I am trying to figure out how to remove the white space you see in the image below (surrounded by a red rectangle). Notice I have a ListView embedded in a parent ListView.
XAML
<ListView x:Name="___listview" HasUnevenRows="True">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Button Image="{Binding ImageName}" Command="{Binding ShowDetailsCommand}" />
<ListView ItemsSource="{Binding Notes}">
<ListView.ItemTemplate>
<DataTemplate>
<TextCell Text="{Binding Note}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
This probably isn't needed, but here is the model...
MODEL
namespace ViewCellClick
{
public class ModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public class Model : ModelBase
{
public Model()
{
_imageName = "ellipses_vertical.png";
_showDetails = true;
ShowDetailsCommand = new Command(() =>
{
ShowDetails = !_showDetails;
ImageName = (_imageName == "ellipses_vertical.png")
? "ellipses_horizontal.png"
: "ellipses_vertical.png";
});
}
bool _showDetails;
public bool ShowDetails
{
get { return _showDetails; }
set { if (_showDetails != value) { _showDetails = value; OnPropertyChanged("ShowDetails"); } }
}
string _imageName;
public string ImageName
{
get { return _imageName; }
set { if (_imageName != value) { _imageName = value; OnPropertyChanged("ImageName"); } }
}
public ICommand ShowDetailsCommand { get; set; }
List<ChildModel> _notes;
public List<ChildModel> Notes { get { return _notes; } set { _notes = value; } }
}
public class ChildModel : ModelBase
{
public ChildModel(string note) { _note = note; }
string _note;
public string Note
{
get { return _note; }
set { if (_note != value) { _note = value; OnPropertyChanged("Note"); } }
}
}
}
You can't do this with Xamarin.Forms.ListView and nesting them is not supported. Really on iOS this would be very difficult and I'm not sure you could get it working without some weird gesture behavior.
Related
Please check the GIF for the problem.
I am actually using two imagebutton here and change IsVisible, since I couldn't accomplish swapping the image by Binding on the source.
ViewModel:
public bool IsAudioPlaying
{
get => player.IsPlaying;
}
...
public void PlayOrPause()
{
if (player.IsPlaying)
player.Pause();
else
player.Play();
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("IsAudioPlaying"));
}
XAML:
<ImageButton AbsoluteLayout.LayoutBounds=".5, 0, 100, 100" AbsoluteLayout.LayoutFlags="PositionProportional" Source="play.png" Padding="20" WidthRequest="80" HeightRequest="80"
CornerRadius="40" VerticalOptions="Center" HorizontalOptions ="Center" BackgroundColor="#cea448" Clicked="PlayOrPause" Margin="10" IsVisible="{Binding IsAudioPlaying, Converter={StaticResource InverseBoolConverter}}" />
<ImageButton AbsoluteLayout.LayoutBounds=".5, 0, 100, 100" AbsoluteLayout.LayoutFlags="PositionProportional" Source="pause.png" Padding="20" WidthRequest="80" HeightRequest="80"
CornerRadius="40" VerticalOptions="Center" HorizontalOptions ="Center" BackgroundColor="#cea448" Clicked="PlayOrPause" Margin="10" IsVisible="{Binding IsAudioPlaying}" />
I am actually using two imagebutton here and change IsVisible, since I couldn't accomplish swapping the image by Binding on the source.
Create a View Model.
public class ViewModel : INotifyPropertyChanged
{
private bool _isAudioPlaying;
public bool IsAudioPlaying
{
get
{
return _isAudioPlaying;
}
set
{
_isAudioPlaying = value;
OnPropertyChanged("IsAudioPlaying");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
Use ObservableCollection to update.
ObservableCollection<ViewModel> observableCollection { get; set; }
public MainPage()
{
InitializeComponent();
observableCollection = new ObservableCollection<ViewModel>()
{
new ViewModel(){ IsAudioPlaying=true}
};
this.BindingContext = observableCollection;
}
private void PlayOrPause(object sender, EventArgs e)
{
if (observableCollection[0].IsAudioPlaying == true)
{
observableCollection[0].IsAudioPlaying = false;
imageButton.Source = "pause.png";
}
else
{
observableCollection[0].IsAudioPlaying = true;
imageButton.Source = "play.png";
}
}
I'm new to Xamarin Forms, and I've met my first challenge. I want a Frame around my Stacklayout within a Listview. When the user selects an item in the Listview I want some controls to appear. This works fine without the Frame, but the Frame does not expand when the controls appear. How can I change or get around this behavior?
