Develop Reference

C# WPF - variable value won't display on Textboxes (DataContext?)

I got a really tricky and annoying problem with my C# WPF Application. I guess it's not a big deal for a good programmer to solve it, but I don't know how to fix it yet. For school, I have to program an application which depicts a process. So I get Data by an XML-File, have to calculate some values, display them for User Interaction etc. and at the end the output is again a file, which can be processed further.
For that, I got different UserControls, which depicts different modules for example, one for the Data Import, the other one for calculating and displayng values and so on. The Main Window is like the free space or the place-maker on which the different modules are loaded depending on where we are in the process.
My problem now is that the values I calculate in my UserControl won't display in my UI respectively my application and I don't really know why. 0 is the only value which is transferred to the application. Curious about it, is that in the Debugger the values are correct, but in the display itself there is only a 0.
Ok, so I show you now the code of the different files (I'm not the best programmer, so maybe the code is sometimes a bit dirty).
I got a Main UserControl, let's call it UC_Main, and in this UserControl you can switch between 3 different other UserControls depending on which Radiobutton in the UC_Main is checked. (The UC_Main is always displayed, because in this there are only the 3 radio buttons and underneath is a big free space, where the different UserControls 1, 2 and 3 are loaded).
UC_Main.xaml
<UserControl.Resources>
<DataTemplate x:Name="UC1_Template" DataType="{x:Type local:UC1}">
<local:UC1 DataContext="{Binding}" />
</DataTemplate>
<DataTemplate x:Name="UC2_Template" DataType="{x:Type local:UC2}">
<local:UC2 DataContext="{Binding}" />
</DataTemplate>
<DataTemplate x:Name="UC3_Template" DataType="{x:Type local:UC3}">
<local:UC3 DataContext="{Binding}" />
</DataTemplate>
</UserControl.Resources>
<Border Padding="10">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<!-- In the First Row there are the radio buttons in the second the
different UserControls 1, 2 or 3 -->
<Grid.RowDefinitions>
<RowDefinition Height="50"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<materialDesign:ColorZone Mode="PrimaryMid" Width="400" HorizontalAlignment="Left">
<StackPanel Grid.Row="0" Orientation="Horizontal" Margin="2">
<RadioButton x:Name="UC1_radiobutton" Checked="UC1_radiobutton_Checked"
Style="{StaticResource MaterialDesignTabRadioButton}"
Margin="4"
IsChecked="True"
Content="UserControl1" />
<RadioButton x:Name="UC2_radiobutton" Checked="UC2_radiobutton_Checked"
Style="{StaticResource MaterialDesignTabRadioButton}"
Margin="4"
IsChecked="False"
Content="UserControl2" />
<RadioButton x:Name="UC3_radiobutton" Checked="UC3_radiobutton_Checked"
Style="{StaticResource MaterialDesignTabRadioButton}"
Margin="4"
IsChecked="False"
Content="UserControl3" />
</StackPanel>
</materialDesign:ColorZone>
<ContentControl Grid.Row="1" Content="{Binding}" />
</Grid>
</Border>
</UserControl>
UC_Main.xaml.cs
public partial class UC_Main : UserControl
{
public UC_Main()
{
InitializeComponent();
}
private void UC1_radiobutton_Checked(object sender, RoutedEventArgs e)
{
DataContext = new UC1();
}
private void UC2_radiobutton_Checked(object sender, RoutedEventArgs e)
{
DataContext = new UC2();
}
private void UC3_radiobutton_Checked(object sender, RoutedEventArgs e)
{
DataContext = new UC3();
}
}
}
To keep it simple, I'll only show you the Code of UserControl 1, because UC 2 and 3 are pretty the same beside other variables or values.
UC1.xaml
<Border Padding="10">
<StackPanel>
<!-- To keep the example simple, I got 1 Row and 2 Colums; in each
is one TextBox -->
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="2*" />
<ColumnDefinition Width="2*" />
</Grid.ColumnDefinitions>
<TextBox x:Name="TextBox1" Grid.Column="0" IsTabStop="False"
Text="{Binding Path=variable1, Mode=TwoWay}"
VerticalAlignment="Center"
HorizontalAlignment="Center"
TextAlignment="Center"
Height="25"
Width="85"
Foreground="DarkGray"
IsReadOnly="True" />
<TextBox x:Name="TextBox2" Grid.Column="1" IsTabStop="False"
Text="{Binding Path=variable2, Mode=TwoWay}"
VerticalAlignment="Center"
HorizontalAlignment="Center"
TextAlignment="Center"
Height="25"
Width="85"
Foreground="DarkGray"
IsReadOnly="True" />
</Grid>
</StackPanel>
</Border>
</UserControl>
UC_1.xaml.cs
public partial class UC1 : UserControl
{
public MainWindow Speaker;
public ValueStore vs;
public UC1()
{
InitializeComponent();
Speaker = MainWindow.AppWindow;
vs = new ValueStore();
DataContext = vs;
}
public void calc_data()
{
// I get the data from the data import (XML-File), which is saved in
// a dictionary (strings), converting them to int (so I can do some
// math operations) and save them in my variable.
// UC_Other is a UserControl, where the data import happens
// dict_other is the dictionary, where the data from the import is
// saved
vs.variable1 =
Convert.ToInt32(MainWindow.AppWindow.UC_other.dict_other["0"].Amount);
vs.variable2 =
Convert.ToInt32(MainWindow.AppWindow.UC_other.dict_other["1"].Amount);
}
I call the function calc_data() in an UserControl before, so the data gets calculated and saved in my variables before my UserControl shows up. I declare a new public instance of my UC1 and call the function via UC1.calc_data(); (which is linked to a Button, that is loading my UC_Main).
ValueStore.cs
public class ValueStore : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string name)
{
if(PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(name));
}
}
private int _variable1;
public int variable1
{
get { return _variable1; }
set { _variable1 = value; OnPropertyChanged("variable1"); }
}
private int _variable2;
public int variable2
{
get { return _variable2; }
set { _variable2 = value; OnPropertyChanged("variable2"); }
}
When I look in the debugger after the method calc_data() is called, the values are correct saved in my ValueStore instance and the TextBoxes are showing me in the Debugger that the correct value is in there (the Debugger says "Name: TextBox1" and "Value: {System.Windows.Controls.TextBox: 100}"; 100 is the value I got from the dictionary), but in my application itself there is only the value 0 displayed.
What I don't really understand is, when I change the type from variable1 to string in my ValueStore.cs and save it in my variable in the method calc_data()(without Convert.ToInt32), it doesn't even show a 0 any more in my application, but in the debugger there is still the value "100".

