I want to reload items into my flowlistview when it reached its bottom. therfore, I would need a function that fires once the end is reached.
I have this flowlistview set up:
<flv:FlowListView
Grid.Column="1"
FlowItemAppearing="listview_allAds_FlowItemAppearing"
FlowColumnCount="2"
IsPullToRefreshEnabled="True"
Refreshing="listview_allAds_Refreshing"
Margin="0,10,0,0"
VerticalScrollBarVisibility="Never"
FlowItemTapped="listview_allAds_FlowItemTapped"
HasUnevenRows="True"
x:Name="listview_allAds" >
<flv:FlowListView.FlowColumnTemplate>
<DataTemplate>
<ContentView Padding="4,3,3,4"> <!--only way to set padding-->
<Frame BorderColor="#ffffff"
HasShadow="True"
Padding="0"
CornerRadius="{OnPlatform Android=5, iOS=5}">
<Grid ...>
</Frame>
</ContentView>
</DataTemplate>
</flv:FlowListView.FlowColumnTemplate>
</flv:FlowListView>
I red that there is a lot you can do with "commands" but I am not sure how to do this.
Can you help me out here?
Thanks!
You could use the FlowItemAppearing. The event you set in your code works well.
async void listview_allAds_ItemAppearing(object sender, ItemVisibilityEventArgs e)
{
if (e.ItemIndex == infos.Count/2)//2 is the FlowColumnCount of your FlowListView
{
await DisplayAlert("Alert", "Scrolled to the bottom", "OK");
}
}
Related
I have a Listview which has toggle switches. I want to select only one item in Listview with toggle switch. When I select second toggle then first toggle must be de-active again. For example in the picture; When I select Rekorida and then I select Merchandizing , Rekorida must turn back disable. Every time only one option can be active. Is it possible to do it in Xamarin?
My listView Code :
<ScrollView>
<ListView x:Name="ShipListView" HasUnevenRows="True" SeparatorVisibility="Default" SelectionMode="Single">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid Margin="4, 3, 4, 3" Padding="2" BackgroundColor="White">
<Grid.RowDefinitions HeightRequest="40">
<RowDefinition></RowDefinition>
<!--<RowDefinition Height="20"></RowDefinition>-->
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="80*"></ColumnDefinition>
<ColumnDefinition Width="*"></ColumnDefinition>
<ColumnDefinition Width="40*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<Label Text="{Binding ShipName}" TextColor="DeepPink" Grid.Column="0" FontAttributes="Bold"/>
<Switch IsToggled="{Binding Selected}" Grid.Column="2" Toggled="OnShipToggled" />
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ScrollView>
And My function
async void OnShipToggled(object sender, ToggledEventArgs e)
{
checkShipSelected = !checkShipSelected;
if(checkShipSelected)
{
ViewCell cell = (sender as Switch).Parent.Parent as ViewCell;
ParametersMemberShipInformation model = cell.BindingContext as ParametersMemberShipInformation;
if (model != null)
{
selectedMemberShipOid = model.Oid;
}
}
else
{
return;
}
}
I'm trying get id of selected item in listview and I do this successfully. Bu I want users can only select one item at the same time because of nice visuality and not be confused.
Fetch your view model in your code behind file and then filter out the selected toggle and marked rest of them as false
private YourViewModel MyViewModel { get => BindingContext as YourViewModel; }
if (model != null)
{
selectedMemberShipOid = model.Oid;
MyViewModel.ShipListView.Where(x=> x.Oid !=
selectedMemberShipOid).Foreach(x=> x.Selected = false)
}
I want to implement the swipe to delete functionality in Xamrin Forms, for which i have tried the following.
