I need to set the property of cotrol which is a dependent of another property of its parent.
I try to explain better my problem with an example. I want to create a toggle switch button that animates a "slider" element into it. The dimensions of the toggle switch is being defined when the usercontrol is inserted into the application window. I want the slider be sized half larger than the switch case. So if the control is large 100, the slider should be 50, or if large 250, the slider should be 125. Then I need a sort of call to a function or something similar:
<UserControl>
<Border Name="switchCase" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
<Border Name="slider" Width="**Container.Width/2**" ></Border>
</Border>
</UserControl>
Is there any possibilities to achieve this ??
Thanks in advance
Paolo
Yes you need databinding with a converter, such as the following example
xmlns:conv="clr-namespace:MyConverters.Converters"
.......
<UserControl.Resources>
<conv:WidthConvertercs x:Key="widthConv"></conv:WidthConvertercs>
</UserControl.Resources>
<Border Name="switchCase" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" >
<Border Name="slider" Width="{Binding ElementName=switchCase, Path=ActualWidth, Converter={StaticResource widthConv}}" Background="DarkMagenta"></Border>
</Border>
Your converter class would be
[ValueConversion(typeof(double), typeof(double))]
class WidthConvertercs : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
double withPar = (double)value;
return withPar/2.0;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
I hope this helps
Out of the box it's not supported by XAML. You can only bind to Properties.
You can write a converter which do the calculation (or you can use
MathConverter)
You can do the calculation in the code behind in event
handlers
If you are following the MVVM pattern you can do the
calculation in the ViewModel (altough it will introduce view
related concepts to the ViewModels which is not always good...)
You can write your own Binding extension
Related
I have a list of objects that I'm binding to the screen. One of the properties is isPurchased. It is a Boolean type.
I don't have a lot of experience with converters so I'm finding this a little difficult. I have 2 questions.
The 1st question is regarding syntax. I copied this example from here.
public class purchasedConverter : IValueConverter
{
public object Convert(inAppPurchases value, Type targetType, object parameter, string language)
{
return;
}
}
If the isPurchased == true then I'd like to set the background color to my stackpanel to a different color.
I changed object value to inAppPurchases value on the Convert method. However, no matter what I tried I could not get a reference to a Background.
I think I want to return Background="somecolor"
My 2nd question (assuming I can do the 1st part), is I'm using StandardStyles.xaml which comes with the Microsoft WinRT projects So my converter would exist there.
<StackPanel Grid.Column="1" VerticalAlignment="Top"
Background="CornflowerBlue" Orientation="Vertical" Height="130"
Margin="0,0,5,0"/>
However, like I said I've tried this before but I wasn't able to figure out how to add the convert to my .xaml file. Where would I reference the converter? Is it on the StandardStyls.xaml or the main .xaml that I'm viewing?
Any help is appreciated.
Background property of StackPanel is type of Brush (Panel.Background msdn) , so we can return object of type SolidColorBrush from Convert method.
Your converter should look like this:
class PurchasedConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
// isPurchased is bool so we can cast it to bool
if ((bool)value == true)
return new SolidColorBrush(Colors.Red);
else
return new SolidColorBrush(Colors.Orange);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
Next you must create instance of this converter in XAML:
<Window.Resources>
<con:PurchasedConverter x:Key="pCon" />
</Window.Resources>
And now you can use this converter to binding Background property in StackPanel:
<StackPanel VerticalAlignment="Top" Orientation="Vertical" Height="130"
Background="{Binding isPurchased, Converter={StaticResource pCon}}"
Margin="0,0,5,0" >
</StackPanel>
I'm trying to create a rectangle in Silverlight where the corners are rounded. However, I do not explicitly specify the width and the height of the rectangle, which means it adapts to the size of the Grid which contains it (the size of the grid depends on the screen resolution amongst other things, and is not known before hand).
I'd like the RadiusX and RadiusY properties to be percentages of the rectangle's width and height respectively. What would be the cleanest way of doing this? Is there a XAML-only way of doing it (without resorting to code-behind)?
Two files below to download I used for testing this http://dl.dropbox.com/u/8679840/SilverlightApplication1.zip
Best way for reuse is to create a Type converter like
<Grid x:Name="LayoutRoot" Background="White">
<Rectangle x:Name="rectangle"
Width="200" Height="200"
RadiusX="{Binding Width, ElementName=rectangle, Converter={StaticResource myConverter}, ConverterParameter=.1}"
RadiusY="{Binding Height, ElementName=rectangle, Converter={StaticResource myConverter}, ConverterParameter=.1}"
/>
</Grid>
and the code behind
namespace SilverlightApplication1
{
public class PercentConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return System.Convert.ToDouble(value) * System.Convert.ToDouble(parameter);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
While Justin King's answer works if the Width and Height are known before hand, it doesn't work if they're not set, and the parent control dynamically lays the rectangle out. Unfortunately, in Silverlight, you cannot use Binding with Converters on ActualWidth and ActualHeight, as they are calculated properties. What this means is that when ActualWidth and ActualHeight change, a property changed event is not raised internally, so the binding wouldn't propagate the changes to the source.
Essentially, at this point, the only option is to subscribe to the LayoutUpdated event and calculate and set the RadiusX and RadiusY properties in code-behind.
Is it better to build 2 different pages? Such that when a button is clicked, it leads to another page with the table? Or can we hide the table until the "expand" button is clicked? Is it better to present the table as a listbox? Thanks.
I think a converter is the way to go, like TerrenceJackson said!
