We Keep Coding

C# UWP Button binding with flyout not refreshing button content

I have a button that displays the value from a class that I created. Everything works fine, except for the fact that the button content does not refresh once the value of the binding is changed in the code. If I exit the screen and come back, the value is correct. Staying on the same screen does not refresh the button content.
The button code is shown below.
<Grid x:Name="Task1Grid" Grid.Row="0" Grid.Column="0" Margin="5,0,5,0">
<Grid.RowDefinitions>
<RowDefinition Height=".2*"/>
<RowDefinition Height=".6*"/>
<RowDefinition Height=".2*"/>
</Grid.RowDefinitions>
<Button Grid.Row="1" Style="{StaticResource RoundedButtonStyle}" Tag="0" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Click="StoplightButton_Click" FontFamily="Global User Interface">
<Button.Content>
<Image Stretch="Uniform" Source="{Binding SelectedRepairOrder.TaskStatusGrid[0], Converter={StaticResource TaskStatusToStopLight}, Mode=OneWay}"/>
</Button.Content>
<Button.Background>
<ImageBrush Stretch="Uniform" ImageSource="{Binding SelectedRepairOrder.TaskStatusGrid[0], Converter={StaticResource TaskStatusToStopLight}, Mode=OneWay}"/>
</Button.Background>
</Button>
<Button x:Name="Task0Time" Tag="0" Style="{StaticResource RoundedButtonStyle}" Visibility="{Binding SelectedRepairOrder.TaskStatusGrid[0].NewTaskstatus, Converter=
{StaticResource TaskStatusToVisibility}}" IsEnabled="{Binding ShowForecastFeatures}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Content="{Binding SelectedRepairOrder.TaskStatusGrid[0].TmTimecmpltask, Converter={StaticResource TaskCompleteTimeToTime}}" Grid.Row="2" Flyout="{StaticResource Task1Flyout}"/>
<TextBlock Grid.Row="0" Text="{Binding ClientInfo.TasksInfo[0].TaskDescription}" TextAlignment="Center" VerticalAlignment="Bottom" FontSize="28"/>
</Grid>
The flyout code is shown below.
<Border x:Name="StopLightBorder" Background="CornflowerBlue" Grid.Row="1" BorderBrush="White" BorderThickness="2">
<Grid x:Name="StopLightGrid" Margin="5" >
<Grid.Resources>
<converter:TaskStatusToStopLight x:Key="TaskStatusToStopLight"/>
<converter:TaskCompleteTimeToTime x:Key="TaskCompleteTimeToTime"/>
<converter:TaskStatusToVisibility x:Key="TaskStatusToVisibility"/>
<Flyout x:Key="Task1Flyout" >
<ListBox ItemsSource="{Binding ForecastTimes}" Tag="0" SelectionChanged="ForecastTimeChanged"/>
</Flyout>
The code which changes the value for the binding is shown below.
private void ForecastTimeChanged(object sender, SelectionChangedEventArgs e)
{
var timeListBox = (ListBox)sender;
var completeTime = Convert.ToDateTime(e.AddedItems[0].ToString());
var taskNum = Convert.ToInt16(((FrameworkElement)sender).Tag);
var result = checkPreviousTaskTimes(completeTime, taskNum);
switch (result)
{
case ForecastResult.ValidTime:
globalContext.SelectedRepairOrder.TaskStatusGrid[taskNum].TmTimecmpltask = completeTime.ToString();
globalContext.SelectedRepairOrder.TaskStatusGrid[taskNum].DtDateoverride = completeTime.ToString();
globalContext.SelectedRepairOrder.TaskStatusGrid[taskNum].TmTimeoverride = completeTime.ToString();
globalContext.SelectedRepairOrder.TaskStatusGrid[taskNum].SendOverrideForecastTime = true;
globalContext.SelectedRepairOrder.WasChanged = true;
globalContext.SelectedRepairOrder.RecordGrid = "1";
((Popup)((FlyoutPresenter)((FrameworkElement)sender).Parent).Parent).IsOpen = false;
break;
default:
showForecastError(result, completeTime, taskNum);
break;
}
}
The Visibility and IsEnabled both work just fine. Not sure what else I can do at this point. It seems that changing the bound data does not have an effect until you leave the screen. I chased this issue all the way through and saw the changes to the data as well as everything else I expected. The flyout causes the forecasttimechanged method to activate. When we go to save this data to the database, the data is correct. The flyout shows the selected time when viewing it on the screen, which is what I want. I see that highlighted in the flyout.
If there is a better control to use than the button, I am all ears at this point. Here is the tricky part. This forecast time can be set in the application as well as the app you are seeing code from. The app has time in 15 minute increments, but the other program that can update this control can put in any time it wishes.
I know there is some control or parameter that needs to be set in order to make this happen properly, but for the life of me, I cannot find it. I have tried everything for the past 3 days now and nothing works.
Help me please.