Wrote a custom renderer for the list view and in the "OnElementChanged" of the renderer am able to access the binded command to the "CustomListView" and am able to add this command to the Swipe Gesture as added below.
swipeGestureRecognizer = new UISwipeGestureRecognizer (() => {
if (command == null) {
Console.WriteLine ("No command set");
return;}
command.Execute (null);
});
However i am having trouble in accessing the specific row(swiped row), so that i could make a button visible/hidden on the swiped row in the list view. Please could you recommend a way to implement the same?
Swipe to delete is now built into Xamarin Froms ListViews using a ContextAction. Here is the most basic tutorial of how to do it. It is very easy to implement.
http://developer.xamarin.com/guides/cross-platform/xamarin-forms/working-with/listview/
You could do something like this:
protected override void OnElementChanged (ElementChangedEventArgs<ListView> e)
{
base.OnElementChanged (e);
var swipeDelegate = new SwipeRecogniserDelegate ();
swipeGestureRecognizer = new UISwipeGestureRecognizer {
Direction = UISwipeGestureRecognizerDirection.Left,
Delegate = swipeDelegate
};
swipeGestureRecognizer.AddTarget (o => {
var startPoint = swipeDelegate.GetStartPoint ();
Console.WriteLine (startPoint);
var indexPath = this.Control.IndexPathForRowAtPoint(startPoint);
if(listView.SwipeCommand != null) {
listView.SwipeCommand.Execute(indexPath.Row);
}
});
this.Control.AddGestureRecognizer (swipeGestureRecognizer);
this.listView = (SwipableListView)this.Element;
}
The key is SwipeRecogniserDelegate. its implemented like so:
public class SwipeRecogniserDelegate : UIGestureRecognizerDelegate
{
PointF startPoint;
public override bool ShouldReceiveTouch (UIGestureRecognizer recognizer, UITouch touch)
{
return true;
}
public override bool ShouldBegin (UIGestureRecognizer recognizer)
{
var swipeGesture = ((UISwipeGestureRecognizer)recognizer);
this.startPoint = swipeGesture.LocationOfTouch (0, swipeGesture.View);
return true;
}
public PointF GetStartPoint ()
{
return startPoint;
}
}
I was able to accomplish this with the new Xamarin.Forms
SwipeView
Pass the current row into the CommandParameter, and use it in the event handler.
FYI: For some reason the SwipeView has a default BackgroundColor of white, which you can override with something else to match your theme.
Xaml:
<ListView Margin="-20,0,0,0" x:Name="photosListView" ItemSelected="OnItemSelected" VerticalOptions="FillAndExpand" SeparatorColor="Gray" VerticalScrollBarVisibility="Default" HasUnevenRows="true" SeparatorVisibility="Default" Background="{StaticResource PrimaryDark}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<SwipeView BackgroundColor="{StaticResource PrimaryDark}" >
<SwipeView.RightItems>
<SwipeItems>
<SwipeItem Text="Delete" BackgroundColor="LightPink" Clicked="OnDeleteRow" CommandParameter="{Binding .}" />
</SwipeItems>
</SwipeView.RightItems>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<StackLayout Orientation="Horizontal">
<CheckBox IsVisible="{Binding SelectEnabled}" Color="{StaticResource White}" IsChecked="{Binding Selected}" Margin="20,0,-15,0" CheckedChanged="OnItemCheckedChanged" />
<Grid WidthRequest="70" HeightRequest="50">
<Grid.Margin>
<OnPlatform x:TypeArguments="Thickness" Android="15,0,0,0" iOS="10,0,0,0" />
</Grid.Margin>
<Image Aspect="AspectFill" Source="{Binding ThumbImageSource}" HorizontalOptions="Fill" />
</Grid>
</StackLayout>
<StackLayout Grid.Column="1" Spacing="0" Padding="0" Margin="0,5,0,0">
<Label Text="{Binding Photo.Description}" TextColor="{StaticResource TextColour}" FontSize="16" FontAttributes="Bold" />
<Label Text="{Binding DateTakenString}" TextColor="{StaticResource TextColour}" FontSize="14" />
</StackLayout>
</Grid>
</SwipeView>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
cs:
public async void OnDeleteRow(object sender, EventArgs e)
{
if (await GetDeleteRowConfirmationFromUser())
{
SwipeItem si = sender as SwipeItem;
PhotoListItem itemToDelete = si.CommandParameter as PhotoListItem;
LocalDatabaseService db = new LocalDatabaseService();
db.DeletePhoto(itemToDelete.Photo);
_listItems.Remove(itemToDelete);
}
}
