Category: UWP Programming

Today, we will take a closer look at various abbreviations used in UWP (Universal Windows Platform) development and their non-abbreviated forms. UWP is a Microsoft platform that allows for the development of applications that can be used from Windows 10 onwards. In this article, we will explain the commonly used abbreviated expressions in UWP code, their meanings, and differences, and we will understand them practically through example code.

1. Basic Concepts of UWP Development

UWP development is an application development environment designed to run the same application across a multitude of devices. It can run on various platforms like Windows 10, Xbox, and HoloLens, and it supports multiple platforms with a single codebase. Therefore, maintaining the efficiency and readability of code is essential when developing UWP applications. This is where abbreviated and non-abbreviated expressions come into play, as they greatly contribute to the conciseness and readability of the code.

2. Understanding Abbreviated and Non-Abbreviated Expressions

An abbreviated expression refers to a concise way used in code to easily convey specific functionalities or actions. In contrast, a non-abbreviated expression is a way of expressing the same functionality more explicitly. The choice between the two expressions can vary depending on the situation, and it can directly impact the readability and maintainability of the code.

2.1. Example of Abbreviated Expression

When defining the UI in a UWP application using ‘xaml’, multiple properties can be written concisely using an abbreviated expression. For example:

<Button Content="Click Me" Width="200" Height="50" Click="Button_Click"/>

The above code is a simplified representation of various properties of the ‘Button’ element in an abbreviated form. This increases the conciseness and readability of the code, allowing developers to understand and use it easily.

2.2. Example of Non-Abbreviated Expression

On the other hand, using a non-abbreviated expression can enhance the clarity of the code. Here’s an example of a non-abbreviated expression that performs a similar function:

<Button Width="200" Height="50" Click="Button_Click">
    <Button.Content>Click Me</Button.Content>
</Button>

Here, the ‘Content’ property is represented as a separate element, making its nature and function more explicit. The non-abbreviated expression helps make clear what each property is, even if the code becomes longer.

3. Commonly Used Abbreviated Expressions in UWP

Let’s introduce a few abbreviated expressions often used in UWP development.

3.1. Abbreviated Expressions in XAML

XAML (XAML Markup Language) is used to define the UI of UWP applications. Abbreviated expressions are particularly noticeable here. For example, the ‘Margin’ property in XAML can be abbreviated as follows:

<Border Margin="10,20,30,40"></Border>

The above expression can be written in a non-abbreviated form as follows:

<Border>
    <Border.Margin>
        <Thickness Left="10" Top="20" Right="30" Bottom="40"/>
    </Border.Margin>
</Border>

3.2. Abbreviated Expressions in C# Code

In C#, abbreviated expressions are still widely used for code conciseness. For example, the following abbreviated method definition can be used:

private void Button_Click(object sender, RoutedEventArgs e) => DoSomething();

When modified to a non-abbreviated form, it appears as follows:

private void Button_Click(object sender, RoutedEventArgs e) 
{
    DoSomething();
}

4. Precautions When Using Abbreviated Expressions

While abbreviated expressions simplify the code, excessive abbreviation can hinder its readability. Therefore, when using abbreviated expressions, you should consider the following:

• Use abbreviations only if they make understanding easier.
• It should be clear what the code does.
• Maintain consistency by considering the rules and styles of the whole team.

5. Combination of Abbreviated and Non-Abbreviated Expressions

The ideal code achieves a harmony between abbreviated and non-abbreviated expressions. For instance, clearly express where non-abbreviated expressions should be used, while combining repetitive patterns with abbreviated expressions to make the code more efficient.

In the UWP (Universal Windows Platform) development environment, one of the most important elements for providing a consistent user experience across various devices is Device-independent pixels (DIP). In this post, we will explain how UWP applications can effectively design across different resolutions and screen sizes using device-independent pixels.

