I tried to use Jet-Image Loader on my windows 8 phone application and it works fine over forms but once i try to apply the Jet-Image caching technique over the aync methods which bind information on async mode it won't work, below is the code which i am using:
XAML:
<ctl:LongListSelector x:Name="ListCards" VerticalAlignment="Center"
LayoutMode="Grid" ItemsSource="{Binding greetingsList}"
SelectionChanged="lstCards_SelectionChanged"
GridCellSize="210,170">enter code here
<ctl:LongListSelector.ItemTemplate>
<DataTemplate>
<StackPanel Width="200" Height="170" VerticalAlignment="Center">
<Image Source="{Binding ImgPath, Converter={StaticResource SampleJetImageLoaderConverter}}"
Width="180" Height="140"
HorizontalAlignment="Center"
Stretch="UniformToFill" />
</StackPanel>
</DataTemplate>
</ctl:LongListSelector.ItemTemplate>
</ctl:LongListSelector>
Code:
public partial class card_List3 : PhoneApplicationPage
{
public class GetGreetingSchema
{
public Uri ImgPath
{
get { return _ImgPath; }
set
{
SetProperty(ref _ImgPath, value);
}
}
}
public ObservableCollection<GetGreetingSchema> greetingsList { get; private set; }
public card_List3()
{
InitializeComponent();
greetingsList = new ObservableCollection<GetGreetingSchema>();
DataContext = this;
}
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
try
{
await LoadDataAsync();
}
catch (Exception listbindException)
{
ReusableMethods.LogStackTrace(listbindException);
}
}
private async Task LoadDataAsync()
{
var dataSource = new Container().Resolve<IfellowsCollection>();
greetingsList = await dataSource.BindGreetingsList(CatId, Contenttype);
ListCards.ItemsSource = greetingsList;
}
}
I found your question here :)
Issue is fixed, now JetImageLoader supports Uri as imageUrl param: https://github.com/artem-zinnatullin/jet-image-loader/issues/8
Related
I have a collectionview that is bound to an ObservableRangeCollectionin my ViewModel.
In my ViewModel there is a Method that runs onAppearing and I want my ColletionViewto be filled from there, but when I do so the collectionveiw dose not display the content only when i reload the content is shown.
View:
<RefreshView Grid.Row="1"
Grid.RowSpan="2"
Command="{Binding RefreshCommand}"
IsRefreshing="{Binding IsBusy, Mode=OneWay}">
<RefreshView.RefreshColor>
<OnPlatform x:TypeArguments="Color">
<On Platform="iOS" Value="White"/>
</OnPlatform>
</RefreshView.RefreshColor>
<CollectionView x:Name="Collection"
ItemsSource="{Binding Locations, Mode=OneWay}"
ItemTemplate="{StaticResource ListDataTemplate}"
RemainingItemsThresholdReachedCommand="{Binding LoadMoreCommand}"
RemainingItemsThreshold="10"
SelectionMode="Single"
BackgroundColor="Transparent"
ItemsLayout="VerticalList"
SelectedItem="{Binding SelectedItem}"
SelectionChangedCommand="{Binding SelectedCommand}">
<CollectionView.EmptyView>
<StackLayout Padding="12">
<Label HorizontalOptions="Center" Text="Keine Daten vorhanden!" TextColor="White"/>
</StackLayout>
</CollectionView.EmptyView>
</CollectionView>
</RefreshView>
ViewModel:
namespace YourPartys.ViewModels
{
public class ListViewModel : ViewModelBase
{
#region Variables
#endregion
#region Propertys
LocationModel selectedItem;
public LocationModel SelectedItem
{
get => selectedItem;
set => SetProperty(ref selectedItem, value);
}
public ObservableRangeCollection<LocationModel> Locations { get;set; } = new ObservableRangeCollection<LocationModel>();
double distance;
public double Distance
{
get => distance;
set => SetProperty(ref distance, value);
}
#endregion
#region Commands
public ICommand FilterButtonCommand { get; }
public ICommand RefreshCommand { get; }
public ICommand SelectedCommand { get; }
public ICommand LoadMoreCommand { get; }
#endregion
//Constructor
public ListViewModel()
{
FilterButtonCommand = new Command(OpenFilter);
RefreshCommand = new AsyncCommand(Refresh);
SelectedCommand = new AsyncCommand(Select);
}
public override async void VModelActive(Page sender, EventArgs eventArgs)
{
base.VModelActive(sender, eventArgs);
var locs = await FirestoreService.GetLocations("Locations");
Locations.AddRange(locs);
}
private void OpenFilter(object obj)
{
PopupNavigation.Instance.PushAsync(new ListFilterPage());
}
private async Task Refresh()
{
IsBusy = true;
var locs = await FirestoreService.GetLocations("Locations");
Locations.AddRange(locs);
IsBusy = false;
}
private async Task Select()
{
if (SelectedItem == null)
return;
var route = $"{nameof(DetailPage)}?Locationid={SelectedItem.Locationid}";
SelectedItem = null;
await AppShell.Current.GoToAsync(route);
}
}
}
There are several problems in your demo.