I know there is some control or parameter that needs to be set in order to make this happen properly, but for the life of me, I cannot find it. I have tried everything for the past 3 days now and nothing works.
From your code, I guess the problem is that you have not implemented INotifyPropertyChanged for binding property. And your logic is complex, you could realize your feature with the easy way like the follow example.
<Button Content="{Binding SelectItem,Mode=OneWay}">
<Button.Flyout>
<Flyout Placement="Top">
<ListBox ItemsSource="{Binding Items}" SelectedItem="{Binding SelectItem,Mode=TwoWay}">
</ListBox>
</Flyout>
</Button.Flyout>
</Button>
Bind the button content with SelectItem, And then the button content will be modified automatically if the ListBox SelectedItem changed.
public class MainPageViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
public List<string> Items { get; set; } = new List<string>();
private string selectItem = "Nico";
public string SelectItem { get { return selectItem; } set { selectItem = value; OnPropertyChanged(); } }
public MainPageViewModel()
{
Items.Add("Nico");
Items.Add("Song");
Items.Add("Xiao");
}

Reach a TextBlock from a specific ListViewItem from the ListView in Windows Phone 8.1 XAML programmatically

I am a new developer on Windows Phone 8.1, I am try to reach a specific ListView item from the ListView collection and be able to color it or color the TextBock inside of it, But I can't reach the item or reach any of items inside of ListView, Please take a look for my below code :
protected async override void OnNavigatedTo(NavigationEventArgs e)
{
SQLiteRT db1 = new SQLiteRT();
var db_connection = await db1.Connection("MyDB.sqlite");
List<MyTBL> t_list = db1.GetTable("SELECT * FROM MyTBL LIMIT 4 ORDER BY RANDOM() ;");
db_connection.Close();
LV_Options.ItemsSource = t_list;
}
// my List View called LV_Options
private void LV_Options_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ListView lv1 = sender as ListView;
if (lv1 == null)
return;
MyTBL wrd = lv1.SelectedItem as MyTBL;
if (wrd == null)
return;
TextBlock tb = lv1.FindName("TB_AMean1") as TextBlock;
tb.FontSize = 17; // here I got debug error (it not worked !!!!!!!)
var item = LV_Options.Items.ElementAt(3); // this seems not work also !!!!
item.BackColor = Color.LightSteelBlue;
}
As you can see above, I tried to reach a specific item by LV_Options.Items.ElementAt(3) but it doesn't work! I also tried to reach the TextBlock from the selected List view item, but also not worked !
(Updated)
XAML code :
<!-- Title Panel -->
<StackPanel Grid.Row="0" Margin="19,0,0,0">
<TextBlock Name="TB_Rslt" Text="Here result of your answer" Style="{ThemeResource TitleTextBlockStyle}" Margin="0,12,0,0"/>
<TextBlock Text="page title" Margin="0,-6.5,0,26.5" Style="{ThemeResource HeaderTextBlockStyle}" CharacterSpacing="{ThemeResource PivotHeaderItemCharacterSpacing}"/>
</StackPanel>
<!--TODO: Content should be placed within the following grid-->
<Grid Grid.Row="1" x:Name="ContentRoot" Margin="19,10,19,15">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<TextBlock Name="TB_Question" Text="Choose Answer " Margin="0,0,25,0" HorizontalAlignment="Right" FontWeight="Bold" FontSize="22" FontFamily="Verdana" RenderTransformOrigin="0.5,0.5" />
<TextBlock Name="TB_EnWord" Text="" Margin="90,0,15,0" HorizontalAlignment="Left" FontWeight="Bold" FontSize="22" FontFamily="Verdana" RenderTransformOrigin="0.5,0.5" TextAlignment="Right" />
<StackPanel Grid.Row="1" Margin="5,22,0,0">
<ListView Name="LV_Options" SelectionChanged="LV_Options_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Margin="6">
<StackPanel VerticalAlignment="Top" Margin="10,0,0,0">
<TextBlock Name="TB_AMean1" Text="{Binding AMean1}" TextWrapping="Wrap"/>
</StackPanel>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackPanel>
<Button Name="Btn_Answer" Content="Ansewr" HorizontalAlignment="Left" Grid.Row="1" VerticalAlignment="Bottom" Click="Btn_Answer_Click"/>
My application is a quiz application that offer 4 choices/options as answers for each question, and when user select a true answer, I want to highlight the true answer(true choice) by make its background to green, and if the user selected wrong answer/option I want to make the background of that answer (a specific List View item) with red.
Any help please ?

