Save registry values in WinCE using a C# app

Question

Hey all,

I'm working on a WinCE 6.0 system with a touchscreen that stores its calibration data (x-y location, offset, etc.) in the system registry (HKLM\HARDWARE\TOUCH). Right now, I'm placing the cal values into registry keys that get put into the OS image at build time. That works fine for the monitor that I get the original cal values from, but when I load this image into another system with a different monitor, the touchscreen pointer location is (understandably) off, because the two monitors do not have the same cal values.

My problem is that I don't know how to properly store values into the registry so that they persist after a power cycle. See, I can recalibrate the screen on the second system, but the new values only exist in volatile memory. I suggested to my boss that we could just tell our customer to leave the power on the unit at all times -- that didn't go over well.

I need advice on how to save the new constants into the registry, so that we can calibrate the monitors once before shipping them out to our customer, and not have to make separate OS images for each unit we build.

A C# method that is known to work in CE6.0 would be helpful. Thanks.

-Odbasta

Answer 1

I think what you're probably looking for is the Flush function of the RegistryKey class. This is normally not necessary (the registry is lazily-flushed by default), but if the power is turned off on the device before the system has a chance to do this, changes will be discarded:

http://msdn.microsoft.com/en-us/library/microsoft.win32.registrykey.flush.aspx

This function is available in .NET Compact Framework version 2.0 and better.

Answer 2

As I understood you need to know how to set a value to the registry during runtime. I hope the codes bellow can help you.

using Microsoft.Win32;

    /// <summary>
    /// store a key value in registry. if it don't exist it will be created. 
    /// </summary>
    /// <param name="mainKey">the main key of key path</param>
    /// <param name="subKey">the path below the main key</param>
    /// <param name="keyName">the key name</param>
    /// <param name="value">the value to be stored</param>
    public static void SetRegistry(int mainKey, String subKey, String keyName, object value)
    {
        if (mainKey != CURRENT_USER && mainKey != LOCAL_MACHINE)
        {
            throw new ArgumentOutOfRangeException("mainKey", "\'mainKey\' argument can only be AppUtils.CURRENT_USER or AppUtils.LOCAL_MACHINE values");
        }

        if (subKey == null)
        {
            throw new ArgumentNullException("subKey", "\'subKey\' argument cannot be null");
        }

        if (keyName == null)
        {
            throw new ArgumentNullException("keyName", "\'keyName\' argument cannot be null");
        }

        const Boolean WRITABLE = true;
        RegistryKey key = null;

        if (mainKey == CURRENT_USER)
        {
            key = Registry.CurrentUser.OpenSubKey(subKey, WRITABLE);

            if (key == null)
            {
                key = Registry.CurrentUser.CreateSubKey(subKey);
            }
        }
        else if (mainKey == LOCAL_MACHINE)
        {
            key = Registry.LocalMachine.OpenSubKey(subKey, WRITABLE);

            if (key == null)
            {
                key = Registry.LocalMachine.CreateSubKey(subKey);
            }
        }

        key.SetValue(keyName, value);

    }

    /// <summary>
    /// find a key value in registry. if it don't exist the default value will be returned.
    /// </summary>
    /// <param name="mainKey">the main key of key path</param>
    /// <param name="subKey">the path below the main key</param>
    /// <param name="keyName">the key name</param>
    /// <param name="defaultValue">the value to be stored</param>

    public static object GetRegistry(int mainKey, String subKey, String keyName, object defaultValue)
    {
        if (mainKey != CURRENT_USER && mainKey != LOCAL_MACHINE)
        {
            throw new ArgumentOutOfRangeException("mainKey", "\'mainKey\' argument can only be AppUtils.CURRENT_USER or AppUtils.LOCAL_MACHINE values");
        }

        if (subKey == null)
        {
            throw new ArgumentNullException("subKey", "\'subKey\' argument cannot be null");
        }

        if (keyName == null)
        {
            throw new ArgumentNullException("keyName", "\'keyName\' argument cannot be null");
        }

        RegistryKey key = Registry.CurrentUser.OpenSubKey(subKey);

        if (mainKey == CURRENT_USER)
        {
            key = Registry.CurrentUser.OpenSubKey(subKey);
        }
        else if (mainKey == LOCAL_MACHINE)
        {
            key = Registry.LocalMachine.OpenSubKey(subKey);
        }

        object result = defaultValue;

        if (key != null)
        {
            result = key.GetValue(keyName, defaultValue);
        }

        return result;
    }