my objects which I use to binding in XAML can have only string properties. But in binding I need other type. I thought that I use Converter function from IValueConverter, where I'll create object from string properties and return this. One property which is a string will be empty, and in binding I'll return other object from Converter method. I tried this but in Convert method my main object from ObservableCollection is null. This's a piece of my XAML
<Maps:MapItemsControl ItemsSource="{Binding}">
<Maps:MapItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Background="Transparent" Tapped="ItemStckPanel">
<Image Source="/Assets/pushpin.gif" Height="30" Width="30"
Maps:MapControl.Location="{Binding Location,
Converter={StaticResource StringToGeopoint}}"
Maps:MapControl.NormalizedAnchorPoint="0.5,0.5"/>
<StackPanel VerticalAlignment="Center" HorizontalAlignment="Center" Margin="5">
<TextBlock FontSize="20" Foreground="Black" Text="{Binding Name}"/>
</StackPanel>
</StackPanel>
</DataTemplate>
</Maps:MapItemsControl.ItemTemplate>
</Maps:MapItemsControl>
And this's my Convert method:
public object Convert(object value, Type targetType, object parameter, string language)
{
Event _event = (Event) parameter;
BasicGeoposition position = new BasicGeoposition();
position.Latitude = _event.Latitude;
position.Longitude = _event.Longitude;
return new Geopoint(position);
}
I want to pass the my actual parent object in Converter method. Solution is change
Maps:MapControl.Location="{Binding Location,
Converter={StaticResource StringToGeopoint}}"
to
Maps:MapControl.Location="{Binding Converter={StaticResource StringToGeopoint}}"
It works :)
The bound object is fed into the "value" parameter of the Convert()-Method.
You're accessing the parameter which corresponds to
<... ConverterParameter= .../>
which isn't set in your xaml.
You would actually have to write your Convert()-Method like this:
public object Convert(object value, Type targetType, object parameter, string language)
{
Event _event = (Event) value;
BasicGeoposition position = new BasicGeoposition();
position.Latitude = _event.Latitude;
position.Longitude = _event.Longitude;
return new Geopoint(position);
}
/UPDATE:
The ItemsSource={Binding} on your Maps:MapItemControl binds to the DataContext of the parent object. This should be your ObservableCollection.
Within the ItemTemplate your Image has a "Location"-Property that is bound to the "Location"-property of each item within your ObservableCollection. You could also write:
{Binding Path=Location, Converter={StaticResource StringToGeopoint}}
Now before that binding is fully evaluated, the Object that is stored in the Location-property is passed to the converter and the result is then handed to the "Location"-Property on the Image.
If you are getting null objects to be passed to the "value"-parameter, that means that the original Binding hands null values to the Converter either because the Property on the source object is null or because the property doesn't exist.
Related
I have a WPF App that has (so far) 2 modes of display, regularmode and widgetmode.
I am using Prism 6 with MVVM design pattern.
MainWindowViewModel knows the mode of display.
ToolBarView has, as expected, a toolbar of buttons and the buttons shall be dynamically changed to different images depending on the mode of the view. If the mode is WidgetMode, it switches to the image with an identical name but with an '_w' added. So instead of "image.png", it's "image_w.png".
What I'd like to do is create a string in ToolBarView that is updated to either String.Empty or to "_w", depending on the mode. I'd also like the image root folder to be a global string, rather than a hardcoded string, so I have defined that in app.xaml.
<Application.Resources>
<sys:String x:Key="ImageURIRoot">/MyApp;component/media/images/</sys:String>
</Application.Resources>
Then in my toolbarview (a usercontrol), I did this:
<UserControl.Resources>
<converters:StringToSourceConverter x:Key="strToSrcConvert"/>
<sys:String x:Key="BtnImgSuffix">_w</sys:String>
.
.
.
</UserControl.Resources>
Note that the string is hardcoded; eventually, I will change it dynamically based off the windowmode.