There are a few things here, but my best guess why your debugging-values are correct while none are updated to the GUI is here:
public partial class UC_Main : UserControl
{
public UC_Main()
{
InitializeComponent();
}
private void UC1_radiobutton_Checked(object sender, RoutedEventArgs e)
{
DataContext = new UC1();
}
private void UC2_radiobutton_Checked(object sender, RoutedEventArgs e)
{
DataContext = new UC2();
}
private void UC3_radiobutton_Checked(object sender, RoutedEventArgs e)
{
DataContext = new UC3();
}
}
You are creating new instances of these classes of the code-behind to the usercontrols. But the usercontrol objects are already created by the UC_Main.xaml so during runtime, you have two objects for example of the UC1 class, one which is your bound to your GUI and one where you store and update your values. The one you see on your GUI doesn't get any values updates, which is why you aren't seeing anything.
I currently can't test the code myself, but from what I can see that is where the issue lies.
Furthermore it is a bit confusing to me, why you are using databinding for code-behind.
(You are using the code-behind of the UC-classes as datacontext for the main class, which is....weird ;) I think in your case no databinding whatsoever is really needed, however if you want to do stuff with databinding you should probably read up on MVVM)

Access unnamed control in xaml from code behind

I've got about 20 of the following underneath a ComboBox (which means that I can't use any x:Name parameter due to duplicate naming):
<ComboBoxItem>
<StackPanel Orientation="Horizontal">
<Image Source="folder/someimage.png" Height="20" Width="20"/>
<TextBlock Text="SampleText" Margin="5,0,0,0"/>
</StackPanel>
</ComboBoxItem>
How can I access the string from the TextBlock inside the SelcetionChanged event?
Currently when I choose the item normally, the selected text (of my ComboBox) is set to
System.Windows.Controls.ComboBoxItem
This is the return value from the ComboBoxItem.ToString() method!
How can I change the return type of my xaml based ComboBoxItem?

