i'm trying to create a Popup page (using Rg.Plugin.Popup) that has to display a stream video got from an API. Everytime i navigate into this page, i want to display a different video, obtained from the API, based on parameters provided by the page I come from (i get them by a message sent by Messenger). It seems to work at first run but, when i close the Popup page, and i open it again the videoView is all black and in the output is written: Failed to get window format.
That's my code ( base on sample provided here: https://code.videolan.org/videolan/LibVLCSharp/tree/master/Samples/Forms):
The code-behind page:
public partial class WebcamVideoPopUpPage : PopupPage
{
public WebcamVideoPopUpPage()
{
var vm = App.Locator.WebCamVideoVM;
this.BindingContext = vm;
InitializeComponent();
}
protected override void OnAppearing()
{
base.OnAppearing();
Messenger.Default.Send(new OnApperingVideoMessage());
}
private void VideoView_MediaPlayerChanged(object sender,
LibVLCSharp.Shared.MediaPlayerChangedEventArgs e)
{
Messenger.Default.Send(new OnVideoViewInitializedMessage());
}
protected override void OnDisappearing()
{
base.OnDisappearing();
}
}
videoView in xaml:
<shared:VideoView x:Name="VideoView"
MediaPlayer ="{Binding MediaPlayer}"
HorizontalOptions ="FillAndExpand"
VerticalOptions ="FillAndExpand"
MediaPlayerChanged ="VideoView_MediaPlayerChanged"/>
the ViewModel:
public class WebcamVideoViewModel : BaseViewModel
{
private LibVLC LibVLC { get; set; }
private bool IsLoaded { get; set; }
private bool IsVideoViewInitialized { get; set; }
private Media media { get; set; }
private MediaPlayer _mediaPlayer;
public MediaPlayer MediaPlayer
{
get { return _mediaPlayer; }
set
{
_mediaPlayer = value;
OnPropertyChanged();
}
}
public WebcamVideoViewModel(INavigationService navigationService, IApiManagerFactory apiFactory) : base(navigationService, apiFactory)
{
Messenger.Default.Register<InfoWebcamVideoMessage>(this, OnReceivedInfoWebcam);
Messenger.Default.Register<OnApperingVideoMessage>(this, OnAppearing);
Messenger.Default.Register<OnVideoViewInitializedMessage>(this, OnVideoViewInitialized);
Task.Run(Initialize);
}
private void Initialize()
{
Core.Initialize();
LibVLC = new LibVLC();
MediaPlayer = new MediaPlayer(LibVLC);
}
private async void OnReceivedInfoWebcam(InfoWebcamVideoMessage msg)
{
var response = await ApiManager.GetVideoWebcam(msg.Mpr, msg.Uuid);
if (response.IsSuccessStatusCode)
{
var stream = await response.Content.ReadAsStreamAsync();
media = new Media(LibVLC, stream);
Play();
}
}
public void OnAppearing(OnApperingVideoMessage msg)
{
IsLoaded = true;
}
public void OnVideoViewInitialized(OnVideoViewInitializedMessage msg)
{
IsVideoViewInitialized = true;
}
private void Play()
{
if (IsLoaded && IsVideoViewInitialized)
{
MediaPlayer.Play(media);
}
}
}
I resolved my problem overriding OnAppering method:
protected override void OnDisappearing()
{
base.OnDisappearing();
VideoView.MediaPlayer.Stop();
VideoView.MediaPlayer = null;
}
Related
How can I get the cursor position inside Editor control?
Ive been looking for an answer but the best I could find was the Cursor class, but that doesnt seem to exist in xamarin.
You could custom a Editor,and use custom renderer to get the SelectionPosition of the EditText.
