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https://github.com/Stone-Red-Code/docs-desktop.git
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Content update - How to add an event handler using code (user story 1878475) (#1287)
* Add article, redirects, toc * Add alternative event handler assignments (commented) * Update dotnet-desktop-guide/net/wpf/events/how-to-add-an-event-handler-using-code.md Co-authored-by: Andy (Steve) De George <[email protected]> * Update dotnet-desktop-guide/net/wpf/events/how-to-add-an-event-handler-using-code.md Co-authored-by: Andy (Steve) De George <[email protected]> * Further edits Co-authored-by: Andy (Steve) De George <[email protected]>
This commit is contained in:
Tris Shores
co-authored by
Andy De George
Andy De George
parent
a5e3c44dcb
commit
8e9afae7f6
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---
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title: "How to add an event handler using code"
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description: Learn how to add an event handler in code-behind for an element in Windows Presentation Foundation (WPF).
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ms.date: "02/01/2021"
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dev_langs:
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- "csharp"
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- "vb"
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helpviewer_keywords:
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- "event handlers [WPF], adding"
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- "XAML [WPF], adding event handlers"
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---
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<!-- The acrolinx score was 99 on 02/01/2021-->
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# How to add an event handler using code (WPF .NET)
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You can assign an event handler to an element in Windows Presentation Foundation (WPF) using markup or code-behind. Although it's customary to assign an event handler in Extensible Application Markup Language (XAML), sometimes you might have to assign an event handler in code-behind. For instance, use code when:
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- You assign an event handler to an element after the markup page that contains the element loads.
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- You add an element and assign its event handler after the markup page that will contain the element loads.
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- You define the element tree for your application entirely in code.
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[!INCLUDE [desktop guide under construction](../../includes/desktop-guide-preview-note.md)]
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## Syntax for event handler assignment
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C# supports event handler assignment using:
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- The `+=` operator, which is also used in the common language runtime (CLR) event handling model.
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- The <xref:System.Windows.UIElement.AddHandler%2A?displayProperty=nameWithType> method.
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VB supports event handler assignment using:
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- The [AddHandler](/dotnet/visual-basic/language-reference/statements/addhandler-statement) statement with the [AddressOf](/dotnet/visual-basic/language-reference/operators/addressof-operator) operator, which is also used in the CLR event handling model.
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- The [Handles](/dotnet/visual-basic/language-reference/statements/handles-clause) keyword in the event handler definition. For more information, see [Visual Basic and WPF event handling](/dotnet/desktop/wpf/advanced/visual-basic-and-wpf-event-handling?view=netframeworkdesktop-4.8&preserve-view=true).
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- The <xref:System.Windows.UIElement.AddHandler%2A?displayProperty=nameWithType> method, together with the `AddressOf` operator to reference the event handler.
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## Example
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The following example uses XAML to define a <xref:System.Windows.Controls.Button> named `ButtonCreatedByXaml` and to assign the `ButtonCreatedByXaml_Click` method as its <xref:System.Windows.Controls.Primitives.ButtonBase.Click> event handler. `Click` is a built-in routed event for buttons that derive from <xref:System.Windows.Controls.Primitives.ButtonBase>.
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:::code language="xaml" source="./snippets/how-to-add-an-event-handler-using-code/csharp/MainWindow.xaml" id="ButtonCreatedByXaml":::
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The example uses code-behind to implement the `ButtonCreatedByXaml_Click` and `ButtonCreatedByCode_Click` handlers, and to assign the `ButtonCreatedByCode_Click` handler to the `ButtonCreatedByCode` and `StackPanel1` elements. Event handler methods can only be implemented in code-behind.
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:::code language="csharp" source="./snippets/how-to-add-an-event-handler-using-code/csharp/MainWindow.xaml.cs" id="ButtonEventHandlers":::
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:::code language="vb" source="./snippets/how-to-add-an-event-handler-using-code/vb/MainWindow.xaml.vb" id="ButtonEventHandlers":::
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When `ButtonCreatedByXaml` is clicked and its event handler runs, `ButtonCreatedByXaml_Click` programmatically:
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1. Adds a new button named `ButtonCreatedByCode` to the already constructed XAML element tree.