After long research I've found a solution. I've created a new UserControl and then added it as item of my ComboBox.
MyComboBoxItem.xaml:
<StackPanel Orientation="Horizontal">
<Image x:Name="img" Source="{Binding Image, ElementName=myComboBoxItem}" Height="18" Width="18"/>
<TextBlock x:Name="txt" Text="{Binding Text, ElementName=myComboBoxItem}" Margin="5,0,0,0"/>
</StackPanel>
MyComboBoxItem.xaml.cs:
public string Text
{
get { return txt.Text; }
set { txt.Text = value; }
}
public override string ToString()
{
return Text;
}
MainWindow.xaml:
<ComboBox>
<local:MyComboBoxItem Image="image1.png" Text="Item1"/>
<local:MyComboBoxItem Image="image2.png" Text="Item2"/>
<local:MyComboBoxItem Image="image3.png" Text="Item3"/>
</ComboBox>
Now it works like a charm and does exactly what I've wanted.

How can I have a ControlTemplate that only creates a container for the default, unaltered visual tree of a control?

I'm trying to figure out how to change a control's template to something that will make it held inside a Grid, like this:
<ControlTemplate x:Key="containedTemplate">
<Grid>
<!-- place templated control here -->
</Grid>
</ControlTemplate>
I of course want any of the inner control's properties to be synced automatically with the templated control.
Can this be done at all?
Here's an hypothetical example for a TextBox template:
<ControlTemplate x:Key="textTemplate" TargetType="{x:Type TextBox}">
<Grid Background="Red">
<TextBox Name="InnerTextBox" Margin="5,5,5,5"/>
</Grid>
</ControlTemplate>
Now if I did apply the template on a TextBox instance like this:
<TextBox Text="{Binding MyTextProperty}" Template="{StaticResource textTemplate}"/>
... then the control would magically be a Grid, containing a TextBox with a few margins and whose Text's property would be bound to MyTextProperty of whatever DataContext instance has been set:
<!-- runtime visual tree I'd like to be produced by the above XAML -->
<Grid Background="Red">
<TextBox Text="{Binding MyTextProperty}" Margin="5,5,5,5"/>
</Grid>
If I had the following code:
<StackPanel>
<TextBox Text="{Binding MyTextProperty}" Template="{StaticResource textTemplate}"/>
<TextBox Text="{Binding MyOtherTextProperty}" Template="{StaticResource textTemplate}"/>
<TextBox Text="{Binding YetAnotherTextProperty}" Template="{StaticResource textTemplate}"/>
</StackPanel>
The resulting tree would be this:
<!-- runtime visual tree I'd like to be produced by the above XAML -->
<StackPanel>
<Grid Background="Red">
<TextBox Text="{Binding MyTextProperty}" Margin="5,5,5,5"/>
</Grid>
<Grid Background="Red">
<TextBox Text="{Binding MyOtherTextProperty}" Margin="5,5,5,5"/>
</Grid>
<Grid Background="Red">
<TextBox Text="{Binding YetAnotherTextProperty}" Margin="5,5,5,5"/>
</Grid>
</StackPanel>
In these examples you can see that the TextBox's Text property is correctly propagated down to the "inner" TextBox instance. The control's default visual tree is also preserved (borders, typing area, etc.).
I'm aware of template parts but as I said I'm trying to find a global approach here, and I DO NOT want to change the control's appearance; only put it inside a container.

frankly, this question exhausted me, i have this only answer but not convince me a lot.
first you should create multi ControlTemplates for each control that you want to set your template then create this class
public class ControlTemplateConverter
{
public static readonly DependencyProperty IsEnabledProperty =
DependencyProperty.RegisterAttached("IsEnabled", typeof(bool), typeof(ControlTemplateConverter), new UIPropertyMetadata(false, IsEnabledChanged));
private static void IsEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ControlTemplate t;
if (d == null) return;
if (d is TextBlock)
t = App.Current.FindResource("TextBoxTemplate") as ControlTemplate;
else if (d is CheckBox)
t = App.Current.FindResource("CheckBoxTemplate") as ControlTemplate;
// and So On
(d as Control).Template = t;
}
public static bool GetIsEnabled(DependencyObject obj)
{
return (bool)obj.GetValue(IsEnabledProperty);
}
public static void SetIsEnabled(DependencyObject obj, bool value)
{
obj.SetValue(IsEnabledProperty, value);
}
}
and your control should like this:
<TextBox local:ControlTemplateConverter.IsEnabled="True"></TextBox>
<CheckBox local:ControlTemplateConverter.IsEnabled="True"></CheckBox>