You're not going to be able to access an element inside a data template like that. Instead, leverage the binding to a view model to set the color and other view-related properties. First, create a wrapper view model for your data class:
public class MyTBLViewModel : INotifyPropertyChanged
{
public MyTBL Entity
{
get { return _entity; }
}
private readonly MyTBL _entity;
public Brush Highlight
{
get { return _brush; }
set
{
_brush = value;
RaisePropertyChanged("Highlight");
}
}
private Brush _highlight;
public double ItemFontSize
{
get { return _itemFontSize; }
set
{
_itemFontSize = value;
RaisePropertyChanged("ItemFontSize");
}
}
private Brush _itemFontSize;
public MyTBLViewModel(MyTBL entity)
{
_entity = entity;
_highlight = new SolidColorBrush(Colors.Transparent);
_itemFontSize = 12;
}
public event PropertyChangedEventArgs PropertyChanged;
protected void RaisePropertyChanged(string propName)
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propName));
}
}
Use this as your ItemsSource:
List<MyTBLViewModel> t_list = db1.GetTable("SELECT * FROM MyTBL LIMIT 4 ORDER BY RANDOM() ;")
.AsEnumerable().Select(entity => new MyTBLViewModel(entity)).ToList();
Now in your view, bind the view elements to "Highlight" and "ItemFontSize", and to any other properties you like:
<ListView.ItemTemplate>
<DataTemplate>
<Grid Margin="6" Background="{Binding Highlight}">
<StackPanel VerticalAlignment="Top" Margin="10,0,0,0">
<TextBlock Name="TB_AMean1" Text="{Binding Entity.AMean1}" TextWrapping="Wrap"
FontSize="{Binding ItemFontSize}"/>
</StackPanel>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
Finally, you can get the data item from the SelectionChangedEventArgs -- use it to update your view-related properties:
private void LV_Options_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
foreach (var item in e.AddedItems.OfType<MyTBLViewModel>())
{
item.Highlight = new SolidColorBrush(Color.LightSteelBlue);
item.ItemFontSize = 17;
}
foreach (var item in e.RemovedItems.OfType<MyTBLViewModel>())
{
item.Highlight = new SolidColorBrush(Colors.Transparent);
item.ItemFontSize = 12;
}
}