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1. Specifies properties for the new button, such as the name, content, and background color.
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1. Assigns the `ButtonCreatedByCode_Click` event handler to `ButtonCreatedByCode`.
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1. Assigns the same `ButtonCreatedByCode_Click` event handler to `StackPanel1`.
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When `ButtonCreatedByCode` is clicked:
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1. The <xref:System.Windows.Controls.Primitives.ButtonBase.Click> routed event is raised on `ButtonCreatedByCode`.
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1. The `ButtonCreatedByCode_Click` event handler assigned to `ButtonCreatedByCode` is triggered.
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1. The `Click` routed event traverses up the element tree to `StackPanel1`.
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1. The `ButtonCreatedByCode_Click` event handler assigned to `StackPanel1` is triggered.
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1. The `Click` routed event continues up the element tree potentially triggering other `Click` event handlers assigned to other traversed elements.
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The `ButtonCreatedByCode_Click` event handler obtains the following information about the event that triggered it:
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- The [sender](xref:System.Windows.RoutedEventHandler) object, which is the element that the event handler is assigned to. The `sender` will be `ButtonCreatedByCode` the first time the handler runs, and `StackPanel1` the second time.
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- The <xref:System.Windows.RoutedEventArgs.Source?displayProperty=nameWithType> object, which is the element that originally raised the event. In this example, the `Source` is always `ButtonCreatedByCode`.
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> [!NOTE]
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> A key difference between a routed event and a CLR event is that a routed event traverses the element tree, whereas a CLR event occurs only on the `sender`. As a result, a routed event `sender` can be any traversed element in the element tree.
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For more information on how to create and handle routed events, see [How to create a custom routed event](/dotnet/desktop/wpf/advanced/how-to-create-a-custom-routed-event?view=netframeworkdesktop-4.8&preserve-view=true) and [Handle a routed event](/dotnet/desktop/wpf/advanced/how-to-handle-a-routed-event?view=netframeworkdesktop-4.8&preserve-view=true).
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## See also
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- [Routed events overview](/dotnet/desktop/wpf/advanced/routed-events-overview?view=netframeworkdesktop-4.8&preserve-view=true)
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- [XAML in WPF](/dotnet/desktop/wpf/advanced/xaml-in-wpf?view=netframeworkdesktop-4.8&preserve-view=true)
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+17
@@ -0,0 +1,17 @@
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using System;
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using System.Collections.Generic;
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using System.Configuration;
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using System.Data;
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using System.Linq;
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using System.Threading.Tasks;
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using System.Windows;
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namespace CodeSampleCsharp
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{
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/// <summary>
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/// Interaction logic for App.xaml
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/// </summary>
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public partial class App : Application
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{
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}
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}
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+10
@@ -0,0 +1,10 @@
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using System.Windows;
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[assembly: ThemeInfo(
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ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
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//(used if a resource is not found in the page,
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// or application resource dictionaries)
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ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
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//(used if a resource is not found in the page,
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||||
// app, or any theme specific resource dictionaries)
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)]
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+25
@@ -0,0 +1,25 @@
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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>WinExe</OutputType>
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<TargetFramework>net6.0-windows</TargetFramework>
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<UseWPF>true</UseWPF>
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<NeutralLanguage>en-us</NeutralLanguage>
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</PropertyGroup>
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|
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<ItemGroup>
|
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<Compile Update="Properties\Resources.Designer.cs">
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<DesignTime>True</DesignTime>
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<AutoGen>True</AutoGen>
|
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<DependentUpon>Resources.resx</DependentUpon>
|
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</Compile>
|
||||
</ItemGroup>
|
||||
|
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<ItemGroup>
|
||||
<EmbeddedResource Update="Properties\Resources.resx">
|
||||
<Generator>ResXFileCodeGenerator</Generator>
|
||||
<LastGenOutput>Resources.Designer.cs</LastGenOutput>
|
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</EmbeddedResource>
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</ItemGroup>
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||||
|
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</Project>
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+16
@@ -0,0 +1,16 @@
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<Window x:Class="CodeSampleCsharp.MainWindow"
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xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
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xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
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Title="How to add an event handler using code" Height="100" Width="300">
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<!--<ButtonCreatedByXaml>-->
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<StackPanel Name="StackPanel1">
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<Button
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Name="ButtonCreatedByXaml"
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Click="ButtonCreatedByXaml_Click"
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Content="Create a new button with an event handler"
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Background="LightGray">
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</Button>
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</StackPanel>
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<!--</ButtonCreatedByXaml>-->
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</Window>
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+61
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Controls.Primitives;
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using System.Windows.Media;
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namespace CodeSampleCsharp
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{
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/// <summary>
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/// Interaction logic for MainWindow.xaml.
