Get Application Bar from Parent - Windows Phone - windows-phone-7

I'm using MVVM architecture in a WP7 phone app. My current view is a user control, which exists inside of a parent page (standard page -- not stand-alone user control). I have passed the main page as a parent to a "parent" property of the user control, and I can access pretty much any control in the parent. For example: this works to access a lockable pivot in the parent:
Dim p As LockablePivot
p = MyParent.FindControl("myLockablePivot")
If p IsNot Nothing Then
..do something with the pivot
End If
My problem is in accessing the ApplicationBar in the parent. This does not work. I have triple checked the x:Name assigned to the application bar. (null reference exception):
Dim ap As ApplicationBar
ap = MyParent.FindName("appBar")
ap.IsVisible = False
Any help would be appreciated.

I hit the same issue, but as Nigel points out in this answer, the
"ApplicationBar isn't a standard Silverlight object, because of that it doesn't really fit in the visual tree, can't be bound to and x:Name doesn't work."
It turns out that there is an ApplicationBar property on the PhoneApplicationPage class. You can use it to access the Application Bar and then grab the Buttons or MenuItems from there.
Here is a C# example of what I did in my page constructor to localize the text:
public MyPage()
{
InitializeComponent();
(this.ApplicationBar.Buttons[0] as ApplicationBarIconButton).Text = AppResources.event_add_menu_item;
}
Admittedly, using the index to locate the item and then having to cast is unfortunate, but at least it works!

Related

Visual Basic: Can not access TextBox attribiutes

Sorry. i am officially new in Visual Basic.
I have created a TextBox in my form. In "View Code" i want to access the Text attribute
(I mean TextBox.Text)
,but the object only gives me these 4: Count,Item,LBound,UBound
Maybe you're changing the Index property instead of the TabIndex property so that it would become a control array thus UBound, LBound, Count and Item properties are present.
And i suspect you are using Visual Basic 6 instead of VB.Net.
See link here the VB6 has Index property that is for Control Array.
My guess, without seeing your code is that your syntax is somehow interacting with an array, try this code:
Public Class Form1
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Me.TextBox1.Text = "Hello World"
End Sub
End Class
Note: The above code represents the default names for a Form, a new TextBox dragged and dropped onto the designer inside of the form's Load event handler.
Are you possibly copying and pasting a textbox rather than double clicking the object in the toolbox. If you look in the name of the object in the properties window you would see txtName(0)

Display a custom login control in Windows Phone with Mvvm light

Ok, so what I am looking to do is to display some sort of login control (maybe a UserControl with a TextBox and PasswordBox) when the app is started.
In a non-mvvm situation, a way of doing this would be to use the PopUp primitive control, add the usercontrol as a child element and off you go.
In an MVVM situation, i'm a bit confused about how you would achieve a simmilar result.
I have looked into messaging with the DialogMessage and this is fine for displaying a typical MessageBox, but what about a custom usercontrol?
any help would be fantastic! I can't seem to find any demo code of this anywhere.
In a MVVM situation you can use a delegate to let your View open the dialog when the ViewModel requests it.
You define a delegate at the VM:
public Func<LoginResult> ShowLoginDialogDelegate;
In your View you define the function that will be called:
private LoginResult ShowLoginDialog()
{
LoginResult result;
// show a dialog and get the login data
return result;
}
Then you "connect" the delegate and method in the View:
_viewModel = new MyViewModel();
DataContext = _viewModel;
_viewModel.ShowLoginDialogDelegate += ShowLoginDialog;
And now you can use it in your ViewModel e.g. when a command is executed like that:
LoginResult result = ShowLoginDialogDelegate();
An easier answer is to control it's visibility through a View State which with a little manipulation can be made to work through databinding allowing the view model to display the "Logon Page" state when required.
I just recently wrote about this for the Silverlight/XNA series which you can view here.
It would be much simplier if the SL4 DataEventrigger was available but hay ho.

Prism 4: Unloading view from Region?

