Quickstart: Responding to user movement with the accelerometer (C#)
You can use the accelerometer to respond to user movement in an app written in C#.
A simple game app relies on a single sensor, the accelerometer, as an input device. These apps typically use only one or two axes for input; but they may also use the shake event as another input source.
Roadmap: How does this topic relate to others? See: Roadmap for Windows Runtime apps using C# or Visual Basic.
Objective: After completing this quickstart you will understand how to use the accelerometer to respond to user movement.
Prerequisites
You should be familiar with XAML, Visual C#, and events.
The device or emulator that you're using must support an accelerometer.
Time to complete: 20 minutes.
Instructions
1. Open Microsoft Visual Studio
Open an instance of Microsoft Visual Studio.
2. Create a new project
Create a new project, choosing a Blank App from the Visual C#/Store Apps project types.
3. Replace the C# code
Open your project's MainPage.xaml.cs file and replace the existing code with the following.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
// Required to support the core dispatcher and the accelerometer
using Windows.UI.Core;
using Windows.Devices.Sensors;
namespace App1
{
public sealed partial class MainPage : Page
{
// Sensor and dispatcher variables
private Accelerometer _accelerometer;
// This event handler writes the current accelerometer reading to
// the three acceleration text blocks on the app's main page.
private async void ReadingChanged(object sender, AccelerometerReadingChangedEventArgs e)
{
await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
AccelerometerReading reading = e.Reading;
txtXAxis.Text = String.Format("{0,5:0.00}", reading.AccelerationX);
txtYAxis.Text = String.Format("{0,5:0.00}", reading.AccelerationY);
txtZAxis.Text = String.Format("{0,5:0.00}", reading.AccelerationZ);
});
}
public MainPage()
{
this.InitializeComponent();
_accelerometer = Accelerometer.GetDefault();
if (_accelerometer != null)
{
// Establish the report interval
uint minReportInterval = _accelerometer.MinimumReportInterval;
uint reportInterval = minReportInterval > 16 ? minReportInterval : 16;
_accelerometer.ReportInterval = reportInterval;
// Assign an event handler for the reading-changed event
_accelerometer.ReadingChanged += new TypedEventHandler<Accelerometer, AccelerometerReadingChangedEventArgs>(ReadingChanged);
}
}
}
}
You'll need to rename the namespace in the previous snippet with the name you gave your project. For example, if you created a project named AccelerometerCS, you'd replace namespace App1 with namespace AccelerometerCS.
4. Replace the XAML code
Open the file MainPage.xaml and replace the original contents with the following XML.
<Page
x:Class="App1.MainPage"
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:App1"
xmlns:d="https://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="https://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Grid x:Name="LayoutRoot" Background="#FF0C0C0C">
<TextBlock HorizontalAlignment="Left" Height="25" Margin="8,20,0,0" TextWrapping="Wrap" Text="X-axis:" VerticalAlignment="Top" Width="62" Foreground="#FFEDE6E6"/>
<TextBlock HorizontalAlignment="Left" Height="27" Margin="8,49,0,0" TextWrapping="Wrap" Text="Y-axis:" VerticalAlignment="Top" Width="62" Foreground="#FFF5F2F2"/>
<TextBlock HorizontalAlignment="Left" Height="23" Margin="8,80,0,0" TextWrapping="Wrap" Text="Z-axis:" VerticalAlignment="Top" Width="62" Foreground="#FFF6F0F0"/>
<TextBlock x:Name="txtXAxis" HorizontalAlignment="Left" Height="15" Margin="70,16,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="61" Foreground="#FFF2F2F2"/>
<TextBlock x:Name="txtYAxis" HorizontalAlignment="Left" Height="15" Margin="70,49,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53" Foreground="#FFF2EEEE"/>
<TextBlock x:Name="txtZAxis" HorizontalAlignment="Left" Height="15" Margin="70,80,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53" Foreground="#FFFFF8F8"/>
</Grid>
</Page>
You'll need to replace the first part of the class name in the previous snippet with the namespace of your app. For example, if you created a project named AccelerometerCS, you'd replace x:Class="App1.MainPage" with x:Class="AccelerometerCS.MainPage". You should also replace xmlns:local="using:App1" with xmlns:local="using:AccelerometerCS".
5. Build, deploy and run the app
Press F5 or select Debug > Start Debugging to build, deploy, and run the app.
Once the app is running, you can change the accelerometer values by moving the device or using the emulator tools.
6. Stop the app
- Press ALT+Tab to return to Visual Studio.
- Press Shift+F5 or select Debug > Stop Debugging to stop the app.
Summary
The previous example demonstrates how little code you'll need to write in order to integrate accelerometer input in your app.
The app establishes a connection with the default accelerometer in the MainPage method.
_accelerometer = Accelerometer.GetDefault();
The app establishes the report interval within the MainPage method. This code retrieves the minimum interval supported by the device and compares it to a requested interval of 16 milliseconds (which approximates a 60-Hz refresh rate). If the minimum supported interval is greater than the requested interval, the code sets the value to the minimum. Otherwise, it sets the value to the requested interval.
uint minReportInterval = _accelerometer.MinimumReportInterval;
uint reportInterval = minReportInterval > 16 ? minReportInterval : 16;
_accelerometer.ReportInterval = reportInterval;
The new accelerometer data is captured in the ReadingChanged method. Each time the sensor driver receives new data from the sensor, it passes the values to your app using this event handler. The app registers this event handler on the following line.
_accelerometer.ReadingChanged += new TypedEventHandler<Accelerometer,
AccelerometerReadingChangedEventArgs>(ReadingChanged);
These new values are written to the TextBlocks found in the project's XAML.
<TextBlock x:Name="txtXAxis" HorizontalAlignment="Left" Height="15" Margin="70,16,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="61" Foreground="#FFF2F2F2"/>
<TextBlock x:Name="txtYAxis" HorizontalAlignment="Left" Height="15" Margin="70,49,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53" Foreground="#FFF2EEEE"/>
<TextBlock x:Name="txtZAxis" HorizontalAlignment="Left" Height="15" Margin="70,80,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top" Width="53" Foreground="#FFFFF8F8"/>