custom a FormEditor in your fomrs project:
public class FormEditor:Editor
{
public int SelectionPosition;
public EventHandler SelectChanageEvent { get; set; }
}
create AndroidEditor in your Android project:
class AndroidEditor : EditorRenderer, EditTextSelectChange
{
private Context mContext;
public AndroidEditor(Context context) : base(context)
{
mContext = context;
}
public void Change(int lastPos, int curPos)
{
((FormEditor)Element).SelectionPosition = curPos;
((FormEditor)Element).SelectChanageEvent.Invoke(this, null);
}
protected override void OnElementChanged(ElementChangedEventArgs<Editor> e)
{
base.OnElementChanged(e);
MyEditText myEditText = new MyEditText(mContext);
myEditText.SetEditTextSelectChange(this);
SetNativeControl(myEditText);
}
}
custom MyEditText in your Android project:
public class MyEditText : FormsEditText
{
private int mLastPos = 0;
private int mCurPos = 0;
private EditTextSelectChange editTextSelectChange;
public void SetEditTextSelectChange(EditTextSelectChange editTextSelectChange)
{
this.editTextSelectChange = editTextSelectChange;
}
public MyEditText(Context context) : base(context)
{
}
protected override void OnSelectionChanged(int selStart, int selEnd)
{
base.OnSelectionChanged(selStart, selEnd);
if (editTextSelectChange != null)
{
mCurPos = selEnd;
editTextSelectChange.Change(mLastPos, mCurPos);
mLastPos = mCurPos;
}
}
public interface EditTextSelectChange
{
void Change(int lastPos, int curPos);
}
}
then use in your page.xaml:
<local:FormEditor x:Name="editor" Placeholder="Hello"></local:FormEditor>
in your page.xaml.cs:
public YourPage()
{
InitializeComponent();
editor.SelectChanageEvent += SelectEvent;
}
private void SelectEvent(object sender, EventArgs e)
{
// you could get the Curson Position by editor.SelectionPosition
Console.WriteLine("curPos = {0}", editor.SelectionPosition);
}
I am tying to further understand MVVM with some example scenario. I have a rootpage with a 'maindisplay' textblock. I would like to display 'status' or 'scenarios' from activation of any form of UI eg. togglebutton on the 'maindisplay' textblock.
I am able to bind the the page navigation info in the rootpageviewmodel to the textblock. However, I am not able to achieve the result when displaying info from different page.
I have checked another post multiple-viewmodels-in-same-view & Accessing a property in one ViewModel from another it's quite similar but it didn't work.
Please help. Thanks.
While accessing the RootPageViewModel should retain the instance?
View
<TextBlock Text="{x:Bind RootViewModel.MainStatusContent, Mode=OneWay}"/>
RootPage.xaml.cs
public sealed partial class RootPage : Page
{
private static RootPage instance;
public RootPageViewModel RootViewModel { get; set; }
public RootPage()
{
RootViewModel = new RootPageViewModel();
this.InitializeComponent();
// Always use the cached page
this.NavigationCacheMode = NavigationCacheMode.Required;
}
public static RootPage Instance
{
get
{
if (instance == null)
{
instance = new RootPage();
}
return instance;
}
}
private void nvTopLevelNav_ItemInvoked(NavigationView sender, NavigationViewItemInvokedEventArgs args)
{
if (args.IsSettingsInvoked)
{
contentFrame.Navigate(typeof(SettingsPage));
RootViewModel.MainStatusContent = "Settings_Page";
}
else
{
var navItemTag = args.InvokedItemContainer.Tag.ToString();
RootViewModel.MainStatusContent = navItemTag;
switch (navItemTag)
{
case "Home_Page":
contentFrame.Navigate(typeof(HomePage));
break;
case "Message_Page":
contentFrame.Navigate(typeof(MessagePage));
break;
}
}
}
}
RootPage ViewModel:
public class RootPageViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private static RootPageViewModel instance = new RootPageViewModel();
public static RootPageViewModel Instance
{
get
{
if (instance == null)
instance = new RootPageViewModel();
return instance;
}
}
public RootPageViewModel()
{
}
private string _mainStatusContent;
public string MainStatusContent
{
get
{
return _mainStatusContent;
}
set
{
_mainStatusContent = value;
OnPropertyChanged();
}
}
protected void OnPropertyChanged([CallerMemberName] string name = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
}
MessagePage.xaml.cs - to access RootPage ViewModel
public sealed partial class MessagePage : Page
{
public MessagePageViewModel MessageViewModel { get; set; }
public MessagePage()
{
MessageViewModel = new MessagePageViewModel();
this.InitializeComponent();
// Always use the cached page
this.NavigationCacheMode = NavigationCacheMode.Required;
}
private void Message1_Checked(object sender, RoutedEventArgs e)
{
RootPageViewModel.Instance.MainStatusContent = "Message 1 Selected";
}
private void Message1_Unchecked(object sender, RoutedEventArgs e)
{
RootPageViewModel.Instance.MainStatusContent = "Message 1 De-Selected";
}
}
When I debug the value did write to the instance but did't update the TextBlock. Did I do anything wrong in my XAML binding?
