Extracting index from Grid.Row\Column DependencyProperty - wpf

I have the following Button:
<Button Grid.Row="0" Grid.Column="0" Command="{Binding DrawXO}">
<Button.CommandParameter>
<MultiBinding Converter="{StaticResource BoardIndexConverter}">
<Binding RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType={x:Type Button}}" Path="(Grid.Row)"></Binding>
<Binding RelativeSource="{RelativeSource Mode=FindAncestor, AncestorType={x:Type Button}}" Path="(Grid.Column)" ></Binding>
</MultiBinding>
</Button.CommandParameter>
</Button>
and the following MultiValueConverter:
class BoardIndexConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
return values.Clone();
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
How do I get the actual value of the Grid.Row\Column from a DependencyProperty in my command?:
class DrawXOCommand : ICommand
{
public bool CanExecute(object parameter)
{
return true;
}
public void Execute(object parameter)
{
var values = (object[])parameter;
var row = (int)(values[0]);
var column = (int)values[1];
}
public event EventHandler CanExecuteChanged;

You should have seen Binding error messages in the Output Window in Visual Studio, because the Button is not an ancestor element here.
Instead of FindAncestor you should use Self to use the Button as source object:
<MultiBinding Converter="{StaticResource BoardIndexConverter}">
<Binding RelativeSource="{RelativeSource Self}" Path="(Grid.Row)"/>
<Binding RelativeSource="{RelativeSource Self}" Path="(Grid.Column)"/>
</MultiBinding>
Your converter may also be implemented a little safer:
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
if (values.Length == 2 && values[0] is int && values[1] is int)
{
return new Tuple<int, int>((int)values[0], (int)values[1]);
}
return null;
}
Then check the command parameter like this:
public void Execute(object parameter)
{
var cell = parameter as Tuple<int, int>;
if (cell != null)
{
var row = cell.Item1;
var column = cell.Item2;
...
}
}

Related

wpf combobox multibinding could not get combobox items (programmatically added or bind to database) of relative source combobox in first step