1.Since you set the BindingContext for your page in xaml as follows:
<ContentPage.BindingContext>
<viewmodels:MainViewModel/>
</ContentPage.BindingContext>
you didn't need to recreate another object MainViewModel in a CS file and reference it. These are two different objects.
MainViewModel viewModel;
viewModel = new MainViewModel();
protected override void OnAppearing()
{
base.OnAppearing();
viewModel.VModelActive(this, EventArgs.Empty);
}
So, you can get the BindingContext in MainPage.xaml.cs in function OnAppearing as follows:
protected override void OnAppearing()
{
base.OnAppearing();
viewModel = (MainViewModel)this.BindingContext;
viewModel.VModelActive(this, EventArgs.Empty);
}
The whole code is
public partial class MainPage : ContentPage
{
MainViewModel viewModel;
public MainPage()
{
InitializeComponent();
// viewModel = new MainViewModel();
}
protected override void OnAppearing()
{
base.OnAppearing();
viewModel = (MainViewModel)this.BindingContext;
viewModel.VModelActive(this, EventArgs.Empty);
}
}
2.when we set the text color of the Label to White,this makes it hard to see the text,so you can reset it to another color,for example Black:
<Label Text="{Binding Name}"
FontSize="30"
TextColor="White"/>
I am trying to populate listview with database table in xamarin forms app
I am getting null pointer exception
Below is XAML for listview
<ListView x:Name="_listView"
ItemsSource="{Binding itemsInList}"
Grid.Column="0"
Grid.Row="0"
SelectedItem="{Binding SelectedItem}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Label Text="{Binding Name}" Grid.Column="0" Grid.Row="0" />
</Grid>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Below is xaml.cs(code behind)
public List <ServiceProvider> itemlist;
public List <ServiceProvider> itemsInList
{
get {return itemlist;}
}
protected override void OnAppearing()
{
base.OnAppearing();
ExpensesDatabase dbcon = new ExpensesDatabase(completePath);
itemlist = dbcon.GetItems(completePath);
// _listView.ItemsSource = itemlist;
}
Below is db file
public class ExpensesDatabase
{
readonly SQLiteConnection database;
public ExpensesDatabase(string dbPath)
{
database = new SQLiteConnection(dbPath);
database.CreateTable < ServiceProvider > ();
}
public List < ServiceProvider > GetItems(string dbPath)
{
return database.Table < ServiceProvider > ().ToList();
}
}
Data is not displayed in listview
If you want the ListView to automatically update as items are added, removed and changed in the underlying list, you'll need to use an ObservableCollection. ObservableCollection is defined in System.Collections.ObjectModel and is just like List, except that it can notify ListView of any changes:
public ObservableCollection<ServiceProvider> itemsInList { get; set; }
Then make sure you have set the right bindingContext and initialized the ObservableCollection:
public MainPage()
{
InitializeComponent();
itemsInList = new ObservableCollection<ServiceProvider>();
BindingContext = this;
}
I write a sample to test and it works on my side, you can have a look at the full code:
public partial class MainPage : ContentPage
{
public ObservableCollection<ServiceProvider> itemsInList { get; set; }
public MainPage()
{
InitializeComponent();
itemsInList = new ObservableCollection<ServiceProvider>();
BindingContext = this;
}
protected override void OnAppearing()
{
base.OnAppearing();
itemsInList.Add(new ServiceProvider() { Name= "a"});
}
}
public class ServiceProvider : INotifyPropertyChanged
{
string name;
public event PropertyChangedEventHandler PropertyChanged;
public ServiceProvider()
{
}
public String Name
{
set
{
if (name != value)
{
name = value;
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("Name"));
}
}
}
get
{
return name;
}
}
}
Feel free to ask me any question if you still can't solve it.