In the DataGrid your Binding should look like this:
<CheckBox Content="Expand" Height="72" Name=MyExpandCheckbox IsChecked="False" />
<DataGrid Visibility="{Binding ElementName=MyExpandCheckbox, Path=IsChecked, Converter={StaticResource BoolToVisibleConverter}}"/>
You have to set the Name of your Button/Checkbox/... for the ElementName in the binding for the visibility-property.
Here is an example of a BoolToVisibilityConverter:
public class BoolToVisibilityConverter : IValueConverter
{
#region IValueConverter member
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return (Boolean)value ? Visibility.Visible : Visibility.Collapsed;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
#endregion
}
i would'nt do it with two seperate pages.
You can use a simple expander and style it for your purpose. Here's a video how to use the expander: http://silverlight.net/learn/videos/all/silverlight-toolkit-creating-a-toolkit-expander/ and here's a simple tutorial http://www.c-sharpcorner.com/Resources/768/.
You could also use a simple toggle button and bind the visibility of the table (DataGrid or ListBox, whatever you want) with a converter to the checked state of the toggle button. Somehow like this:
<ToggleButton x:Name="myToggleButton" />
<DataGrid Visibility="{Binding ElementName, Path=IsChecked, Converter={StaticResource BoolToVisibleConverter}}"/>
The BoolToVisibleConverter is a class which implements IValueConverter (http://msdn.microsoft.com/en-us/library/system.windows.data.ivalueconverter.aspx).
I don't know your exact aim, but I guess the expander approach is good for you.
Hope this helps.
BR,
TJ
I need to develop a Label control in WPF, on .NET 3.5 and VisualStudio 2010, in which the FontSize will automatically make the text fill the control area.
I don't know if I should create a CustomControl inheriting from Label or if I should create a UserControl which contains a Label control.
I've seen an example here using a ValueConverter, but I'm not understanding its behavior, here: change font size dynamically.
Can anyone give me a clue about that?
Update:
I found the solutiion using the DoubleConverter from the example I've posted before:
The soultion is using a ValueConverter, which I extracted from the example, but added the NumerFormat IFormatProvider to correctly parse "0.1" value, I found that at Decimal d1 = Decimal.Parse("0.1"); // = 1?!?:
[ValueConversion(typeof(object), typeof(double))]
public class DoubleConverter : IValueConverter
{
public object Convert(object value, Type targetType,
object parameter, CultureInfo culture)
{
double dblValue = (double)value;
double scale = Double.Parse(((string)parameter), System.Globalization.CultureInfo.InvariantCulture.NumberFormat);
return dblValue * scale;
}
public object ConvertBack(object value, Type targetType,
object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Then, you have to instantiate in XAML the DoubleConverter, and specify the binding in the FonSize Property:
<UserControl x:Class="<Namespace>.LabelAutoFontSize"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:me="clr-namespace:<Namespace>"
mc:Ignorable="d"
d:DesignHeight="60" d:DesignWidth="278">
<UserControl.Resources>
<me:DoubleConverter x:Key="doubleConverter" />
</UserControl.Resources>
<Grid>
<Label
x:Name="lbl"
FontSize="{
Binding Path=Width,
RelativeSource={RelativeSource AncestorType={x:Type UserControl}},
Converter={StaticResource doubleConverter},
ConverterParameter=0.116}"
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch"
Content="LabelAutoFontSize"
d:LayoutOverrides="Width"
HorizontalContentAlignment="Center"
VerticalContentAlignment="Center" />
</Grid>
</UserControl>
An important point is that the value for ConverterParameter depends absolutely from the font assigned. Each font may need a different value and you have to "play around" to get the correct value to fit exactly.
<Viewbox>
<TextBlock>asd</TextBlock>
</Viewbox>
Also does the job.
i got some xaml here and what i m trying to do it's simply bind a property call Property (not the real name) on the width of a rectangle and to convert the value of this property with the converter name Conv and it's working perfectly with {TemplateBinding Property} or DataContext={TemplateBinding Property} or with a relative source (like in the code sample).
My problem is that the converterParameter should also be a binding property, but i m not able to bind any property in the converterParameter. So the 30 in the sample should be something like {Binding Path=SecondProperty}. If anyone got that problem or maybe if anyone got some other way to bind stuff in custom control thanks a lot ;)
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:controls="clr-namespace:RatingControl">
<Style TargetType="controls:Ctr">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="controls:Ctr">
<Grid>
<Grid.Resources>
<controls:Converter x:Name="Conv" />
</Grid.Resources>
<Rectangle x:Name="rect" Width="{Binding Path=Property, RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource Conv}, ConverterParameter=30}" Height="20" />
It doesn't look like that's possible: http://msdn.microsoft.com/en-us/library/system.windows.data.binding.converterparameter(VS.95).aspx
You can add a property to the Converter class and bind to that.
You can't bind to a property of the Binding object, since it isn't a DependencyProperty in fact Binding isn't a DependencyObject. This is understandable can you imagine the complexity of managing dependency trees and the possiblity of recursive or circular bindings in bindings.
However you could use a Specialised converter for the task:-
public class MySpecialConverter: IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
Ctr obj = (Ctr)value;
var val = obj.Property;
var param = obj.SecondProperty;
// Do your intended code with val and param here.
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException("This converter only works for one way binding");
}
}
now your Xaml looks like:-
<Rectangle x:Name="rect" Height="20"
Width="{Binding RelativeSource={RelativeSource TemplatedParent}, Converter={StaticResource Conv}" />
It's a really good solution but it's not working bcs my first property must be bind (twoWay) because if i got any change on it the converter must convert again the value so i get the result back and show the real result.