I have some problem in wpf application.
In XAML:
<Expander Header="SomeHeader" Style="{StaticResource ExpanderStyle}" IsExpanded="{Binding ElementName=Errors, Converter={StaticResource visibilityConverter}, Path=IsExpanded}" >
<RichTextBox ScrollViewer.VerticalScrollBarVisibility="Visible" Style="{StaticResource RichTextBoxStyle}" Foreground="Red" IsReadOnly="True">
<FlowDocument>
<Paragraph>
<ItemsControl ItemsSource="{Binding Path=Errors}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" Style="{StaticResource ErrorTextBlockStyle}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Paragraph>
</FlowDocument>
</RichTextBox>
</Expander>
In my ViewModelClass:
private List<string> errors;
public List<string> Errors
{
get { return errors; }
set
{
errors = value;
OnPropertyChanged("Errors");
}
}
In constructor:
public MainWindowViewModel()
{
if (IsInDesignMode) return;
Errors = new List<string>();
}
In test method:
private void TestExcute()
{
Errors = "Some error";
}
In this situation error message not displayed in wpf window. But if I change code in constructor to next:
public MainWindowViewModel()
{
if (IsInDesignMode) return;
Errors = new List<string>{"errorMessage1", "errorMessage2"};
}
Displayed:
errorMessage1
errorMessage2
What is the reason ?
I have new question. In this wpf application I also used Expander control. How create auto expand open, then Errors.count > 0?
I create converter :
public class VisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType,
object parameter, System.Globalization.CultureInfo culture)
{
LoadFile loadFile = (LoadFile)value;
if (loadingFile.ExcelErrors.Count > 0)
{
return Visibility.Visible;
}
else
{
return Visibility.Collapsed;
}
}
public object ConvertBack(object value, Type targetType,
object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
LoadFile is a class where declared Errors property.
I think you made an error in your TestExcute while writing question did you mean to write Errors.Add("some error")?
If so then your ItemsControl wont react to change because there is no change on property Errors - setter is not invoked.
Change your List<string> to ObservableCollection<string> this class notifies that its content has change and UI will react to that.
Related
What I want it to bind TextBoxes to my dictionaries values.
I could find some posts about it already but :
One means having my dictionary as context :
XML :
<TextBox x:Name="FirstLine" Text="{Binding Path=[FirstLine]}"/>
XAML :
public ImportProfilesOptions()
{
InitializeComponent();
contexte = new ViewModelImportProfilesOptions();
DataContext = contexte.ParamsData;
}
The other one using Templates :
<ItemsControl x:Name="dictionaryItemsControl" ItemsSource="{Binding dictionary}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Key}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
But I would like to use it, without using Templates (I need to add in labels some translates I take from properties), and without setting my dictionary as context. Something like that :
XML
<TextBox x:Name="FirstLine" Text="{Binding Path=ParamsDate[FirstLine]}" />
XAML
contexte = new ViewModelImportProfilesOptions();
DataContext = contexte;
But then, binding is not working anymore.
You can't do this out of the box, though you could create your own converter I guess:
public class SomeFunkyConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (!(value is Dictionary<string,string> dictionary))
return null;
if (!(parameter is string key))
return null;
return !dictionary.TryGetValue(key, out var result) ? null : result;
}
// ill leave this up to you
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
=> throw new NotSupportedException();
}
Usage
<TextBlock Text="{Binding Path=ParamsDate,
ElementName=TextBox,
Converter={StaticResource SomeFunkyConverter},
ConverterParameter='Bob'}"/>
Note : Completely untested
I have a ListView in XAML and a List<string> that holds local embedded image paths. I am not able to show images in List. By the way I am able to show as a single image by
<Image Source="{local:ImageResource TypingApplication.Images.Icons.Search.png}" />
But I cannot show the images in ListView. Here is my XAML code
<ListView x:Name="ListView"
ItemsSource="{Binding ListItems}"
IsEnabled="True"
IsVisible="True"
RowHeight="40"
Opacity="0.9">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Image Source="{local:ImageResource TypingApplication.Images.Icons.{Binding .}}"/>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
I have added ImageResourceExtension in Extensions folder and xmlns:local="clr-namespace:TypingApplication.Extensions" in XAML, as I mentioned I can show Single Image, only there is problem with ListView.