UWP C# MVVM How To Access ViewModel from Other Page
The better way is make static variable for RootPage, but not make singleton instance for RootPage and RootPageViewModel.
For example:
public RootPage ()
{
this.InitializeComponent();
this.NavigationCacheMode = NavigationCacheMode.Required;
Instance = this;
RootViewModel = new RootPageViewModel();
}
public static RootPage Instance;
Usage
private void Message1_Checked(object sender, RoutedEventArgs e)
{
RootPage.Instance.RootViewModel.MainStatusContent = "Message 1 Selected";
}
private void Message1_Unchecked(object sender, RoutedEventArgs e)
{
RootPage.Instance.RootViewModel.MainStatusContent = "Message 1 De-Selected";
}
I am working on a Xamarin.Forms app that will store a list of receipes for some chemicals. The chemicals have names (not user changeable) and concentrations. I want the user to be able to change the concentrations in the form and store them.
I have it to where I can modify values in the list with the UPDATE button, I can add (or delete) members of the list, all persistent. However, I cannot figure out how to change the values in the list within the Entry box, itself.
I tried to do something like Arvind Chourasiya did here, but I could not quite figure out the equivalent "connection.Update." I think the SQLite can't be connected to because it's not in the right event, but I am not sure.
My most functional C# code is...
using System;
using System.ComponentModel;
using Xamarin.Forms;
using SQLite;
using System.Collections.ObjectModel;
using System.Runtime.CompilerServices;
namespace contactBook
{
public class Recipe : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
private string _name;
[MaxLength(255)]
public string Name
{
get { return _name; }
set
{
if (_name == value)
return;
_name = value;
OnPropertyChanged();
}
}
private double _concentration;
public double Concentration
{
get
{ return _concentration; }
set
{
if (_concentration == value)
return;
_concentration = value;
OnPropertyChanged();
}
}
private void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
// Learn more about making custom code visible in the Xamarin.Forms previewer
// by visiting https://aka.ms/xamarinforms-previewer
[DesignTimeVisible(false)]
public partial class MainPage : ContentPage
{
private SQLiteAsyncConnection _connection;
private ObservableCollection<Recipe> _recipes;
public MainPage()
{
InitializeComponent();
_connection = DependencyService.Get<ISQLiteDb>().GetConnection();
//setBasicReceipies();
}
protected override async void OnAppearing()
{
await _connection.CreateTableAsync<Recipe>();
var recipes = await _connection.Table<Recipe>().ToListAsync();
_recipes = new ObservableCollection<Recipe>(recipes);
recipesListView.ItemsSource = _recipes;
base.OnAppearing();
}
async void setBasicReceipies() // worked during tests
{
var recipe1 = new Recipe { Name = "NH3", Concentration = 0.0 };
var recipe2 = new Recipe { Name = "H2SO4", Concentration = 0.1 };
var recipe3 = new Recipe { Name = "NaCl", Concentration = 0.2 };
await _connection.InsertAsync(recipe1);
await _connection.InsertAsync(recipe2);
await _connection.InsertAsync(recipe3);
}
async void OnAdd(object sender, System.EventArgs e)
{
var recipe = new Recipe { Name = "test ", Concentration = 0.0 };
await _connection.InsertAsync(recipe);
_recipes.Add(recipe);
}
async void OnUpdate(object sender, System.EventArgs e)
{
var recipe = _recipes[0];
recipe.Concentration += 0.05;
await _connection.UpdateAsync(recipe);
}
async void OnDelete(object sender, System.EventArgs e)
{
var recipe = _recipes[0];
await _connection.DeleteAsync(recipe);
_recipes.Remove(recipe);
}
//async void Entry_PropertyChanged(System.Object sender, System.ComponentModel.PropertyChangedEventArgs e)
//{
// await _connection.UpdateAllAsync();
//}
}
}
Main Page
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
NavigationPage.SetHasNavigationBar(this, false);
btnStartGame.Clicked += btnStartGame_Clicked;
}
public async void btnStartGame_Clicked(object sender, EventArgs e)
{
GlobalVariables globalVar = new GlobalVariables();