1. What are Device-independent Pixels?

Device-independent pixels are a unit used in modern application development environments like UWP, which define the size of design elements regardless of the number of pixels on the actual screen. They serve primarily the following purposes:

• Maintain design consistency: Ensures that the user interface (UI) appears consistently across various resolutions and screen sizes.
• Optimize resource management: Allows the same UI elements to be used across different devices.
• Enhance accessibility: Supports all users to have the same experience regardless of screen size.

2. DPI (Dots Per Inch) and Device-independent Pixels

DIP is defined based on DPI (Dots Per Inch). 1 DIP is defined as 1/96 inch, so on a screen with 96 DPI, 1 DIP is equivalent to 1 pixel. However, as resolution increases, DPI also increases, which can make UI elements defined as 1 DIP appear smaller on high-resolution screens.

Example: DPI Calculation

Assuming you’re using a device with 120 DPI, 1 DIP actually becomes 1.25 pixels. Therefore, a UI element with a width of 100 DIP is calculated as follows:

100 DIP * (120 DPI / 96 DPI) = 125 pixels

3. Using Device-independent Pixels in UWP

In UWP, device-independent pixels are used to define the sizes of UI elements. Here is an example of UI configuration using device-independent pixels in XAML:

<StackPanel Width="300" Height="200">
    <TextBlock Text="Hello, UWP!" FontSize="24" />
    <Button Content="Click Me" Width="100" Height="50" />
</StackPanel>

In the example above, the StackPanel has a width of 300 DIP and a height of 200 DIP, and both the text and the button are defined with sizes in device-independent pixels. UWP automatically adjusts these values to fit the operating system, providing optimal UI for the user’s device.

4. Examples of Utilizing Device-independent Pixels

Now let’s look at how to utilize device-independent pixels through a real example. The following is an example with a basic structure of a UWP application:

<Page
    x:Class="UWPApp.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <Grid Background="White">
        <StackPanel VerticalAlignment="Center" HorizontalAlignment="Center">
            <TextBlock Text="Welcome to UWP!" FontSize="36" Margin="0,0,0,20"/>
            <Button Content="Start" Width="200" Height="60" FontSize="24"/>
        </StackPanel>
    </Grid>
</Page>

The code above creates a basic layout structure using Grid and StackPanel. The size of the TextBlock and the button are all defined in DIP units, ensuring that the UI displays consistently across all devices.

5. Responding to Screen Size and Resolution

UWP allows for the creation of more complex layouts to respond to various screen sizes and resolutions using XAML. The Visual State Manager (VSM) can be used to define different screen states and offer various layouts. For example:

<VisualStateManager.VisualStateGroups>
    <VisualStateGroup x:Name="AdaptiveStates">
        <VisualState x:Name="Narrow">
            <Storyboard>
                <DoubleAnimation Storyboard.TargetName="MyButton" 
                    Storyboard.TargetProperty="Width" 
                    To="150" Duration="0:0:0.2" />
            </Storyboard>
        </VisualState>
        <VisualState x:Name="Wide">
            <Storyboard>
                <DoubleAnimation Storyboard.TargetName="MyButton" 
                    Storyboard.TargetProperty="Width" 
                    To="300" Duration="0:0:0.2" />
            </Storyboard>
        </VisualState>
    </VisualStateGroup>
</VisualStateManager.VisualStateGroups>

This code snippet shows an example of adjusting the size of a button based on the state. By defining layouts for narrow and wide screens, it provides an optimal experience for users.

6. Handling DPI Changes

When the DPI changes, UWP automatically adjusts the UI of the application. However, developers may need to handle this manually in some cases. To do this, it is necessary to handle DPI change events to reset the appropriate UI.

protected override void OnDpiChanged(DpiChangedEventArgs e)
{
    // Process for the new DPI
    double newDpiX = e.NewDpi.DpiScaleX;
    double newDpiY = e.NewDpi.DpiScaleY;

    // Handle resizing of UI elements, etc.
}

7. Conclusion

In UWP, device-independent pixels are essential for providing a consistent user experience across various resolutions and screen sizes. By understanding and utilizing this unit, developers can create better UI and UX, maximizing compatibility across different devices. Based on the explanations provided in this post, it is encouraged to actively use the concept of device-independent pixels in actual application development.