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/// </summary>
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public partial class MainWindow : Window
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{
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public MainWindow()
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{
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InitializeComponent();
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}
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//<ButtonEventHandlers>
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// The click event handler for the existing button 'ButtonCreatedByXaml'.
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private void ButtonCreatedByXaml_Click(object sender, RoutedEventArgs e)
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{
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// Create a new button.
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Button ButtonCreatedByCode = new();
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// Specify button properties.
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ButtonCreatedByCode.Name = "ButtonCreatedByCode";
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ButtonCreatedByCode.Content = "New button and event handler created in code";
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ButtonCreatedByCode.Background = Brushes.Yellow;
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// Add the new button to the StackPanel.
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StackPanel1.Children.Add(ButtonCreatedByCode);
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// Assign an event handler to the new button using the '+=' operator.
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ButtonCreatedByCode.Click += new RoutedEventHandler(ButtonCreatedByCode_Click);
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// Assign an event handler to the new button using the AddHandler method.
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// AddHandler(ButtonBase.ClickEvent, new RoutedEventHandler(ButtonCreatedByCode_Click);
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// Assign an event handler to the StackPanel using the AddHandler method.
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StackPanel1.AddHandler(ButtonBase.ClickEvent, new RoutedEventHandler(ButtonCreatedByCode_Click));
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}
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// The Click event handler for the new button 'ButtonCreatedByCode'.
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private void ButtonCreatedByCode_Click(object sender, RoutedEventArgs e)
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{
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string sourceName = ((FrameworkElement)e.Source).Name;
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string senderName = ((FrameworkElement)sender).Name;
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Debug.WriteLine($"Routed event handler attached to {senderName}, " +
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$"triggered by the Click routed event raised by {sourceName}.");
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}
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//</ButtonEventHandlers>
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// Debug output when ButtonCreatedByCode is clicked:
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// Routed event handler attached to ButtonCreatedByCode, triggered by the Click routed event raised by ButtonCreatedByCode.
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// Routed event handler attached to StackPanel1, triggered by the Click routed event raised by ButtonCreatedByCode.
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}
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}
|
||||
+63
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//------------------------------------------------------------------------------
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||||
// <auto-generated>
|
||||
// This code was generated by a tool.
|
||||
// Runtime Version:4.0.30319.42000
|
||||
//
|
||||
// Changes to this file may cause incorrect behavior and will be lost if
|
||||
// the code is regenerated.
|
||||
// </auto-generated>
|
||||
//------------------------------------------------------------------------------
|
||||
|
||||
namespace CodeSampleCsharp.Properties {
|
||||
using System;
|
||||
|
||||
|
||||
/// <summary>
|
||||
/// A strongly-typed resource class, for looking up localized strings, etc.
|
||||
/// </summary>
|
||||
// This class was auto-generated by the StronglyTypedResourceBuilder
|
||||
// class via a tool like ResGen or Visual Studio.
|
||||
// To add or remove a member, edit your .ResX file then rerun ResGen
|
||||
// with the /str option, or rebuild your VS project.
|
||||
[global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "16.0.0.0")]
|
||||
[global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
|
||||
[global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
|
||||
internal class Resources {
|
||||
|
||||
private static global::System.Resources.ResourceManager resourceMan;
|
||||
|
||||
private static global::System.Globalization.CultureInfo resourceCulture;
|
||||
|
||||
[global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
|
||||
internal Resources() {
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Returns the cached ResourceManager instance used by this class.
