I need some help sorting the visibility of entry on a button click. I have tried a few different things. and the following code is the best result that I have got so far. But its not perfect either.
Requirement: When the page shows in the screen, it would have just a button visible, and when the user clicks on the button, it shows the entry, if they click on the button again, the entry should be set to invisible. If i click outside else where in the page, it should also hide the entry.
XAML.
<controls:CustomButton
Text="Submit"
TextColor="White"
HorizontalOptions="FillAndExpand"
Command="{Binding TextSubmitCommand}"
Icon="WhiteKeyboard"/>
<controls:CustomEntry
x:Name="ItemEntry"
TextColor="White"
HeightRequest="50"
HorizontalTextAlignment="Center"
VerticalOptions="Center"
IsVisible="{Binding EntryVisible, Mode=TwoWay}">
<controls:CustomEntry.Behaviors>
<behaviors:EventToCommand
Command="{Binding LocationSearchCommand}"
EventName="Completed"/>
</controls:CustomEntry.Behaviors>
<controls:CustomEntry.Triggers>
<DataTrigger TargetType="controls:CustomEntry"
Binding="{Binding EntryVisible}"
Value="true">
<Trigger.EnterActions>
<triggers:EntryFocusTrigger/>
</Trigger.EnterActions>
</DataTrigger>
</controls:CustomEntry.Triggers>
</controls:CustomEntry>
View Model
public bool EntryVisible { get; set; } = false;
public Command TextSubmitCommand
{
get
{
return new Command(() =>
{
EntryVisible = !EntryVisible;
});
}
}
Trigger
public class EntryFocusTrigger : TriggerAction<CustomEntry>
{
protected override void Invoke(CustomEntry entry)
{
entry.Focus();
}
}
With the above code, it works perfectly fine toggling the visibility on button click. But if i click else where in the page, the keyboard hides, but the entry will still be there. So i tried adding an event trigger.
Added the following xaml to the custom entry in (XAML Page)
<EventTrigger Event="Unfocused">
<triggers:EntryUnfocusTrigger />
</EventTrigger>
and the actual trigger is defined as:
public class EntryUnfocusTrigger : TriggerAction<CustomEntry>
{
public bool IsVisible { get; set; }
protected override void Invoke(CustomEntry entry)
{
if(entry.IsFocused == false){
entry.IsVisible = false;
}
}
}
But after adding the above code, the entry does not show at all after the first toggle. What would be a clean way to get this working. Look forward for your help.
Try adding this Trigger to hide when the Entry is not Focused:
<Trigger TargetType="controls:CustomEntry"
Property="IsFocused" Value="False">
<Setter Property="IsVisible" Value="false" />
</Trigger>
With this one you don't need a custom Trigger class.
Hope this helps.-
Related
I am trying to make funcionality, to make larger text across whole application for user when he clicks a 'increase font size' button. Using MVVM, I have done it like this:
Increase font size button click
increase value of double field 'fontSize' which is binded to almost every text in layout
Update UI with new value after button click
However I don't know how to achieve this in Collectionview where I have got Binding in .xaml file, with some particular List (item is model class). The collectionview DataTemplate contains labels where I want to increase font size. Is there a way to do this without adding 'fontSize' field in my model class. If not how to update UI with 'new' List with increased font sizes.
I appreciate any help, tips and discussions.
Thank you.
You can create bindableproperty(fontsize) in your viewmodel and use Relative Binding so the label in Collectionview can change it's fontsize,code like:
ViewMode:
public class ColViewModel:BindableObject
{
public ObservableCollection<Student> students { set; get; }
public static readonly BindableProperty FontSizeProperty =
BindableProperty.Create("fontsize", typeof(int), typeof(ColViewModel), null);
public int fontsize
{
get { return (int)GetValue(FontSizeProperty); }
set { SetValue(FontSizeProperty, value); }
}
public ICommand IncreaseCommand { private set; get; }
public ColViewModel()
{students = new ObservableCollection<Student>();
getStudents();
fontsize = 24;
IncreaseCommand = new Command(() => {
fontsize++;
});
}
View:
<StackLayout>
<Label Text="This is a Title" FontSize="{Binding fontsize}"/>
<CollectionView ItemsSource="{Binding students}">
<CollectionView.ItemTemplate>
<DataTemplate>
<Label Text="{Binding Name}" FontSize="{Binding Source={RelativeSource AncestorType={x:Type local:ColViewModel}}, Path=fontsize}"/>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
<Button Text="Click to increase fontsize" Command="{Binding IncreaseCommand}"/>
</StackLayout>
Edit:
xmlns:local="clr-namespace:MyForms2.ViewModels"
Creating a Registration page, I need to get the following data from user.
