[英]WPF UserControl ComboBox set SelectedValue and raise ChangeEvent
I'm relatively new to WPF and so there are some Problems. 我对WPF比较陌生,因此存在一些问题。
I need UserControls and I have a trouble with one which contains a ComboBox. 我需要UserControls,但其中一个包含ComboBox的应用程序出现了问题。 I need to set the Value within Initialisation, but it doesn't work.
我需要在初始化中设置值,但是它不起作用。 And I need the ChangedEvent routed to the MainWindow.
而且我需要将ChangedEvent路由到MainWindow。
My UserControl-XAML: 我的UserControl-XAML:
<UserControl x:Class="xyz.FileLineDropBox"
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"
Name="UC">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30" />
<ColumnDefinition Width="110" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="30" />
</Grid.ColumnDefinitions>
<Label Grid.Column="1" VerticalAlignment="Center" Content="{Binding ElementName=UC, Path=Description}" />
<ComboBox Grid.Column="2" VerticalAlignment="Center" HorizontalAlignment="Left" Width="40" SelectionChanged="valueChangedEventHandler" SelectedItem="Value">
<!-- simple Alternative to Spin / NumericUpDown -->
<ComboBoxItem Content="1" />
<ComboBoxItem Content="2" />
<ComboBoxItem IsSelected="True" Content="3" />
<ComboBoxItem Content="4" />
</ComboBox>
</Grid>
My UserControl-Behind-Code: 我的UserControl背后代码:
namespace xyz{
public partial class FileLineDropBox : UserControl {
...
//Description///////////////////////////////////////////////////////////
public string Description{
get { return (string)GetValue(DescriptionProperty); }
set { SetValue(DescriptionProperty, value); }
}
public static readonly DependencyProperty DescriptionProperty = DependencyProperty.Register("Description", typeof(string), typeof(FileLineDropBox), new UIPropertyMetadata(""));
//Value/////////////////////////////////////////////////////////////////
public string Value{
get { return (string)GetValue(ValueProperty); }
set { SetValue(ValueProperty, value); }
}
public static readonly DependencyProperty ValueProperty = DependencyProperty.Register("Value", typeof(string), typeof(FileLineDropBox), new UIPropertyMetadata(""));
////////////////////////////////////////////////////////////////////////
// Eventhandler (Text / Selection changed)
private void valueChangedEventHandler(object sender, SelectionChangedEventArgs e){
SelectionChangedEventArgs args = new SelectionChangedEventArgs(ValueChangedEvent, e.RemovedItems, e.AddedItems);
RaiseEvent(args);
}
////////////////////////////////////////////////////////////////////////
// Routing the EventHandler up to the MainWindow
public static readonly RoutedEvent ValueChangedEvent = EventManager.RegisterRoutedEvent("ValueChangedEvent", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(FileLineDropBox));
public event SelectionChangedEventHandler ValueChanged{
add { AddHandler(ValueChangedEvent, value); }
remove { RemoveHandler(ValueChangedEvent, value); }
}
}
In MainWindow-Behind-Code I want to set the Value, but it is not linked to the wanted Value (Selection). 在MainWindow-Behind-Code中,我想设置值,但未链接到所需的值(选择)。 And the Adding of the EventHandler causes an Error while Executing:
并且在执行过程中添加EventHandler会导致错误:
public partial class MainWindow : Window {
FileLineDropBox myLineDropBox;
public MainWindow() {
...
Init3_CodedComponents();
myLineDropBox.Value = "4";
}
private void Init3_CodedComponents(){
AddHandler(FileLineDropBox.ValueChangedEvent, new SelectionChangedEventHandler(FileLineComboBox_CntChangedEvent)); // Abo of EventHandler from FileLine
...
myLineDropBox = new FileLineDropBox();
myLineDropBox.Description = "blub";
myGrids[1].Children.Add(myLineDropBox);
myGrids[1].RowDefinitions.Add(new RowDefinition());
Grid.SetRow(myLineDropBox, linePos);
...