UWP (Universal Windows Platform) is an application platform designed to operate on a variety of Windows devices. UWP applications provide various functions necessary for creating user interfaces (UI), handling events, and structuring business logic. In this article, we will detail event handlers and code behind, which are key components of UWP development. Additionally, we will guide you with example code for immediate application in practice.

1. UWP Application Structure

UWP applications consist of the following main components:

• XAML: A markup language that defines the user interface.
• C# or VB.NET: Programming languages used to define the application’s business logic.
• Code Behind Files: C# or VB.NET files that connect the UI elements defined in XAML with event handlers.

2. What is an Event Handler?

An event handler is a method that executes when a specific event occurs. In UWP, event handlers are used to handle interactions such as a user clicking a button or selecting an item from a list. This helps maintain the connection between the UI and business logic.

2.1 Types of Events

UWP provides various types of events. Common events include:

• Click: Occurs when a button is clicked.
• TextChanged: Occurs when the text in a text box changes.
• SelectionChanged: Occurs when the selection in a ComboBox or ListBox changes.
• Loaded: Occurs when a page is loaded.

3. What is Code Behind?

Code behind refers to C# or VB.NET files associated with XAML files that define UI elements and their behavior. For instance, the actions to perform when a button is clicked are defined in the code behind. Code behind exists as files with the same name as the XAML file but with .cs or .vb extensions.

3.1 Creating Code Behind

When you create a new UWP project in Visual Studio, a code behind file is automatically generated along with the default XAML file. Users can write event handler methods in this file to control the behavior of UI elements.

4. Example: Handling Button Click Events

In this section, we will look at an example of how to handle button click events in a basic UWP application.

4.1 Writing the XAML File

The following XAML code defines a simple UI containing a button and a text block:

<Page
    x:Class="MyUwpApp.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:MyUwpApp"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid>
        <StackPanel VerticalAlignment="Center" HorizontalAlignment="Center">
            <Button x:Name="MyButton" Content="Click Me" Click="MyButton_Click"/>
            <TextBlock x:Name="MyTextBlock" Text="Hello, World!" Margin="0,20,0,0" FontSize="24"/>
        </StackPanel>
    </Grid>
</Page>

4.2 Writing Code Behind

To handle the button click event above, the code behind file is written as follows:

using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace MyUwpApp
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        private void MyButton_Click(object sender, RoutedEventArgs e)
        {
            MyTextBlock.Text = "Button Clicked!";
        }
    }
}

5. Rules for Events

When creating event handlers, it is recommended to follow these rules:

• Give event handler names meaningful descriptions. For example: MyButton_Click.
• Event handlers should always be defined with private access modifiers.
• Event handlers perform event handling and UI update tasks.

6. Handling Complex Events

Event handlers can implement more complex logic. For instance, you can implement actions when a user selects an item from a ComboBox, or dynamically change UI elements based on input text.

6.1 Handling SelectionChanged Event of ComboBox

<ComboBox x:Name="MyComboBox" SelectionChanged="MyComboBox_SelectionChanged">
    <ComboBoxItem Content="Option 1"/>
    <ComboBoxItem Content="Option 2"/>
    <ComboBoxItem Content="Option 3"/>
</ComboBox>

Code behind:

private void MyComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    ComboBox comboBox = sender as ComboBox;
    if (comboBox != null && comboBox.SelectedItem != null)
    {
        ComboBoxItem selectedItem = (ComboBoxItem)comboBox.SelectedItem;
        MyTextBlock.Text = $"You selected: {selectedItem.Content}";
    }
}

7. Data Binding and Events

In UWP, the MVVM (Model-View-ViewModel) pattern can be utilized to separate UI and business logic through data binding. In this case, event handling is managed in the view model, while the UI is automatically updated according to data binding.

