Wie maxlength für Combobox in WPF setzen?
https://stackoverflow.com/questions/1572887
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Wie kann ich maxlength zu Combobox, die ein Stil angewendet wird, mit.
Danke
Lösung
Wenn DependencyProperty verwenden wir die maxlength des Kombinationsfelds festlegen können ohne Ihre Stil / Vorlage zu ändern.
public class EditableComboBox
{
public static int GetMaxLength(DependencyObject obj)
{
return (int)obj.GetValue(MaxLengthProperty);
}
public static void SetMaxLength(DependencyObject obj, int value)
{
obj.SetValue(MaxLengthProperty, value);
}
// Using a DependencyProperty as the backing store for MaxLength. This enables animation, styling, binding, etc...
public static readonly DependencyProperty MaxLengthProperty = DependencyProperty.RegisterAttached("MaxLength", typeof(int), typeof(EditableComboBox), new UIPropertyMetadata(OnMaxLenghtChanged));
private static void OnMaxLenghtChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
{
var comboBox = obj as ComboBox;
if (comboBox == null) return;
comboBox.Loaded +=
(s, e) =>
{
var textBox = comboBox.FindChild(typeof(TextBox), "PART_EditableTextBox");
if (textBox == null) return;
textBox.SetValue(TextBox.MaxLengthProperty, args.NewValue);
};
}
}
Anwendungsbeispiel:
<ComboBox ComboboxHelper:EditableComboBox.MaxLength="50" />
Wo ComboboxHelper ist:
xmlns: ComboboxHelper = "clr- Namensraum: yourNameSpace , Montage = Yourassembly "
comboBox.FindChild (...) Methode geschrieben wird hier .
Andere Tipps
Sie können auch die maxlength.If die maxlength doest Änderung den GotFocus oder Loaded-Ereignis des ComboBox verwenden zu viel für die Einstellung während der Laufzeit Sie geladenes Ereignis oder sonst Verwendung GotFocus-Ereignis verwenden können,
<ComboBox Height="30" IsEditable="True" Loaded="ComboBox_Loaded"/>
und in der jeweiligen Veranstaltung ...
var obj = (ComboBox)sender;
if (obj != null)
{
var myTextBox = (TextBox)obj.Template.FindName("PART_EditableTextBox",obj);
if (myTextBox != null)
{
myTextBox.MaxLength = maxLength;
}
}
Sie sind richtig. Es gibt eine maxlength für eine Textbox, aber nicht für eine Combobox. Sie haben eine eigene mit einem Textbox als Vermittler rollen. Hier einige Code:
public int MaxLength {get; set;}
protected override void OnGotFocus(System.Windows.RoutedEventArgs e)
{
base.OnGotFocus(e);
TextBox thisTextBox = (TextBox)base.GetTemplateChild("PART_EditableTextBox");
if (thisTextBox != null)
thisTextBox.MaxLength = MaxLength;
}
Diese Textbox kommt null. Der Stil ist wie folgt gegeben.
<ControlTemplate x:Key="ComboBoxToggleButton" TargetType="ToggleButton">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="{Binding Path=(local:ToggleComboBox.Width),
RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ComboBox}}}" />
</Grid.ColumnDefinitions>
<Border x:Name="Border"
Grid.Column="1"
CornerRadius="2"
Background="#CCFFCC"
BorderBrush="#000080"
BorderThickness="4" />
<Border Grid.Column="0"
CornerRadius="8,8,8,8"
Margin="0"
Background="#CCFFCC"
BorderBrush="#000080"
BorderThickness="4,4,4,4" />
<Image x:Name="Arrow"
Grid.Column="1"
Source="Arrow.png" Margin="4,4,4,4"
HorizontalAlignment="Center"
VerticalAlignment="Center"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="ToggleButton.IsMouseOver" Value="true">
<Setter TargetName="Border" Property="Background" Value="{StaticResource DarkBrush}" />
</Trigger>
<Trigger Property="ToggleButton.IsChecked" Value="true">
<Setter TargetName="Border" Property="Background" Value="{StaticResource PressedBrush}" />
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}" />
<Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource DisabledBorderBrush}" />
<Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
<!--<Setter TargetName="Arrow" Property="Fill" Value="{StaticResource DisabledForegroundBrush}" />-->
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