How do I unload a view from a Prism Region?
I am writing a WPF Prism app with a Ribbon control in the Shell. The Ribbon's Home tab contains a region, RibbonHomeTabRegion, into which one of my modules (call it ModuleA) loads a RibbonGroup. That works fine.
When the user navigates away from ModuleA, the RibbonGroup needs to be unloaded from the RibbonHomeTabRegion. I am not replacing the RibbonGroup with another view--the region should be empty.
EDIT: I have rewritten this part of the question:
When I try to remove the view, I get an error message that "The region does not contain the specified view." So, I wrote the following code to delete whatever view is in the region:
// Get the regions views
var regionManager = ServiceLocator.Current.GetInstance<IRegionManager>();
var ribbonHomeTabRegion = regionManager.Regions["RibbonHomeTabRegion"];
var views = ribbonHomeTabRegion.Views;
// Unload the views
foreach (var view in views)
{
ribbonHomeTabRegion.Remove(view);
}
I am still getting the same error, which tells me there is something pretty basic that I am doing incorrectly.
Can anyone point me in the right direction? Thanks for your help.
I found my answer, although I can't say I fully understand it. I had used IRegionManager.RequestNavigate() to inject the RibbonGroup into the Ribbon's Home tab, like this:
// Load RibbonGroup into Navigator pane
var noteListNavigator = new Uri("NoteListRibbonGroup", UriKind.Relative);
regionManager.RequestNavigate("RibbonHomeTabRegion", noteListNavigator);
I changed the code to inject the view by Registering it with the region, like this:
// Load Ribbon Group into Home tab
regionManager.RegisterViewWithRegion("RibbonHomeTabRegion", typeof(NoteListRibbonGroup));
Now I can remove the RibbonGroup using this code:
if(ribbonHomeTabRegion.Views.Contains(this))
{
ribbonHomeTabRegion.Remove(this);
}
So, how you inject the view apparently matters. If you want to be able to remove the view, inject by registration with the Region Manager
StockTraderRI Example Project by Microsoft contains the following example of removing views from region in ViewModel.
private void RemoveOrdersView()
{
IRegion region = this._regionManager.Regions[RegionNames.ActionRegion];
object ordersView = region.GetView("OrdersView");
if (ordersView != null)
{
region.Remove(ordersView);
}
}
Is it possible you have a RegionAdapter that is wrapping the view inside another view before adding it? The ribbonHomeTabRegion should have a property with the collection of views - is there anything inside it?

