I need to know when the listview has scrolled past the first item in the list.

I am currently looking at the native renderer events for scrolling and although I am using a custom renderer they are not fired.

How can I hook into the scroll events?

Thanks for the help,

John

Good Day  

The imageEditor after loading the image , other Toolbar items work nicely but the cropping which put a cross on the centre of the image. crashes when you try to adjust the image with an error 

Unhandled Exception:

System.ArgumentException: An item with the same key has already been added. Key: 0

Thanks

Hi there,

I have a question regarding pie chart redrawing. I am not sure if it works, but is it possible to dynamically update the values of an existing pie chart?

I was able to display the chart when page started(image1 in attach files). I am trying to trigger an event through Xamarin Picker and update the number of the same chart.I was able to change the variable(an ObservableCollection), but the chart never changed.

Is there anything I missed?

I am using RadSlideView in my project. It contains of ContentViews each of them is RelativeLayout with some content. Previously I was using "RelativeToParent" constraing, but now I need to use "RelativeToView". If I use RelativeToView constaint, I have this exception: "System.ArgumentNullException: 'Value cannot be null. Parameter name: key'. This exception occurs only when I place my relative layout inside the SlideVIew and use RelativeToView constraint.

In this case exception occurs:

In this case everything is okay (I don't place RelativeLayout into the RadSlideVIew):

I was evaluating the Xamarin.Forms controls and tried to build a testgrid with a template column.

The column contains an imagebutton with bound IsVisible property.

The grid renders correct but as soon as you start scrolling the grid the invisible imagebuttons go wild and start to get visible.

Image 1 is before scrolling up and down a few times.

Image 2 is after scrolling.

This happens on all platforms (ios,android,uwp)

XAML:

Hi!

Here is my example application: https://drive.google.com/open?id=1HtD5CNjyibRtnQ6dVikYpvuluGgeLEyF

I have a MasterDetailPage as default MainPage.

There is a RadListView in the MenuPage, and a Button in the DetailPage.

When the Button is clicked, it will set MainPage to a new ContentPage( e.g. Application.Current.MainPage = new NewMainPage(); ), then an unhandled exception occcured.

How to fix this problem?

Unhandled Exception:

Hi,

Having used the demo app, I am now trying to add the RadPdfViewer control only to my solution. I am following these instructions (https://docs.telerik.com/devtools/xamarin/controls/pdfviewer/pdfviewer-getting-started).

I initially tried the NuGet package but ran into an "error MSB6006: "java.exe" exited with code 2." situation. I tried increasing the java max heap size passed my current value of 1G, but this did not get resolved.

I then tried the manual DLL reference method, however upon building the solution, I run into the following error :-

error: package com.telerik.android.common does not exist

Therefore, from the list of DLLs for the Android project, it seems like Telerik.Xamarin.Android.Common.dll is missing.

I then reference Telerik.Xamarin.Android.Common.dll and although I am now able to build the solution, I run into the following exception when trying to navigate to a page that contains the RadPdfViewer control :-

NativeResourceProvider.ToPlatformPixels (System.Double dip)
System.TypeInitializationException: Exception of type 'System.Exception' was thrown

Am I missing some additional references?

As a side note, is there a way to fix the "error MSB6006: "java.exe" exited with code 2." when using the NuGet package, as this would ideally be my preference.