I want to disable some items of combobox by specific conditions. For this issue, I used multibinding.
If I described all items of combobox in xaml, there is no problem. But I want to populate combobox items programmatically. So in this case , I could not get items, returns null, and throw me out of the program in the first step.
my xaml codes are like that:
<Window.Resources>
<local:TekerDisabler x:Key="tekerDisabler"/>
</Window.Resources>
<Grid>
<ComboBox x:Name="cbx" HorizontalAlignment="Left" Margin="41,125,0,0" VerticalAlignment="Top" Width="227">
<ComboBox.ItemContainerStyle>
<Style TargetType="ComboBoxItem">
<Setter Property="IsEnabled">
<Setter.Value>
<MultiBinding Converter="{StaticResource tekerDisabler}">
<Binding ElementName="txt1" Path="Text"/>
<Binding ElementName="txt2" Path="Text"/>
<Binding ElementName="txt3" Path="Text"/>
<Binding RelativeSource="{RelativeSource Self}"/>
</MultiBinding>
</Setter.Value>
</Setter>
</Style>
</ComboBox.ItemContainerStyle>
</ComboBox>
<TextBox x:Name="txt1" HorizontalAlignment="Left" Height="23" Margin="41,38,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
<TextBox x:Name="txt2" HorizontalAlignment="Left" Height="23" Margin="207,38,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="211" TextChanged="txt2_TextChanged"/>
<TextBox x:Name="txt3" HorizontalAlignment="Left" Height="24" Margin="478,37,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="196"/>
</Grid>
and my c# codes are like that:
namespace App1.Pencereler
{
public partial class deneme : Window
{
public deneme()
{
InitializeComponent();
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
cbx.Items.Add("0");
cbx.Items.Add("1");
cbx.Items.Add("2");
cbx.Items.Add("3");
}
private void txt2_TextChanged(object sender, TextChangedEventArgs e)
{
cbx.SelectedIndex = 1;
}
}
class TekerDisabler : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
bool enable = true;
var itemler = values[3] as ComboBoxItem;
if (itemler == null || values[0].ToString() == null || values[1].ToString() == null || values[2].ToString() == null)
{ enable = true; }
else
{
switch (values[0].ToString())
{
case "a":
switch (values[1].ToString())
{
case "b":
switch (values[2].ToString())
{
case "c":
switch (itemler.Content.ToString())
{
case "0":
case "2":
enable = false;
break;
default:
enable = true;
break;
}
break;
default:
enable = true;
break;
}
break;
default:
enable = true;
break;
}
break;
default:
enable = true;
break;
}
}
return enable;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
For Example, in the first step, I write txt1:a, txt2:b, txt3:d and so all items' display enabled, and then I write txt1:a, txt2:b, txt3:c and contents of combobox (0,2) disabled, there is no problem. But when running program, in the first step I write txt1:a, txt2:b, txt3:c when drop down combobox, program trow me out.
How to overcome this problem?
Error Message and details are like that:
And Error details are like that:
System.NullReferenceException
HResult=0x80004003
İleti=Nesne başvurusu bir nesnenin örneğine ayarlanmadı.
Kaynak=App1
StackTrace:
konum App1.Pencereler.TekerDisabler.Convert(Object[] values, Type targetType, Object parameter, CultureInfo culture) D:\C Sharp\WPF\App1\App1\Pencereler\deneme.xaml.cs içinde: 60. satır
konum System.Windows.Data.MultiBindingExpression.TransferValue()
konum System.Windows.Data.MultiBindingExpression.Transfer()
konum System.Windows.Data.MultiBindingExpression.UpdateTarget(Boolean includeInnerBindings)
konum System.Windows.Data.MultiBindingExpression.AttachToContext(Boolean lastChance)
konum System.Windows.Data.MultiBindingExpression.AttachOverride(DependencyObject d, DependencyProperty dp)
konum System.Windows.Data.BindingExpressionBase.OnAttach(DependencyObject d, DependencyProperty dp)
It would be interesting to know what exact error you get.
I assume the ComboBoxItem.Content returns null. The item containers are rendered (generated) after the ComboBox is opened. Only the data items exist at this moment. So opening the drop down the first time all item containers are null and about to be rendered.
Anyway, the following simplified version of your code will very likely fix your problem:
TekerDisabler.cs
public class TekerDisabler : IMultiValueConverter
{
#region Implementation of IMultiValueConverter
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
var currentItem = values[0] as string;
var predicate = "abc";
string input = string.Concat(values.Skip(1).Cast<string>());
return !(input.Equals(predicate, StringComparison.Ordinal)
&& (currentItem.Equals("0", StringComparison.Ordinal)
|| currentItem.Equals("2", StringComparison.Ordinal)));
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) =>
throw new NotSupportedException();
#endregion
}
TekerDisabler.cs - Alternative version
public class TekerDisabler : IMultiValueConverter
{
#region Implementation of IMultiValueConverter
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
var currentItem = values[0] as string;
var predicate = "abc";
string input = string.Concat(values.Skip(1).Cast<string>());
return !(values[1].Equals("a", StringComparison.Ordinal)
&& values[2].Equals("b", StringComparison.Ordinal)
&& values[3].Equals("c", StringComparison.Ordinal)
&& (currentItem.Equals("0", StringComparison.Ordinal)
|| currentItem.Equals("2", StringComparison.Ordinal)));
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) =>
throw new NotSupportedException();
#endregion
}
MainWindow.xamlk.cs
partial class MainWIndow : Window
{
public static readonly DependencyProperty ItemsProperty = DependencyProperty.Register(
"Items",
typeof(ObservableCollection<string>),
typeof(MainWindow),
new PropertyMetadata(default(ObservableCollection<string>)));
public ObservableCollection<string> Items
{
get => (ObservableCollection<string>) GetValue(MainWindow.ResultsProperty);
set => SetValue(MainWindow.ResultsProperty, value);
}
}
MainWindow.xaml
<ComboBox ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=main:MainWindow}, Path=Items}">
<ComboBox.ItemContainerStyle>
<Style TargetType="ComboBoxItem">
<Setter Property="IsEnabled">
<Setter.Value>
<MultiBinding Converter="{StaticResource CellForegroundMultiValueConverter}">
<Binding />
<Binding ElementName="TextBox1" Path="Text" />
<Binding ElementName="TextBox2" Path="Text" />
<Binding ElementName="TextBox3" Path="Text" />
</MultiBinding>
</Setter.Value>
</Setter>
</Style>
</ComboBox.ItemContainerStyle>
</ComboBox>
<TextBox x:Name="TextBox1" />
<TextBox x:Name="TextBox2" />
<TextBox x:Name="TextBox3" />
I accomlished to overcome my problem by adding
cbx.IsDropDownOpen = true;
cbx.IsDropDownOpen = false;
after
cbx.Items.Add("0");
cbx.Items.Add("1");
cbx.Items.Add("2");
cbx.Items.Add("3");
in 'Window_Loaded' event.