First Name
Last Name
Username
Email
Password
Date of Birth
Gender
User Role
For the last two parameters, I am unable to find how to use radio buttons in Xamarin.Forms. Following is my code for the Registration Page.
<StackLayout BackgroundColor="#30af91" Padding="60">
<Entry Text="{Binding FirstName}" Placeholder="First Name"/>
<Entry Text="{Binding LastName}" Placeholder="Last Name"/>
<Entry Text="{Binding UserName}" Placeholder="Last Name"/>
<Entry Text="{Binding Email}" Placeholder="Email" />
<Entry Text="{Binding Password}" Placeholder="Password" IsPassword="True"/>
<Entry Text="{Binding ConfirmPassword}" Placeholder="Confirm Password" IsPassword="True"/>
<DatePicker MinimumDate="1/1/1948" MaximumDate="12/31/2007"/>
<!--Radio buttons for Gender
1. Male 2.Female-->
<!--Radio Buttons for UserRole
1. Admin 2.Participant-->
<Button Command="{Binding RegisterCommand}" Text="Register"/>
<Label Text="{Binding Message}" />
</StackLayout>
Xamarin forms does not provide Radio Button.
You can either use
1)Switch
2)Picker
or any other component to fulfill your requirement
UPDATE
The xamarin forms update version 4.6 has introduced the Radio button control, Here is the official documentation
I think there is a simpler solution that is fairly easy and requires no libraries. Really a a radio group is just a fancy ListView. You would just need to create a viewModel for each radio button that has a IsSelected flag and switch between 2 images. I had a need to allow a user to select how long a token persisted:
XAML
<ListView
HasUnevenRows="True"
HorizontalOptions="FillAndExpand"
ItemsSource="{Binding Durations}"
ItemSelected="ListView_ItemSelected"
SelectedItem="{Binding SelectedDuration}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout
Orientation="Horizontal">
<Image
HeightRequest="18"
IsVisible="{Binding IsSelected}"
Source="radioButtonChecked.png"
WidthRequest="18"/>
<Image
HeightRequest="18"
IsVisible="{Binding IsUnselected}"
Source="radioButtonUnchecked.png"
WidthRequest="18"/>
<Label
Margin="8,0,0,0"
Text="{Binding Caption}"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
We create a listview in our content page and listen for the ItemSelected event. Each list item is a horizontal stack panel where we flip between two images depending on the selected state
Code Behind
public partial class LoginPage : ContentPage
{
LoginPageViewModel LoginPageViewModel { get; }
public LoginTwoFactorFrequencyPage ()
{
BindingContext = LoginPageViewModel = new LoginPageViewModel();
InitializeComponent ();
}
private void ListView_ItemSelected(object sender, SelectedItemChangedEventArgs e)
{
LoginPageViewModel.UpdateSelected(e.SelectedItem as PersistenceDuration);
}
}
The page's code behind instantiates a view model and calls an UpdateSelected method with the newly selected item on the page's view model*
RadioButton ViewModel
The view model for each radio button:
public class PersistenceDuration : ViewModelBase
{
bool isSelected;
public string Caption { get; set; }
public TwoFactorTokenPersistenceDuration Duration { get; set; }
public bool IsSelected
{
get => isSelected;
set
{
isSelected = value;
OnPropertyChanged();
OnPropertyChanged("IsUnselected");
}
}
public bool IsUnselected => !IsSelected;
public PersistenceDuration(string caption, TwoFactorTokenPersistenceDuration duration)
{
Caption = caption;
Duration = duration;
IsSelected = false;
}
}
The radio button view model holds selection info and the caption. We make sure to fire OnPropertyChanged whenever the selected state changes
Page ViewModel
public class LoginPageViewModel : ViewModelBase
{
PersistenceDuration duration;
PersistenceDuration selectedDuration;
public ObservableCollection<PersistenceDuration> Durations { get; }
public PersistenceDuration SelectedDuration
{
get => selectedDuration;
set
{
if (value != null)
{
duration = value;
UpdateSelected(duration);
}
OnPropertyChanged();
}
}
public LoginTwoFactorFrequencyViewModel()
{
Durations = new ObservableCollection<PersistenceDuration>(
new List<PersistenceDuration>()
{
new PersistenceDuration(AppResources.Save_code__forever, TwoFactorTokenPersistenceDuration.Forever),
new PersistenceDuration(AppResources.ChatRequireEvery30Days, TwoFactorTokenPersistenceDuration.ThirtyDays),
new PersistenceDuration(AppResources.ChatRequireEveryLogin, TwoFactorTokenPersistenceDuration.None),
});
}
public void UpdateSelected(PersistenceDuration persistenceDuration)
{
foreach (var item in Durations)
item.IsSelected = persistenceDuration == item;
}
}
In the page view model we create a list of radio button view models that the XAML binds to. When we UpdateSelected() all the IsSelected states are updated which trigger binding updates which flip the image.
