This code work well, but the button visibility is collapsed in the design.
how can i set this to visible?
<!--Resources-->
<BooleanToVisibilityConverter x:Key="BoolToVis" />
<Button Visibility="{Binding Converter={StaticResource BoolToVis}, Source={x:Static local:ConfigUser.Prc}}" Grid.Row="1"/>
If I get right what you want. What you need is the button to appear in design mode and also appear when your boolean is set to true at runtime.
You can create your converter that test if it's in design mode in addition of your boolean:
using System;
using System.ComponentModel;
using System.Globalization;
using System.Windows;
using System.Windows.Data;
public class DesignVisibilityConverter : IValueConverter {
public object Convert(object value, Type targetType, object parameter, CultureInfo culture) {
if (value is bool) {
return ((bool) value) || DesignerProperties.GetIsInDesignMode(Application.Current.MainWindow)
? Visibility.Visible
: Visibility.Collapsed;
}
return Visibility.Collapsed;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) {
throw new NotImplementedException();
}
}
This one defaults to visible. Here is my Inverse BoolToVis
[ValueConversion(typeof(bool), typeof(Visibility))]
public class InverseBooleanToVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return (value != null && (bool)value) ?
Visibility.Collapsed : Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return (value != null) && ((Visibility)value == Visibility.Collapsed);
}
}
Related
My issue is that when I use a converter on one of the multibinding's binding. It doesn't send the right thing to the converter. As per the DOC(https://learn.microsoft.com/en-us/dotnet/maui/fundamentals/data-binding/multibinding?view=net-maui-7.0) in the Consume a IMultiValueConverter it should work, so I don't know what I'm doing wrong...
My multibinding class is the following:
public class BooleanAndConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
if (values == null || !targetType.IsAssignableFrom(typeof(bool)))
{
return false;
}
foreach (var value in values)
{
if (!(value is bool b))
{
return false;
}
else if (!b)
{
return false;
}
}
return true;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
}
I have a Boolean inverter class which is the following:
public class InverseBooleanConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (targetType != typeof(bool))
throw new InvalidOperationException("The target must be a boolean");
return !(bool)value;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
}
Then in my XAML I'm using it like so:
<Button Text="Passer à la ronde suivante" Command="{Binding NextRoundCommand}">
<Button.IsVisible>
<MultiBinding Converter="{StaticResource BooleanAndConverter}">
<Binding Path="isGameStarted"/>
<Binding Path="isPlayersPlaying" Converter="{StaticResource InvertedBoolConverter}"/>
</MultiBinding>
</Button.IsVisible>
</Button>
When the inverter converter gets called in the multibinding, instead of receiving a TagetType of bool, it receive a "System.object", so it throws the InvalidOperationException.
Why when using normal bindings it receive a targettype of bool and in multibinding it doesn't?
Thanks
I couldn't see other code, but I tested the sample code DataBindingDemos, it works on my side.
But I found that you didn't implement function ConvertBack for both of your (BooleanAndConverter and InverseBooleanConverter ).
And if I replace the code of ConvertBack to yous as follows, the app will throw exception.
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
You can refer to the following code:
public class InverterConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
bool? b = value as bool?;
if (b == null)
{
return false;
}
return !b.Value;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return Convert(value, targetType, parameter, culture);
}
}
public class AllTrueMultiConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
if (values == null || !targetType.IsAssignableFrom(typeof(bool)))
{
return false;
// Alternatively, return BindableProperty.UnsetValue to use the binding FallbackValue
}
foreach (var value in values)
{
if (!(value is bool b))
{
return false;
// Alternatively, return BindableProperty.UnsetValue to use the binding FallbackValue
}
else if (!b)
{
return false;
}
}
return true;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
if (!(value is bool b) || targetTypes.Any(t => !t.IsAssignableFrom(typeof(bool))))
{
// Return null to indicate conversion back is not possible
return null;
}
if (b)
{
return targetTypes.Select(t => (object)true).ToArray();
}
else
{
// Can't convert back from false because of ambiguity
return null;
}
}
}
For more information, you can check: AllTrueMultiConverter.cs and InverterConverter.cs
I use a converter to fill the remaining space of a hidden column in WPF (set width to 0.0), but in fact I need the ratio 1.7* vs * if visible!