}
...
private void FileLineComboBox_CntChangedEvent(object sender, SelectionChangedEventArgs e){
if(!isInitialized)return;
ComboBox myCb = sender as ComboBox;
int maxId;
string sMaxId = (e.AddedItems[0] as ComboBoxItem).Content as string;
int.TryParse(sMaxId, out maxId);
...
}
}
Edit, Solution for first Problem is following: 编辑,第一个问题的解决方案如下:
changed in XAML: XAML中的更改:
<ComboBox Grid.Column="2" ... Name="FileLineCB" ... /> <ComboBox Grid.Column =“ 2” ... Name =“ FileLineCB” ... />
removed Value-Binding-Code from Behind Code 从隐藏代码中删除了Value-Binding-Code
added in Behind-Code: 在背后代码中添加:
public void CB_Add_Item(string NewItem) { this.FileLineCB.Items.Add(NewItem); } public void CB_Select_Item(string SelectThis) { this.FileLineCB.SelectedItem = SelectThis; }
Problems solved, but maybe not the best Way. 问题解决了,但也许不是最好的方法。 If one has a better or more recommended Way, pls add this here.
如果有更好或更推荐的方式,请在此处添加。
Here is my Solution: XAML 这是我的解决方案:XAML
<UserControl x:Class="xyz.FileLineDropBox"
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"
Name="UC">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30" />
<ColumnDefinition Width="110" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="30" />
</Grid.ColumnDefinitions>
<Label Grid.Column="1" VerticalAlignment="Center" Content="{Binding ElementName=UC, Path=Description}" />
<ComboBox Grid.Column="2" VerticalAlignment="Center" HorizontalAlignment="Left" Width="40" Name="FileLineCB" SelectedItem="{Binding ElementName=UC, Path=Value}" SelectionChanged="valueChangedEventHandler" />
</Grid>
Behind-Code: 幕后代码:
namespace xyz {
public partial class FileLineDropBox : UserControl {
...
//Changing ComboBox/////////////////////////////////////////////////////
public void CB_Add_Item(string NewItem) {
this.FileLineCB.Items.Add(NewItem);
}
public void CB_Select_Item(string SelectThis) {
this.FileLineCB.SelectedItem = SelectThis;
}
//Value/////////////////////////////////////////////////////////////////
public string Value{
get { return (string)GetValue(ValueProperty); }
set { SetValue(ValueProperty, value); }
}
public static readonly DependencyProperty ValueProperty = DependencyProperty.Register("Value", typeof(string), typeof(FileLineDropBox), new UIPropertyMetadata(""));
////////////////////////////////////////////////////////////////////////
// Eventhandler (Text / Selection changed)
private void valueChangedEventHandler(object sender, RoutedEventArgs e){
RaiseEvent(new RoutedEventArgs(FileLineDropBox.ValueChangedEvent));
}
////////////////////////////////////////////////////////////////////////
// Routing the EventHandler up to the MainWindow
public static readonly RoutedEvent ValueChangedEvent = EventManager.RegisterRoutedEvent("ValueChangedEvent", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(FileLineDropBox));
public event RoutedEventHandler ValueChanged{
add { AddHandler(ValueChangedEvent, value); }
remove { RemoveHandler(ValueChangedEvent, value); }
}
}
} }
MainWindow: 主窗口:
//init
private void Init3_CodedComponents(){
myLineDropBox.CB_Add_Item("1");
myLineDropBox.CB_Add_Item("2");
...
myLineDropBox.CB_Select_Item("4");
...
AddHandler(FileLineDropBox.ValueChangedEvent, new RoutedEventHandler(FileLineComboBox_CntChangedEvent));
}
// EventHandler
private void FileLineComboBox_CntChangedEvent(object sender, RoutedEventArgs e){
...
int.TryParse(myLineDropBox.Value, out maxId);
...
}
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