You will still need to do something about the highlight when someone selects an item, but that is easy enough to find on the internet :)
You can use XLabs plugin from manage NuGets package. After installing you can use like this:
In Xaml:
controls:BindableRadioGroup x:Name="Radiobtn"
In C#:
string[] gender = {"MAlE","FEMALE"}
Radiobtn.Add(gender)
Refer Link
https://github.com/XLabs/Xamarin-Forms-Labs/tree/master/samples/XLabs.Samples/XLabs.Samples/Pages/Controls
You can get the radio button effect without a package. Use Labels with text unicode circle \u26AA or \u25CB. Attach a tab gesture recognizer to each label.
When tapped, change the text of the selected button to unicode circle bullet \u29BF and change the text of the other button(s) back to unicode circle \u26AA.
Test on your preferred platforms as each platform may display somewhat differently. You may need to adjust the font size as you change the text.
If you want real radiobuttons you can xlabs their package (https://github.com/XLabs/Xamarin-Forms-Labs/tree/master/src/Forms/XLabs.Forms/Controls/RadioButton)
Personally I'd just use a picker, Xlabs package hasn't been updated in a while so their might be some bugs in the radiobutton
You can use image as a radio button. When tou you click on it, it can change. It is not a good way to do it though.
This is xaml code:
<Image Scale="0.7" HorizontalOptions="Start" x:Name="radioButton" Source="unRadioBtn.png">
<Image.GestureRecognizers>
<TapGestureRecognizer Tapped="radioButton_Clicked"></TapGestureRecognizer>
</Image.GestureRecognizers>
</Image>
And this is .cs:
private void radioButton_Clicked(object sender, EventArgs e)
{
radioButton.Source = "radioBtn.png";
}
Xamarin.Forms 4.6 introduced a new RadioButton control. You can find the documentation here: https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/radiobutton
You can use the switch component. Also you can see the implementation for a checkbox component from the XLabs project which is now discontinued, get the code and modify it as you need.
Hint: You're gonna need the custom renderers per platform for it to work .
You need to use Picker
https://developer.xamarin.com/api/type/Xamarin.Forms.Picker/
Actually it is the best alternative to RadionButton On Xamarin.forms
XLabs RadioButton and BindableRadioGroup work well: XLabs RadioButton for Xamarin Forms
Here's a simple Yes/No radio using the BindableRadioGroup:
var answers = new List<string>();
answers.Add("Yes");
answers.Add("No");
var RadioGroup = new XLabs.Forms.Controls.BindableRadioGroup()
{
ItemsSource = answers,
Orientation = StackOrientation.Horizontal
};
Xamarin Forms now provides a Radio Button control.
See docs here:
https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/radiobutton
As of XF 4.8 this is still experimental and I've not yet used this feature so can't comment on its stability.
first of all sorry for my english.
I am developing a WP7 app, and I still haven't completely understood the data binding structure. I have a page that has some data obtained through data binding. Data is generated within the .cs, and it works fine.
But on another page I have some data that is obtained from data binding too, but I want it to come from a UI input text instead. It's simple, just a textbox and a textblock, so the user writes something on the textbox and so it shows up on the textblock that's on the same page. But it's not working, the textblock remains empty.
It's something like this:
<TextBox Name="TestInput">
<TextBlock Text="{Binding TestText}">
Above is what's on the XAML.
public partial class NewItem : PhoneApplicationPage
{
public String TestText { get; set; }
public NewItem()
{
InitializeComponent();
TestText = "TestInput.Text";
}
}
And this above is what's on the C#.
