I have a WPF application with Page navigation. I use MvvmLight toolkit. I have two pages: FirstPage (default page) and SecondPage. On FirstPage I navigate to SecondPage.
I want to pass a parameter to SecondPage.
//code on FirstPage
NavigationService.NavigateTo(new Uri("SecondPage.xaml", UriKind.Relative));
Messenger.Default.Send<string>("my mess");
//code on SecondPage
//constructor
public SecondPage()
{
Messenger.Default.Register<string>(this, GetMess);
}
private void GetMess(string obj)
{
}
When you first start it's not working. I can create an instance of SecondPage,
PageSecond page = new PageSecond();
but it is not beautiful. Help me please.
You are not following the MVVM principle with code like this in the code-behind. So following your start here is a simple (non-MVVM) way answer this:
Code on FirstPage -
Page secondPage = new SecondPage("Hello");
NavigationService.Navigate(secondPage);
Code on SecondPage
// Public parameterless constructor - needed for designer
public SecondPage()
{
InitializeComponent();
}
// Constructor with parameter
public SecondPage(string parameter)
{
InitializeComponent();
MyTextBox.Text = parameter;
}
Related
I'm developing a Windows application (UWP) that has two pages, I want the best practice to pass parameters between pages.
it's my scenario:
We have two pages, each open and remain at the middle of the screen and a Button on each page, which send the message to the other page when we click on it.
I also want to pass information continuously and repeatedly.
in Page1.cs:
Page2 page2;
public Page1()
{
this.InitializeComponent();
CreatPage2();
}
// creat page 2
private async void CreatPage2()
{
var NewWindow = CoreApplication.CreateNewView();
int NewWindowid = 0;
await NewWindow.Dispatcher.RunAsync(CoreDispatcherPriority.High, () =>
{
Frame newframe = new Frame();
newframe.Navigate(typeof(Page2), this);
Window.Current.Content = newframe;
Window.Current.Activate();
ApplicationView.GetForCurrentView().Title = "page2";
NewWindowid = ApplicationView.GetForCurrentView().Id;
});
await Windows.UI.ViewManagement.ApplicationViewSwitcher.TryShowAsStandaloneAsync(NewWindowid);
}
//Button
private void ChangeP2_Click(object sender, RoutedEventArgs e)
{
// send a message to the texblock in the page2
page2.TexBlock2.Text=$"From page1 :{e.ToString()}";
// change text color of the texblock in the page2
page2.Foreground= new SolidColorBrush(Windows.UI.Colors.Red);
}
in Page2.cs:
Page1 page1;
protected override void OnNavigatedTo(NavigationEventArgs e)
{
page1 = e.Parameter as Page1;
base.OnNavigatedTo(e);
}
public Page2()
{
this.InitializeComponent();
}
//Button
private void ChangeP1_Click(object sender, RoutedEventArgs e)
{
// send a message to the texblock in the page1
page1.TexBlock1.Text=$"From page2 :{e.ToString()}";
// change text color of the texblock in the page1
page1.Foreground= new SolidColorBrush(Windows.UI.Colors.Red);
}
the above code just work for the page2 to the page1. (it can change the textblock of pagea).
Please help me, I can't find a solution that work on two pages
Naah… the best way is to use a standard pattern that consist of an app ViewModel class, which contains all the common app data that you want to use in the logic layer.
I always do it like this:
1) I use the MainPage automatically created as the "shell" of the app, with a property that is the AppViewModel.
The MainPage (and thus the AppViewModel) can be accessed from everywhere in the app, by setting itself as a static field in its own class.
This is the code, simpler than you think:
public sealed partial class MainPage : Page
{
public AppViewModel ViewModel { get; set; } = new AppViewModel();
public static MainPage Current { get; set; }
public MainPage()
{
this.InitializeComponent();
Current = this;
}
}
2) The AppViewModel itself is a class that must implement the INotifyPropertyChanged interface, in order to enable bindable properties and functions.
It is common, among developers, to create a base class that implements it and then derive all the classes that needs bindable properties from it.