Passing data from page to page

I'm looking for the best practice on how to pass data from page to page.
In Page A I have a button that fires off Page B.
On Page B I have 6 textboxes that allow the user to enter information.
When the user is done, the click on a button that brings them back to Page A.
I want to pass that data back to Page A.
I've seen suggestions to:
build XML documents and save to Isolated Storage
use the App class to store information in properties
pass it like a query string
I'm looking for the Best practice. Is there one that Microsoft recommends or one that is generally accepted as the best way?
Thanks
PhoneApplicationService.Current.State["yourparam"] = param
NavigationService.Navigate(new Uri("/view/Page.xaml", UriKind.Relative));
then in other page simply
var k = PhoneApplicationService.Current.State["yourparam"];
Personally I'd store the values entered on Page B in a model(object) that is also accessible to Page A.
Depending on how you're navigating to Page A the second time, one or more of the following may be usful to help understand passing values between pages:
How to pass the image value in one xaml page to another xaml page in windows phone 7?
Passing a complex object to a page while navigating in a WP7 Silverlight application
How to pass an object from a xaml page to another?
How to pass a value between Silverlight pages for WP7?
How do I navigate from one xaml page to another, and pass values?
One thing you can consider is to use MVC: let your App be the controller, store all data in the model, and the pages are just views that contains pure UI logic. In this case your pages are painters and you pass your model object around. This gives nice isolation of business logic and the UI so that you can rev them easily.
BTW, Silverlight and XAML are great tools for MVC so it's a natural match.
There's a couple of things at play here. First of all, if/when the user uses the Back button to return to page A instead of your button, is the information in the text boxes exchanged or not (is Back = Cancel, or is Back = OK?)
That said, if you're using NavigationService.GoBack (which you should be instead of NavigationService.Navigate, because if you use the Navigate call, repeated hits of the back key will cause all kinds of bad UX for your users), then QueryStrings are not an option. Because pages really have no way to reference each other in the WP7 Silverlight nav system, you need to use a 3rd party to hold your data. For that, you can turn to (a) Isolated Storage (slow & heavy, but fail-safe), (b) Use the PhoneApplicationService.State dictionary, or (c) use Global properties of some kind, either hung off of the application object, or using Statics/Singletons...
Remember to watch for Tombstoning behavior when you do this - your page will process the OnNavigatedTo method when (a) you navigate into it in your application (b) you navigate back to it when you complete your work on Page B, or (c) you tombstone your app from that page and return to your application using the Back key.
Sorry I didn't give a more direct answer there - a lot depends on your specific circumstances. In the most general case, I'd strongly consider using the App State Dictionary on the PhoneApplicationService...it is lightweight, easy to use, and survives tombstoning. Just be sure that your keys are as unique as they need to be.
If you create a new Windows Phone project and use the Windows Phone Databound Template you will have most of the work done for you.
What you will want to do is set up the ViewModel to contain all the data for your app. You can serialize and deserialize this data using IsolatedStorage so that it's saved across application sessions and when Tombstoning.
In the template you will notice MailViewModel and ItemViewModel. MainViewModel stores all the data your application needs including an ObservableCollection of ItemViewModel, and ItemViewModel represents the individual data type for your application.
On the DetailsPage.xaml page you'll want to DataBind each textbox to the App.MainViewModel Items. Set the binding to TwoWay if you want the ViewModel to get updated as soon as the user manipulates the data on DetailsPage.xaml. You can optionally set the Binding to OneWay and then have an OK button that writes the changes back to the ViewModel and saves to IsolatedStorage.
Here is an example of what a Binding looks like:
<TextBlock x:Name="ListTitle" Text="{Binding LineOne}" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
In this case LineOne is a property in ItemViewModel and the page gets this data from the query string when the user selects an item from the MainPage.xaml. The DataContext for the page determs where the databound information comes from.
Here is the snippet where the MainPage passes the selected item from the ViewModel to the DetailsPage.
// Handle selection changed on ListBox
private void MainListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
// If selected index is -1 (no selection) do nothing
if (MainListBox.SelectedIndex == -1)
return;
// Navigate to the new page
NavigationService.Navigate(new Uri("/DetailsPage.xaml?selectedItem=" + MainListBox.SelectedIndex, UriKind.Relative));
// Reset selected index to -1 (no selection)
MainListBox.SelectedIndex = -1;
}
Here is how the DetailsPage gets the selected item.
protected override void OnNavigatedTo(NavigationEventArgs e)
{
string selectedIndex = "";
if (NavigationContext.QueryString.TryGetValue("selectedItem", out selectedIndex))
{
int index = int.Parse(selectedIndex);
DataContext = App.ViewModel.Items[index];
}
}
Play around with the default template above and ask any additional questions.
The beauty of databinding and the ObservableCollection is that you can just update the data and the UX will reflect those changes immediatley. This is because any changes to the data fires off an event:
public string LineOne
{
get
{
return _lineOne;
}
set
{
if (value != _lineOne)
{
_lineOne = value;
NotifyPropertyChanged("LineOne");
}
}
}
NotifyPropertyChanged() that broadcasts this information to the View.
You can also keep it simple and use PhoneApplicationService.Current.State which is basically a hashtable. You will need to implement your own marshalling to and from isolated storage if you want anything to outlive the app.
Omar's suggestion to use the Windows Phone Databound Template is probably the best idea on this page. It amounts to the same as my suggestion but you will get a better result (more maintainable code) at the cost of a longer steeper learning curve.
I suggest you do it my way and then do it again Omar's way.
as i implemented like this.. Whether its correct or not i dont know..
When u click news list page it should open the news detail page.
I want to pass the selected news item contents from news List-Page to news-details Page.
the News list page contains following method.
protected override void OnNavigatedFrom(System.Windows.Navigation.NavigationEventArgs e)
{
NewsDetailsPage newsDetailPage = (e.Content as NewsDetailsPage);
if (newsDetailPage != null)
newsDetailPage.SelectedNewsItem = SelectedNewsItem; //Contains the news details
base.OnNavigatedFrom(e);
}
In the News details Page. U can access that(SelectedNewsItem) object.
This may or may not be correct.
One option is to use Application.Resources:
Store data:
Application.Current.Resources.Add("NavigationParam", customers);
NavigationService.Navigate(new Uri("/Page2.xaml", UriKind.Relative));
Retrieve data:
var customers = (List<Customer>) Application.Current.Resources["NavigationParam"];
Here's a blog post with describes this in more detail: http://mikaelkoskinen.net/windows-phone-pass-data-between-pages-application-resources/ (author: me)

Access controls of parent dialog in VB6

I have a dialog in vb6 which changes the values being displayed in its parent dialog.
The x1 is displayed in txt_c1 text in parent dialog and it has a txt_1validate function too for the text box. Now i want to change the value of txt_c1 txtbox from child dialog and then call its validate function. But the problem is that txt_c1 is not available in child dialog.
Please note that i am working in vb6 in the MS VB 6.0 IDE
Forms are just classes and can therefore be instantiated explictly (and you will probably find your life easier if you do rather than using the automatic instantiation in VB6) and references to forms can be assigned.
You can solve your problem by creating a public property on your child dialog (Form1.frm) of type Form that you set to the instance of the parent dialog thus giving you access to the controls andd methods on the parent from the child.
My VB6 is somewhat rusty (and I don't have an installed instance available) so this isn't going to be actual, correct code - but something along the lines of the following should work
In the code that calls the child:
Form childDialog = new Form1
childDialog.Parent = this
childDialog.ShowModal
Then in the child dialog:
Parent.txt_c1 = newValue
if not Parent.Validate then
...
end if

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