I then put the Buttons in a Listbox
<ListBoxItem Style="{StaticResource MainButton_Container}">
<Button Command="{Binding ButtonActionDelegateCommand}" Style="{StaticResource Main_Button}">
<Image Source="{Binding Source={StaticResource ImageURIRoot}, Converter={StaticResource strToSrcConvert}, ConverterParameter='{}{0}button.png'}" />
</Button>
</ListBoxItem>
Converter code:
public class StringToSourceConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (parameter is string)
{
return string.Format(parameter.ToString(), value);
}
return null;
}
public object ConvertBack(object value, Type targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
return null;
}
}
So that works. But what I want is to have the ConverterParameter equal "{}{0}button{1}.png", where {0} is the URI Root and {1} is the suffix. But I can't figure out how to do it. I know it's simple, but I can't put my finger on it!
Please help!
Figured it out and it was through multibinding. The way I did it was create a converter that inherits from IMultiValueConverter. Its "Convert" method looks like this:
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
ImageSourceConverter conv = new ImageSourceConverter();
int suffixPos = ((String)parameter).Length - 4;
var returnValue = ((String)parameter).Insert(suffixPos, values[1].ToString());
returnValue = Path.Combine(values[0].ToString(), returnValue);
ImageSource imgsrc = conv.ConvertFromString(returnValue) as ImageSource;
return imgsrc;
}
The xaml looks like this:
<Image Height="30" Width="40" diag:PresentationTraceSources.TraceLevel="High">
<Image.Source>
<MultiBinding Converter="{StaticResource stringsToSrcConvert}" ConverterParameter="buttonImg.png">
<Binding Source="{StaticResource ImageURIRoot}"/>
<Binding Source="{StaticResource BtnImgSuffix}"/>
</MultiBinding>
</Image.Source>
</Image>
Also, had to modify the URIRoot
<Application.Resources>
<sys:String x:Key="ImageURIRoot">pack://application:,,,/MyApp;component/media/images/</sys:String>
</Application.Resources>
Thanks, Clemens!
Here what i have in xaml:
<DataGrid Name="dataGrid">
<DataGridTemplateColumn Header = "Base" Width="100">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="50"/>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<RadioButton Grid.Column="0" GroupName="{Binding Index}" Name="ABCD" Content="ABCD" IsChecked="True" Checked="radioButton_Checked"/>
<RadioButton Grid.Column="1" GroupName="{Binding Index}" Name="XYZ" Content="XYZ" Checked="radioButton_Checked" />
</Grid>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid>
Here are some codes in some function (any) xaml.cs:
DataGridRow row = (DataGridRow)dataGrid.ItemContainerGenerator.ContainerFromIndex(i);
FrameworkElement radioButton = dataGrid.Columns[0].GetCellContent(row) as FrameworkElement;
radioButton.Visibility = Visibility.Hidden;
I can hide the visibility as I am hiding whole cell. but i want to change a radio button content in runtime from "XYZ" to "HAHAHA". How can i achieve this?
You might be able to use a value converter to achieve this. This can be used to change the name based on the index value;
public class IndexToXYZOrHaHaHaConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var index = (int) value;
if (index > 10)
{
return "XYZ";
}
return "HaHaHa";
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
You'll need to create an instance of the class by adding a static resource to your resource dictionary.
<local:IndexToXYZOrHaHaHaConverter x:Key="IndexToXYZOrHaHaHaConverter"/>
You'll then need to change the content of the radio button from "xyz" to this;
Content="{Binding Index, Converter={StaticResource IndexToXYZOrHaHaHaConverter}}"
This should dynamically switch the value between xyz and HaHaHa depending on the index. In the example I gave this depends on whether the value is greater or less than 10, which is probably not what you want so you'll have to fix the logic. I've also assumed that index is an integer, you may need to change that too if index is something else.
Converters are great for setting properties based on bound values that don't directly correspond to the value they are bound to e.g. converting a string to a color.
Hope this is of some help.
I have a list of DownloadOperation in ObservableCollection and the variable has the property Progress.TotalBytesToReceive & Progress.BytesReceived.
When i tried to bind this property to max & value of progress bar it gives me binding expression error property does not found. I bind other property ResultFile.Name and it success. Is there any possible way to fix this?
UPDATE :
I found that I need to use converter from progress to get the totalbytes value, but the problem now the value is not updated, and seems like observablecollection does not watch the bytes received value.
