I have Windows Phone 8.1 app and I need to navigate from a page to a new instance of the same page. For example:
Main Page -> Canvas-?
Where 'Canvas' - xaml page, '?' - guid of instance. I know that in wp8 it is going like this:
NavigationService.Navigate(new Uri("/Canvas.xaml?guid=" + myGuid, UriKind.Relative));
I write this code in MainPage.cs.Xaml:
private void addNewCanvas_Click(object sender, RoutedEventArgs e)
{
string cnvsGuid = Guid.NewGuid().ToString();
System.Diagnostics.Debug.WriteLine(cnvsGuid);
tabs.Add(new CanvasTab(){label=String.Format("New Canvas {0}",countOfOpenTabs),canvasGuid=cnvsGuid});
countOfOpenTabs++;
this.tabsGrid.ItemsSource=null;
this.tabsGrid.ItemsSource=tabs;
System.Diagnostics.Debug.WriteLine(tabsGrid.Items.Count());
this.Frame.Navigate(typeof(Canvas),cnvsGuid);
}
private void tabsGrid_ItemClick(object sender, ItemClickEventArgs e)
{
this.Frame.Navigate(typeof(Canvas), ((CanvasTab)e.ClickedItem).canvasGuid);
System.Diagnostics.Debug.WriteLine(((CanvasTab)e.ClickedItem).canvasGuid);
}
private void navigationHelper_LoadState(object sender, LoadStateEventArgs e)
{
if (e.PageState != null)
{
this.tabs = e.PageState["tabs"] as List<CanvasTab>;
this.tabsGrid.ItemsSource = null;
this.tabsGrid.ItemsSource = tabs;
}
}
private void navigationHelper_SaveState(object sender, SaveStateEventArgs e)
{
e.PageState["tabs"] = tabs;
}
And Add This Code to constructor of MainPage:
this.NavigationCacheMode = NavigationCacheMode.Enabled;
this.navigationHelper = new NavigationHelper(this);
this.navigationHelper.LoadState += this.navigationHelper_LoadState;
this.navigationHelper.SaveState += this.navigationHelper_SaveState;
And write code in Canvas.cs.xaml:
private void navigationHelper_LoadState(object sender, LoadStateEventArgs e)
{
if (e.PageState != null)
{
UIElementCollection canvasItems = e.PageState["canvasItems"] as UIElementCollection;
foreach (UIElement itm in canvasItems)
{
this.mainCanvas.Children.Add(itm);
}
this.mainCanvas.UpdateLayout();
}
}
private void navigationHelper_SaveState(object sender, SaveStateEventArgs e)
{
e.PageState["canvasItems"] = this.mainCanvas.Children;
}
And write this code in constructor of Canvas:
this.navigationHelper = new NavigationHelper(this);
this.navigationHelper.LoadState += this.navigationHelper_LoadState;
this.navigationHelper.SaveState += this.navigationHelper_SaveState;
this.NavigationCacheMode = NavigationCacheMode.Required;
And it always only caching only one canvas for all Guids.
Try using NavigationCacheMode.Required
within your constructor
.
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