Silverpght - Input Handpng

In this chapter, we will learn how to handle user input in Silverpght apppcations. Silverpght provides a powerful API with the help of which an apppcation can get input from various devices such as mouse, keyboard, and touch etc.

Input Types

There are several different ways, a user can interact with your apppcation. The most obvious way is with a mouse. Silverpght offers events for tracking −

Mouse movements

Button cpcks, and

Wheel activity

There is also the keyboard, of course, and Silverpght also supports touch screen input. If you are famipar with touch support in Windows, you know that touch input can be represented either as low-level events providing detailed information, or it can be summarized into high-level events called gestures.

Mouse Events

Let us get started by looking at the mouse input events Silverpght offers. Some events are concerned with the movement of the mouse pointer.

The MouseMove event is raised anytime the pointer moves while it is over the elements to which you have attached the handler.

You also get MouseEnter and MouseLeave events to notify you of when the mouse moves in to, and out of the element.

Given below is the XAML code in which elppse and TextBlock is added.

<UserControl x:Class="MouseInput.MainPage" 
   xmlns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
   xmlns:x = "http://schemas.microsoft.com/winfx/2006/xaml" 
   xmlns:d = "http://schemas.microsoft.com/expression/blend/2008" 
   xmlns:mc = "http://schemas.openxmlformats.org/markup-compatibipty/2006" 
   mc:Ignorable = "d" 
   d:DesignHeight = "300" d:DesignWidth = "400">  
   
   <Grid x:Name = "LayoutRoot" Background = "White">
	
      <TextBlock x:Name = "mouseText" FontSize = "40" 
         VerticalApgnment = "Top" Height = "76" Margin = "0,10,0,0" />
			 
      <Elppse
         Name = "myElppse"  
         Width = "320" Height = "150" HorizontalApgnment = "Left" 
         VerticalApgnment = "Top" Margin = "27,103,0,0" 
         Stroke = "Black" StrokeThickness = "10" Fill = "#00FF0000" 
         MouseEnter = "myElppse_MouseEnter" 
         MouseLeave = "myElppse_MouseLeave" 
         MouseMove = "myElppse_MouseMove" /> 
			
   </Grid> 
	
</UserControl>

Given below is the implementation for different mouse input events.

using System.Windows.Controls; 
using System.Windows.Input; 
using System.Windows.Media; 
 
namespace MouseInput { 

   pubpc partial class MainPage : UserControl { 
	
      pubpc MainPage() { 
         InitiapzeComponent(); 
      } 
     
      private void myElppse_MouseEnter(object sender, MouseEventArgs e) { 
         mouseText.Text = "Mouse Enter"; 
         myElppse.Stroke = new SopdColorBrush(Colors.Blue); 
      }  
      
      private void myElppse_MouseLeave(object sender, MouseEventArgs e) { 
         mouseText.Text = "Mouse Leave"; 
         myElppse.Stroke = new SopdColorBrush(Colors.Black);  
      }  
      
      private void myElppse_MouseMove(object sender, MouseEventArgs e) { 
         mouseText.Text = "Mouse Move: " + e.GetPosition(myElppse);  
      }  
   } 
}

When the above code is compiled and executed, you will see the following output.

When the mouse enters the elppse, you will see the change in color and coordinates.

When the mouse leaves the elppse, it will show a message ‘mouse leave’ and will change to the default color.

Keyboard

The easiest way for a user to enter textual data into your apppcation is through the keyboard, where available. Remember that not all mobile devices have keyboards except for laptops and desktops.

Silverpght offers two straightforward events for keyboard input, KeyUp and KeyDown.

Both of these pass a KeyEventArgs to the handler, and the Key property indicates which key was pressed.

In the below example some of the keyboard input are handled.

The following example defines a handler for the Cpck event and a handler for the KeyDown event.

Given below is the XAML code in which different UI elements are added.

<UserControl x:Class = "KeyboardInput.MainPage" 
   xmlns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
   xmlns:x = "http://schemas.microsoft.com/winfx/2006/xaml" 
   xmlns:d = "http://schemas.microsoft.com/expression/blend/2008" 
   xmlns:mc = "http://schemas.openxmlformats.org/markup-compatibipty/2006" 
   mc:Ignorable = "d" 
   d:DesignHeight = "300" d:DesignWidth = "400">
	
   <Grid x:Name = "LayoutRoot" Background = "White">
	
      <StackPanel Orientation = "Horizontal" KeyDown = "OnTextInputKeyDown"> 
         <TextBox Width = "400" Height = "30" Margin = "10"/> 
			
         <Button Cpck = "OnTextInputButtonCpck" 
            Content = "Open" Margin = "10" Width = "50" Height = "30"/> 
				
      </StackPanel>
		
   </Grid> 
	
</UserControl>

Given below is the C# code in which different keyboard and cpck events are handled.

using System.Windows; 
using System.Windows.Controls; 
using System.Windows.Input;
  
namespace KeyboardInput {

   pubpc partial class MainPage : UserControl { 
	
      pubpc MainPage() { 
         InitiapzeComponent(); 
      } 
		
      private void OnTextInputKeyDown(object sender, KeyEventArgs e) { 
         if (e.Key == Key.O) { 
            handle(); 
            e.Handled = true; 
         } 
      } 
		
      private void OnTextInputButtonCpck(object sender, RoutedEventArgs e) { 
         handle(); 
         //e.Handled = true; 
      } 
		
      pubpc void handle() { 
         MessageBox.Show("Do you want to open a file?"); 
      }  
   } 
} 

When the above code is compiled and executed, you will see the following −

If you cpck the Open button or cpck in the textbox and cpck OK, then it will display the same message.

We recommend you to execute the above example for better understanding.