Questions on UI for Xamarin Forum

2 answers

101 views

VisualElementRenderer UpdateTabStop Error

Hi,

I am getting an error with the SideDrawer after updating to the latest version of Xamarin Forms, the issue seems to occur when the back button is clicked and the SideDrawer is visible, we also have a TabbedPage in our app and if you click the same tab as is visible when the SideDrawer is visible it causes the same crash.

We use Azure mobile app centre, so all the information for the crash is below:

Xamarin.Forms Version - 3.3.0.912540

Telerik.UI Version - 2018.3.1018.1, we had the same issue with previous build too 2018.2.620.2 but tried upgrading.

Error is:

VisualElementRenderer`1[TElement].UpdateTabStop ()
System.NullReferenceException: Object reference not set to an instance of an object

Threads:

VisualElementRenderer`1[TElement].UpdateTabStop ()
IVisualElementRenderer.SetElement (Xamarin.Forms.VisualElement element)
RadPlatform.RetireRenderer (Xamarin.Forms.VisualElement visualElement)
RadViewContainer.ClearContainer ()
RadViewContainer.Dispose (System.Boolean disposing)
NSObject.Dispose ()
SideDrawerRenderer.OnElementDetached (Telerik.XamarinForms.Primitives.RadSideDrawer oldElement)
IosRendererBase`2[S,T].OnElementChanged (Xamarin.Forms.Platform.iOS.ElementChangedEventArgs`1[TElement] e)
VisualElementRenderer`1[TElement].SetElement (TElement element)
VisualElementRenderer`1[TElement].Dispose (System.Boolean disposing)
ViewRenderer`2[TView,TNativeView].Dispose (System.Boolean disposing)
NSObject.Dispose ()
DisposeHelpers.DisposeModalAndChildRenderers (Xamarin.Forms.Element view)
Platform.HandleChildRemoved (System.Object sender, Xamarin.Forms.ElementEventArgs e)
Element.OnDescendantRemoved (Xamarin.Forms.Element child)
Element.OnDescendantRemoved (Xamarin.Forms.Element child)
Element.OnChildRemoved (Xamarin.Forms.Element child)
VisualElement.OnChildRemoved (Xamarin.Forms.Element child)
Page.OnInternalRemoved (Xamarin.Forms.VisualElement view)
Page.InternalChildrenOnCollectionChanged (System.Object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
ObservableCollection`1[T].OnCollectionChanged (System.Collections.Specialized.NotifyCollectionChangedAction action, System.Object item, System.Int32 index)
ObservableCollection`1[T].RemoveItem (System.Int32 index)
Collection`1[T].Remove (T item)
NavigationPage+<Xamarin-Forms-INavigationPageController-RemoveAsyncInner>d__69.MoveNext ()
TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task)
TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task)
TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task)
TaskAwaiter`1[TResult].GetResult ()
NavigationRenderer+<UpdateFormsInnerNavigation>d__75.MoveNext ()
TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task)
TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task)
TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task)
TaskAwaiter.GetResult ()
NavigationRenderer+ParentingViewController+<DidMoveToParentViewController>d__41.MoveNext ()
AsyncMethodBuilderCore+<>c.<ThrowAsync>b__6_0 (System.Object state)
NSAsyncSynchronizationContextDispatcher.Apply ()
(wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate)
UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName)
Application.Main (System.String[] args)

SideDrawer

answered on 24 Oct 2018

1 answer

171 views

Autocomplete inside ListView

Hi I am new to xamarin forms. How can I use selecteditem for the multiple Autocomplete controller which are inside a Listview already

<telerikDataControls:RadListView x:Name="listView" ItemsSource="{Binding QuantityRows}" ItemTapped="Item_Selected" Grid.Row="1">
<telerikDataControls:RadListView.ItemTemplate>
<DataTemplate>
<telerikListView:ListViewTemplateCell>
<telerikListView:ListViewTemplateCell.View>
<Label Text="{Binding FieldDescription}"></Label>
<telerikInput:RadAutoComplete x:Name="autoCompleteWatermark"

ItemsSource="{Binding Listing}"
TextSearchPath="Name"
VerticalOptions="Start"
NoResultsMessage="there are no matching items..."
Watermark="Search here..." />
</telerikListView:ListViewTemplateCell.View>
</telerikListView:ListViewTemplateCell>
</DataTemplate>
</telerikDataControls:RadListView.ItemTemplate>
</telerikDataControls:RadListView>

AutoComplete

answered on 23 Oct 2018

1 answer

156 views

CartesianGridLineAnnotation - not shown correctly

Hi,

I have an issue with the Telerik Chart control in Xamarin on Android - please see the attached screenshot.
I added a CartesianGridLineAnnotation using the following code:

chartCounter.Annotations.Add(new CartesianGridLineAnnotation() { Axis = verticalAxis, Value = fColorMaxContract, Stroke = Color.FromHex("EB6909"), StrokeThickness = 2, DashArray = new double[] { 8, 8 } });

The line should be at value 200 but is "hanging down" on the right side. I magnified this a little so it is easier to see.
I had this issue with older versions but still in Telerik.UI.for.Xamarin v2018.3.1018.1 to which I upgraded now.