Here it is:
public class BaseBind : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName] string propertyName = null) =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
protected bool SetProperty<T>(ref T storage, T value,
[CallerMemberName] String propertyName = null)
{
if (object.Equals(storage, value)) return false;
storage = value;
OnPropertyChanged(propertyName);
return true;
}
}
Then you derive AppViewModel class (and all the other model and viewmodel classes) from it… populating it with all the common properties that you need to share across pages.
I have even added a derived property, in order to show how you can share even multiple data types at once, and a function:
public class AppViewModel : BaseBind
{
public AppViewModel()
{
// ...
}
// All common app data
private string sampleCommonString;
public String SampleCommonString
{
get { return sampleCommonString; }
set { SetProperty(ref sampleCommonString, value); OnPropertyChanged(nameof(SampleDerivedProperty1)); OnPropertyChanged(nameof(SampleDerivedProperty2)); }
}
public String SampleDerivedProperty1 => "return something based on SampleCommonString";
public String SampleDerivedProperty2
{
get
{
<<evaluate SampleCommonString>>
return "Same thing as SampleDerivedProperty1, but more explicit";
}
}
// This is a property that you can use for functions and internal logic… but it CAN'T be binded
public String SampleNOTBindableProperty { get; set; }
public void SampleFunction()
{
// Insert code here.
// The function has to be with NO parameters, in order to work with simple {x:Bind} markup.
// If your function has to access some specific data, you can create a new bindable (or non) property, just as the ones above, and memorize the data there.
}
}
3) Then, in order to access all this from another Page, just create an AppViewModel field in that page, as seen below:
public sealed partial class SecondPage : Page
{
public AppViewModel ViewModel => MainPage.Current.ViewModel;
public SecondPage()
{
this.InitializeComponent();
}
}
...and you can easily bind XAML controls properties to the AppViewModel itself:
<TextBlock Text="{x:Bind ViewModel.SampleCommonString, Mode=OneWay}"/>
<Button Content="Sample content" Click="{x:Bind ViewModel.SampleFunction}"/>
(Mode=OneWay is for real-time binding, in order that the property is immediately updated even in the UI, while Mode=TwoWay is used for those properties that can be edited from the control itself, by the user, in order to interact with app logic).
Hope this helped.
Best regards and happy new year.
When I re-navigate to my first page (Called Mainpage) from a viewmodel it displays an empty page.
I understand that this is related to the stack but no matter what I try it stays empty. Does anyone has any ideas? I find related threads but not in the same way.
Mainpage constructor:
public Login()
{
InitializeComponent();
}
Code in the viewmodel
await Application.Current.MainPage.Navigation.PopToRootAsync();
await Application.Current.MainPage.Navigation.PushAsync(new Login());
Ok so for extra info:
Setting my rootpage:
public partial class App : Application
{
public App()
{
InitializeComponent();
NavigationPage navigationPage = new NavigationPage(new Login()); << Renamed mainpage to login after the suggestion over here
MainPage = navigationPage;
}
I call my rootpage after login. I want to make sure my code logs-out my user after the person his/hers ADAL token has expired. It would happen like this in my viewmodel:
var auth = DependencyService.Get<IAuthenticator>();
auth.logout();
await Application.Current.MainPage.Navigation.PopToRootAsync(true);
(Without pushAsync is does not navigate at all and stays at the current page. This is called straight after the new page is loaded and the user is logged-in)
In your App.cs you should have defined a NavigationPage passing the root of your navigation stack.
Let's say:
public class App : Application
{
public App ()
{
NavigationPage navigationPage = new NavigationPage (new MainPage ());
MainPage = navigationPage;
}
}
The root of your application will be MainPage.
Wherever in your application will call the Navigation.PopToRootAsync(); method, you'll go back to your root page. (MainPage in this case)
You don't need to push in the stack the MainPage because it's already there, you're popping out all the pages excluding the root.