Here is my C# code that contains List and Constructor
public List<string> ListItems
{
get
{
return new List<string>()
{
"Home.png",
"Favorite.png",
"Search.png"
};
}
}
public HomePage()
{
InitializeComponent();
this.BindingContext = this;
}
Please note that I am using shared Images in my project. I have set Properties of all Images to Embedded resource in SolutionExplorer.
Change list to ObservableCollection
IValueConverter implementation to convert your binding to desired value
The image property should be set to EmbeddedResource
public class EmbeddedToImageSourceConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is string fileName && parameter is String assemblyName)
{
try
{
var imageSource = ImageSource.FromResource(assemblyName + "." + fileName, typeof(EmbeddedToImageSourceConverter).GetTypeInfo().Assembly);
return imageSource;
}
catch (Exception)
{
return value;
}
}
else
return value;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return value;
}
}
XAML
<ContentPage.Resources>
<local:EmbeddedToImageSourceConverter x:Key="converter" />
</ContentPage.Resources>
In the listview add binding w.r.to converter resource we just created.
<Image Source="{Binding ., Converter={StaticResource converter}, ConverterParameter='TypingApplication.Images.Icons'}" />
If you are not using View Model (MVVM), you can directly specify image file's name in XAML as:
<Image Source="{Binding Source='ImageFileName.png', Converter={StaticResource converter}, ConverterParameter='TypingApplication.Images.Icons'}" />
If you want to add Embedded image in listview, according to json's reply, your binding have some problem, you can use IValueConverter to convert image path as correct.
I do one sample according to your code, you can take a look:
<ListView HasUnevenRows="True" ItemsSource="{Binding ListItems}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Image
HeightRequest="100"
Source="{Binding ., Converter={StaticResource imageconverter}}"
WidthRequest="100" />
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<ContentPage.Resources>
<local:imageconverter x:Key="imageconverter" />
</ContentPage.Resources>
The Image converter:
public class imageconverter : IValueConverter
{
public string Source { get; set; }
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
Source = (string)value;
if (Source == null)
return null;
// Do your translation lookup here, using whatever method you require
var imageSource = ImageSource.FromResource("demo3."+Source, typeof(ImageResourceExtension).GetTypeInfo().Assembly);
return imageSource;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
You can change demo3 as TypingApplication according to your code.
public partial class Page14 : ContentPage
{
public ObservableCollection<string> ListItems { get; set; }
public Page14()
{
InitializeComponent();
ListItems = new ObservableCollection<string>()
{
"image1.jpg","image2.png","image3.png"
};
this.BindingContext = this;
}
}
As Prateek's reply, I suggest you can change List<> to Observablecollection<>, because it implement INotifyPropertyChanged interface, notify data changed.
https://learn.microsoft.com/en-us/dotnet/api/system.collections.objectmodel.observablecollection-1?view=netframework-4.8
I effectively have -
<UserControl ...>
<Grid>
<TreeView Name="nTree">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate DataType="NodeType" ItemsSource="{Binding Children}">
<StackPanel Orientation="Horizontal">
<Image x:Name="icon" />
<TextBlock Text="{Binding Name}" />
</StackPanel>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
</Grid>
</UserControl>
NodeType is a type returned by an underlying library. I would like to set the icon images source based on the name provided - however I can't modify NodeType to add a getter.
So ideally what I would like is the icon image source to be bound to a function on the UserControl class which receives the Name and returns an ImageSource.
i.e.
public partial class Panel : UserControl
{
public Panel(NodeType n)
{
nTree.Items.add(n);
}
public ImageSource GetIcon(string name)
{
...
}
}
This feels like it should be possible but i'm struggling to work it out. Assistance would be appreciated.
