Specify MessageBoxOptions

Cause

A method calls an overload of the MessageBox.Show method that does not take a System.Windows.Forms.MessageBoxOptions argument.

Rule Description

To display a message box correctly for cultures that use a right to left reading order, the RightAlign and RtlReading members of the MessageBoxOptions enumeration must be passed to the Show method. Examine the Control.RightToLeft property of the containing control to determine whether to use a right to left reading order.

How to Fix Violations

To fix a violation of this rule, call an overload of the Show method that takes a MessageBoxOptions argument.

When to Suppress Warnings

It is safe to suppress a warning from this rule if the code library will not be localized for a culture that uses a right to left reading order.

Example

The following example shows a method that displays a message box with options appropriate for the reading order of the culture. A resource file, which is not shown, is required to build the example. Follow the comments in the example to build the example without a resource file and test the right to left feature.

Imports System
Imports System.Globalization
Imports System.Resources
Imports System.Windows.Forms

Namespace GlobalizationLibrary
    Class Program

        <STAThread()> _
        Shared Sub Main()
            Dim myForm As New SomeForm()

            ' Uncomment the following line to test the right to left feature. 
            ' myForm.RightToLeft = RightToLeft.Yes
            Application.Run(myForm)
        End Sub 
    End Class 

    Public Class SomeForm : Inherits Form
        Private _Resources As ResourceManager
        Private WithEvents _Button As Button

        Public Sub New()
            _Resources = New ResourceManager(GetType(SomeForm))
            _Button = New Button()
            Controls.Add(_Button)
        End Sub 

        Private Sub Button_Click(ByVal sender As Object, ByVal e As EventArgs) Handles _Button.Click
            ' Switch the commenting on the following 4 lines to test the form. 
            'Dim text As String = "Text" 
            'Dim caption As String = "Caption" 
            Dim text As String = _Resources.GetString("messageBox.Text")
            Dim caption As String = _Resources.GetString("messageBox.Caption")

            RtlAwareMessageBox.Show(CType(sender, Control), text, caption, _
            MessageBoxButtons.OK, MessageBoxIcon.Information, _
            MessageBoxDefaultButton.Button1, CType(0, MessageBoxOptions))
        End Sub 
    End Class 

    Public Module RtlAwareMessageBox

        Public Function Show(ByVal owner As IWin32Window, ByVal text As String, ByVal caption As String, ByVal buttons As MessageBoxButtons, ByVal icon As MessageBoxIcon, ByVal defaultButton As MessageBoxDefaultButton, ByVal options As MessageBoxOptions) As DialogResult
            If (IsRightToLeft(owner)) Then
                options = options Or MessageBoxOptions.RtlReading Or _
                MessageBoxOptions.RightAlign
            End If 

            Return MessageBox.Show(owner, text, caption, _
            buttons, icon, defaultButton, options)
        End Function 

        Private Function IsRightToLeft(ByVal owner As IWin32Window) As Boolean 
            Dim control As Control = TryCast(owner, Control)

            If (control IsNot Nothing) Then 
                Return control.RightToLeft = RightToLeft.Yes
            End If 

            ' If no parent control is available, ask the CurrentUICulture 
            ' if we are running under right-to-left. 
            Return CultureInfo.CurrentUICulture.TextInfo.IsRightToLeft
        End Function 
    End Module 
End Namespace

using System;
using System.Globalization;
using System.Resources;
using System.Windows.Forms;

namespace GlobalizationLibrary
{
    class Program
    {
        [STAThread]
        static void Main()
        {
            SomeForm myForm = new SomeForm();
            // Uncomment the following line to test the right-to-left feature. 
            //myForm.RightToLeft = RightToLeft.Yes;
            Application.Run(myForm);
        }
    }

    public class SomeForm : Form
    {
        private ResourceManager _Resources;
        private Button _Button;
        public SomeForm()
        {
            _Resources = new ResourceManager(typeof(SomeForm));
            _Button = new Button();
            _Button.Click += new EventHandler(Button_Click);
            Controls.Add(_Button);
        }

        private void Button_Click(object sender, EventArgs e)
        {
            // Switch the commenting on the following 4 lines to test the form. 
            // string text = "Text";
            // string caption = "Caption";
            string text = _Resources.GetString("messageBox.Text");
            string caption = _Resources.GetString("messageBox.Caption");
            RtlAwareMessageBox.Show((Control)sender, text, caption,
            MessageBoxButtons.OK, MessageBoxIcon.Information,
            MessageBoxDefaultButton.Button1, (MessageBoxOptions)0);
        }
    }

    public static class RtlAwareMessageBox
    {
        public static DialogResult Show(IWin32Window owner, string text, string caption, MessageBoxButtons buttons, MessageBoxIcon icon, MessageBoxDefaultButton defaultButton, MessageBoxOptions options)
        {
            if (IsRightToLeft(owner))
            {
                options |= MessageBoxOptions.RtlReading |
                MessageBoxOptions.RightAlign;
            }

            return MessageBox.Show(owner, text, caption,
            buttons, icon, defaultButton, options);
        }

        private static bool IsRightToLeft(IWin32Window owner)
        {
            Control control = owner as Control;

            if (control != null)
            {
                return control.RightToLeft == RightToLeft.Yes;
            }

            // If no parent control is available, ask the CurrentUICulture 
            // if we are running under right-to-left. 
            return CultureInfo.CurrentUICulture.TextInfo.IsRightToLeft;
        }
    }
}

See Also

Concepts

Resources in Applications

Reference

System.Resources.ResourceManager