how to change the image style received from webservice in windows phone 7

I am sharing the screen shot of my application. The image which is coming i want it to be in the side and should be small in size. Here i am not getting the full image also. Can anyone help me to fit the image in the listbox and appear it in the side.
My xaml code is:
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<ListBox Name="listBox1">
<ListBox.ItemTemplate>
<DataTemplate>
<Button>
<Button.Content>
<ScrollViewer HorizontalScrollBarVisibility="Auto" Height="80" Width="400">
<!--<ScrollViewer Height="80">-->
<StackPanel Orientation="Horizontal" Margin="0,0,0,0">
<StackPanel Orientation="Vertical" Height="80">
<TextBlock Text="{Binding Path=News_Title}" TextWrapping="Wrap" ></TextBlock>
<TextBlock Text="{Binding Path=News_Description}" TextWrapping="Wrap"></TextBlock>
<TextBlock Text="{Binding Path=Date_Start}" TextWrapping="Wrap"></TextBlock>
<Image Source="{Binding ImageBind }" />
</StackPanel>
</StackPanel>
</ScrollViewer>
</Button.Content>
</Button>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
My .cs code is:
public class Newss
{
public string News_Title { get; set; }
public string News_Description { get; set; }
public string Date_Start { get; set; }
public string image_path { get; set; }
public BitmapImage ImageBind{get;set;}
}
public News()
{
InitializeComponent();
KejriwalService.aapSoapClient client = new KejriwalService.aapSoapClient();
client.getarvindNewsCompleted += new EventHandler<KejriwalService.getarvindNewsCompletedEventArgs>(client_getarvindNewsCompleted);
client.getarvindNewsAsync();
}
void client_getarvindNewsCompleted(object sender, KejriwalService.getarvindNewsCompletedEventArgs e)
{
string result = e.Result.ToString();
List<Newss> listData = new List<Newss>();
XDocument doc = XDocument.Parse(result);
foreach (var location in doc.Descendants("UserDetails"))
{
Newss data = new Newss();
data.News_Title = location.Element("News_Title").Value;
//data.News_Description = location.Element("News_Description").Value;
data.Date_Start = location.Element("Date_Start").Value;
data.image_path = location.Element("image_path").Value;
data.ImageBind = new BitmapImage(new Uri( #"http://political-leader.vzons.com/ArvindKejriwal/images/uploaded/"+data.image_path, UriKind.Absolute));
listData.Add(data);
}
listBox1.ItemsSource = listData;
}

Try to move your Image outside inner StackPanel :
.....
<StackPanel Orientation="Horizontal" Margin="0,0,0,0">
<StackPanel Orientation="Vertical" Height="80">
<TextBlock Text="{Binding Path=News_Title}" TextWrapping="Wrap" ></TextBlock>
<TextBlock Text="{Binding Path=News_Description}" TextWrapping="Wrap"></TextBlock>
<TextBlock Text="{Binding Path=Date_Start}" TextWrapping="Wrap"></TextBlock>
</StackPanel>
<Image Source="{Binding ImageBind }" />
</StackPanel>
.....
That will make the Image appear besides the Text. Then try to set Width and Height properties of Image control to fixed value, and set Stretch property appropriately. See this post for reference about setting Stretch property.

There're too many wrong things here, and I don't know what you want.
You've put buttons inside items of ListBox. You should either remove buttons and rely on listbox own items selection mechanism for handling touch elents, or continue using buttons but replace ListBox with ItemsControl that doesn’t handle touch.
You’ve put ScrollViewer inside those buttons. So if you have 10 items, you’ll have 10 buttons, each with its own scroll viewer. Why you did that?
You’ve set height of your StackPanel to 80. When specifying fixed height, Silverlight often does not care whether the content fits or no, instead it clips things. It’s rarely a good idea to specify absolute size of elements.
Instead of using two nested stack panels, you should use single Grid with two rows and two columns, where image occupies both rows of the second column (using Grid.RowSpan property).
And you’re asking question about changing image style? You should fix the rest of your XAML first…

Can I swap a buttons content databind to a different databind in code?