Code below.
XAML:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:MVVMTest"
x:Class="MVVMTest.MainPage">
<StackLayout>
<ListView HasUnevenRows="True" SelectedItem="{Binding SelectedViewItem, Mode=TwoWay}" ItemsSource="{Binding Items}" >
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame BackgroundColor="White" BorderColor="Black">
<StackLayout>
<Label Text="{Binding Name}"></Label>
<Entry Text="{Binding Details}" IsVisible="{Binding ShowDetails}"></Entry>
</StackLayout>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
XAML.cs
namespace MVVMTest
{
public partial class MainPage : ContentPage
{
public MainPage()
{
BindingContext = new ViewModel()
{
Items = new List<ViewModelItem>()
{
new ViewModelItem()
{
Name = "Test",
Details = "details"
},
new ViewModelItem()
{
Name = "Test2",
Details = "details2"
}
}
};
InitializeComponent();
}
}
}
Model:
namespace MVVMTest
{
public class ViewModel : INotifyPropertyChanged
{
private ViewModelItem _selectedViewItem;
private List<ViewModelItem> _items;
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public ViewModelItem SelectedViewItem
{
get
{
return _selectedViewItem;
}
set
{
_selectedViewItem = value;
OnPropertyChanged();
if (value != null)
{
value.ShowDetails = !value.ShowDetails;
SelectedViewItem = null;
}
}
}
public List<ViewModelItem> Items
{
get
{
return _items;
}
set
{
_items = value;
OnPropertyChanged();
}
}
public ViewModel()
{
}
}
public class ViewModelItem : INotifyPropertyChanged
{
private bool _showDetails;
private string _details;
private string _name;
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public string Name
{
get
{
return _name;
}
set
{
_name = value;
OnPropertyChanged();
}
}
public bool ShowDetails
{
get
{
return _showDetails;
}
set
{
_showDetails = value;
OnPropertyChanged();
}
}
public string Details
{
get
{
return _details;
}
set
{
_details = value;
OnPropertyChanged();
}
}
}
}
I ended up using the PropertyChanged event to react to when the ListView was displayed or hidden. In the eventhandler, I set the HeightRequest of the Frame and this forces it to resize itself.
Alternative solution/help can be found here:
https://forums.xamarin.com/discussion/comment/366577
XAML:
<StackLayout>
<ListView HasUnevenRows="True" SelectedItem="{Binding SelectedViewItem, Mode=TwoWay}" ItemsSource="{Binding Items}" >
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame BackgroundColor="White" BorderColor="Black" Margin="2" Padding="2" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand">
<StackLayout>
<Label Text="{Binding Name}"></Label>
<ListView HasUnevenRows="True" Margin="2" ItemsSource="{Binding DetailObjects}" IsVisible="{Binding ShowDetails}" PropertyChanged="ListView_PropertyChanged">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Entry Text="{Binding Details}"></Entry>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
Code behind:
public partial class MainPage : ContentPage
{
public MainPage()
{
BindingContext = new ViewModel()
{
Items = new List<ViewModelItem>()
{
new ViewModelItem()
{
Name = "Test",
DetailObjects = new List<ViewModelItemDetails>
{
new ViewModelItemDetails
{
Details = "details1"
},
new ViewModelItemDetails
{
Details = "details2"
}
}
},
new ViewModelItem()
{
Name = "Test2",
DetailObjects = new List<ViewModelItemDetails>
{
new ViewModelItemDetails
{
Details = "details1"
},
new ViewModelItemDetails
{
Details = "details2"
}
}
}
}
};
InitializeComponent();
}
private void ListView_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
if (!(sender is ListView list)) return;
if (e.PropertyName == ListView.IsVisibleProperty.PropertyName)
{
Element parent = list;
Frame frame = null;
while (frame == null && parent != null)
{
if (parent is Frame) frame = parent as Frame;
parent = parent.Parent;
}
if (list.IsVisible)
{
list.HeightRequest = list.ItemsSource.Cast<ViewModelItemDetails>().Count() * 50;
if (frame != null) frame.HeightRequest = list.HeightRequest + 50;
}
else
{
if (frame != null) frame.HeightRequest = 50;
}
}
}
}
I need to pass data from a ListView to a TodoDetail page where I have a Telerik DataForm, but I don't know how to make it work. If I use normal Xamarin Forms controls it works fine, but need it to work with the Telerik DataForm control.