<ListView DataContext="{Binding Download}"
ItemsSource="{Binding}">
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch" />
</Style>
</ListView.ItemContainerStyle>
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel Margin="5">
<TextBlock Text="{Binding ResultFile.Name}"
FontSize="20"
Foreground="Black"/>
<ProgressBar Maximum="100"
Value="{Binding Progress, Converter={StaticResource ByteReceivedConverter}}"/>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
I have this as viewmodel, the activeDownloads contains list of observable download.
public ObservableCollection<DownloadOperation> activeDownloads = new ObservableCollection<DownloadOperation>();
And I tried to extract the BytesReceived & TotalBytesToReceive in code behind
double received = 0;
double total = 0;
foreach (var item in activeDownloads)
{
received += item.Progress.BytesReceived;
total += item.Progress.TotalBytesToReceive;
}
if (total != 0) {
var percentage = received / total * 100;
It works without any problem, The observablecollection also works fine, when I add download it automatically change the view without I have to update the datacontext manually, same result if the download finish/removed. But if I directly bind the Progress.BytesReceived to the progressbar Value it gives me Path Error, but I am able to bind it to Progress property. So I make a converter to retrieve the value.
Here is Convereter I use to convert the Progress property :
public class ByteReceivedConverter:IValueConverter
{
public object Convert(object value, Type targetType, object parameter, string language)
{
BackgroundDownloadProgress bytes = (BackgroundDownloadProgress)value;
if (bytes.TotalBytesToReceive != 0)
return bytes.BytesReceived/bytes.TotalBytesToReceive*100;
else return 0;
}
public object ConvertBack(object value, Type targetType, object parameter, string language)
{
throw new NotImplementedException();
}
}
And is it possible to make this DownloadOperation has observability to the bytesreceived level?, since I did not make this property, I just retrieve it from meta. Or am I doing it wrong? because for now the problem i got is the view does not aware that the bytesreceived value is change.
If it's not possible should I make another viewmodel with INotifyPropertyChanged implemented?
First of all, you don't need to use a converter; binding the Max and Value properties would have been fine, but you probably didn't make the source values as public properties or you had the Path set incorrectly in the binding.
With the way you are doing it now, you will need to raise the property changed event of INotifyPropertyChanged for the Progress property each time BytesReceived is updated, because that is the property that you are binding to.
I have a textblock in my listbox called "feedTitle" which I want to change the forground color of. I use Foreground="{Binding Converter={StaticResource NewsTextColorConverter}}" for the binding of the forground color. Now the strange problem is that, if I choose a color in the listpicker("Lys" or "Dark" value) it runs the IValueConverter Convert method, but it dont show the color in the GUI, only if I restart my whole app it shows the color I chosen. It's like it only set the color of the forground of the textblock once.
MainPage.xaml
<ListBox Grid.Row="1" Name="feedListBox" ScrollViewer.VerticalScrollBarVisibility="Auto" SelectionChanged="feedListBox_SelectionChanged">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel VerticalAlignment="Top">
<TextBlock TextDecorations="Underline" FontSize="24" Name="feedTitle" TextWrapping="Wrap" Margin="12,0,0,0" Foreground="{Binding Converter={StaticResource NewsTextColorConverter}}" Text="{Binding Title.Text, Converter={StaticResource RssTextTrimmer}}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
And in my app file:
App.xaml
<Application.Resources>
<converter:NewsTextColorConverter xmlns:converter="clr-namespace:NordjyskeRss" x:Key="NewsTextColorConverter" />
</Application.Resources>
I use a listpicker where a user select the value "Mørk" or "Lys" and then I want the textblock forground color to update its forground color. I call the Convert method and pass null as arguments, it seems to run the method fine:
MainPage.cs
private void lpkThemes_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
// Make sure we don't handle the event during initiation.