The constructor of the page won't be called but you can rely on the Appearing event that is fired when the page is displayed.
initialize static NavigationPage variable in App.cs
public class App : Application
{
public static NavigationPage NavPage;
public App ()
{
NavPage= new NavigationPage (new MainPage ());
MainPage = NavPage;
}
}
use NavigationPage variable of App.cs for navigate main page from third page
public partial class thirdPage : ContentPage
{
public thirdPage ()
{
InitializeComponent ();
main.Clicked += Main_Clicked;
}
private void Main_Clicked(object sender, EventArgs e)
{
App.NavPage.PopToRootAsync(true);
}
}
I write my first WPF application, which consist of several pages:
Welcome page with some logo
Login page with login form
Main page with account info
MainWindow contains <Frame> WPF Control, and I use animation to show next/previous page.
I write my own MainAnimation class to perform animation.
This application works fine on my laptop, but when I try to run it on the machine of my friend animation just do nothing.
I think that trouble related with Dispatcher.Invoke() method calling, and I tried to find solution over the web (here here here and here) and I tried:
use Application.Current.Dispatcher
use Dispatcher.BeginInvoke() instead of Dispatcher.Invoke()
but it does nothing.
So, I show Welcome page only 2 seconds and Login page must loaded automatically.
This is the code of WelcomePage.xaml.cs file:
public partial class WelcomePage : Page {
public WelcomePage (MainWindow parent) {
InitializeComponent();
this.parent = parent;
Task.Factory.StartNew(() => ShowLoginForm());
}
private MainWindow parent;
private void ShowLoginForm()
{
Thread.Sleep(2000);
this.parent.GoToLoginForm();
}
}
This is the code of MainWindow.xaml.cs file:
public partial class MainWindow : Window {
public MainWindow () {
InitializeComponent();
animation = new MainAnimation(this, this, Main, new WelcomePage(this));
}
private MainAnimation animation;
public void GoToLoginForm() => animation.ShowNextPage(new LoginPage(this));
public void GoToVideosForm() => animation.ShowNextPage(new MainPage(this));
}
And this is related parts on MainAnimation class (MainAnimation.cs):
public class MainAnimation
{
public MainAnimation(FrameworkElement resourcesOwner, DispatcherObject dispatcherOwner, Frame currentPageContainer, Page firstPage)
{
this.resourcesOwner = resourcesOwner;
this.dispatcherOwner = dispatcherOwner;
this.currentPageContainer = currentPageContainer;
pages = new Stack<Page>();
pages.Push(firstPage);
currentPageContainer.Content = pages.Peek();
}
private Stack<Page> pages;
private FrameworkElement resourcesOwner;
private DispatcherObject dispatcherOwner;
private Frame currentPageContainer;
private void ShowPageForward()
{
dispatcherOwner.Dispatcher.Invoke((Action)delegate {
if (currentPageContainer.Content != null)
{
var page = currentPageContainer.Content as Page;
if (page != null)
{
page.Loaded -= NextPage_Loaded;
UnloadPageForward(page);
}
}
else
{
LoadPageForward();
}
});
}
private void UnloadPageForward(Page page)
{
Storyboard sb = (resourcesOwner.FindResource("SlideForwardOut") as Storyboard).Clone();
sb.Completed += StoryboardForward_Completed;
sb.Begin(currentPageContainer);
}
private void StoryboardForward_Completed(object sender, EventArgs e)
{
LoadPageForward();
}
private void LoadPageForward()
{
pages.Peek().Loaded += NextPage_Loaded;
currentPageContainer.Content = pages.Peek();
}
private void NextPage_Loaded(object sender, RoutedEventArgs e)
{
Storyboard sb = resourcesOwner.FindResource("SlideForwardIn") as Storyboard;
sb.Begin(currentPageContainer);
}
}
I'm new with WPF and may be just don't understand some details, so I will be happy if you help me to solve this small but very offensive issue.
Update #1: software versions
OS for development: Windows 10 x64
OS for test: Windows 8.1 x64
VS version: Visual Studio 2017 Community Edition
Application target framework: v.4.5
Since WPF controls have thread affinity it doesn't make much sense to create them on a background thread in most cases.