BUT!! It doesn't end here. Since the textblock wasn't showing anything, I ended desperately trying to assign some plain String to the TestText property. Like this:
TestText = "HELLO WORLD";
But when the app starts and the page loads, the textblock shows nothing. I just don't understand what am I missing, or doing wrong.
I will appreciate if someone could clear me up the databinding structure, or at least explain me what did I do wrong so I can figure it out myself.
Thanks in advance guys!
You have to assign the DataContext before you want the binding effect.So whenever there is a change in the text box, you write the code in the textchanged event.
this.DataContext=TestText
And one more change that you need to perform is that you are not actually setting the property.It should be like
TestText=TestInput.Text
for your understanding of binding i am putting a simple working example..just follow this..
this is you page on which you bind the data of textbox to someproperty textboxText..when you finished writing in this textbox.then all the writtentext automatically come ino this property. and this property is also binded to textbloack so when your textbloack got focus it will got to the get of the property and automatically fill it.
<Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
<StackPanel Orientation="Horizontal" >
<TextBox x:Name="testTextbox" Height="50" Width="200" Text="{Binding TextboxText,Mode=TwoWay}" />
<TextBlock x:Name="testTextblock" Height="50" Width="1000" Text="{Binding TextboxText,Mode=OneWay}" Foreground="White" />
</StackPanel>
</Grid>
this is your page.cs class in which i have also shown you how to implement inotifyproperty changed..it will help you in future..
public sealed partial class MainPage : Page,INotifyPropertyChanged
{
public MainPage()
{
this.InitializeComponent();
this.DataContext = this;
}
private string _TextboxText;
public string TextboxText
{
get
{
return _TextboxText;
}
set
{
_TextboxText = value;
FirePropertyChanged("TextboxText");
testTextblock.UpdateLayout();
}
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
}
public event PropertyChangedEventHandler PropertyChanged;
protected void FirePropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
I'm using MVVM in this project, I have a listbox which bind to a collection of Customers. I want to create an event to navigate a detailsPage using id of the elementselected:
<ListBox ItemsSource="{Binding Customers}" x:Name="state_list" SelectionChanged="state_list_SelectionChanged">
<i:Interaction.Triggers>
<i:EventTrigger EventName="selectionchanged">
<cmd:EventToCommand Command="{Binding stateSelectedCommand}" PassEventArgsToCommand="True" />
</i:EventTrigger>
</i:Interaction.Triggers>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding nom}" />
<!--TextBlock Text="{Binding LastName}" />
<TextBlock Text="{Binding Text, ElementName=tbCount}" /-->
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I can't figure out how to get the selected item to add it to the uri and then use it to get data. An example or tutorial would be helpful. Thanks :)
I would create a "SelectedCustomer" property in the ViewModel (next to you Customers property) and bind it to the SelectedItem. Then, on the setter of that property you can navigate to your desired page. This way you eliminate the messy events and command.
<ListBox x:Name="state_list
ItemsSource="{Binding Customers}"
SelectedItem="{Binding SelectedCustomer, Mode=TwoWay}">
...
public Customer SelectedCustomer
{
get
{
return _selectedCustomer;
}
set
{
if (value != null)
{
_selectedCustomer = value;
//Navigate to your page here, either with Navigator class or any other mechanism you have in place for changing content on screen
}
}
}
AlexDrenea gives you a good way of binding SelectedItem to a property on your viewmodel. If you are wanting to navigate based on this in an MVVM architecture, I would suggest using messaging to get it done.
I cover this in a blog post I did a while back, but the short summary of doing this within MVVMLight, is to create a Navigator class that sits at the application level.
public class Navigator
{
private PhoneApplicatoinFrame RootFrame;
public Navigator(PhoneApplicationFrame frame)
{
RootFrame = frame;
RegisterMessages();
}
private void RegisterMessages()
{
Messenger.Default.Register<ShowTrackerMessage>(this, ShowTracker);
}
private void ShowTracker(ShowTrackerMessage msg)
{
RootFrame.Navigate(new Uri("/Views/ItemLocationCompassView.xaml", UriKind.RelativeOrAbsolute));
}
}
Then, as part of your application start-up, create it and pass it a reference to your RootFrame:
private static Navigator _navigator;
public static Navigator Nav
{
get { return _navigator; }
}
...
_navigator = new Navigator(this.RootFrame);
Then, you have a couple choices on how you send the Navigation message.
Option 1: In your ViewModel, hook into the PropertyChanged event (part of INotifyPropertyChanged), and send the appropriate message when your SelectedItem property changes.