I cannot find any examples to make me understand how and if I can change the databind in c# at the click of a button on, in my case a toggleswitch, Basically I have 32 buttons in my app and those 32 buttons act the same but need different text with-in them depending on some toggle switches they are currently databinded so the text can be saved and retrieved from local storage but what values it gets depends on the state of these toggle switches.
So I currently have :
<Button x:Name="_ovButton1" Content="{Binding Source={StaticResource AppSettings}, Path=ovName1_1Value, Mode=TwoWay}" Margin="2,0,250,0" VerticalAlignment="Top" FontSize="14" Height="72" FontWeight="Bold" MouseLeftButtonUp="_ovButton1_MouseLeftButtonUp" MouseLeftButtonDown="_ovButton1_MouseLeftButtonDown" ClickMode="Hover" Hold="_ovButton1_Hold"/>
and I want when a user changes the state of a toggleswitch to change the
{StaticResource AppSettings}, Path=ovName1_1Value, Mode=TwoWay}
to for example:
{StaticResource AppSettings}, Path=ovName1_2Value, Mode=TwoWay}
but I cannot find any example that shows how to do that in c#
what code do I need to do that?

You can specify the target of databinding in code like this:
MyData myDataObject = new MyData(DateTime.Now);
Binding myBinding = new Binding("MyDataProperty");
myBinding.Source = myDataObject;
myText.SetBinding(TextBlock.TextProperty, myBinding);
See more at http://msdn.microsoft.com/en-us/library/ms742863.aspx

-- Edit Note I don't have access to a WP8 Emulator to test this ---
In the view model it looks like this:
public List<string> Members
{
get { return _Members; }
set { _Members = value; OnPropertyChanged(); }
}
public MainVM()
{
// Simulate Asychronous access, such as to a db.
Task.Run(() =>
{
Thread.Sleep(2000);
Members = new List<string>() {"Alpha", "Beta", "Gamma", "Omega"};
});
}
The code behind on the main page sets the datacontext (shared with all the child controls) as such:
public MainWindow()
{
InitializeComponent();
// Set the windows data context so all controls can have it.
DataContext = new MainVM();
}
The Mainpage Xaml to bind to members is like this
<Button Height="30"
Width="80"
Margin="10"
DataContext="{Binding Members}"
Content="{Binding Path=[0] }" />
<Button Height="30"
Width="80"
Margin="10"
DataContext="{Binding Members}"
Content="{Binding Path=[1] }" />
<Button Height="30"
Width="80"
Margin="10"
DataContext="{Binding Members}"
Content="{Binding Path=[2] }" />
<Button Height="30"
Width="80"
Margin="10"
DataContext="{Binding Members}"
Content="{Binding Path=[3] }" />
The result is this visually:
I based this on my blog article Xaml: ViewModel Main Page Instantiation and Loading Strategy for Easier Binding for more info and a fuller example.

I think your best bet is going to be to use a collection of strings and bind to that collection. You can either change the collection when a toggle is switched, or keep 6 collections and bind to the collection that is for the toggle.
Xaml:
<ItemsControl x:Name="Buttons" ItemsSource="{Binding ButtonTextCollection}">
<ItemsControl.ItemsPanel>
<toolkit:WrapPanel/>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Width="100" Height="70" Content="{Binding}" Click="OnButtonClick"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
Your code-behind would have the event handler for your button click
private void OnButtonClick(object sender, RoutedEventArgs e)
{
var text = ((Button) sender).Content.ToString();
// Send the text
}
Your ViewModel would hold the ButtonTextCollection property and would change based on the toggle.
public ICollection<string> ButtonTextCollection
{
get { return _buttonTextCollection; }
set
{
_buttonTextCollection = value;
OnPropertyChanged("ButtonTextCollection");
}
}
When you want to change the text, you would change the ButtonTextCollection
public void ChangeButtonText()
{
ButtonTextCollection = new Collection<string> {"A", "B",...};
}