How can I calculate the real value to set for the converter?
Converter:
public class ColumnWidthConverter : IValueConverter
{
public object Convert(
object value,
Type targetType,
object parameter,
System.Globalization.CultureInfo culture)
{
var isVisible = (bool) value;
var width = parameter as string == "*"
? new GridLength(1, GridUnitType.Star).Value
: double.Parse(parameter as string);
return isVisible ? width : 0.0;
}
public object ConvertBack(
object value,
Type targetType,
object parameter,
System.Globalization.CultureInfo culture)
{
return Binding.DoNothing;
}
}
As you can see I tried with new GridLength(1, GridUnitType.Star).Valuebut it's not the correct way!
XAML (condensed):
<appf:ViewUserControl.Resources>
<local:ColumnWidthConverter x:Key="ColumnWidthConverter" />
</appf:ViewUserControl.Resources>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1.7*"/>
<ColumnDefinition Width="{Binding Path=Visible, Converter={StaticResource ColumnWidthConverter}, ConverterParameter=*}"/>
</Grid.ColumnDefinitions>
Visible is just a boolean property in the corresponding ViewModel!
Sometimes it's easy: use string instead of double value
public class ColumnWidthConverter : IValueConverter
{
public object Convert(
object value,
Type targetType,
object parameter,
System.Globalization.CultureInfo culture)
{
var isVisible = (bool) value;
var width = parameter as string;
return isVisible ? width : "0.0";
}
public object ConvertBack(
object value,
Type targetType,
object parameter,
System.Globalization.CultureInfo culture)
{
return Binding.DoNothing;
}
}
I need to bind color to fill the rectangle.
XAML:
<Rectangle Fill="{Binding Colorr}"
VerticalAlignment="Center"
Height="3" Width="16"
Margin="3, 1, 5, 0"
Visibility="Visible"/>
ViewModel:
public ItemViewModel()
{
Colorr = Colors.Red;;
}
public Color Colorr
{
get {
return color; }
set
{
color = value;
NotifyOfPropertyChange(() => Colorr);
}
}
The resulting rectangle is not visible (or is transparent - it's hard to say...) instead of being visible and red. How can I get rid of this problem?
The other way around is to use ColorToBrushConverter, just like the one below:
using System.Windows.Data;
using System.Windows.Media;
public class ColorToBrushConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return new SolidColorBrush((Color)value);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return (value as SolidColorBrush).Color;
}
}
Then in XAML define the converter as resource and use it like this:
<Rectangle Fill="{Binding Colorr, Converter={StaticResource ColorToBrushConverter}}"/>
Rectangle.Fill (which it inherits from Shape) is a Brush, not a Color. So make your property a Brush instead:
private Brush _colorr = Brushes.Red;
public Brush Colorr
{
get
{
return _colorr;
}
set
{
_colorr = value;
NotifyOfPropertyChange(() => Colorr);
}
}
There may be other problems, but you need to fix this one first.
I have made minor changes to the Color BrushConverter proposed by Vaidas's to take care of the possible null reference exception:
using System.Windows.Data;
using System.Windows.Media;
namespace Common.Client.Wpf.Converters
{
public class ColorToBrushConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value is null ? null : new SolidColorBrush((Color)value);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return (value as SolidColorBrush)?.Color;
}
}
}
I'm trying to binding the TextColor from a label on ViewCell:
Label myLabel = new Label { Text = "SomeText" };
myLabel.SetBinding(Label.TextColorProperty,
new Binding("TheTextColor", BindingMode.TwoWay, new LabelTextColorConverter()));
Here's the converter:
public class LabelTextColorConverter : IValueConverter
{
public bool OldValue { get; set; }
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
OldValue = (bool) value;
Debug.WriteLine("asdadasdsadsada");
if ((bool)value)
return Color.Red;
else
return Color.Silver;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
Debug.WriteLine("qwqweqewqeeqe");
return OldValue;
}
}
The debug output doesn't appear, and the color doesn't change either. I don't see anything wrong.