|
||||
/// </summary>
|
||||
[global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
|
||||
internal static global::System.Resources.ResourceManager ResourceManager {
|
||||
get {
|
||||
if (object.ReferenceEquals(resourceMan, null)) {
|
||||
global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("CodeSampleCsharp.Properties.Resources", typeof(Resources).Assembly);
|
||||
resourceMan = temp;
|
||||
}
|
||||
return resourceMan;
|
||||
}
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Overrides the current thread's CurrentUICulture property for all
|
||||
/// resource lookups using this strongly typed resource class.
|
||||
/// </summary>
|
||||
[global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
|
||||
internal static global::System.Globalization.CultureInfo Culture {
|
||||
get {
|
||||
return resourceCulture;
|
||||
}
|
||||
set {
|
||||
resourceCulture = value;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
+120
@@ -0,0 +1,120 @@
|
||||
<?xml version="1.0" encoding="utf-8"?>
|
||||
<root>
|
||||
<!--
|
||||
Microsoft ResX Schema
|
||||
|
||||
Version 2.0
|
||||
|
||||
The primary goals of this format is to allow a simple XML format
|
||||
that is mostly human readable. The generation and parsing of the
|
||||
various data types are done through the TypeConverter classes
|
||||
associated with the data types.
|
||||
|
||||
Example:
|
||||
|
||||
... ado.net/XML headers & schema ...
|
||||
<resheader name="resmimetype">text/microsoft-resx</resheader>
|
||||
<resheader name="version">2.0</resheader>
|
||||
<resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
|
||||
<resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
|
||||
<data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
|
||||
<data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
|
||||
<data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
|
||||
<value>[base64 mime encoded serialized .NET Framework object]</value>
|
||||
</data>
|
||||
<data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
|
||||
<value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
|
||||
<comment>This is a comment</comment>
|
||||
</data>
|
||||
|
||||
There are any number of "resheader" rows that contain simple
|
||||
name/value pairs.
|
||||
|
||||
Each data row contains a name, and value. The row also contains a
|
||||
type or mimetype. Type corresponds to a .NET class that support
|
||||
text/value conversion through the TypeConverter architecture.
|
||||
Classes that don't support this are serialized and stored with the
|
||||
mimetype set.
|
||||
|
||||
The mimetype is used for serialized objects, and tells the
|
||||
ResXResourceReader how to depersist the object. This is currently not
|
||||
extensible. For a given mimetype the value must be set accordingly:
|
||||
|
||||
Note - application/x-microsoft.net.object.binary.base64 is the format
|
||||
that the ResXResourceWriter will generate, however the reader can
|
||||
read any of the formats listed below.
|
||||
|
||||
mimetype: application/x-microsoft.net.object.binary.base64
|
||||
value : The object must be serialized with
|
||||
: System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
|
||||
: and then encoded with base64 encoding.
|
||||
|
||||
mimetype: application/x-microsoft.net.object.soap.base64
|
||||
value : The object must be serialized with
|
||||
: System.Runtime.Serialization.Formatters.Soap.SoapFormatter
|
||||
: and then encoded with base64 encoding.
|
||||
|
||||
mimetype: application/x-microsoft.net.object.bytearray.base64
|
||||
value : The object must be serialized into a byte array
|
||||
: using a System.ComponentModel.TypeConverter
|
||||
: and then encoded with base64 encoding.
