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ApplicationSettingsBase Class

Acts as a base class for deriving concrete wrapper classes to implement the application settings feature in Window Forms applications.

Namespace:  System.Configuration
Assembly:  System (in System.dll)
public abstract class ApplicationSettingsBase : SettingsBase, 
	INotifyPropertyChanged

ApplicationSettingsBase adds the following functionality to the SettingsBase class, which is used by Web-based applications:

  • The ability to detect attributes on a derived, settings wrapper class. ApplicationSettingsBase supports the declarative model used for wrapper class properties, as described later.

  • Higher-level Save and Reload methods.

  • Additional validation events that you can handle to ensure the correctness of individual settings.

In the application settings architecture, to access a group of settings properties you need to derive a concrete wrapper class from ApplicationSettingsBase. The wrapper class customizes ApplicationSettingsBase in the following ways:

  • For every settings property to be accessed, a corresponding strongly typed public property is added to the wrapper class. This property has get and set accessors for read/write application settings, but only a get accessor for read-only settings.

  • Appropriated attributes must be applied to the wrapper class's public properties to indicate characteristics of the settings property, such as the setting's scope (application or user), whether the setting should support roaming, the default value for the setting, the settings provider to be used, and so on. Each property is required to specify its scope, using either ApplicationScopedSettingAttribute or UserScopedSettingAttribute. Application-scoped settings are read-only if the default LocalFileSettingsProvider is used.

The ApplicationSettingsBase class uses reflection to detect these attributes at run time. Most of this information gets passed to the settings provider layer, which is responsible for storage, persistence format, and so on.

When an application has multiple settings wrapper classes, each class defines a settings group. Each group has the following characteristics:

  • A group can contain any number or type of property settings.

  • If the group name is not explicitly set by the decorating the wrapper class with a SettingsGroupNameAttribute, then a name is automatically generated.

By default, all client-based applications use the LocalFileSettingsProvider to provide storage. If an alternate settings provider is desired, then the wrapper class or property must be decorated with a corresponding SettingsProviderAttribute.

For more information about using application settings, see Application Settings for Windows Forms.

The following code example demonstrates the use of application settings to persist the following attributes of the main form: location, size, background color, and title bar text. All of these attributes are persisted as single application settings properties in the FormSettings class, named FormLocation, FormSize, FormBackColor and FormText, respectively. All except for FormText and Size are data bound to their associated form properties and have a default setting value applied using DefaultSettingValueAttribute.

The form contains four child controls that have the following names and functions:

  • A button named btnBackColor used to display the Color common dialog box.

  • A button named btnReload used to Reload the application settings.

  • A button named btnReset used to Reset the application settings.

  • A textbox named tbStatus used to display status information about the program.

Notice that after every execution of the application, an additional period character is appended to the title text of the form.

This code example requires a Form with a ColorDialog class named colorDialog1, and a StatusStrip control with a ToolStripStatusLabel named tbStatus. Additionally, it requires three Button objects named btnReload, btnReset, and btnBackColor.

partial class Form1 : Form
{
    private FormSettings frmSettings1 = new FormSettings();

    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        this.FormClosing += new FormClosingEventHandler(Form1_FormClosing);

        //Associate settings property event handlers.
        frmSettings1.SettingChanging += new SettingChangingEventHandler(
                                            frmSettings1_SettingChanging);
        frmSettings1.SettingsSaving += new SettingsSavingEventHandler(
                                            frmSettings1_SettingsSaving);

        //Data bind settings properties with straightforward associations.
        Binding bndBackColor = new Binding("BackColor", frmSettings1, 
            "FormBackColor", true, DataSourceUpdateMode.OnPropertyChanged);
        this.DataBindings.Add(bndBackColor);
        Binding bndLocation = new Binding("Location", frmSettings1, 
            "FormLocation", true, DataSourceUpdateMode.OnPropertyChanged);
        this.DataBindings.Add(bndLocation);

        // Assign Size property, since databinding to Size doesn't work well. 
         this.Size = frmSettings1.FormSize;

        //For more complex associations, manually assign associations.
        String savedText = frmSettings1.FormText;
        //Since there is no default value for FormText. 
        if (savedText != null)
            this.Text = savedText;
    }

    private void Form1_FormClosing(object sender, FormClosingEventArgs e)
    {
        //Synchronize manual associations first.
        frmSettings1.FormText = this.Text + '.';
        frmSettings1.FormSize = this.Size;
        frmSettings1.Save();
    }

    private void btnBackColor_Click(object sender, EventArgs e)
    {
        if (DialogResult.OK == colorDialog1.ShowDialog())
        {
            Color c = colorDialog1.Color;
            this.BackColor = c;
        }
    }

    private void btnReset_Click(object sender, EventArgs e)
    {
        frmSettings1.Reset();
        this.BackColor = SystemColors.Control;
    }

    private void btnReload_Click(object sender, EventArgs e)
    {
        frmSettings1.Reload();
    }

    void frmSettings1_SettingChanging(object sender, SettingChangingEventArgs e)
    {
        tbStatus.Text = e.SettingName + ": " + e.NewValue;
    }

    void frmSettings1_SettingsSaving(object sender, CancelEventArgs e)
    {
        //Should check for settings changes first.
        DialogResult dr = MessageBox.Show(
                        "Save current values for application settings?",
                        "Save Settings", MessageBoxButtons.YesNo);
        if (DialogResult.No == dr)
        {
            e.Cancel = true;
        }
    }

}

//Application settings wrapper class 
sealed class FormSettings : ApplicationSettingsBase
{
    [UserScopedSettingAttribute()]
    public String FormText
    {
        get { return (String)this["FormText"]; }
        set { this["FormText"] = value; }
    }

    [UserScopedSettingAttribute()]
    [DefaultSettingValueAttribute("0, 0")]
    public Point FormLocation
    {
        get { return (Point)(this["FormLocation"]); }
        set { this["FormLocation"] = value; }
    }

    [UserScopedSettingAttribute()]
    [DefaultSettingValueAttribute("225, 200")]
    public Size FormSize
    {
        get { return (Size)this["FormSize"]; }
        set { this["FormSize"] = value; }
    }


    [UserScopedSettingAttribute()]
    [DefaultSettingValueAttribute("LightGray")]
    public Color FormBackColor
    {
        get { return (Color)this["FormBackColor"]; }
        set { this["FormBackColor"] = value; }
    }

}
System.Object
  System.Configuration.SettingsBase
    System.Configuration.ApplicationSettingsBase
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

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