如何在Windows Phone的永久性存储文件中记录加速度计读数

Question

``I am trying to develop a Windows phone application which can record accelerometer readings after every 10 secs or so to a persistent file storage area.

For that, I have written a program code which gets the accelerometer readings and displays them seperately( one textblock for x reading, one for y reading and one for z reading). Then I store all these readings together in a Textbox and use the TextChanged event to record the changes to the file. The readings are stored to an Isolated File storage area.

The different functions are working fine but the problem I am facing is that the file is showing only the last value of acccelerometer read or in other words, the textbox is saving only the last value read.

Can anyone suggest why is this happenning and what can I do to solve this? The code I used is as follows:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using Microsoft.Devices.Sensors;
using Microsoft.Xna.Framework;
using System.Windows.Threading;
using System.IO.IsolatedStorage;
using System.IO;

namespace PhoneApp1
{
    public partial class MainPage : PhoneApplicationPage
    {
        Accelerometer a;
        // Constructor
        public MainPage()
        {
            InitializeComponent();
            if (!Accelerometer.IsSupported)
            {
                status.Text = "Sensor not supported";
                start.IsEnabled = false;
                stop.IsEnabled = false;
            }
            }

        private void start_Click(object sender, RoutedEventArgs e)
        {
            if (a == null)
            {
                a = new Accelerometer();

            }
            try
            {
                status.Text = "Starting Accelerometer";
                a.TimeBetweenUpdates = TimeSpan.FromMilliseconds(1000);
                a.CurrentValueChanged += new EventHandler<SensorReadingEventArgs<AccelerometerReading>>(a_CurrentValueChanged);
                a.Start();
            }
            catch (Exception e1)
            {
                status.Text = e1.Message;
            }
        }

        private void stop_Click(object sender, RoutedEventArgs e)
        {
            if (a != null)
            {
                a.Stop();
                status.Text = "Accelerometer stopped";
            }
            else
            {
                status.Text = "Accelerometer not started";
            }
        }
        void a_CurrentValueChanged(Object sender, SensorReadingEventArgs<AccelerometerReading> sr)
        {
            Dispatcher.BeginInvoke(() => UpdateUI(sr.SensorReading));
        }
        void UpdateUI(AccelerometerReading ar)
        {
            DispatcherTimer newTimer = new DispatcherTimer();
            newTimer.Interval = TimeSpan.FromSeconds(1);
            status.Text = "Getting Accelerometer Readings";
            Vector3 xyz = ar.Acceleration;
            values.Text = "X: " + xyz.X.ToString("0.00") + "\t" + "Y: " + xyz.Y.ToString("0.00") + "\t" + "Z: " + xyz.Z.ToString("0.00");
            newTimer.Tick += OnTimerTick;
            newTimer.Start();

        }
        void OnTimerTick(Object sender, EventArgs args)
        {
            IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication();
            isoStore.CreateDirectory("Accelerometer");
            IsolatedStorageFileStream fileStream=isoStore.OpenFile("Accelerometer\\myFile.txt",FileMode.Append,FileAccess.Write);
            using(StreamWriter writeFile=new StreamWriter(fileStream))
            {
            writeFile.WriteLine(values.Text);
            writeFile.Close();
            }
        }

        private void read_Click(object sender, RoutedEventArgs e)
        {
            IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();
            IsolatedStorageFileStream fileStream = myIsolatedStorage.OpenFile("Accelerometer\\myFile.txt", FileMode.Open, FileAccess.Read);
            fileStream.Position = 0;
            using (StreamReader reader = new StreamReader(fileStream))
            {
                values.Text += "\n" + reader.ReadToEnd();
            }
        }
    }

Answer 1

I copy-pasted your code and it works fine for me. Try resizing the values textblock and setting the textwrapping property to wrap, maybe that is the reason you dont see them

Also I wouldnt use a new Dispatchertimer object every time, initalizing, and starting, you could have just one for the whole app

hope that helps you!