Hi. When i close this page, I get a NullReferenceException. Appeared after upgrading to 4.0. If I use ListView, then the problem disappears. If I will not add children to baseGrid, then the problem disappears. Please, help me.

using App.Models.ModelsJsonForMethods;
using System;
using System.Collections.ObjectModel;
using Telerik.XamarinForms.DataControls;
using Telerik.XamarinForms.DataControls.ListView;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace App.Views
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class Page1 : ContentPage
    {
        RadListView listView;
        ObservableCollection<ImportanceInfo> listInfo = new ObservableCollection<ImportanceInfo>();
        public Page1()
        {
            InitializeComponent();
            Refresh();
        }
        private void Refresh()
        {
            listView = new RadListView
            {
                ItemsSource = listInfo,
                ItemTemplate = new DataTemplate(() =>
                {
                    Label stageLabel = new Label();
                    stageLabel.HorizontalOptions = LayoutOptions.Center;
                    stageLabel.VerticalOptions = LayoutOptions.Center;
                    stageLabel.Margin = new Thickness(15, 0, 0, 0);
                    stageLabel.FontSize = 18;
                    stageLabel.SetBinding(Label.TextProperty, new Binding(nameof(ImportanceInfo.StatusName)));
                    Label briefInformationLabel = new Label();
                    briefInformationLabel.HorizontalOptions = LayoutOptions.Start;
                    briefInformationLabel.VerticalOptions = LayoutOptions.Center;
                    briefInformationLabel.FontSize = 18;
                    briefInformationLabel.SetBinding(Label.TextProperty, new Binding(nameof(ImportanceInfo.CommentText)));
                    Label dateLabel = new Label();
                    dateLabel.HorizontalOptions = LayoutOptions.Center;
                    dateLabel.VerticalOptions = LayoutOptions.Center;
                    dateLabel.FontSize = 18;
                    dateLabel.SetBinding(Label.TextProperty, new Binding(nameof(ImportanceInfo.DateSession)));
                    Grid grid = new Grid
                    {
                        RowDefinitions =
                        {
                                new RowDefinition { Height = new GridLength(1, GridUnitType.Star) },
                        },
                        ColumnDefinitions =
                        {
                                new ColumnDefinition { Width = new GridLength(0.3, GridUnitType.Star) },
                                new ColumnDefinition { Width = new GridLength(0.5, GridUnitType.Star) },
                                new ColumnDefinition { Width = new GridLength(0.2, GridUnitType.Star) },
                        },
                        ColumnSpacing = 3,
                        RowSpacing = 3
                    };
                    grid.Children.Add(stageLabel, 0, 0);
                    grid.Children.Add(briefInformationLabel, 1, 0);
                    grid.Children.Add(dateLabel, 2, 0);
                    return new ListViewTemplateCell
                    {
                        View = grid
                    };
                })
            };
            StackLayout layout = new StackLayout
            {
                Spacing = 0
            };
            Grid baseGrid = new Grid
            {
                RowDefinitions =
                            {
                                new RowDefinition { Height = 56 },
                            },
                ColumnDefinitions =
                            {
                                new ColumnDefinition { Width = new GridLength(0.3, GridUnitType.Star) },
                                new ColumnDefinition { Width = new GridLength(0.5, GridUnitType.Star) },
                                 new ColumnDefinition { Width = new GridLength(0.2, GridUnitType.Star) }
                }
            };
            baseGrid.Children.Add(new Label { Text = "Stage" }, 0, 0);
            baseGrid.Children.Add(new Label { Text = "Info" }, 1, 0);
            baseGrid.Children.Add(new Label { Text = "Date" }, 2, 0);
            layout.Children.Add(baseGrid);
            layout.Children.Add(listView);
            ImportanceInfo x = new ImportanceInfo();
            x.CommentText = "111";
            x.ShortText = "222";
            x.Unid = "000";
            x.StatusName = "333";
            x.DateSession = DateTime.Now.ToString();
            listInfo.Add(x);
            this.Content = layout;
        }
    }
}