|
||||
-->
|
||||
<xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
|
||||
<xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
|
||||
<xsd:element name="root" msdata:IsDataSet="true">
|
||||
<xsd:complexType>
|
||||
<xsd:choice maxOccurs="unbounded">
|
||||
<xsd:element name="metadata">
|
||||
<xsd:complexType>
|
||||
<xsd:sequence>
|
||||
<xsd:element name="value" type="xsd:string" minOccurs="0" />
|
||||
</xsd:sequence>
|
||||
<xsd:attribute name="name" use="required" type="xsd:string" />
|
||||
<xsd:attribute name="type" type="xsd:string" />
|
||||
<xsd:attribute name="mimetype" type="xsd:string" />
|
||||
<xsd:attribute ref="xml:space" />
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
<xsd:element name="assembly">
|
||||
<xsd:complexType>
|
||||
<xsd:attribute name="alias" type="xsd:string" />
|
||||
<xsd:attribute name="name" type="xsd:string" />
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
<xsd:element name="data">
|
||||
<xsd:complexType>
|
||||
<xsd:sequence>
|
||||
<xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
|
||||
<xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
|
||||
</xsd:sequence>
|
||||
<xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
|
||||
<xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
|
||||
<xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
|
||||
<xsd:attribute ref="xml:space" />
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
<xsd:element name="resheader">
|
||||
<xsd:complexType>
|
||||
<xsd:sequence>
|
||||
<xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
|
||||
</xsd:sequence>
|
||||
<xsd:attribute name="name" type="xsd:string" use="required" />
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
</xsd:choice>
|
||||
</xsd:complexType>
|
||||
</xsd:element>
|
||||
</xsd:schema>
|
||||
<resheader name="resmimetype">
|
||||
<value>text/microsoft-resx</value>
|
||||
</resheader>
|
||||
<resheader name="version">
|
||||
<value>2.0</value>
|
||||
</resheader>
|
||||
<resheader name="reader">
|
||||
<value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
|
||||
</resheader>
|
||||
<resheader name="writer">
|
||||
<value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
|
||||
</resheader>
|
||||
</root>
|
||||
+9
@@ -0,0 +1,9 @@
|
||||
<Application x:Class="CodeSampleCsharp.App"
|
||||
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
|
||||
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
|
||||
xmlns:local="clr-namespace:CodeSampleCsharp"
|
||||
StartupUri="MainWindow.xaml">
|
||||
<Application.Resources>
|
||||
|
||||
</Application.Resources>
|
||||
</Application>
|
||||
+9
@@ -0,0 +1,9 @@
|
||||
<Application x:Class="Application"
|
||||
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
|
||||
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
|
||||
xmlns:local="clr-namespace:CodeSampleVb"
|
||||
StartupUri="MainWindow.xaml">
|
||||
<Application.Resources>
|
||||
|
||||
</Application.Resources>
|
||||
</Application>
|
||||
+6
@@ -0,0 +1,6 @@
|
||||
Class Application
|
||||
|
||||
' Application-level events, such as Startup, Exit, and DispatcherUnhandledException
|
||||
' can be handled in this file.
|
||||
|
||||
End Class
|
||||
+11
@@ -0,0 +1,11 @@
|
||||
Imports System.Windows
|
||||
|
||||
'The ThemeInfo attribute describes where any theme specific and generic resource dictionaries can be found.
|
||||
'1st parameter: where theme specific resource dictionaries are located
|
||||
'(used if a resource is not found in the page,
|
||||
' or application resource dictionaries)
|
||||
|
||||
'2nd parameter: where the generic resource dictionary is located
|
||||
'(used if a resource is not found in the page,
|
||||
'app, and any theme specific resource dictionaries)
|
||||
<Assembly: ThemeInfo(ResourceDictionaryLocation.None, ResourceDictionaryLocation.SourceAssembly)>
|
||||
+23
@@ -0,0 +1,23 @@
|
||||
<Project Sdk="Microsoft.NET.Sdk">
|
||||
|
||||
<PropertyGroup>
|
||||
<OutputType>WinExe</OutputType>
|
||||
<TargetFramework>net6.0-windows</TargetFramework>
|
||||
<RootNamespace>CodeSampleVb</RootNamespace>
|
||||
<NeutralLanguage>en-us</NeutralLanguage>
|
||||
<UseWPF>true</UseWPF>
|
||||
</PropertyGroup>
|
||||
|
||||
<ItemGroup>
|
||||
<Import Include="System.Windows" />
|
||||
<Import Include="System.Windows.Controls" />
|
||||
<Import Include="System.Windows.Data" />
|
||||
<Import Include="System.Windows.Documents" />
|
||||
<Import Include="System.Windows.Input" />
|
||||
<Import Include="System.Windows.Media" />
|
||||
<Import Include="System.Windows.Media.Imaging" />
|
||||
<Import Include="System.Windows.Navigation" />
|
||||
<Import Include="System.Windows.Shapes" />
|
||||
</ItemGroup>
|
||||
|
||||
</Project>
|
||||
+16
@@ -0,0 +1,16 @@
|
||||
<Window x:Class="CodeSampleVb.MainWindow"
|
||||
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
|
||||
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
|
||||
Title="How to add an event handler using code" Height="100" Width="300">
|
||||
|
||||
<!--<ButtonCreatedByXaml>-->
|
||||
<StackPanel Name="StackPanel1">
|
||||
<Button
|
||||
Name="ButtonCreatedByXaml"
|
||||
Click="ButtonCreatedByXaml_Click"
|
||||
Content="Create a new button with an event handler"
|
||||
Background="LightGray">
|
||||
</Button>
|
||||
</StackPanel>
|
||||
<!--</ButtonCreatedByXaml>-->
|
||||
</Window>
|
||||
+57
@@ -0,0 +1,57 @@
|
||||
Imports System.Windows.Controls.Primitives
|
||||
|
||||
Namespace CodeSampleVb
|
||||
|
||||
' <summary>
|
||||
' Interaction logic for MainWindow.xaml.