Prevent uneven Border CornerRadius

I'm trying to make a Pill button, where the CornerRadius is half the height of the button (giving a half-circle on each end of the button. Really, I'd want it to be half the smaller dimension of the button (so tall and skinny ones would work)
As I increase the CornerRadius (for instance if I bound it to the height), it distorts the corner until it's a full ellipse. Is there a way to keep the radius round?
You could use a multibinding and multiconverter.
You might also want to consider a different divisor. Maybe 3.
<Border Background="Blue">
<Border.CornerRadius>
<MultiBinding Converter="{local:MultiDividerConverter Divisor=2}">
<Binding Path="ActualWidth"
RelativeSource="{RelativeSource Self}"
/>
<Binding Path="ActualHeight"
RelativeSource="{RelativeSource Self}"
/>
</MultiBinding>
</Border.CornerRadius>
</Border>
and
public class MultiDividerConverter : MarkupExtension, IMultiValueConverter
{
public double Divisor { get; set; } = 2.0;
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
double minDim = values.Select(x => System.Convert.ToDouble(x ?? 0.0)).Min();
if (minDim == 0)
return new CornerRadius(0);
return new CornerRadius(minDim / Divisor);
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
return null;
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
return this;
}
}

FallBackValue in IMultiValueConverter is UnsetValue

I am trying to use a single IMultiValueConverter for more than one controls in XAML.
I am using a simple string Literal to tell what value the IMultiValueConverter is supposed to return.
But I am getting DependencyProperty.UnsetValue in values[2],ie value of parametter named Command when it comes to convert function of ModifierCategoryEnableDisable.
Similar arrangment is working on similar controls on this XAML form within other IMultiValueConverters but not here.
Please guide what am i missing?
NOTE:
CurrentRec is the currently selected object from the ViewModel
DM_CategoryData is a Class and Current_Selected_Category is a List<DM_CategoryData> in the ViewModel's current object,ie CurrenRec.
XAML:
<GroupBox Width="226" Height="117" Margin="0" Canvas.Top="252" Header="Modifiers" Canvas.Left="55" >
<GroupBox.IsEnabled>
<MultiBinding Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" Converter="{StaticResource MDNS}">
<Binding Path="SearchFound" />
<Binding Path="CurrentRec.Current_Selected_Category"/>
<Binding Path="Command" FallbackValue="1" />
</MultiBinding>
</GroupBox.IsEnabled>
</GroupBox>
C#:
public class ModifierCategoryEnableDisable : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
string Command = values[2].ToString();
bool Retval1 = false;
string Retval2 = "";
switch(Command)
{
case "1":
bool SearchFound = (bool)values[0];
DM_CategoryData CurrentSelectedItemCategory = (DM_CategoryData)(values[1]);
Retval1 = SearchFound && (CurrentSelectedItemCategory == null ? true : CurrentSelectedItemCategory.IsModifier.Equals("1") ? false : true);
break;
case "2":
Retval2 = "0";
break;
}
if(Command.Equals("1"))
{
return Retval1;
}
else
{
return Retval2;
}
}
}
In order to provide additional static data to a multibinding converter, use a ConverterParameter:
<MultiBinding Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" Converter="{StaticResource MDNS}" ConverterParameter="1">
<Binding Path="SearchFound" />
<Binding Path="CurrentRec.Current_Selected_Category"/>
</MultiBinding>
And check the parameter in the Convert method:
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
string Command = parameter as string;
// ...
}
You are trying to set the fallbackvalue for GroupBox.IsEnabled property and it is a bool type. But you are setting the value as 1. So only Values[2] returns the UnsetValue. Try to set bool value as Fallbackvalue.