Here is my code:
Todo.xaml
list item tapped handler
private async void ToDoTaskTap(object sender, ItemTappedEventArgs e)
{
var user = ToDoTask.SelectedItem as tblEmpTask;
if (user != null)
{
var mainViewModel = BindingContext as MainViewModel;
if (mainViewModel != null)
{
mainViewModel.Selected = user;
await Navigation.PushAsync(new ToDoDetail(mainViewModel));
}
}
}
tblEmpTask.cs
public class tblEmpTask
{
public string strTaskName { get; set; }
}
TodoDetail.xaml
<telerikInput:RadDataForm x:Name="dataForm">
<telerikInput:RadDataForm.Source>
<local1:MainViewModel />
</telerikInput:RadDataForm.Source>
</telerikInput:RadDataForm>
MainViewModel.cs
public class MainViewModel : INotifyPropertyChanged
{
public tblEmpTask Selected
{
get { return _Selected; }
set
{
_Selected = value;
OnPropertChanged();
}
}
[DisplayOptions(Header = "Name")]
public string Name
{
get { return this.Selected.strTaskName; }
set
{
if (value != this.Selected.strTaskName)
{
this.Selected.strTaskName = value;
OnPropertChanged();
}
}
}
}
You must add a binding between the SelectedItem and the ListView
Here's an example:
ViewModel:
public List<object> ItemsSource { get; set; }
public object SelectedItem {
set { SelectedItemChanged(value); }
}
async void SelectedItemChanged(object value) {
await App.Current.MainPage.Navigation.PushAsync(new AboutPage(SelectedItem));
}
Page:
<ListView
ItemsSource="{Binding ItemsSource}"
SelectedItem="{Binding SelectedItem, Mode=OneWayToSource}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Label Text="{Binding .}"></Label>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
I am coding a Xamarin.Forms project and I have a list view but whenever I show hidden content, for example, make an entry visible it the ViewCell overlaps the one beneath it.
Is there a way I could .Update() the listview or something to refresh it and make them all fit.
I don't want the refresh to cause it to go back to the top though.
Android seems to be able to automatically update the height when I show something.
I tried using HasUnevenRows="True" but that still didn't fix it.
Code:
Message.xaml
<StackLayout>
<local:PostListView x:Name="MessageView" HasUnevenRows="True" IsPullToRefreshEnabled="True" Refreshing="MessageView_Refreshing" SeparatorVisibility="None" BackgroundColor="#54a0ff">
<local:PostListView.ItemTemplate>
<DataTemplate>
<local:PostViewCell>
<StackLayout>
<Frame CornerRadius="10" Padding="0" Margin="10, 10, 10, 5" BackgroundColor="White">
<StackLayout>
<StackLayout x:Name="MessageLayout" BackgroundColor="Transparent" Padding="10, 10, 15, 10">
...
<Label Text="{Binding PostReply}" FontSize="15" TextColor="Black" Margin="10, 0, 0, 10" IsVisible="{Binding ShowReply}"/>
<StackLayout Orientation="Vertical" IsVisible="{Binding ShowReplyField}" Spacing="0">
<Entry Text="{Binding ReplyText}" Placeholder="Reply..." HorizontalOptions="FillAndExpand" Margin="0, 0, 0, 5"/>
...
</StackLayout>
<StackLayout x:Name="MessageFooter" Orientation="Horizontal" IsVisible="{Binding ShowBanners}">
<StackLayout Orientation="Horizontal">
...
<Image x:Name="ReplyIcon" Source="reply_icon.png" HeightRequest="20" HorizontalOptions="StartAndExpand" IsVisible="{Binding ShowReplyButton}">
<Image.GestureRecognizers>
<TapGestureRecognizer Command="{Binding ReplyClick}" CommandParameter="{Binding .}"/>
</Image.GestureRecognizers>
</Image>
...
</StackLayout>
...
</StackLayout>
</StackLayout>
</StackLayout>
</Frame>
</StackLayout>
</local:PostViewCell>
</DataTemplate>
</local:PostListView.ItemTemplate>
</local:PostListView>
</StackLayout>
Message.cs
using Newtonsoft.Json;
using SocialNetwork.Classes;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Net.Http;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace SocialNetwork
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MessagePage : ContentPage
{
public MessagePage()
{
InitializeComponent();
LoadPage();
}
private async void LoadPage()
{
await LoadMessages();
}
private async void RefreshPage()
{
await LoadMessages();
MessageView.EndRefresh();
}
private async Task LoadMessages()
{
//*Web Request*
MessageView.ItemsSource = FormatPosts(this, Navigation, page_result);
...