var item = LV_Options.Items.ElementAt(3);
This line is incorrect. It will not return you a TextBlock. I don't know what a .BackColor is, and it should not compile. The Items property in a ListView will return you a list of ListViewItems. If you want to access the inside element from a ListViewItem, you'll need to access the ContentTemplateRoot property.
Do not use var ever. It lets you assume that you know the type, whereas if you explicitly typed the declaration you would realize you're doing it wrong.
MyTBL wrd = lv1.SelectedItem as MyTBL;
if (wrd == null)
return;
TextBlock tb = lv1.FindName("TB_AMean1") as TextBlock;
What is a MyTBL type? FindName is only available to framework DependencyObjects so I'm assuming it's a user control? You have to provide a lot more code to show us what you're doing and what you're setting the ListView's ItemsSource and ItemTemplate with and what these errors are and how you have 2 breaking debug errors at once and what the error messages are.
Comprehending runtime error messages is a huge part of being a good developer.

Telerik RadJumpList using DataVirtualizationMode.Automatic

I have a problem where im trying to use a Telerik Jump List with DataVirtualizationMode.Automatic, but i can't get it to work. The reason why i want to use this, is because i want my app to only download the data(games) which is in the current view of the Jump List control and not the whole data everytime. For example if i have searched for "Batman", and its returning 50 games, i don't want it to download and load all the games, only those i can see in the Jump List control.
Here is a sample of using DataVirtualizationMode.Automatic from Telerik, but i couldn't get it to work with my app: http://www.telerik.com/help/windows-phone/raddataboundlistbox-features-datavirtualization-automatic.html
Below is my Jump List control which i want to use with data virtualization.
MainPage.xaml:
<phone:PivotItem Header="Browse">
<Grid>
<telerikPrimitives:RadTextBox Name="txtSearch" HorizontalAlignment="Left" VerticalAlignment="Top" Height="80" Width="390"/>
<telerikPrimitives:RadImageButton Name="imgBtnSeachGame" VerticalAlignment="Top" HorizontalAlignment="Right" ButtonShape="Ellipse" BorderThickness="2" Margin="0,8,0,0" Click="imgBtnSeachGame_Click"></telerikPrimitives:RadImageButton>
<Controls:RadJumpList Name="jlGameList" ItemsSource="{Binding}" Tap="jlGameList_Tap" Margin="0,90,0,0" DataVirtualizationMode="Automatic">
<Controls:RadJumpList.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
<RowDefinition Height="20"></RowDefinition>
</Grid.RowDefinitions>
<Border Grid.Row="0" Background="{StaticResource PhoneAccentBrush}"
Padding="{StaticResource PhoneTouchTargetOverhang}"
Margin="0,0,0,0">
<TextBlock Name="tblGameTitle" Style="{StaticResource PhoneTextGroupHeaderStyle}" ManipulationStarted="tblGameTitle_ManipulationStarted" ManipulationCompleted="tblGameTitle_ManipulationCompleted">
<Run Text="{Binding GameTitle}"></Run>
</TextBlock>
</Border>
<Grid Background="#242424" Grid.Row="1">
<Image Name="imgGameList" Margin="0,0,0,0" Stretch="Fill" HorizontalAlignment="Left" VerticalAlignment="Top" Height="96" Width="96">
<Image.Source>
<BitmapImage UriSource="{Binding BoxArtFrontThumb}"
CreateOptions="BackgroundCreation" DecodePixelHeight="96" DecodePixelWidth="96" />
</Image.Source>
</Image>
<TextBlock Margin="110,0,0,0" Text="Platform" FontWeight="Bold" TextWrapping="Wrap" Foreground="YellowGreen" FontSize="{StaticResource PhoneFontSizeNormal}"/>
<TextBlock Name="txtPlatform" Margin="110,20,0,0" Text="{Binding Platform}"></TextBlock>
<TextBlock Text="Release Date" FontWeight="Bold" Margin="110,46,0,0" Foreground="YellowGreen" FontSize="{StaticResource PhoneFontSizeNormal}"/>