Can WPF Databinding source include a parameter?

Can I pass an index number into this list (SomeList)?
FontSize="{Binding FontSize, Source={x:Static ut:ViewSetupData.SomeList}, FallbackValue=12}"
You can put a constant indexer in the Path:
{Binding Path=[(sys:Int32)0], Source={x:Static ut:ViewSetupData.SomeList}}
But you can't bind a property of a Binding, so there's no way to stuff a parameter in there. However, you can combine multiple bindings in a MultiBinding, so you could use one of those with a multi-value converter:
C#:
public class IListIndexerConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
// You might want a little more error-checking than this...
return ((IList)values[0])[(int)values[1]];
}
public virtual object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
return null;
}
}
XAML:
<TextBlock>
<TextBlock.Resources>
<local:IListIndexerConverter x:Key="ListIndexer" />
</TextBlock.Resources>
<TextBlock.Text>
<MultiBinding Converter="{StaticResource ListIndexer}">
<Binding Source="{x:Static ut:ViewSetupData.SomeList}" />
<Binding
ElementName="MyComboBox"
Path="SelectedIndex"
/>
</MultiBinding>
</TextBlock.Test>
</TextBlock>
Update
While you were marking this as the solution, I was writing a more complete solution that addressed your need to grab a property from the list item:
C#:
public class ListItemPropertyGetter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
try
{
var list = values[0] as IList;
var index = (int)(values[1] ?? 0);
var propname = values[2] as String;
object item = list[index];
var prop = item.GetType().GetProperty(propname);
var propvalue = prop.GetValue(item);
return propvalue;
}
catch
{
return null;
}
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
// Gotta put these somewhere
public static List<FontSizeThing> FontSizeThings { get; } =
new List<FontSizeThing>
{
new FontSizeThing(10),
new FontSizeThing(10.5),
new FontSizeThing(11),
new FontSizeThing(12),
new FontSizeThing(14),
new FontSizeThing(15),
};
}
public class FontSizeThing {
public FontSizeThing(double n) { FontSize = n; }
public double FontSize { get; set; }
}
XAML:
<ComboBox x:Name="FontSizeOptionCombo">
<sys:Int32>0</sys:Int32>
<sys:Int32>1</sys:Int32>
<sys:Int32>2</sys:Int32>
<sys:Int32>3</sys:Int32>
<sys:Int32>4</sys:Int32>
</ComboBox>
<TextBlock Text="Testing">
<TextBlock.Resources>
<hconv:ListItemPropertyGetter x:Key="ListItemPropertyGetter" />
</TextBlock.Resources>
<TextBlock.FontSize>
<MultiBinding Converter="{StaticResource ListItemPropertyGetter}" StringFormat="{}{0}">
<Binding Source="{x:Static hconv:ListItemPropertyGetter.FontSizeThings}" />
<Binding ElementName="FontSizeOptionCombo" Path="SelectedItem" />
<Binding Source="FontSize" />
</MultiBinding>
</TextBlock.FontSize>
</TextBlock>
FINAL UPDATE
Note that if I had merely populated FontSizeOptionCombo with the FontThings themselves, I could very simply have bound like this:
<ComboBox
x:Name="OtherCombo"
ItemsSource="{x:Static hconv:ListItemPropertyGetter.FontSizeThings}"
DisplayMemberPath="FontSize"
FontSize="{Binding SelectedItem.FontSize, ElementName=OtherCombo, FallbackValue=20}"
/>
If that fits in with what you're doing, it's by far the nicest way.