I have this template:
<?xml version="1.0" encoding="utf-8"?>
<Grid Padding="20,0" xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:Japanese;assembly=Japanese"
x:Class="Japanese.Templates.DataGridTemplate"
x:Name="this" HeightRequest="49" Margin="0">
<Grid.GestureRecognizers>
<TapGestureRecognizer
Command="{Binding TapCommand, Source={x:Reference this}}"
CommandParameter="1"
NumberOfTapsRequired="1" />
</Grid.GestureRecognizers>
<Label Grid.Column="0" Text="{Binding Test" />
</Grid>
Behind this I have:
public partial class DataGridTemplate : Grid
{
public DataGridTemplate()
{
InitializeComponent();
}
public static readonly BindableProperty TapCommandProperty =
BindableProperty.Create(
"Command",
typeof(ICommand),
typeof(DataGridTemplate),
null);
public ICommand TapCommand
{
get { return (ICommand)GetValue(TapCommandProperty); }
set { SetValue(TapCommandProperty, value); }
}
}
and I am trying to call the template like this in file: Settings.xaml.cs
<template:DataGridTemplate TapCommand="openCFSPage" />
hoping that it will call my method here in file: Settings.cs
void openCFSPage(object sender, EventArgs e)
{
Navigation.PushAsync(new CFSPage());
}
The code compiles but when I click on the grid it doesn't call the openCFSPage method.
1) Does anyone have an idea what might be wrong?
2) Also is there a way that I can add a parameter to the template and then have that parameter passed to my method in the CS back end code?
Note that I would like to avoid adding a view model if possible. The application is small and I'd like to just have the code I need in the CS code of the page that calls the template.
Please note that the simplest way to implement this would be through MVVM (i.e. a view-model), but if you want to side-step this option (as you mentioned in the question) then you can use one of the following options
Option1 : Wrap delegate into command object
If you look at it from the perspective of a XAML parser, you are technically trying to assign a delegate to a property of type ICommand. One way to avoid the type mismatch would be to wrap the delegate inside a command-property in the page's code-behind.
Code-behind [Settings.xaml.cs]
ICommand _openCFSPageCmd;
public ICommand OpenCFSPageCommand {
get {
return _openCFSPageCmd ?? (_openCFSPageCmd = new Command(OpenCFSPage));
}
}
void OpenCFSPage(object param)
{
Console.WriteLine($"Control was tapped with parameter: {param}");
}
XAML [Settings.xaml]
<!-- assuming that you have added x:Name="_parent" in root tag -->
<local:DataGridView TapCommand="{Binding OpenCFSPageCommand, Source={x:Reference _parent}}" />
Option2 : Custom markup-extension
Another option (a bit less mainstream) is to create a markup-extension that wraps the delegate into a command object.
[ContentProperty("Handler")]
public class ToCommandExtension : IMarkupExtension
{
public string Handler { get; set; }
public object Source { get; set; }
public object ProvideValue(IServiceProvider serviceProvider)
{
if (serviceProvider == null)
throw new ArgumentNullException(nameof(serviceProvider));
var lineInfo = (serviceProvider?.GetService(typeof(IXmlLineInfoProvider)) as IXmlLineInfoProvider)?.XmlLineInfo ?? new XmlLineInfo();
object rootObj = Source;
if (rootObj == null)
{
var rootProvider = serviceProvider.GetService<IRootObjectProvider>();
if (rootProvider != null)
rootObj = rootProvider.RootObject;
}
if(rootObj == null)
{
var valueProvider = serviceProvider.GetService<IProvideValueTarget>();
if (valueProvider == null)
throw new ArgumentException("serviceProvider does not provide an IProvideValueTarget");
//we assume valueProvider also implements IProvideParentValues
var propInfo = valueProvider.GetType()
.GetProperty("Xamarin.Forms.Xaml.IProvideParentValues.ParentObjects",
BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
if(propInfo == null)
throw new ArgumentException("valueProvider does not provide an ParentObjects");
var parentObjects = propInfo.GetValue(valueProvider) as IEnumerable<object>;
rootObj = parentObjects?.LastOrDefault();
}
if(rootObj != null)
{
var delegateInfo = rootObj.GetType().GetMethod(Handler,
BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
if(delegateInfo != null)
{
var handler = Delegate.CreateDelegate(typeof(Action<object>), rootObj, delegateInfo) as Action<object>;
return new Command((param) => handler(param));
}
}