<TextBlock Name="txtReleaseDate" Margin="110,66,0,0" Text="{Binding ReleaseDate}"></TextBlock>
<!--</StackPanel>-->
</Grid>
<Grid Grid.Row="2"></Grid>
</Grid>
</DataTemplate>
</Controls:RadJumpList.ItemTemplate>
</Controls:RadJumpList>
</Grid>
</phone:PivotItem>
Below is where i bind my DataContext to my GetGamesListItems ObservableCollection in my GameData class. The imgBtnSearchGame_Click event method is being called when a user have typed for example "Batman" in my textbox txtSearch and tapped the button, it will then send the text to my GetGamesListData method.
MainPage.cs:
GameData gd = new GameData();
public MainPage()
{
InitializeComponent();
jlGameList.DataContext = gd.GetGamesListItems;
}
private void imgBtnSeachGame_Click(object sender, RoutedEventArgs e)
{
if (!string.IsNullOrEmpty(txtSearch.Text))
{
gd.GetGamesListData(txtSearch.Text, "", "");
}
}
Below is where i download the data in XML for the game name searched for. For example if it is "Batman" it will find and return all games with "Batman". The "BoxArtFrontThumb" Property is where im storing all the images for each game and is using async, because sometimes there can be quite alot of images it has to download and show.
GameData.cs
public void GetGamesListData(string name, string platform, string genre)
{
var webClient = new WebClient();
webClient.DownloadStringCompleted += GetGamesListRequestCompleted;
webClient.DownloadStringAsync(new Uri("http://thegamesdb.net/api/GetGamesList.php?name=" + name));
}
private async void GetGamesListRequestCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error == null)
{
GetGamesListItems.Clear();
var feedXml = XDocument.Parse(e.Result);
var gameDataTasks = feedXml.Root.Descendants("Game").Select(
async x => new GetGamesList
{
ID = (int)x.Element("id"),
GameTitle = (string)x.Element("GameTitle"),
ReleaseDate = (string)x.Element("ReleaseDate") ?? "N/A",
Platform = (string)x.Element("Platform") ?? "N/A",
BoxArtFrontThumb = new Uri(await GetBoxArtFrontThumbAsync((int)x.Element("id")), UriKind.RelativeOrAbsolute),
}).ToList();
var gameData = await Task.WhenAll(gameDataTasks);
foreach (var item in gameData)
{
GetGamesListItems.Add(item);
}
}
}
Below is where its finding and storing the images for the games.
public async Task<string> GetBoxArtFrontThumbAsync(int id)
{
var client = new HttpClient();
var result = await client.GetStringAsync("http://thegamesdb.net/api/GetArt.php?id=" + id);
var feedXml = XDocument.Parse(result);
var gameData = feedXml.Root.Descendants("Images").Select(x => new GetArt
{
BoxArtFrontThumb = new Uri(GetBoxArtFrontThumb(x), UriKind.RelativeOrAbsolute),
}).ToList();
return gameData.Single().BoxArtFrontThumb.ToString();
}
private static string GetBoxArtFrontThumb(XElement gameNode)
{
string data = "http://thegamesdb.net/banners/" + (string)gameNode.Descendants("boxart")
.FirstOrDefault(b => (string)b.Attribute("side") == "front");
if (data == "http://thegamesdb.net/banners/")
{
data = "/NoImage.jpg";
}
return data;
}
I really hope i explained this well enough and hope that there is someone that can help me solve this problem. Thanks.

Although you are using JumpList, the mechanism for Virtualizing the data is the same as the DataBoundListBox. (You can find more information here in the DataBoundListBox docs. There is a good tutorial using an OData service.)
In order for the Automatic mode to work properly, you need to be using Telerik's VirtualizingDataCollection object and initialize it with the proper arguments (count and page size).
I don't see this in the code you have provided above, can you please open a support ticket so that I can investigate further? See my comment above for the link. Let me know the ticket number and I'll provide further assistance.