}
public IList<MessageObject> FormatPosts(Page page, INavigation navigation, string json)
{
IList<MessageObject> Posts = new List<MessageObject>() { };
var messages = JsonConvert.DeserializeObject<List<Message>>(json);
foreach (var message in messages)
{
MessageObject mo = MessageObject.CreateMessage(...);
Posts.Add(mo);
}
return Posts;
}
public async void ShowOptionActions(string id, string poster_id, object message)
{
...
}
public async void ShowReportOptions(string id, string poster_id)
{
...
}
public void SubmitReplyClick(string id, object msg)
{
...
}
public async void SendReplyAsync(string id, object msg, string reply)
{
await SendReply(id, msg, reply);
}
public void ReplyCommandClick(string id, object msg)
{
MessageObject message = (MessageObject) msg;
message.ShowReplyField = message.ShowReplyField ? false : true;
//Update Cell Bounds
}
private async Task SendReply(string id, object msg, string reply)
{
MessageObject message = (MessageObject)msg;
...
message.PostReply = reply;
//Update Cell Bounds
}
public async void LikeMessageClick(string id, object message)
{
await LikeMessage(id, message);
}
private async Task LikeMessage(string id, object msg)
{
...
}
public async void DeleteMessage(string id, object msg)
{
MessageObject message = (MessageObject)msg;
message.ShowBanners = false;
message.ShowReply = false;
...
//Update Cell Bounds
}
public async Task ReportMessage(...)
{
...
}
private void MessageView_Refreshing(object sender, EventArgs e)
{
RefreshPage();
}
}
public class MessageObject : INotifyPropertyChanged
{
private Boolean showBannersValue = true;
private string replyValue = String.Empty;
private bool showReplyValue;
private bool showReplyButtonValue;
private bool showReplyFieldValue;
private Command replyCommandValue;
private Command replySubmitValue;
private string replyTextValue;
...
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private MessageObject(...)
{
...
}
public static MessageObject CreateMessage(...)
{
return new MessageObject(...);
}
public Boolean ShowBanners
{
get
{
return this.showBannersValue;
}
set
{
if (value != this.showBannersValue)
{
this.showBannersValue = value;
NotifyPropertyChanged();
}
}
}
public Boolean ShowReplyField
{
get
{
return this.showReplyFieldValue;
}
set
{
if(value != this.showReplyFieldValue)
{
this.showReplyFieldValue = value;
NotifyPropertyChanged();
}
}
}
public string PostReply
{
get
{
return this.replyValue;
}
set
{
if (value != this.replyValue)
{
this.replyValue = value;
NotifyPropertyChanged();
}
}
}
public Boolean ShowReply
{
get
{
return this.showReplyValue;
}
set
{
if(value != this.showReplyValue)
{
this.showReplyValue = value;
NotifyPropertyChanged();
}
}
}
public Boolean ShowReplyButton
{
get
{
return this.showReplyButtonValue;
}
set
{
if (value != this.showReplyButtonValue)
{
this.showReplyButtonValue = value;
NotifyPropertyChanged();
}
}
}
public string ReplyText
{
get
{
return this.replyTextValue;
}
set
{
if(value != this.replyTextValue)
{
this.replyTextValue = value;
NotifyPropertyChanged();
}
}
}
public Command ReplyClick
{
get
{
return this.replyCommandValue;
}
set
{
if (value != this.replyCommandValue)
{
this.replyCommandValue = value;
NotifyPropertyChanged();
}
}
}
...
}
}
Save your IList<MessageObject> which gets returned from your FormatPosts method in a field IList<MessageObject> _messages = new List<MessageObject>()
And use the following snippet to update the ListView whenever you need, includes a check to see if the device runs on iOS:
if(Device.RuntimePlatform == Device.iOS)
{
MessageView.ItemsSource = null;
MessageView.ItemsSource = _messages;
}
Especially with iOS there are issues resizing rows in a ListView according to changes of cells (see here). There is a method ForceUpdateSize on Cell, which should notify the ListView that the size of the cell has changed, which should cause the ListView to resize its rows.