throw new XamlParseException($"Can not find the delegate referenced by `{Handler}` on `{Source?.GetType()}`", lineInfo);
}
}
Sample usage
<local:DataGridView TapCommand="{local:ToCommand OpenCFSPage}" />
You have 2 options depending on the the use case :
FYI, there's no way to call another method directly from the view (its a bad design pattern to do so)
Using Event Aggregator :
Create interface
public interface IEventAggregator
{
TEventType GetEvent<TEventType>() where TEventType : EventBase, new();
}
All you have to do is call it from you TapCommand
_eventAggregator.GetEvent<ItemSelectedEvent>().Publish(_selectedItem);
Then in your Settings.cs you can Create a method that can receive the data
this.DataContext = new ListViewModel(ApplicationService.Instance.EventAggregator);
Inheritance and Polymorphism / Making openCFSPage a service :
Creating a interface / service that links both models
public interface IOpenCFSPage
{
Task OpenPage();
}
and a method :
public class OpenCFSPage : IOpenCFSPage
{
private INavigationService _navigationService;
public OpenCFSPage(INavigationService navigationService){
_navigationService = navigationService;
}
public async Task OpenPage()
{
await _navigationService.NavigateAsync(new CFSPage());
}
}
Settings.xaml:
<template:DataGridTemplate TapCommand="{Binding OpenCFSPage}" />
<!-- Uncomment below and corresponding parameter property code in DataGridTemplate.xaml.cs to pass parameter from Settings.xaml -->
<!--<template:DataGridTemplate TapCommand="{Binding OpenCFSPage}" CommandParameter="A" />-->
Settings.xaml.cs:
public Settings()
{
InitializeComponent();
OpenCFSPage = new Command(p => OpenCFSPageExecute(p));
BindingContext = this;
}
public ICommand OpenCFSPage { get; private set; }
void OpenCFSPageExecute(object p)
{
var s = p as string;
Debug.WriteLine($"OpenCFSPage:{s}:");
}
DataGridTemplate.xaml:
<?xml version="1.0" encoding="UTF-8"?>
<Grid xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:Japanese;assembly=Japanese"
Padding="0,20"
HeightRequest="49" Margin="0"
x:Class="Japanese.DataGridTemplate">
<Grid.GestureRecognizers>
<TapGestureRecognizer
Command="{Binding TapCommand}"
CommandParameter="1"
NumberOfTapsRequired="1" />
</Grid.GestureRecognizers>
<Label Grid.Column="0" Text="Test" />
</Grid>
DataGridTemplate.xaml.cs:
public partial class DataGridTemplate : Grid
{
public DataGridTemplate()
{
InitializeComponent();
}
public static readonly BindableProperty TapCommandProperty =
BindableProperty.Create(
nameof(TapCommand), typeof(ICommand), typeof(DataGridTemplate), null,
propertyChanged: OnCommandPropertyChanged);
public ICommand TapCommand
{
get { return (ICommand)GetValue(TapCommandProperty); }
set { SetValue(TapCommandProperty, value); }
}
//public static readonly BindableProperty CommandParameterProperty = BindableProperty.Create(
// nameof(CommandParameter), typeof(string), typeof(DataGridTemplate), null);
//public string CommandParameter
//{
// get { return (string)GetValue(CommandParameterProperty); }
// set { SetValue(CommandParameterProperty, value); }
//}
static TapGestureRecognizer GetTapGestureRecognizer(DataGridTemplate view)
{
var enumerator = view.GestureRecognizers.GetEnumerator();
while (enumerator.MoveNext())
{
var item = enumerator.Current;
if (item is TapGestureRecognizer) return item as TapGestureRecognizer;
}
return null;
}
static void OnCommandPropertyChanged(BindableObject bindable, object oldValue, object newValue)
{
if (bindable is DataGridTemplate view)
{
var tapGestureRecognizer = GetTapGestureRecognizer(view);
if (tapGestureRecognizer != null)
{
tapGestureRecognizer.Command = (ICommand)view.GetValue(TapCommandProperty);
//tapGestureRecognizer.CommandParameter = (string)view.GetValue(CommandParameterProperty);
}
}
}
}
Check this code you help you. Here you have to pass a reference of list view and also you need to bind a command with BindingContext.
<ListView ItemsSource="{Binding Sites}" x:Name="lstSale">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout Orientation="Vertical">
<Label Text="{Binding FriendlyName}" />
<Button Text="{Binding Name}"
HorizontalOptions="Center"
VerticalOptions="Center"
Command="{Binding
Path=BindingContext.RoomClickCommand,
Source={x:Reference lstSale}}"
CommandParameter="{Binding .}" />
</StackLayout>
</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 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.