|
||||
' </summary>
|
||||
Partial Public Class MainWindow
|
||||
Inherits Window
|
||||
|
||||
Public Sub New()
|
||||
InitializeComponent()
|
||||
End Sub
|
||||
|
||||
'<ButtonEventHandlers>
|
||||
' The click event handler for the existing button 'ButtonCreatedByXaml'.
|
||||
Private Sub ButtonCreatedByXaml_Click(sender As Object, e As RoutedEventArgs)
|
||||
|
||||
' Create a new button and specify button properties.
|
||||
Dim ButtonCreatedByCode As New Button With {
|
||||
.Name = "ButtonCreatedByCode",
|
||||
.Content = "New button and event handler created in code",
|
||||
.Background = Brushes.Yellow
|
||||
}
|
||||
|
||||
' Add the new button to the StackPanel.
|
||||
StackPanel1.Children.Add(ButtonCreatedByCode)
|
||||
|
||||
' Assign an event handler to the new button using the AddHandler statement.
|
||||
AddHandler ButtonCreatedByCode.Click, AddressOf ButtonCreatedByCode_Click
|
||||
|
||||
' Assign an event handler to the new button using the AddHandler method.
|
||||
' ButtonCreatedByCode.AddHandler(ButtonBase.ClickEvent, New RoutedEventHandler(AddressOf ButtonCreatedByCode_Click))
|
||||
|
||||
' Assign an event handler to the StackPanel using the AddHandler method.
|
||||
StackPanel1.AddHandler(ButtonBase.ClickEvent, New RoutedEventHandler(AddressOf ButtonCreatedByCode_Click))
|
||||
|
||||
End Sub
|
||||
|
||||
' The Click event handler for the new button 'ButtonCreatedByCode'.
|
||||
Private Sub ButtonCreatedByCode_Click(sender As Object, e As RoutedEventArgs)
|
||||
|
||||
Dim sourceName As String = CType(e.Source, FrameworkElement).Name
|
||||
Dim senderName As String = CType(sender, FrameworkElement).Name
|
||||
|
||||
Debug.WriteLine($"Routed event handler attached to {senderName}, " +
|
||||
$"triggered by the Click routed event raised by {sourceName}.")
|
||||
|
||||
End Sub
|
||||
'</ButtonEventHandlers>
|
||||
|
||||
' Debug output when ButtonCreatedByCode is clicked:
|
||||
' Routed event handler attached to ButtonCreatedByCode, triggered by the Click routed event raised by ButtonCreatedByCode.
|
||||
' Routed event handler attached to StackPanel1, triggered by the Click routed event raised by ButtonCreatedByCode.
|
||||
End Class
|
||||
|
||||
End Namespace
|
||||
@@ -78,6 +78,12 @@ items:
|
||||
- name: Systems
|
||||
expanded: true
|
||||
items:
|
||||
- name: Events
|
||||
items:
|
||||
- name: Common tasks
|
||||
items:
|
||||
- name: Add an event handler using code
|
||||
href: events/how-to-add-an-event-handler-using-code.md
|
||||
- name: Properties
|
||||
items:
|
||||
- name: Dependency properties
|
||||
|
||||
Reference in New Issue
Block a user