PullToRefreshListView
PullToRefreshListView copied to clipboard
XamlBrewer
Delegate to an instance method cannot have null 'this'
What am I doing wrong? I have a mistake: Delegate to an instance method cannot have null 'this'. http://i.imgur.com/wosgusv.png http://i.imgur.com/zWkILsv.png My app for Windows Phone 8.1 only. I use Deani Hansen's Pull-to-Refresh ScrollViewer, but the same error with PullToRefreshListView. http://i.imgur.com/nBGYZqp.png http://i.imgur.com/xiH8q3Q.png http://i.imgur.com/OUrezgv.png
Something goes wrong in the OnApplyTemplate method. Can you double check that the style template is in your project (Themes\Generic.xaml - name and path is important) ? I assume that this is your problem.
in my solution added Class Library Controllers with PullToRefreshListView class and Themes\Generic.xaml file. http://i.imgur.com/yXZ014K.png
Generic.xaml
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:controls="using:Controllers.Controls"
mc:Ignorable="d">
<Style TargetType="controls:PullToRefreshScrollViewer">
<Setter
Property="VerticalAlignment"
Value="Stretch" />
<Setter
Property="HorizontalAlignment"
Value="Stretch" />
<Setter
Property="Foreground"
Value="Black" />
<Setter
Property="Template">
<Setter.Value>
<ControlTemplate
TargetType="controls:PullToRefreshScrollViewer">
<Grid
x:Name="ContainerGrid">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup
x:Name="VisualStateGroup">
<VisualStateGroup.Transitions>
<VisualTransition
GeneratedDuration="0:0:0.2"
To="ReadyToRefresh" />
</VisualStateGroup.Transitions>
<VisualState
x:Name="Normal" />
<VisualState
x:Name="ReadyToRefresh">
<Storyboard>
<ObjectAnimationUsingKeyFrames
Storyboard.TargetProperty="(UIElement.Visibility)"
Storyboard.TargetName="TextPull">
<DiscreteObjectKeyFrame
KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames
Storyboard.TargetProperty="(UIElement.Visibility)"
Storyboard.TargetName="TextRefresh">
<DiscreteObjectKeyFrame
KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<DoubleAnimation
Duration="0"
To="0.5"
Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.Rotation)"
Storyboard.TargetName="Arrow"
d:IsOptimized="True" />
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<ScrollViewer
Margin="0,0,0,-100"
x:Name="ScrollViewer"
RenderTransformOrigin="0.5,0.5">
<ScrollViewer.RenderTransform>
<CompositeTransform
TranslateY="-100" />
</ScrollViewer.RenderTransform>
<Grid>
<Grid.RowDefinitions>
<RowDefinition
Height="auto" />
<RowDefinition
Height="*" />
</Grid.RowDefinitions>
<Border
Height="{TemplateBinding RefreshHeaderHeight}"
x:Name="PullToRefreshIndicator"
Background="Transparent">
<Grid
HorizontalAlignment="Center">
<Grid.ColumnDefinitions>
<ColumnDefinition
Width="auto" />
<ColumnDefinition
Width="auto" />
</Grid.ColumnDefinitions>
<Grid
Width="40">
<Viewbox
x:Name="Arrow"
Height="15"
VerticalAlignment="Top"
Margin="0,4,0,0"
RenderTransformOrigin="0.5,0.5">
<Viewbox.RenderTransform>
<CompositeTransform
Rotation="180" />
</Viewbox.RenderTransform>
<Path
Width="12"
Height="12.9999"
Stretch="Fill"
Fill="{TemplateBinding ArrowColor}"
Data="M 20.4289,10.4376L 25,15.0087L 23.571,16.4376L 20.0291,12.8957L 20.0291,21.9999L 18.0083,21.9999L 18.0083,12.8583L 14.4289,16.4377L 13,15.0087L 17.5624,10.429L 19.0087,9" />
</Viewbox>
</Grid>
<TextBlock
Grid.Column="1"
Foreground="{TemplateBinding Foreground}"
FontSize="20"
x:Name="TextPull"
Text="{TemplateBinding PullText}" />
<TextBlock
Foreground="{TemplateBinding Foreground}"
FontSize="20"
x:Name="TextRefresh"
Visibility="Collapsed"
Text="{TemplateBinding RefreshText}"
Grid.Column="1" />
</Grid>
</Border>
<ContentPresenter
Content="{TemplateBinding Content}"
Grid.Row="1" />
</Grid>
</ScrollViewer>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="controls:PullToRefreshListView">
<Setter Property="IsTabStop"
Value="False" />
<Setter Property="TabNavigation"
Value="Once" />
<Setter Property="IsSwipeEnabled"
Value="True" />
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility"
Value="Disabled" />
<Setter Property="ScrollViewer.VerticalScrollBarVisibility"
Value="Auto" />
<Setter Property="ScrollViewer.HorizontalScrollMode"
Value="Disabled" />
<Setter Property="ScrollViewer.IsHorizontalRailEnabled"
Value="False" />
<Setter Property="ScrollViewer.VerticalScrollMode"
Value="Enabled" />
<Setter Property="ScrollViewer.IsVerticalRailEnabled"
Value="False" />
<Setter Property="ScrollViewer.ZoomMode"
Value="Disabled" />
<Setter Property="ScrollViewer.IsDeferredScrollingEnabled"
Value="False" />
<Setter Property="ScrollViewer.BringIntoViewOnFocusChange"
Value="True" />
<Setter Property="VerticalAlignment"
Value="Stretch" />
<Setter Property="HorizontalAlignment"
Value="Stretch" />
<Setter Property="Foreground"
Value="Black" />
<Setter Property="ItemContainerTransitions">
<Setter.Value>
<TransitionCollection>
<AddDeleteThemeTransition />
<ContentThemeTransition />
<ReorderThemeTransition />