7.1 Creating a ViewModel

using System.ComponentModel;

public class MyViewModel : INotifyPropertyChanged
{
    private string _text;

    public string Text
    {
        get { return _text; }
        set
        {
            if (_text != value)
            {
                _text = value;
                OnPropertyChanged(nameof(Text));
            }
        }
    }

    public void OnButtonClick()
    {
        Text = "Button Clicked from ViewModel!";
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

7.2 Setting Up Binding

ViewModel can be bound in XAML as follows:

<Page.DataContext>
    <local:MyViewModel />
</Page.DataContext>

Set the button Click event to be called from the ViewModel:

<Button Content="Click Me" Click="OnButtonClick"/>

8. Conclusion

In this article, we explored the importance of event handlers and code behind in UWP application development. Event handlers link the user interface to business logic, and code behind defines UI behavior. This flow is essential for building robust UWP applications. We hope this has been helpful in your development journey.

This example lays the foundation for UWP application development and prepares you to extend into more complex applications. Through continuous practice and application, we encourage you to develop your own amazing applications.

In UWP (Universal Windows Platform) development, event handlers are crucial elements that interact with the user interface (UI). In this article, we will help you gain a deeper understanding of the concept, usage, and practical examples of event handlers in UWP.

What is an Event Handler?

An event handler is a method that is executed when a specific event occurs. For example, code is executed in response to actions like clicking a button or entering text. Events are vital elements that enable interaction between the user and the application in UWP applications.

UWP Event Model

UWP provides various event models. These include the following events:

• Input events of UI elements (e.g., Click, PointerPressed, TextChanged)
• Events for state changes of data
• Application lifecycle events (e.g., Activated, Suspending)

Registering Event Handlers

Event handlers are registered for specific UI elements. For example, you can register a handler for a button click event. Here is a basic way to register an event handler in C#.

private void MyButton_Click(object sender, RoutedEventArgs e)
{
    // Code to execute when the button is clicked
    MyTextBox.Text = "The button has been clicked!";
}

// Registering the button click event handler
MyButton.Click += MyButton_Click;

Parameters of Event Handlers

Event handlers typically have two parameters: sender and e. The sender parameter represents the object that raised the event, and e contains the event arguments that include additional data or status information. Below is an example code using the parameters.

private void MyButton_Click(object sender, RoutedEventArgs e)
{
    Button clickedButton = sender as Button;
    clickedButton.Content = "Clicked";
}

Examples of Various Event Handlers

Now, let’s look at some other examples of event handlers.

1. Button Click Event

private void Page_Loaded(object sender, RoutedEventArgs e)
{
    MyButton.Click += MyButton_Click;
}

private void MyButton_Click(object sender, RoutedEventArgs e)
{
    MyTextBox.Text = "The button has been clicked!";
}

2. Text Box Change Event

This is an event that occurs when text is entered.

private void Page_Loaded(object sender, RoutedEventArgs e)
{
    MyTextBox.TextChanged += MyTextBox_TextChanged;
}

private void MyTextBox_TextChanged(object sender, TextChangedEventArgs e)
{
    // Executes every time the text is changed
    string text = MyTextBox.Text;
    // Code to handle...
}

3. Mouse Pointer Events

This event occurs when the mouse pointer is over a UI element.

private void Page_Loaded(object sender, RoutedEventArgs e)
{
    MyImage.PointerEntered += MyImage_PointerEntered;
    MyImage.PointerExited += MyImage_PointerExited;
}

private void MyImage_PointerEntered(object sender, PointerRoutedEventArgs e)
{
    MyTextBox.Text = "The mouse is over the image.";
}

private void MyImage_PointerExited(object sender, PointerRoutedEventArgs e)
{
    MyTextBox.Text = "The mouse has left the image.";
}

Removing Event Handlers

When you no longer need an event, you should remove the handler. This is important to prevent memory leaks. You can remove it as follows.

MyButton.Click -= MyButton_Click;

Asynchronous Event Handlers

UWP also supports asynchronous event handlers. This separates long-running tasks from the UI thread, improving user experience. You can use the async and await keywords for asynchronous processing.

private async void MyButton_Click(object sender, RoutedEventArgs e)
{
    MyTextBox.Text = "Starting task...";
    await Task.Delay(2000); // Wait for 2 seconds
    MyTextBox.Text = "Task complete!";
}

Conclusion

Event handlers are essential tools for handling basic interactions in UWP applications. They are utilized in close conjunction with various UI elements, providing a richer user experience through techniques such as event registration, parameter usage, and asynchronous processing. Let’s leverage what we’ve learned to ensure your applications work excellently.

