Detailed explanation of basic WPF concepts in C#

1. What is WPF?

C# WPF, or Windows Presentation Foundation, is a UI framework for building Windows desktop applications. WPF supports a wide range of application development capabilities, including application models, resources, controls, graphics, layouts, data binding, documentation, and security. It is part of the .NET Framework, which allows developers to create applications using .NET languages such as C#. WPF uses Extensible Application Markup Language (XAML) to provide a declarative model for application programming, which allows developers to define the structure and style of the user interface while using languages such as C# to implement the logic and behavior of the application.

At the heart of WPF is a resolution-independent and vector-based rendering engine designed to take advantage of modern graphics hardware. WPF extends this core with a complete set of application development capabilities including Extensible Application Markup Language (XAML), controls, data binding, layout, 2-D and 3-D graphics, animations, styles, templates, documents, media, text, and layouts. WPF is included in the Microsoft .NET Framework and can generate applications that incorporate other elements of the .NET Framework class library. (FromWPF Introduction | Microsoft Learn）

2. The main features of WPF

Rich controls: Provides a comprehensive set of controls for building user interfaces.
Data binding: Supports mechanisms to display and interact data between UI elements and data objects.
Graphics and animations: Provides powerful graphics and animation support to create attractive user interfaces.
Styles and templates: The appearance of the control can be easily changed through styles and templates to achieve consistency of UI elements.
layout: Provides flexible layout systems, such as Grid, StackPanel, etc., to meet different user interface needs.
3D graphics: Supports 3D rendering, allowing you to create more complex graphics and custom themes.
multimedia: Supports the integration of media elements such as images, audio and video.

3. WPF applications are usually composed of UI and backend code defined by XAML files (such as C#).

1. User interface for XAML file definition

XAML (eXtensible Application Markup Language) is an XML-based markup language used to define the user interface of WPF applications.

XAML files describe the layout, controls, styles, and data binding of the interface.

It allows developers to define UI elements in a declarative way, so that interface design and logical code are separated, making it easy to maintain and collaborate with multiple people.

The main components of XAML:

Namespace declaration: Defines the namespace that can be used in XAML files, usually the namespace of WPF.
Root element: UsuallyWindoworUserControl, represents the root container of a window or user control.
Layout Controls:likeGrid、StackPanel、WrapPaneletc., used to organize and lay out other controls.
UI controls:likeButton、TextBox、Labeletc., used to build interactive elements of the user interface.
Styles and templates: Define the style and template of the control to unify the appearance and behavior of the control.
Data binding: Bind UI elements with data source to realize automatic update and interaction of data.
Event handler: Bind event handlers to execute specific logic when user interactions.

Sample XAML code:

<Window x:Class=""
        xmlns="/winfx/2006/xaml/presentation"
        xmlns:x="/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </>
        <TextBox x:Name="inputTextBox" ="0" Margin="10"/>
        <Button x:Name="clickMeButton" Content="Click Me" ="1" Margin="10" Click="clickMeButton_Click"/>
    </Grid>
</Window>

2. Backend code (such as C#)

Backend code is usually written in C# language, responsible for implementing the application's business logic, data processing, event processing and other functions.

It interacts with UI elements in XAML files, responds to user actions, updates the status of UI elements, and handles application lifecycle events.

The main tasks of backend code:

Event handling: Respond to user operations, such as button clicks, text input, etc.
Data binding: Implement data binding between UI elements and data source, and automatically update the status of UI elements.
Business logic: Handle the core functions of the application, such as data processing, calculation, file operation, etc.
Error handling: Handle runtime errors and exceptions to ensure the stability of the application.
Resource Management: Load and release applications' resources, such as images, data files, etc.

Example C# code:

using ;

namespace WpfApp
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void clickMeButton_Click(object sender, RoutedEventArgs e)
        {
            ("You clicked the button!");
             = "Button clicked";
        }
    }
}

In this example, the XAML file defines a window containing text boxes and buttons. In C# codeclickMeButton_ClickThe method responds to the button click event, displays a message box, and updates the contents of the text box.

Through this separation, WPF applications can more flexibly manage and maintain user interface and backend logic, making the development process more efficient and modular. At the same time, this separation also helps multi-person collaborative development, designers can focus on XAML interface design, while developers can focus on the implementation of back-end logic.

4. C#WPF tags and code hiding

In WPF (Windows Presentation Foundation), XAML files and code-behind are two main components of building the user interface.

XAML files are responsible for defining the structure and layout of the interface, while code hiding includes interface logic and event handlers.

XAML Files:XAML (eXtensible Application Markup Language) is a declarative XML language used to define the user interface of WPF applications. In XAML files, you can define windows, controls, layouts, resources, and data bindings. XAML files usually.xamlis an extension.
Code-behind: Code hiding refers to the background code file associated with the XAML file. In these files, you can write event handlers, business logic, and data processing code in C# or other .NET languages. Code-behind files are usually the same name as XAML files, but with the extension.cs(For C#) or.vb(For Visual Basic).

In XAML files, you can usex:ClassDirectives associate XAML tags with partial classes in code-behind. This division class contains the page's logic and event handlers.

For example, if you have a nameThe XAML file, its code-behind may be, which definesMainWindowclass logic.

xml：

<Window x:Class=""
        xmlns="/winfx/2006/xaml/presentation"
        xmlns:x="/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Button Content="Click Me" Click="Button_Click"/>
    </Grid>
</Window>

Hide the file in the corresponding codeIn, you can define the handler for button click events:

using ;

namespace WpfApp
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            // Event processing logic            ("Button clicked!");
        }
    }
}

In WPF, the combination of XAML files and code-behind allows designers and developers to work separately, designers can focus on interface design, while developers can focus on logical implementations, which helps improve development efficiency and maintenance. At the same time, this separation also makes the code more modular and easy to manage and expand.

Summarize

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