntry != null)
{
this.BackStack.Push(this.CurrentJournalEntry);
}
break;
case NavigationMode.Back:
this.BackStack.Pop();
if (this.CurrentJournalEntry != null)
{
this.ForwardStack.Push(this.CurrentJournalEntry);
}
break;
}
this.CurrentJournalEntry = je;
#endregion
#region OnNavigatedAsync~() calls
this.UpdateCans();
if (currentPage != null)
{
await currentPage.OnNavigatedFromInternalAsync(args);
}
await this.OnNavigatedAsync(args);
await newPage.OnNavigatedToInternalAsync(args);
#endregion
#region Transition part
await newPagePresenter.WaitForLoadedAsync();
await newPagePresenter.WaitForNonZeroSizeAsync();
if (this.ShouldWaitForImagesToLoad == true &&
newPage.ShouldWaitForImagesToLoad != false ||
newPage.ShouldWaitForImagesToLoad == true &&
this.ShouldWaitForImagesToLoad != false)
{
await newPage.WaitForImagesToLoadAsync(WaitForImagesToLoadTimeout);
}
newPagePresenter.Opacity = 1.0;
if (navigationMode == NavigationMode.Back)
{
await this.TransitionBackwardAsync(
currentPage,
newPage,
_currentPagePresenter,
newPagePresenter);
}
else
{
await this.TransitionForwardAsync(
currentPage,
newPage,
_currentPagePresenter,
newPagePresenter);
}
if (_currentPagePresenter != null)
{
_pagePresentersPanel.Children.Remove(_currentPagePresenter);
_frameCache.Store(currentPage);
}
_currentPagePresenter = newPagePresenter;
#endregion
return(true);
}
finally
{
this.IsHitTestVisible = true;
_isNavigating = false;
this.UpdateCans();
//DC.TraceLocalized(GetNavigationState());
}
}