if (e.RemovedItems != null && e.RemovedItems.Count > 0)
{
if (this.lpkThemes.SelectedItem != null)
{
settings[THEMES_SETTING_KEY] = lpkThemes.SelectedItem.ToString();
if (lpkThemes.SelectedItem.ToString() == "Mørk")
{
n.Convert(null, null, null, null);
}
else
{
n.Convert(null, null, null, null);
}
}
}
}
This is where I use a IValueConverter to check for what color to use on the textblock and then add it:
MainPage.cs
public class NewsTextColorConverter : IValueConverter
{
protected IsolatedStorageSettings settings = IsolatedStorageSettings.ApplicationSettings;
protected const string THEMES_SETTING_KEY = "Themes";
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (settings.Contains(THEMES_SETTING_KEY))
{
string themesValue = (string)settings[THEMES_SETTING_KEY];
if (themesValue == "Mørk")
{
return new SolidColorBrush(Colors.Green);
}
else
{
return new SolidColorBrush(Colors.Blue);
}
}
return new SolidColorBrush(Colors.Green);
//throw new NotSupportedException("ColorToBurshConverter only supports converting from Color and String");
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
I think you need to redesign your app in the following way:
Add the following line into your app.xaml or page resources: <SolidColorBrush x:Key="brushListItemsForeground" Color="#FFFFFFFF" />
Replace Foreground="{Binding Converter={StaticResource NewsTextColorConverter}}" with Foreground="{StaticResource brushListItemsForeground}"
In your SelectionChanged:
var brush = (SolidColorBrush)Application.Current.Resources["brushListItemsForeground"]; if you’ve added the brush to app.xaml, or = (SolidColorBrush)this.Resources["brushListItemsForeground"]; if you’ve added the brush to page resources. Then change the Color property of the brush based on your settings.
P.S. There’re also other correct ways: e.g. create a SettingsContainer class that implements INotifyPropertyChanged, add it into some resource dictionary <local:SettingsContainer x:Key="mySettings" />, then bind to its properties e.g. Foreground="{Binding listItemsForeground, Source={StaticResource mySettings}}", when you need to change the value, change the listItemsForeground property of your class and raise PropertyChanged.
Currently, you’re abusing value converter using then as value providers, they were not designed for that, and that is why you have issues updating those values.
Can anyone please let me know how I could make a Converter return text with varying font-sizes, so that the bound textblock can display it? If this is not possible with a TextBlock, I can use alternative element as well.
Here is the code that I have right now, this obviously doesn't work
In my XAML file:
<TextBlock Text="{Binding Converter={StaticResource LabelFormatConerter}}"/>
In my XAML.cs file:
public class LabelFormatConerter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
TextBlock tb = new TextBlock();
Run runLargeFont = new Run();
runLargeFont.FontSize = 18;
runLargeFont.Text = "Larger Font Text";
tb.Inlines.Add(runBase);
Run runSmallFont = new Run();
runSmallFont.FontSize = 8;
runSmallFont.BaselineAlignment = BaselineAlignment.Superscript;
runSmallFont.Text = "Smaller Font Text";
tb.Inlines.Add(runSmallFont);
return tb.Text;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
This should work for you:
<TextBlock FontFamily="Calibri">
<Run>Normal Text</Run>
<Run Typography.Variants="Superscript">Test</Run>
<Run Typography.Variants="Subscript">7</Run>
</TextBlock>
Not all fonts support super\subscripts, so I had to specify it explictly.
What will be your input? Two/three separate values, or one value that you need to split into a normal value, superscript and subscript?
This might be possible to do with a TextBlock but I don't know how. Your converter returns a collection of Run objects, while the Text property expects a string.
An alternative is to user an items control:
<ItemsControl ItemsSource="{Binding Converter={StaticResource LabelFormatConerter}}" />
and return
tb.Inlines
from your converter. (ideally you just create just a collection inside your converter, not a new TextBlock)
A converter is not the right tool for this job - this is what ContentTemplate is there for. Simply use a ContentControl, bind the data to the Content property and display the data however your want to in your ContentTemplate:
<ContentControl Content="{Binding Person}">
<ContentControl.ContentTemplate>
<DataTemplate>
<TextBlock>
<Run FontSize="18" Text="{Binding FirstName}" />
<Run FontSize="8" Text="{Binding LastName}" />
</TextBlock>
</DataTemplate>
</ContentControl.ContentTemplate>
</ContentControl>