Set selected item or selected index for listbox contains binded items source WPF

I'm newbie on WPF. I didn't success to set selected index\selected value to list box of images items.
My current code is:
On xaml:
<ListBox Name="symbolSrc" Grid.Row="1" Width="485" Height="100" HorizontalAlignment="Left" Margin="7,-35,0,0" ItemTemplate="{StaticResource cmbTemplate}" IsSynchronizedWithCurrentItem="True" SelectedValuePath="photo">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="Padding" Value="6 0 0 0" />
</Style>
</ListBox.ItemContainerStyle>
<ListBox.ItemsSource>
<MultiBinding Converter="{StaticResource SymbolComboboxItemsFilter}">
<Binding ElementName ="RadioButLR" Path="IsChecked" Mode="OneWay"/>
<Binding ElementName ="RadioButHR" Path="IsChecked" Mode="OneWay"/>
</MultiBinding>
</ListBox.ItemsSource>
<ListBox.SelectedValue>
<MultiBinding Converter="{StaticResource SymbolComboboxSelectedItem}">
<Binding ElementName ="RadioButLR" Path="IsChecked" Mode="OneWay"/>
<Binding ElementName ="RadioButHR" Path="IsChecked" Mode="OneWay"/>
</MultiBinding>
</ListBox.SelectedValue>
</ListBox>
On xaml.cs:
public class SymbolComboboxItemsFilterConverter: IMultiValueConverter
{
public class symbolCmbBoxItem
{
public string photo { get; set; }
public string photoName { get; set; }
}
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
List<symbolCmbBoxItem> itemsList = new List<symbolCmbBoxItem>();
string targetDir = System.Windows.Forms.Application.ExecutablePath + "\\..\\..\\..\\INIT\\IC";
string[] filesArray = Directory.GetFiles(targetDir, "*", SearchOption.TopDirectoryOnly);
if ((bool)values[0])
{
foreach (string file in filesArray.Where(s => s.Contains("_LR")))
{
itemsList.Add(new symbolCmbBoxItem { photo = file, photoName = "" });
}
}
else
{
foreach (string file in filesArray.Where(s => s.Contains("_HR")))
{
itemsList.Add(new symbolCmbBoxItem { photo = file, photoName = "" });
}
}
return itemsList;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
public class SymbolComboboxItemsSelectedIndex : IMultiValueConverter
{
public class symbolCmbBoxItem
{
public string photo { get; set; }
public string photoName { get; set; }
}
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
List<symbolCmbBoxItem> itemsList = new List<symbolCmbBoxItem>();
string targetDir = System.Windows.Forms.Application.ExecutablePath + "\\..\\..\\..\\INIT\\IC";
string[] filesArray = Directory.GetFiles(targetDir, "*", SearchOption.TopDirectoryOnly);
if ((bool)values[0])
{
string item = filesArray.Where(s => s.Contains("_LR")).First();
return new symbolCmbBoxItem { photo = item, photoName = "" };
}
else
{
string item = filesArray.Where(s => s.Contains("_HR")).First();
return new symbolCmbBoxItem { photo = item, photoName = "" };
}
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
I also tried set the selected item by using:
SelectedItem="1"
And it didn't work.
Also tried to using the same multi converter at above and set always the selected item to "1" and it also didn't work.
(In order to set listbox of images I used by below reference:
http://www.codescratcher.com/wpf/wpf-combobox-with-image/ )
Any ideas please?
Your help is very appreciated!

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