List box with over 100 items crashes

I am working on windows phone 8 app.
I have List box with over 200 items to display.
<DataTemplate x:Key="DataTemplate1">
<Grid VerticalAlignment="Center" HorizontalAlignment="Center">
<Grid.RowDefinitions>
<RowDefinition/>
</Grid.RowDefinitions>
<Border Grid.Row="0" Background="White" Height="400" Width="400" CornerRadius="30,30,30,30">
</Border>
<Grid Grid.Row="0" HorizontalAlignment="Center" VerticalAlignment="Top">
<TextBlock HorizontalAlignment="Center"
VerticalAlignment="Center"
Margin="5,20,5,5"
Foreground="#000000"
Text="{Binding Title}"/>
</Grid>
</Grid>
</DataTemplate>
But it crashes, i have debugged it till 100 items it works but after that it crashes.
In the PhoneApplicationPage_Loaded method i have
private void PhoneApplicationPage_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
myList.Add(new MyObject("A","A value"));
myList.Add(new MyObject("B", "B value"));
myList.Add(new MyObject("C", "C value"));
and so on... 200 items
ListBoxItems.ItemsSource = myList;
}
how can i fix this ?
Update :
<ItemsPanelTemplate x:Key="ItemsPanelTemplate">
<local:CollectionFlowPanel ItemHeight="400"
ItemWidth="400"
FocusedItemOffset="120"
UnfocusedItemOffset="20"
ItemVisibility="5">
<VirtualizingStackPanel />
</local:CollectionFlowPanel>
</ItemsPanelTemplate>
</phone:PhoneApplicationPage.Resources>
<Grid x:Name="LayoutRoot" Background="#000000">
<local:CollectionFlow x:Name="ListBoxItems"
ItemTemplate="{StaticResource DataTemplate}"
ItemsPanel="{StaticResource ItemsPanelTemplate}"/>
</Grid>

Ensure you have VirtualizingStackPanel inside the ItemsPanelTemplate of your list box, see this answer for more info.
Here's the XAML you likely need for your ListBox:
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<VirtualizingStackPanel />
</ItemsPanelTemplate>
</ListBox.ItemsPanel>

You need to read following blog from msdn on visualization of the data in list and grid.
Using virtualization with a list or grid
Without seeing your whole xaml code I cannot suggest the exact answer but my guess is that you in xaml ListBox is placed inside a canvas/StackPanel or scrollviewer control.
When the size of the ItemsControl's viewport isn't restricted, the control doesn't perform virtualization. Instead, it creates an item container for each item in its collection. Some common containers that don't restrict the viewport size are Canvas, StackPanel, and ScrollViewer. You can enable virtualization in this situation by setting the size of ItemsControl directly, instead of letting it be sized by its parent container.
Here, we set the Height and Width on the GridView. This restricts the size of the viewport, and items outside of the viewport are virtualized.
Below are 2 scenarios one will throw out of memory exception and other will work fine(use your same code behind and test)
1. ListBox in Canvas
<Canvas .....
<ListBox Name="ListBoxItems".....
</ListBox>
</Canvas>
Above code will throw out of memory exception as items control's viewport is not defined (if you still want to use Canvas than define width/height if ListBox in that case the port of Items control is defined and virtulazation will apply)
2. ListBox in Grid
<Grid .....
<ListBox Name="ListBoxItems".....
</ListBox>
</Grid>
The above code will not throw out of memory exception as virtuallization is applied on the listbox.
Hope this will help

How big is your object ? If your object is too big you might not be able to load them all at once.