StackTrace:

  at Xamarin.Forms.Platform.Android.PageRenderer.Xamarin.Forms.Platform.Android.IOrderedTraversalController.UpdateTraversalOrder () [0x000ea] in <9392e6d0fb4f4401a79989cd08844170>:0 
  at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].UpdateParentPageTraversalOrder () [0x00025] in <9392e6d0fb4f4401a79989cd08844170>:0 
  at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].OnElementPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x00116] in <9392e6d0fb4f4401a79989cd08844170>:0 
  at (wrapper delegate-invoke) <Module>.invoke_void_object_PropertyChangedEventArgs(object,System.ComponentModel.PropertyChangedEventArgs)
  at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:211 
  at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:353 
  at Xamarin.Forms.Element.set_Parent (Xamarin.Forms.Element value) [0x00094] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:210 
  at Xamarin.Forms.Element.OnChildRemoved (Xamarin.Forms.Element child) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:335 
  at Xamarin.Forms.ViewCell.set_View (Xamarin.Forms.View value) [0x00019] in D:\a\1\s\Xamarin.Forms.Core\Cells\ViewCell.cs:25 
  at Telerik.XamarinForms.DataControlsRenderer.Android.ListView.CellContainerBase.Dispose (System.Boolean disposing) [0x00034] in <aace7404487f477ba4b06b1a101e6de8>:0 
  at Java.Lang.Object.Dispose () [0x00000] in <ff9f3f3d4e134974a889db1b532c9b6e>:0 
  at Telerik.XamarinForms.DataControlsRenderer.Android.FormsListViewDataSourceAdapterBase.ClearCachedViews () [0x00023] in <aace7404487f477ba4b06b1a101e6de8>:0 
  at Telerik.XamarinForms.DataControlsRenderer.Android.RadListViewDataSourceAdapter.ClearCachedViews () [0x00000] in <aace7404487f477ba4b06b1a101e6de8>:0 
  at Telerik.XamarinForms.DataControlsRenderer.Android.RadListViewDataSourceAdapter.Dispose (System.Boolean disposing) [0x00003] in <aace7404487f477ba4b06b1a101e6de8>:0 
  at Java.Lang.Object.Dispose () [0x00000] in <ff9f3f3d4e134974a889db1b532c9b6e>:0 
  at Telerik.XamarinForms.DataControlsRenderer.Android.ListViewRenderer.OnElementDetached (Telerik.XamarinForms.DataControls.RadListView oldElement) [0x0003c] in <aace7404487f477ba4b06b1a101e6de8>:0 
  at Telerik.XamarinForms.Common.Android.AndroidRendererBase`2[S,T].Dispose (System.Boolean disposing) [0x0001f] in <061fdf8718854839bc5c73d56b04eafa>:0 
  at Java.Lang.Object.Dispose () [0x00000] in <ff9f3f3d4e134974a889db1b532c9b6e>:0 
  at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].Dispose (System.Boolean disposing) [0x000a4] in <9392e6d0fb4f4401a79989cd08844170>:0 
  at Xamarin.Forms.Platform.Android.Platform+DefaultRenderer.Dispose (System.Boolean disposing) [0x0000a] in <9392e6d0fb4f4401a79989cd08844170>:0 
  at Java.Lang.Object.Dispose () [0x00000] in <ff9f3f3d4e134974a889db1b532c9b6e>:0 
  at Xamarin.Forms.Platform.Android.VisualElementRenderer`1[TElement].Dispose (System.Boolean disposing) [0x000a4] in <9392e6d0fb4f4401a79989cd08844170>:0 
  at Xamarin.Forms.Platform.Android.PageRenderer.Dispose (System.Boolean disposing) [0x00011] in <9392e6d0fb4f4401a79989cd08844170>:0 
  at Java.Lang.Object.Dispose () [0x00000] in <ff9f3f3d4e134974a889db1b532c9b6e>:0 
  at Xamarin.Forms.Platform.Android.AppCompat.FragmentContainer.OnDestroyView () [0x0003c] in <9392e6d0fb4f4401a79989cd08844170>:0 
  at Android.Support.V4.App.Fragment.n_OnDestroyView (System.IntPtr jnienv, System.IntPtr native__this) [0x00008] in <96541ba8a6104b52aadf4218488f978c>:0 
  at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.52(intptr,intptr)