This seems like a bug to me.

Best regards,

Thomas

Chart

answered on 23 Oct 2018

1 answer

106 views

AutoCompleteView does not work on Android 4.2.2

AutoCompleteView does not seem to trigger the SuggestionItemSelected event. It shows the SuggestionView but selecting the value does not do anything. It works fine Android 8.1 but not on 4.2.2

Thanks

AutoCompleteView

answered on 22 Oct 2018

3 answers

124 views

Stop Android switching view mode

If I double tap on the Android calendar it switches to year mode. Is there a way to stop this such that the calendar is fixed in month mode?

Calendar & Scheduling

answered on 19 Oct 2018

1 answer

143 views

RadLegend sometimes disappears permanently when its parent controls toggle IsVisible

I have a RadLegend in my UI situated under a couple of controls that toggle visibility, in this case for a simple styled tab layout. But when the parent toggles back to visible, sometimes the RadLegend does not reappear. In some cases, when the data for the corresponding pie chart is updated, the legend will disappear right away.

Here's my layout (this page ends up as the Detail of a MasterDetailPage):

<?xml version="1.0" encoding="utf-8" ?>

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"

xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"

xmlns:local="clr-namespace:MyApp.Views"

xmlns:telerikChart="clr-namespace:Telerik.XamarinForms.Chart;assembly=Telerik.XamarinForms.Chart"

x:Class="MyApp.Views.DowntimeDashboardPage"

Style="{StaticResource DefaultContentPageStyle}"

Title="{Binding Title}">

<ContentPage.ToolbarItems>

<ToolbarItem Command="{Binding ShowFilters}">

<ToolbarItem.Icon>

<OnPlatform x:TypeArguments="FileImageSource" iOS="{x:Null}" Android="ic_action_filter.png">

</OnPlatform>

</ToolbarItem.Icon>

<ToolbarItem.Text>

<OnPlatform x:TypeArguments="x:String" iOS="Filters" Android="{x:Null}" />

</ToolbarItem.Text>

</ToolbarItem>

</ContentPage.ToolbarItems>

<ContentPage.Content>

<StackLayout Style="{StaticResource InnerPageStackLayoutStyle}" Spacing="20">

<StackLayout Orientation="Horizontal" HorizontalOptions="Center" Spacing="0" Margin="20">

<local:ToggleButton Text=" Top 5 " IsToggled="{Binding TopFiveIsToggled}" />

<local:ToggleButton Text=" Trend " IsToggled="{Binding TrendIsToggled}" />

<local:ToggleButton Text=" Category " IsToggled="{Binding CategoryIsToggled}" />

</StackLayout>

<Label Text="Nothing Found"

HorizontalOptions="Center"

VerticalOptions="Center"

IsVisible="{Binding ShowNothingFound}" />

<Grid HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand"

IsVisible="{Binding ShowData}">

<telerikChart:RadCartesianChart x:Name="topFiveChart"

HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand"

BackgroundColor="Transparent"

Margin="0, 0, 0, 40"

IsVisible="{Binding TopFiveIsToggled}">

<!--<telerikChart:RadCartesianChart.ChartBehaviors>

<telerikChart:ChartSelectionBehavior DataPointSelectionMode="Single" SeriesSelectionMode="None" />

</telerikChart:RadCartesianChart.ChartBehaviors>-->

<telerikChart:RadCartesianChart.HorizontalAxis>

<telerikChart:CategoricalAxis LabelFitMode="MultiLine" PlotMode="BetweenTicks" MajorTickThickness="2"

LabelTextColor="White" ShowLabels="True" />

</telerikChart:RadCartesianChart.HorizontalAxis>

<telerikChart:RadCartesianChart.VerticalAxis>

<telerikChart:NumericalAxis Minimum="0" LabelTextColor="White" />

</telerikChart:RadCartesianChart.VerticalAxis>

<telerikChart:RadCartesianChart.Grid>

<telerikChart:CartesianChartGrid MajorLinesVisibility="Y" MajorLineThickness="1" />

</telerikChart:RadCartesianChart.Grid>

<telerikChart:RadCartesianChart.Series>

<telerikChart:BarSeries AllowSelect="True" CategoryBinding="LegendTitle" LabelBinding="Label"