I have an image control in my main page and the code is as follows:
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<StackPanel HorizontalAlignment="Left" Height="597" VerticalAlignment="Top" Width="440">
<Image x:Name="hinh1" Height="488" Stretch="Fill"/>
<ProgressBar Name="loading" Height="10" IsIndeterminate="True" Visibility="Collapsed"/>
</StackPanel>
</Grid>
and in code behind i have this code :
Uri hinh = new Uri
("http://taigamejar.net/wp-content/uploads/2014/01/Hinh-Anh-Dep-5.jpg", UriKind.Absolute);
hinh1.Source = new BitmapImage(hinh);
While waiting for the image to load, I want to call progress bar run to inform the user that it is loading. Once the the image has loaded, the progress bar should disappear. How can I do this?
If I were you, I would prefer to use , not ProgressBar.
So, I'll give
protected override void OnNavigatedTo(NavigationEventArgs e)
{
loading.IsActive = true;
Uri hinh = new Uri
("http://taigamejar.net/wp-content/uploads/2014/01/Hinh-Anh-Dep-5.jpg", UriKind.Absolute);
hinh1.Source = new BitmapImage(hinh);
hinh1.ImageOpened+=hinh1_ImageOpened; //loadingbar will be disappear when this triggered
}
private void hinh1_ImageOpened(object sender, RoutedEventArgs e)
{
loading.IsActive = false; //this will disable the progressring.
}
And XAML:
<StackPanel HorizontalAlignment="Left" Height="597" VerticalAlignment="Top" Width="400">
<Image x:Name="hinh1" Height="488" Stretch="Fill" ImageOpened="hinh1_ImageOpened"/>
<ProgressRing Name="loading" Height="109" IsActive="True" />
</StackPanel>
If you don't have WP8.1 SDK yet, you can get ProgressRing here: http://www.onurtirpan.com/onur-tirpan/english/windows-phone-english/using-progressring-in-windows-phone/
I made some ExpanderViews and hardcoded everything. That worked and looked nice so I wanted to clean up and only write one ExpanderView in xaml and load everything else with a binding.
As far as I understood I need a ListBox around the whole thing to make it more dynamic?
This is my code so far:
<ListBox ItemsSource="{Binding ContactDe}">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<toolkit:ExpanderView Header="{Binding}"
ItemsSource="{Binding LocationName}"
IsNonExpandable="False">
<toolkit:ExpanderView.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding LocationName}" FontFamily="{StaticResource PhoneFontFamilySemiBold}" LineHeight="{StaticResource LongListSelectorGroupHeaderFontSize}" />
</DataTemplate>
</toolkit:ExpanderView.HeaderTemplate>
<toolkit:ExpanderView.ExpanderTemplate>
<DataTemplate>
<TextBlock Text="test" />
</DataTemplate>
</toolkit:ExpanderView.ExpanderTemplate>
<toolkit:ExpanderView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Information}" />
</DataTemplate>
</toolkit:ExpanderView.ItemTemplate>
</toolkit:ExpanderView>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The ContactViewModel-Class:
public class ContactDeViewModel : INotifyPropertyChanged
{
private string _locationName;
public string LocationName
{
get
{
return _locationName;
}
set
{
if (value != _locationName)
{
_locationName = value;
NotifyPropertyChanged("LocationName");
}
}
}
private List<string> _information;
public List<string> Information
{
get
{
return _information;
}
set
{
if (value != _information)
{
_information = value;
NotifyPropertyChanged("Information");
}
}
}
}
And this is where I fill the ContactViewModel:
this.ContactDe.Add(new ContactDeViewModel()
{
LocationName = "Stuttgart",
Information = new List<string>
{
"some text"
}
}
);
this.ContactDe.Add(new ContactDeViewModel()
{
LocationName = "Böblingen",
Information = new List<string>
{
"more text"
}
}
);
I made a SampleViewModel-File where I have:
<vm:MainViewModel.ContactDe>
<vm:ContactDeViewModel LocationName="Location 1" />
<vm:ContactDeViewModel LocationName="Location 2" />
</vm:MainViewModel.ContactDe>
In the preview-window it shows me 2 ExpanderViews with Location 1 and 2. But the same code doesn't work with the emulator or a real device. I don't really understand which Binding-Acces does what. It would already help me a lot if I could see a full example. I googled many tutorials but most only show 1 side, like a xaml without seing how the data is stored.