Unfortunately you can't bind to methods, you need to convert the method to a property
you can do this in several ways
the easiest would be to have: (though this should be on your VM not your V)
public ImageSource Icon
{
...
}
or you can use a value converter:(the best fit for what you are descibing)
public class ImageConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
GetImageLogic
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException("One way only");
}
}
the 3rd option would be to use an CommandBinding :
then bind to the command
CommandBinding OpenCmdBinding = new CommandBinding(
ApplicationCommands.Open,
OpenCmdExecuted,
OpenCmdCanExecute);
this.CommandBindings.Add(OpenCmdBinding);
void OpenCmdExecuted(object target, ExecutedRoutedEventArgs e)
{
String command, targetobj;
command = ((RoutedCommand)e.Command).Name;
targetobj = ((FrameworkElement)target).Name;
MessageBox.Show("The " + command + " command has been invoked on target object " + targetobj);
}
void OpenCmdCanExecute(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
}
I have a traffic application. The light status is updated in the listbox.
<ListBox x:Name="lbxCallProgress" ItemsSource="{Binding Messages,Mode=TwoWay}" Height="373" FontSize="8" ScrollViewer.VerticalScrollBarVisibility="Visible">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
For the Messages:
public partial class MainWindow : Window
{
public ObservableCollection<string> Messages { get; set; }
To update messages to the listbox.
void UpdateMessage(string message)
{
try
{
Dispatcher.BeginInvoke((Action)delegate()
{
Dispatcher.BeginInvoke(new Action(() => { this.Messages.Add(message); }));
});
}
Now if the string message contains the keyword "green", then I want to set the item color on the listbox as color green, etc.
How?
here you go
with the power of WPF binding you can use the value to bind to the desired property Background and the implicit converter will do the rest for you.
<DataTemplate>
<TextBlock Text="{Binding}" Background="{Binding}"/>
</DataTemplate>
you can choose to bind Foreground in case if you want to change the text color
Using converters
if simple binding is not sufficient enough you may use converters to perform custom logic of conversion, eg converting The light is red to Brushes.Red
public class MyColorConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
string text = value as string;
if(text.Contains("red"))
return Brushes.Red;
return Brushes.White;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return DependencyProperty.UnsetValue;
}
}
usage
<DataTemplate xmlns:l="your namespace to converter class">
<DataTemplate.Resources>
<l:MyColorConverter x:Key="MyColorConverter" />
</DataTemplate.Resources>
<TextBlock Text="{Binding}" Background="{Binding Converter={StaticResource MyColorConverter}}"/>
</DataTemplate>
I want to convert the localization meta tag e.g. en-US to the display name, in this case English. The meta tag is stored in a ObservableCollection because it will be modified on runtime. I want to bind the display name to a combo box.
ComboBox:
<ComboBox Grid.Column="1" Grid.Row="1" Width="200" VerticalAlignment="Center" HorizontalAlignment="Center" SelectedIndex="0" ItemsSource="{Binding Path=ServerData.AvailableTemplateLanguages}">
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding, Converter=LanguageTagToNameConverter}" FontSize="12"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
Converter:
class LanguageTagToNameConverter : IValueConverter
{
public object Convert(object value,
Type targetType,
object parameter,
CultureInfo culture)
{
return CultureInfo.GetCultureInfo(value.ToString()).DisplayName;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
ObservableCollection:
public class ServerDataObj : ModelBase
{
private ObservableCollection<string> _availableTemplateLanguages = new ObservableCollection<string> { "de-DE", "en-US" };
public ObservableCollection<string> AvailableTemplateLanguages
{
get
{
return _availableTemplateLanguages;
}
set
{
_availableTemplateLanguages = value;
OnPropertyChanged("AvailableTemplateLanguages");
}
}
}
Unfortunately this approach does not work.
You need to put converter into resources:
<Window>
<Window.Resources>
<LanguageTagToNameConverter x:Key="convLang"/>
</Window.Resources>
...
<TextBlock Text="{Binding, Converter={StaticResource convLang}}"/>