If you want to wait for 2 seconds before you show the login page, you could either use a DispatcherTimer or wait asynchronously:
public partial class WelcomePage : Page
{
public WelcomePage(MainWindow parent)
{
InitializeComponent();
this.parent = parent;
ShowLoginForm();
}
private MainWindow parent;
private async void ShowLoginForm()
{
await Task.Delay(2000);
this.parent.GoToLoginForm();
}
}
Then you won't need any calls to Dispatcher.Invoke.
I have two Pages and one MainWindow.. I load the Pages in two Frames.. Now I want to execute methods from each other.. How can I do this?
This is Page1.cs:
public partial class Page1 : Page
{
public Method1()
{
doSomething;
}
}
This is Page2.cs:
public partial class Page2 : Page
{
public Method2()
{
doSomethingElse;
}
}
In my MainWindow the following happens:
Frame1.Source = new Uri("/Source/Pages/Page1.xaml", UriKind.RelativeOrAbsolute);
Frame2.Source = new Uri("/Source/Pages/Page2.xaml", UriKind.RelativeOrAbsolute);
Is there any way, to execute Method2 from Page1.cs, and Method1 from Page2.cs?
Regards
One way to do this is through their common parent, the window.
Looking at this (modified accordingly)
public partial class MainWindow : Window
{
public Page1 Page1Ref = null;
public Page1 Page2Ref = null;
public MainWindow()
{
InitializeComponent();
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
Frame1.Source = new Uri("/Source/Pages/Page1.xaml", UriKind.Relative);
Frame1.ContentRendered += Frame1_ContentRendered;
// do the same for the Frame2
}
private void Frame1_ContentRendered(object sender, EventArgs e)
{
var b = Frame1.Content as Page1; // Is now Home.xaml
Page1Ref = b;
if(Page2Ref != null) // because you don't know which of the pages gets rendered first
{
Page2Ref.Page1Ref = Page1Ref; // add the Page1Ref prop to your Page2 class
Page1Ref.Page2Ref = Page2Ref; // here the same
}
}
// do the same for the other page
}
from this question
you should be able to set a reference once a page is loaded to the other page .
Better yet, you might want to let the Pages know of their window parent and access the other page through it. Either way, is bad design, I'm telling you.
Is not a solution to be proud of, you might better look into MVVM, and go with it.
Let me know if it worked for you.
I am trying to open (using any method) the TabbedPage from ContentPage.
My main App code:
public class App : Application
{
public App ()
{
MainPage = new ConnectPage ();
}
}
My ConnectPage uses XAML, code:
.cs file:
public partial class ConnectPage : ContentPage
{
public ConnectPage ()
{
InitializeComponent ();
}
void connectDevice(object sender, EventArgs args){
connect_btn.Text = "Connecting...";
connect_btn.IsEnabled = false;
var mainapp_page = new MainApp ();
Navigation.PushAsync (mainapp_page);
}
}
XAML file:
<Button x:Name="connect_btn" Text="Connect Now" Clicked="connectDevice"></Button>
Above method throws error:
PushAsync is not supported globally on iOS, please use a
NavigationPage
My MainApp.cs (which contain tabs):
public class MainApp : ContentPage
{
public MainApp ()
{
var tabs = new TabbedPage ();
tabs.Children.Add (new Tab1Page{Title="Tab1" });
tabs.Children.Add (new Tab2Page{Title="Tab2" });
tabs.Children.Add (new Tab3Page{Title="Tab3" });
}
}
You can either update your'r app's MainPage property and set that to the page you want to display, use stack navigation or present a page modally.
Setting a new main page will provide no way for the user to go back:
App.Current.MainPage = new SomeOtherPage ();
If you want to use stack navigation, you will have to wrap your initial page into a NavigationPage:
public partial class App : Application
{
public App ()
{
InitializeComponent ();
this.MainPage = new NavigationPage (new FirstPage ());
}
}
Than you can use Navigation.PushAsync().
If you want to present a page modally, so it is shown on top of your current page and can be dismissed, use:
Navgiation.PushModalAsync(new Page());
However, this will still require to wrap your current page into a NavigationPage.
There are other ways too, like CarouselPage or MasterDetailPage. I recommend you look at the documentation for all of your options.