Did you try using the for loop?
public List<Fellow> fellowList { get; set; }
private void PhoneApplicationPage_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
fellowList = new List<Fellow>();
for (int i = 0; i < 2; i++)
{
Fellow fellow = new Fellow();
fellow.x = "B" + i;
fellow.value = "B Value" + i;
fellowList.Add(fellow);
}
this.DataContext = this;
ListBoxItems.ItemsSource = fellowList;
}
public class Fellow
{
public string x { get; set; }
public string value { get; set; }
}
Hope it helps..change the view model according to your wish

Clear image cache from Grid background

Hopefully I can explain what I need and what the problem is
I have the followings list box
<ListBox Margin="0,8,0,0" toolkit:TiltEffect.IsTiltEnabled="True" x:Name="ImageList" ItemsSource="{Binding Images}" HorizontalAlignment="Center" BorderThickness="4">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid Background="{Binding imageID, Converter={StaticResource ImageConverter}}" Width="125" Height="125" Margin="6" Tap="list_OnTap">
<TextBlock Name="description" Foreground="{Binding TextColor}" Text="{Binding text}" Visibility="{Binding ShowText, Converter={StaticResource BooleanToVisibilityConverter}}" VerticalAlignment="Center" HorizontalAlignment="Center" TextAlignment="Center" TextWrapping="Wrap"/>
<toolkit:ContextMenuService.ContextMenu>
<toolkit:ContextMenu IsZoomEnabled="False" Name="deletectx">
<toolkit:MenuItem Header="delete" Click="delete_Click"/>
</toolkit:ContextMenu>
</toolkit:ContextMenuService.ContextMenu>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<toolkit:WrapPanel/>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
</ListBox>
</Grid>
The above code makes a grid of images, I used Grid background to show the image because I needed to show my text on the image (Not sure if there is any other way to do this)
This page load about 30 images with the size 125x125 pixel and about 4kb each. I noticed that it consumes a lot of memory. I read some posts here about clearing the cache of the images, but I don't know how I'm supposed to do that with the above code considering I'm setting a grid background as my image not an image control.
I might be able to access the grid inside the listbox, but whatever I do with it, will be applied to the first image only not the rest. I need to clear the images cache on my navigate away event.
Another question , I also have some performance problem , entering this page takes a little bit of time and I get low frame rate warning in Windows Phone App Analyser, not sure if what I'm doing (loading images through Converter for each listbox item) is right or not !
How can I make this faster ?

To be sure that you can reclaim any memory used by the default image caching behaviour you can use to following: (snipped from another project and edited slightly but should work as is.)
protected override void OnNavigatingFrom(NavigatingCancelEventArgs e)
{
if (e.NavigationMode == NavigationMode.Back)
{
// Unload all images so as to reclaim any allocated memory
foreach (var child in VisualTreeHelperEx.GetVisualChildren(this.ImageList).Where(c => c is Image))
{
var image = child as Image;
if (image != null)
{
var bitmapImage = image.Source as BitmapImage;
if (bitmapImage != null)
{
System.Diagnostics.Debug.WriteLine("unloading " + bitmapImage.UriSource);
bitmapImage.UriSource = null;
}
image.Source = null;
}
}
}
}
Which uses this helper:
public static class VisualTreeHelperEx
{
public static IEnumerable<DependencyObject> GetVisualChildren(DependencyObject element)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
return GetVisualChildrenAndSelfIterator(element).Skip(1);
}
public static IEnumerable<DependencyObject> GetVisualChildrenAndSelfIterator(DependencyObject element)
{
Debug.Assert(element != null, "element should not be null!");
yield return element;
int count = VisualTreeHelper.GetChildrenCount(element);
for (int i = 0; i < count; i++)
{
yield return VisualTreeHelper.GetChild(element, i);
}
}
}
This may have it's own performance issues so use with care and test the impact on actual performance.
The performance problem on page load is probably due to all the images being loaded at once. You could drip feed them into the list after the page has loaded to avoid this. If the actual images are larger than the background area you should set the DecodePixelHeight and DecodePixelWidth. It may also be worth removing the converter and adding a property with the full path as lots of complex converters can impact performance.