We hope this article helps deepen your understanding of UWP event handlers. We encourage you to continuously practice and learn to develop more complex applications.

UWP (Universal Windows Platform) development is a powerful platform for developing apps across various devices. UWP offers various UI elements and events to optimize the user experience. In particular, start and end events are very important in UI interaction. In this article, we will take a closer look at the start and end events in UWP.

1. What are Start and End Events?

Start events are triggered when a user first interacts with a UI element. For example, these occur in situations such as button clicks or mouse entering. On the other hand, end events occur when the interaction with a UI element has ended or when the user leaves the UI element. Typical examples include releasing the mouse button from a button or changing focus to another element.

1.1. Types of Start Events

• Click: Occurs when a button, etc. is clicked.
• PointerEntered: Occurs when the mouse pointer enters a UI element.
• FocusEngaged: Occurs when a UI element gains focus.

1.2. Types of End Events

• PointerExited: Occurs when the mouse pointer exits a UI element.
• LostFocus: Occurs when a UI element loses focus.

2. How to Handle Events in UWP

Handling events in UWP is simple. Define the UI elements in XAML and connect the event handling in C# code for those elements. For example, to handle a button click event, define the button in XAML and create a Click event handler in C#.

2.1. Defining a Button in XAML

        
        <Button x:Name="myButton" Content="Click Here" Click="myButton_Click" />
        
    

2.2. Handling Events in C# Code

        
        private void myButton_Click(object sender, RoutedEventArgs e)
        {
            // Code executed when the button is clicked
            textBlock.Text = "The button has been clicked.";
        }
        
    

3. Example of Start and End Events

In this section, we will create an example that uses start and end events. This example is structured to change the content of a text block when the mouse enters and exits a button.

3.1. XAML Code

        
        <StackPanel>
            <TextBlock x:Name="textBlock" FontSize="24" />
            <Button x:Name="hoverButton" Content="Hover Here" 
                    PointerEntered="hoverButton_PointerEntered" 
                    PointerExited="hoverButton_PointerExited" />
        </StackPanel>
        
    

3.2. C# Code

        
        private void hoverButton_PointerEntered(object sender, PointerRoutedEventArgs e)
        {
            textBlock.Text = "The mouse has entered the button.";
        }
        
        private void hoverButton_PointerExited(object sender, PointerRoutedEventArgs e)
        {
            textBlock.Text = "The mouse has exited the button.";
        }
        
    

4. Handling Events in Various UI Elements

In UWP, you can handle start and end events across a variety of UI elements beyond just buttons. For example, you can improve the user experience by handling these events in images, list views, sliders, and more.

4.1. Start and End Events in Images

        
        <Image x:Name="myImage" Source="image.png" 
               PointerEntered="myImage_PointerEntered" 
               PointerExited="myImage_PointerExited" />
        
    

4.2. Image Handling C# Code

        
        private void myImage_PointerEntered(object sender, PointerRoutedEventArgs e)
        {
            textBlock.Text = "The mouse has entered the image.";
        }
        
        private void myImage_PointerExited(object sender, PointerRoutedEventArgs e)
        {
            textBlock.Text = "The mouse has exited the image.";
        }
        
    

5. Performance Considerations

When using start and end events for UI elements, performance should be considered. Particularly, if many events are triggered, unnecessary processing tasks may pile up. Therefore, it is important to perform the minimum necessary work in event handling, and consider asynchronous processing if needed.

6. Conclusion

Start and end events in UWP are elements that greatly enhance the user experience. Through this guide, you have been able to understand the basic concepts and apply them through actual example code. It is recommended to utilize these events properly to develop more interactive and intuitive apps.

References

• Getting Started with UWP
• UWP Controls and Control