Why do you need Two Way binding for this? I don't think it's necessary.
myLabel.SetBinding(Label.TextColorProperty, new Binding("TheTextColor", BindingMode.OneWay, new LabelTextColorConverter()));
Then:
public class LabelTextColorConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
bool val = (bool)value;
if (val)
return Color.Red;
else
return Color.Silver;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
... and it should work fine. Also make sure you're setting BindingContext for your page/controls correctly.
I am new to WPF MVVM. Here's what my viewmodel is doing:
A button is pressed and a ping command is launched to see if servers are availables:
-If true, the button is set to Hidden.
-If false, a label with a message ("Servers not availables) is set to
visible
How can I reuse the following IsVisible method to set the Label's visibility?
using System;
using System.Diagnostics;
using System.Windows;
using System.Windows.Input;
namespace WpfTest
{
public class PrnViewModel1 : ViewModelBase
{
private ICommand m_PrnServPingCommand;
private Visibility _isVisible=Visibility.Visible;
public PrnViewModel1()
{
PrnServPingCommand = new RelayCommand(new Action<object>(PrnServPing));
}
public ICommand PrnServPingCommand
{
get
{
return m_PrnServPingCommand;
}
set
{
m_PrnServPingCommand = value;
}
}
public void PrnServPing(object obj)
{
string[] serverNames = { "svmsimp1", "svmsimp2" };
bool serversArePingable = Cmethods.PingableAll(serverNames);
if (serversArePingable)
{
IsVisible = Visibility.Hidden; //Button is Hidden
}
else
{
//*** Label with Message "Servers not pingable" set to visible
}
}
public Visibility IsVisible
{
get
{
return _isVisible;
}
set
{
_isVisible = value;
OnPropertyChanged("IsVisible");
}
}
}
}
You can use an IValueConverter to reverse the Visibility on your label.
Here is an example implementation:
public static class Extensions
{
public static System.Windows.Visibility Reversed(this System.Windows.Visibility visibility)
{
if (visibility == System.Windows.Visibility.Visible)
visibility = System.Windows.Visibility.Collapsed;
else if (visibility == System.Windows.Visibility.Collapsed || visibility == System.Windows.Visibility.Hidden)
visibility = System.Windows.Visibility.Visible;
return visibility;
}
}
public class VisibilityReversedConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return ((System.Windows.Visibility)value).Reversed();
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return ((System.Windows.Visibility)value).Reversed();
}
}
Usage:
<TextBlock Text="Servers not available" Visibility="{Binding Visibility, Converter={StaticResource VisibilityReversedConverter}}" ... />
Don't forget to instantiate the converter in the Resources. See here for a tutorial on converters.
I myself often use Visibility type in ViewModel (to avoid writing converters to control layout, because Hidden != Collapsed).
What you need here is either 2 properties to control label and button visibility or single property (bool) to switch which one is displayed and converter (with parameter to invert or just 2 converters).
Here is solution which uses converter and parameter (bonus - MarkupExtension!):
public class SuperConverter : MarkupExtension, IValueConverter
{
public SuperConverter() { }
public override object ProvideValue(IServiceProvider serviceProvider)
{
return this;
}
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is bool)
{
bool inverted = false;
if (parameter != null && parameter.ToString().Contains("Inverted"))
inverted = true;
return (inverted && (bool)value || !inverted && !((bool)value)) ? Visibility.Hidden : Visibility.Visible;
}
throw new InvalidCastException();
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
and use it (you have to have bool IsOperationInProgress in ViewModel, which value will toggle display of either text or button):
<TextBlock Visibility="{Binding IsOperationInProgress, Converter={l:SuperConverter}}" ... />
<Button Visibility="{Binding IsOperationInProgress, Converter={l:SuperConverter}, ConverterParameter=Inverted}" ... />