Option 2: Tie into the SelectionChanged event of your ListBox. I use the MVVMLight's EventToCommand to send that event to a RelayCommand in my ViewModel, then react appropriately to send the message to the Navigator object.
I cover this in more detail at: http://www.smartchitecture.com/?p=27
I'm trying the MVVM Light Toolkit. Though I still think having multiple ViewModels for such small apps is overkill, I like the concepts. What I still can't quite understand is how (or I should say "what is the recommended way") to navigate from one page to another when the selection changes in a ListBox.
The big problem with this toolkit is that it forces you to learn MVVM via other sources before using it, rather than show you what (its vision of) MVVM is from within the framework, accompanying samples and documentation. Are there samples out there showing the different concepts? And please, no videos.
Have you tried modifying your ListBox ItemTemplate to have each item be a HyperlinkButton and just setting the NavigateURI attribute to the Page you want to navigate to?
I still have not figured out how to do this (navigate to a details page upon selection changed in a listbox) without any codebehind in the view. However, if you are OK with having just a little codebehind in the view here's what I recommend:
<ListBox x:Name="MainListBox" Margin="0,0,-12,0" ItemsSource="{Binding Items}"
SelectionChanged="MainListBox_SelectionChanged"
SelectedItem="{Binding Path=SelectedListItem, Mode=TwoWay}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Margin="0,0,0,17" Width="432">
<TextBlock Text="{Binding LineOne}" TextWrapping="Wrap" Style="{StaticResource PhoneTextExtraLargeStyle}"/>
<TextBlock Text="{Binding LineTwo}" TextWrapping="Wrap" Margin="12,-6,12,0" Style="{StaticResource PhoneTextSubtleStyle}"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
First, per above bind to the SelectedItem property of the Listbox with a TwoWay binding to a property in your ViewModel (SelectedListItem in the above).
Then in your codebehind for this page implement the handler for MainListBox_SelectionChanged:
// 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", UriKind.Relative));
}
This is the only codebehind you need in your main view.
In your main ViewModel you need a SelectedListItem property:
public const string SelectedListItemPropertyName = "SelectedListItem";
private ItemViewModel _SelectedListItem;
/// <summary>
/// Sample ViewModel property; this property is used in the view to display its value using a Binding
/// </summary>
/// <returns></returns>
public ItemViewModel SelectedListItem
{
get
{
return _SelectedListItem;
}
set
{
if (value != _SelectedListItem)
{
_SelectedListItem = value;
RaisePropertyChanged(SelectedListItemPropertyName);
}
}
}
Now, the trick to getting the context passed to your details page (the context being what list item was selected) you need to setup the DataContext in your Details view:
public DetailsPage()
{
InitializeComponent();
if (DataContext == null)
DataContext = App.ViewModel.SelectedListItem;
}
Hope this helps.
eventually you'll want to do more than just navigate, potentially navigate after setting a custom object.
Here is a MVVM-light way of doing this.
You'll first want to bind your listbox selected item to a property in your viewmodel
<ListBox ItemsSource="{Binding Events}" Margin="0,0,-12,0" SelectedItem="{Binding SelectedEvent, Mode=TwoWay}">
Declare your SelectedEvent property
public const string SelectedEventPropertyName = "SelectedEvent";
private Event _selectedEvent;
public Event SelectedEvent
{
get {return _selectedEvent;}
set
{
if (_selectedEvent == value)
{
return;
}
var oldValue = _selectedEvent;
_selectedEvent = value;
// Update bindings and broadcast change using GalaSoft.MvvmLight.Messenging
RaisePropertyChanged(SelectedEventPropertyName, oldValue, value, true);
}
}
You can then define an interaction trigger bound to the tap event
<i:Interaction.Triggers>
<i:EventTrigger EventName="Tap">
<cmd:EventToCommand Command="{Binding EventPageCommand, Mode=OneWay}"/>
</i:EventTrigger>
</i:Interaction.Triggers>
In your viewmodel, define your EventPageCommand as a RelayCommand:
public RelayCommand EventPageCommand { get; private set; }
public MainViewModel()
{
EventPageCommand = new RelayCommand(GoToEventPage);
}
and finally declare your GoToEventPage method
private void GoToEventPage()
{
_navigationService.NavigateTo(new Uri("/EventPage.xaml", UriKind.Relative));
}
note that you can do other actions before navigating to your new page, plus your selected item from your list box is currently set in the property you bound it too.