ValueBinding="Minutes" ShowLabels="True" ItemsSource="{Binding TopFiveData}" />

</telerikChart:RadCartesianChart.Series>

</telerikChart:RadCartesianChart>

<telerikChart:RadCartesianChart x:Name="trendChart"

HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand"

BackgroundColor="Transparent"

Margin="0, 0, 0, 40" IsVisible="{Binding TrendIsToggled}">

<!--<telerikChart:RadCartesianChart.ChartBehaviors>

<telerikChart:ChartSelectionBehavior DataPointSelectionMode="Single" SeriesSelectionMode="None" />

</telerikChart:RadCartesianChart.ChartBehaviors>-->

<telerikChart:RadCartesianChart.HorizontalAxis>

<telerikChart:DateTimeContinuousAxis LabelFitMode="Rotate" PlotMode="BetweenTicks" MajorTickThickness="2"

LabelFormat="MM/dd HH:mm"

LabelTextColor="White" ShowLabels="True" />

</telerikChart:RadCartesianChart.HorizontalAxis>

<telerikChart:RadCartesianChart.VerticalAxis>

<telerikChart:NumericalAxis Minimum="0" LabelTextColor="White" />

</telerikChart:RadCartesianChart.VerticalAxis>

<telerikChart:RadCartesianChart.Grid>

<telerikChart:CartesianChartGrid MajorLinesVisibility="Y" MajorLineThickness="1" />

</telerikChart:RadCartesianChart.Grid>

<telerikChart:RadCartesianChart.Series>

<telerikChart:SplineAreaSeries StrokeThickness="2"

Stroke="{StaticResource TrendChartLineColor}"

Fill="{StaticResource TrendChartFillColor}"

LabelBinding="Label"

ValueBinding="Minutes"

CategoryBinding="Timestamp"

ShowLabels="False"

ItemsSource="{Binding TrendData}" />

</telerikChart:RadCartesianChart.Series>

</telerikChart:RadCartesianChart>

<StackLayout HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" Margin="0"

IsVisible="{Binding CategoryIsToggled}">

<telerikChart:RadPieChart x:Name="categoryChart" BackgroundColor="Transparent"

HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">

<!--<telerikChart:RadPieChart.ChartBehaviors>

<telerikChart:ChartSelectionBehavior DataPointSelectionMode="Single" SeriesSelectionMode="None" />

</telerikChart:RadPieChart.ChartBehaviors>-->

<telerikChart:RadPieChart.Series>

<telerikChart:PieSeries ItemsSource="{Binding CategoryData}"

ShowLabels="True"

AllowSelect="False"

ValueBinding="Minutes"

LabelBinding="Label"

LegendTitleBinding="LegendTitle">

</telerikChart:PieSeries>

</telerikChart:RadPieChart.Series>

</telerikChart:RadPieChart>

<StackLayout BackgroundColor="{StaticResource PieChartLegendBackgroundColor}"

HorizontalOptions="FillAndExpand"

VerticalOptions="End"

Margin="20"

Padding="20">

<telerikChart:RadLegend LegendProvider="{x:Reference categoryChart}" Orientation="Horizontal"

HorizontalOptions="FillAndExpand"

LegendItemFontColor="White">

<telerikChart:RadLegend.LegendItemIconSize>

<Size Width="40" Height="40" />

</telerikChart:RadLegend.LegendItemIconSize>

</telerikChart:RadLegend>

</StackLayout>

</Grid>

</StackLayout>

</ContentPage.Content>

</ContentPage>

I also posted a bug here:

https://feedback.telerik.com/Project/168/Feedback/Details/258089-radlegend-sometimes-disappears-when-a-parent-control-changes-visibility-with-isvi

Chart

answered on 18 Oct 2018

3 answers

121 views

Point with Categorical and Numerical Values

Hello,

1. Can anyone tell me how could I get to make Points on my chart for every data point with Numerical as Y-Value and Categorical as X-Value?

I tried to make it with ScatterPointSeries. It worked on iOS, but crash on android. Because originally ScatterPointSeries uses numerical for both X & Y Values (Code below)

2. And , kindly check my RadLegend on my code as well, it does not show.

Thank you.

var hAxis = new CategoricalAxis();

hAxis.LabelFontSize = 6;

var vAxis = new NumericalAxis();

vAxis.LabelFontSize = 7;

vAxis.LabelFormat = "#,#.#";

chart = new RadCartesianChart

{

HorizontalAxis = hAxis,

VerticalAxis = vAxis,

VerticalOptions = LayoutOptions.FillAndExpand,