globalVar.CurrentSeconds = 20;
StartPage startPage = new StartPage();
startPage.setGlobalVariables(globalVar);
await Navigation.PushAsync(startPage);
}
}
Start Page
public partial class StartPage : ContentPage
{
GlobalVariables globalVar;
public StartPage()
{
InitializeComponent();
this.BindingContext = globalVar;
NavigationPage.SetHasNavigationBar(this, false);
}
public void setGlobalVariables(GlobalVariables globalVar)
{
this.globalVar = globalVar;
}
private void btnSample_Clicked(object sender, System.EventArgs e)
{
globalVar.CurrentSeconds++;
DisplayAlert("AW", globalVar.CurrentSeconds.ToString(), "AW");
}
}
GlobalVariables.cs
public class GlobalVariables : INotifyPropertyChanged
{
private int _currentSeconds;
public int CurrentSeconds
{
get { return _currentSeconds; }
set
{
if (_currentSeconds != value)
{
_currentSeconds = value;
Device.BeginInvokeOnMainThread(async () =>
{
await FingerSmash2.App.Current.MainPage.DisplayAlert("AW", "AW", "AW");
});
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName] string name = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
}
With this codes, every time btnSample_Clicked runs, the set{} in CurrentSeconds will also fire. But the problem is, the DisplayAlert inside set{} does not fire at all, only the DisplayAlert inside btnSample_Clicked.
How to also fire the DisplayAlert inside set{}? Or if not possible, is there a way to fire an event in Start Page from GlobalVariables?
Your code seems fine.
As described in Xamarin Live Player iOS DisplayActionSheet/Alert it may be related to the Xamarin Live Player.
Deploying your app on an device or even the emulator should ensure if your code is correct or not !
I'm using Xamarin Forms and I'm having an issue use InsertPageBefore() method with existing objects of Pages.
Here is my view code:
private FirstPage firstPage;
private SecondPage secondPage = new SecondPage();
private ThirdPage thirdPage = new ThirdPage();
private async void ItemSelectedMethod()
{
var root = App.NavigationPage.Navigation.NavigationStack[0];
if (SelectedItem == Items[0])
{
if (!IsFirstChoose)
{
App.NavigationPage.Navigation.InsertPageBefore(firstPage, root);
await App.NavigationPage.PopToRootAsync(false);
}
}
if (SelectedItem == Items[1])
{
App.NavigationPage.Navigation.InsertPageBefore(secondPage, root);
await App.NavigationPage.PopToRootAsync(false);
}
if (SelectedItem == Items[2])
{
App.NavigationPage.Navigation.InsertPageBefore(thirdPage, root);
await App.NavigationPage.PopToRootAsync(false);
}
IsFirstChoose = false;
rootPageViewModel.IsPresented = false;
}
It's throw exception "System.ArgumentException: 'Cannot insert page which is already in the navigation stack'". How to switch between existing objects of pages? I don't want create new object in InsertPageBefore(). I tried use it code, before call InsertPageBefore():
foreach (var item in App.NavigationPage.Navigation.NavigationStack.ToList())
App.NavigationPage.Navigation.RemovePage(item);
But it's not working... Can anyone help me?
It didn't work with UWP. Here is agly workaround for you but you really need to read how to work with Master-Detail pages.
public partial class App : Application
{
public static RootPage RootPage { get; private set; } //DON'T DO THIS,
//FIND A BETTER WAY
public App()
{
InitializeComponent();
RootPage = new RootPage();
MenuPage menuPage = new MenuPage(RootPage.vm);
RootPage.Master = menuPage;
RootPage.Detail = new NavigationPage(new MainPage());// NavigationPage;
MainPage = RootPage;
}
protected override void OnStart()
{
// Handle when your app starts
}
protected override void OnSleep()
{
// Handle when your app sleeps
}
protected override void OnResume()
{
// Handle when your app resumes
}
}
Then
private async void ItemSelectedMethod()
{
if (SelectedItem == Items[0])
{
App.RootPage.Detail = new NavigationPage(mainPage);
}
if (SelectedItem == Items[1])
{
App.RootPage.Detail = new NavigationPage(secondPage);
}
if (SelectedItem == Items[2])
{
App.RootPage.Detail = new NavigationPage(thirdPage);
}
rootPageViewModel.IsPresented = false;
}