edit:
Now I edited the viewModel, so it's not a List<string> but a List<Info> with Info only containing string Text. So now I can say ItemsSource="{Binding Text}" which should be only 1 string at a time, right?
As stated in comment to #dellywheel's answer, that you set DataContext this way :
d:DataContext="{d:DesignData SampleData/MainViewModelSampleData.xaml}"
that set DataContext for use in design-time only, hence it doesn't work in run-time. To set DataContext with similar approach for use in run-time, you can try this way :
<ListBox ItemsSource="{Binding ContactDe}">
<ListBox.DataContext>
<vm:MainViewModel/>
</ListBox.DataContext>
........
........
</ListBox>
or this way to set DataContext in page level :
<phone:PhoneApplicationPage>
<phone:PhoneApplicationPage.DataContext>
<vm:MainViewModel/>
</phone:PhoneApplicationPage.DataContext>
........
........
</phone:PhoneApplicationPage>
Another suggestion, prefer ObservableCollection rather than List for use along with data binding. ObservableCollection automatically notify view to refresh whenever item added to or removed from collection.
You need to change your bindings slightly
<toolkit:ExpanderView Header="{Binding LocationName}"
ItemsSource="{Binding Information}"
IsNonExpandable="False">
<toolkit:ExpanderView.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" FontFamily="{StaticResource honeFontFamilySemiBold}" LineHeight="{StaticResource LongListSelectorGroupHeaderFontSize}" />
</DataTemplate>
</toolkit:ExpanderView.HeaderTemplate>
<toolkit:ExpanderView.ExpanderTemplate>
<DataTemplate>
<TextBlock Text="test" />
</DataTemplate>
</toolkit:ExpanderView.ExpanderTemplate>
<toolkit:ExpanderView.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" />
</DataTemplate>
</toolkit:ExpanderView.ItemTemplate>
</toolkit:ExpanderView>
Hope that helps
I have a XAML:
<phone:Pivot Name="pivot" SelectionChanged="pivot_SelectionChanged">
<phone:Pivot.ItemTemplate>
<DataTemplate>
<ViewportControl Name="viewport">
<Canvas Name="canvas">
<Image Name="image"
RenderTransformOrigin="0,0"
CacheMode="BitmapCache"
Source="{Binding ImageSource}">
<Image.RenderTransform>
<ScaleTransform x:Name="xform"/>
</Image.RenderTransform>
</Image>
</Canvas>
</ViewportControl>
</DataTemplate>
</phone:Pivot.ItemTemplate>
</phone:Pivot>
Can I get current ViewportControl, Canvas, etc for selected item? For example
private void pivot_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
//get ViewportControl, Canvas, etc
}
Not necessarily with SelectionChanged, may have other solutions?
Yes, but you have to search for them. You need to use VisualTreeHelper and hunt for children of the desired type.
Or you can have some mapping in the code-behind for all controls and the parent pivot items.