Oh, I faced the same thing.
I guess that you just need to add this somewhere in your listview:
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid Grid.row='0'>
...
</Grid>
// This, in my case, makes my cell expand when it's true. Normal behavior
<Grid Grid.row='1' isVisible="{Binding Expand}">
...
</Grid>
</Grid>
Plus, if you want to update cells individually, I use a CustomObservableCollection:
public class CustomObservableCollection<T> : ObservableCollection<T>
{
public CustomObservableCollection() { }
public CustomObservableCollection(IEnumerable<T> items) : this()
{
foreach(var item in items)
this.Add(item);
}
public void ReportItemChange(T item)
{
NotifyCollectionChangedEventArgs args =
new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Replace,
item,
item,
IndexOf(item));
OnCollectionChanged(args);
}
}
With a Custom ListView to do ItemClickCommand:
public class CustomListView : ListView
{
#pragma warning disable 618
public static BindableProperty ItemClickCommandProperty = BindableProperty.Create<CustomListView, ICommand>(x => x.ItemClickCommand, null);
#pragma warning restore 618
public CustomListView(ListViewCachingStrategy cachingStrategy = ListViewCachingStrategy.RetainElement) :
base(cachingStrategy)
{
this.ItemTapped += this.OnItemTapped;
}
public ICommand ItemClickCommand
{
get { return (ICommand)this.GetValue(ItemClickCommandProperty); }
set { this.SetValue(ItemClickCommandProperty, value); }
}
private void OnItemTapped(object sender, ItemTappedEventArgs e)
{
if(e.Item != null && this.ItemClickCommand != null && this.ItemClickCommand.CanExecute(e.Item))
{
this.ItemClickCommand.Execute(e.Item);
this.SelectedItem = null;
}
}
}
then in xaml:
...
...
<Customs:CustomListView
HasUnevenRows="true"
ItemsSource="{Binding PersonList}"
IsPullToRefreshEnabled="True"
RefreshCommand="{Binding DoRefreshCommand}"
ItemClickCommand="{Binding ItemClickCommand}">
...
...
</Customs:CustomListView>
Finally:
public Command<Person> ItemClickCommand { get; set; }
...
ItemClickCommand = new Command<Person>(SelectionExecute);
...
private void SelectionExecute(Person arg)
{
arg.Expand = !arg.Expand;
foreach(var item in PersonList)
{
if(item.Key == arg.Id)// you will change this probably
item.ReportItemChange(arg);
}
}
Hope it help a bit :)
I Am working with a ListView Control in XF application. My XAML Code looks like this.
<ListView ItemsSource="{Binding RechargeList}" HasUnevenRows="True" VerticalOptions="FillAndExpand">
<ListView.ItemTemplate>
<DataTemplate>
<TextCell Text="{Binding Path=SelectedParkingID}" TextColor="Red" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
While my code behind looks like
private ObservableCollection<Recharge> _RechargeList = new ObservableCollection<Recharge>();
public ObservableCollection<Recharge> RechargeList
{
get
{
return _RechargeList;
}
set
{
SetProperty(ref _RechargeList, value);
}
}
And I add Items to Collection in DelegateCommand Event
RechargeList.Add(new Recharge() { SelectedParkingIDParkingID = ParkingID, RechargeAmount = double.Parse(RechargeAmount), BalanceAmount = 10 });
However, the Listview fails to refresh. Could some one help me ?
Looks like you have a typo
<TextCell Text="{Binding Path=SelectedParkingID}" TextColor="Red" />
Should be
<TextCell Text="{Binding Path=SelectedParkingIDParkingID }" TextColor="Red" />
based on what your model looks like. If you try to bind to a property that doesn't exist, it fails softly. So you're adding an item, but the TextCell doesn't render since it has no content.
Please try to implement INotifyPropertyChanged interface in your class.
public class Data : INotifyPropertyChanged
{
// boiler-plate
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
protected bool SetField<T>(ref T field, T value, string propertyName)
{
if (EqualityComparer<T>.Default.Equals(field, value)) return false;
field = value;
OnPropertyChanged(propertyName);
return true;
}
// props
private string name;
public string Name
{
get { return name; }
set { SetField(ref name, value, "Name"); }
}
}
Each property is then just something like:
private string name;
public string Name
{
get { return name; }
set { SetField(ref name, value, "Name"); }
}