<EntranceThemeTransition IsStaggeringEnabled="False" />
</TransitionCollection>
</Setter.Value>
</Setter>
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<ItemsStackPanel Orientation="Vertical" />
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="controls:PullToRefreshListView">
<Grid x:Name="ContainerGrid">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="VisualStateGroup">
<VisualStateGroup.Transitions>
<VisualTransition GeneratedDuration="0:0:0.2"
To="ReadyToRefresh" />
</VisualStateGroup.Transitions>
<VisualState x:Name="Normal" />
<VisualState x:Name="ReadyToRefresh">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)"
Storyboard.TargetName="TextPull">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Collapsed</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)"
Storyboard.TargetName="TextRefresh">
<DiscreteObjectKeyFrame KeyTime="0">
<DiscreteObjectKeyFrame.Value>
<Visibility>Visible</Visibility>
</DiscreteObjectKeyFrame.Value>
</DiscreteObjectKeyFrame>
</ObjectAnimationUsingKeyFrames>
<DoubleAnimation Duration="0"
To="0.5"
Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.Rotation)"
Storyboard.TargetName="Arrow"
d:IsOptimized="True" />
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}">
<ScrollViewer Margin="0"
x:Name="ScrollViewer"
TabNavigation="{TemplateBinding TabNavigation}"
HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}"
HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"
IsHorizontalScrollChainingEnabled="{TemplateBinding ScrollViewer.IsHorizontalScrollChainingEnabled}"
VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}"
VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}"
IsVerticalScrollChainingEnabled="{TemplateBinding ScrollViewer.IsVerticalScrollChainingEnabled}"
IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}"
IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}"
ZoomMode="{TemplateBinding ScrollViewer.ZoomMode}"
IsDeferredScrollingEnabled="{TemplateBinding ScrollViewer.IsDeferredScrollingEnabled}"
BringIntoViewOnFocusChange="{TemplateBinding ScrollViewer.BringIntoViewOnFocusChange}"
AutomationProperties.AccessibilityView="Raw">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Border Height="{TemplateBinding RefreshHeaderHeight}"
x:Name="PullToRefreshIndicator"
Background="Transparent">
<Grid HorizontalAlignment="Center">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="auto" />
<ColumnDefinition Width="auto" />
</Grid.ColumnDefinitions>
<Grid Width="40">
<Viewbox x:Name="Arrow"
Height="15"
VerticalAlignment="Top"
Margin="0,4,0,0"
RenderTransformOrigin="0.5,0.5">
<Viewbox.RenderTransform>
<CompositeTransform Rotation="180" />
</Viewbox.RenderTransform>
<Path Width="12"
Height="13"
Stretch="Fill"
Fill="{TemplateBinding ArrowColor}"
Data="M 20.4289,10.4376L 25,15.0087L 23.571,16.4376L 20.0291,12.8957L 20.0291,21.9999L 18.0083,21.9999L 18.0083,12.8583L 14.4289,16.4377L 13,15.0087L 17.5624,10.429L 19.0087,9" />
</Viewbox>
</Grid>
<TextBlock Grid.Column="1"
Foreground="{TemplateBinding Foreground}"
FontSize="20"
x:Name="TextPull"
Text="{TemplateBinding PullText}" />
<TextBlock Foreground="{TemplateBinding Foreground}"
FontSize="20"
x:Name="TextRefresh"
Visibility="Collapsed"
Text="{TemplateBinding RefreshText}"
Grid.Column="1" />
</Grid>
</Border>
<ItemsPresenter Header="{TemplateBinding Header}"
HeaderTemplate="{TemplateBinding HeaderTemplate}"
HeaderTransitions="{TemplateBinding HeaderTransitions}"
Footer="{TemplateBinding Footer}"
FooterTemplate="{TemplateBinding FooterTemplate}"
FooterTransitions="{TemplateBinding FooterTransitions}"
Padding="{TemplateBinding Padding}"
Grid.Row="1" />
<AppBarButton x:Name="RefreshButton"
Icon="Refresh"
Label="Refresh"
RequestedTheme="Light"
Margin="20"
HorizontalAlignment="Right"
VerticalAlignment="Top"
Visibility="Collapsed"
Grid.Row="1"/>
</Grid>
</ScrollViewer>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>
In me project VkMedia added reference to Controllers. And in Mainview.xaml code:
xmlns:controls="using:Controllers.Controls"
....
<controls:PullToRefreshListView
ItemsSource="{Binding TrackListItems}"
RefreshCommand="{Binding RefreshCommand}">
<controls:PullToRefreshListView.ItemTemplate>
<DataTemplate>
<Grid>
<TextBlock Text="{Binding FirstName}" />
</Grid>
</DataTemplate>
</controls:PullToRefreshListView.ItemTemplate>
</controls:PullToRefreshListView>
ops..xaml in class library - it is not right ? It looks like it's my fault
Moved Controls and Themes folder in my project. But nothing has changed, the error remained. App working fine. Error only in Xaml Designer.
you can prevent this error by disabling project code button which stands at the bottom of the xaml designer window. its probably happening due to that we created a subclass of listview. xaml designer may not be able to create a new instance of a custom element. so because of that while invoking refreshcontent event 'this' keyword returns null.