<ControlTemplate x:Key="ComboBoxTextBox" TargetType="TextBox">
<Border x:Name="PART_ContentHost" Focusable="False" Background="{TemplateBinding Background}" />
</ControlTemplate>
<Style x:Key="ComboBoxStyle" TargetType="ComboBox">
<Setter Property="SnapsToDevicePixels" Value="true"/>
<Setter Property="OverridesDefaultStyle" Value="true"/>
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
<Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
<Setter Property="MinWidth" Value="120"/>
<Setter Property="MinHeight" Value="20"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBox">
<Grid>
<ToggleButton Name="ToggleButton"
Template="{StaticResource ComboBoxToggleButton}"
Grid.Column="2"
Focusable="false"
IsChecked="{Binding Path=IsDropDownOpen,
Mode=TwoWay,
RelativeSource={RelativeSource TemplatedParent}}"
ClickMode="Press"/>
<ContentPresenter Name="ContentSite"
IsHitTestVisible="False"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
Margin="9,2,28,2"
VerticalAlignment="Center"
HorizontalAlignment="Left" />
<TextBox x:Name="PART_EditableTextBox"
Style="{x:Null}"
Template="{StaticResource ComboBoxTextBox}"
HorizontalAlignment="Left"
VerticalAlignment="Center"
Margin="3,3,23,3"
Focusable="True"
Background="Transparent"
Visibility="Hidden"
IsReadOnly="{TemplateBinding IsReadOnly}"/>
<Popup Name="Popup"
Placement="Bottom"
IsOpen="{TemplateBinding IsDropDownOpen}"
AllowsTransparency="True"
Focusable="False"
PopupAnimation="Slide">
<Grid Name="DropDown"
SnapsToDevicePixels="True"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder"
Background="#CCFFCC"
BorderBrush="#000080"
BorderThickness="2"/>
<ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True">
<ScrollViewer.Resources>
<sys:Double x:Key="{x:Static SystemParameters.VerticalScrollBarWidthKey}">25</sys:Double>
</ScrollViewer.Resources>
<StackPanel IsItemsHost="True" />
</ScrollViewer>
</Grid>
</Popup>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="HasItems" Value="false">
<Setter TargetName="DropDownBorder" Property="MinHeight" Value="95"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
</Trigger>
<Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="true">
<Setter TargetName="DropDownBorder" Property="CornerRadius" Value="4"/>
<Setter TargetName="DropDownBorder" Property="Margin" Value="0,2,0,0"/>
</Trigger>
<Trigger Property="IsEditable" Value="true">
<Setter Property="IsTabStop" Value="false"/>
<Setter TargetName="PART_EditableTextBox" Property="Visibility" Value="Visible"/>
<Setter TargetName="ContentSite" Property="Visibility" Value="Hidden"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="ItemContainerStyle" >
<Setter.Value>
<Style TargetType="{x:Type ComboBoxItem}">
<Setter Property="FontSize" Value="20" />
</Style>
</Setter.Value>
</Setter>
</Style>
Ich habe PreviewKeyDown Ereignis, sehr einfach + Sie Warnung oder etwas zeigen können.
Registrieren Sie das Verfahren unten an deine ComboBox.PreviewKeyDown + = Ereignis,
KeyDown-Ereignis wird nicht ausgelöst, wenn der Benutzer mit Space.
private void ComboBox_PreviewKeyDown(object sender, KeyEventArgs e)
{
if (ComboBox.Text.Length > 19) // allow max 20 chars
{
if (e.Key != Key.Back) // allow removing chars
{
e.Handled = true; // block any additional key press if there is more than allowed max
System.Media.SystemSounds.Beep.Play(); // optional: beep to let user know he is out of space :)
}
}
}
fand ich einfache Lösung über XAML. In comboBox Ressourcen können wir Stil für Textbox gesetzt und über Setter Set maxlenth.
<ComboBox Name="comboBox" Width="100" IsEditable="True">
<ComboBox.Resources>
<Style TargetType="{x:Type TextBox}">
<Setter Property="MaxLength" Value="yourValue"></Setter>
</Style>
</ComboBox.Resources>
</ComboBox>
EDIT: Das funktioniert mit Actipro ComboBox. Für gewöhnlich comboBox diese Arbeit zu machen, haben Sie einen Blick hier
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