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ErrorIconAlignment Enumeration

Specifies constants indicating the locations that an error icon can appear in relation to the control with an error.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

'Declaration
Public Enumeration ErrorIconAlignment
'Usage
Dim instance As ErrorIconAlignment

public enum ErrorIconAlignment
public enum ErrorIconAlignment

 Member nameDescription
BottomLeftThe icon appears aligned with the bottom of the control and the left of the control. 
BottomRightThe icon appears aligned with the bottom of the control and the right of the control. 
MiddleLeftThe icon appears aligned with the middle of the control and the left of the control. 
MiddleRightThe icon appears aligned with the middle of the control and the right of the control. 
TopLeftThe icon appears aligned with the top of the control and to the left of the control. 
TopRightThe icon appears aligned with the top of the control and to the right of the control. 

This enumeration is used by ErrorProvider.

The following example demonstrates using the ErrorProvider class to notify the user of a data entry error. The example creates a Form that contains a TextBox control, a NumericUpDown control, and a ComboBox control, each validating its content, and an ErrorProvider for each control. The example sets error icon options using the BlinkRate and BlinkStyle properties and the SetIconAlignment and SetIconPadding methods. The SetError method is called with or without appropriate error text during a control's Validated event, depending upon the content in the control.

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Namespace ErrorProvider

    Public NotInheritable Class Form1
        Inherits System.Windows.Forms.Form
    
        Private label1 As System.Windows.Forms.Label
        Private label2 As System.Windows.Forms.Label
        Private label3 As System.Windows.Forms.Label      
        Private label4 As System.Windows.Forms.Label
        Private label5 As System.Windows.Forms.Label
        Private label6 As System.Windows.Forms.Label
        Friend WithEvents favoriteColorComboBox As System.Windows.Forms.ComboBox 
        Friend WithEvents nameTextBox1 As System.Windows.Forms.TextBox 
        Friend WithEvents ageUpDownPicker As System.Windows.Forms.NumericUpDown      
        Private ageErrorProvider As System.Windows.Forms.ErrorProvider 
        Private nameErrorProvider As System.Windows.Forms.ErrorProvider 
        Private favoriteColorErrorProvider As System.Windows.Forms.ErrorProvider
        
        <System.STAThread()>  _
        Public Shared Sub Main()
            System.Windows.Forms.Application.Run(New Form1())
        End Sub 'Main

        Public Sub New()
            
            Me.nameTextBox1 = New System.Windows.Forms.TextBox()
            Me.label1 = New System.Windows.Forms.Label()
            Me.label2 = New System.Windows.Forms.Label()
            Me.ageUpDownPicker = New System.Windows.Forms.NumericUpDown()
            Me.favoriteColorComboBox = New System.Windows.Forms.ComboBox()
            Me.label3 = New System.Windows.Forms.Label()
            Me.label4 = New System.Windows.Forms.Label()
            Me.label5 = New System.Windows.Forms.Label()
            Me.label6 = New System.Windows.Forms.Label()

            ' Name Label
            Me.label1.Location = New System.Drawing.Point(56, 32)
            Me.label1.Size = New System.Drawing.Size(40, 23)
            Me.label1.Text = "Name:"

            ' Age Label
            Me.label2.Location = New System.Drawing.Point(40, 64)
            Me.label2.Size = New System.Drawing.Size(56, 23)
            Me.label2.Text = "Age (3-5)"

            ' Favorite Color Label
            Me.label3.Location = New System.Drawing.Point(24, 96)
            Me.label3.Size = New System.Drawing.Size(80, 24)
            Me.label3.Text = "Favorite color"

            ' ErrorBlinkStyle.AlwaysBlink Label
            Me.label4.Location = New System.Drawing.Point(264, 32)
            Me.label4.Size = New System.Drawing.Size(160, 23)
            Me.label4.Text = "ErrorBlinkStyle.AlwaysBlink"

            ' ErrorBlinkStyle.BlinkIfDifferentError Label
            Me.label5.Location = New System.Drawing.Point(264, 64)
            Me.label5.Size = New System.Drawing.Size(200, 23)
            Me.label5.Text = "ErrorBlinkStyle.BlinkIfDifferentError"

            ' ErrorBlinkStyle.NeverBlink Label
            Me.label6.Location = New System.Drawing.Point(264, 96)
            Me.label6.Size = New System.Drawing.Size(200, 23)
            Me.label6.Text = "ErrorBlinkStyle.NeverBlink"

            ' Name TextBox
            Me.nameTextBox1.Location = New System.Drawing.Point(112, 32)
            Me.nameTextBox1.Size = New System.Drawing.Size(120, 20)
            Me.nameTextBox1.TabIndex = 0

            ' Age NumericUpDown
            Me.ageUpDownPicker.Location = New System.Drawing.Point(112, 64)
            Me.ageUpDownPicker.Maximum = New System.Decimal(New Integer() {150, 0, 0, 0})
            Me.ageUpDownPicker.TabIndex = 4

            ' Favorite Color ComboBox
            Me.favoriteColorComboBox.Items.AddRange(New Object() {"None", "Red", "Yellow", _
                                                                                    "Green", "Blue", "Purple"})
            Me.favoriteColorComboBox.Location = New System.Drawing.Point(112, 96)
            Me.favoriteColorComboBox.Size = New System.Drawing.Size(120, 21)
            Me.favoriteColorComboBox.TabIndex = 5

            ' Set up how the form should be displayed and add the controls to the form.
            Me.ClientSize = New System.Drawing.Size(464, 150)
            Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.label6, Me.label5, Me.label4, _
                                          Me.label3, Me.favoriteColorComboBox, Me.ageUpDownPicker, Me.label2, _
                                          Me.label1, Me.nameTextBox1})

            Me.Text = "Error Provider Example"

            ' Create and set the ErrorProvider for each data entry control.
     
            nameErrorProvider = New System.Windows.Forms.ErrorProvider()
            nameErrorProvider.SetIconAlignment(Me.nameTextBox1, ErrorIconAlignment.MiddleRight)
            nameErrorProvider.SetIconPadding(Me.nameTextBox1, 2)
            nameErrorProvider.BlinkRate = 1000
            nameErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.AlwaysBlink
            
            ageErrorProvider = New System.Windows.Forms.ErrorProvider()
            ageErrorProvider.SetIconAlignment(Me.ageUpDownPicker, ErrorIconAlignment.MiddleRight)
            ageErrorProvider.SetIconPadding(Me.ageUpDownPicker, 2)
            ageErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.BlinkIfDifferentError
            
            favoriteColorErrorProvider = New System.Windows.Forms.ErrorProvider()
            favoriteColorErrorProvider.SetIconAlignment(Me.favoriteColorComboBox, ErrorIconAlignment.MiddleRight)
            favoriteColorErrorProvider.SetIconPadding(Me.favoriteColorComboBox, 2)
            favoriteColorErrorProvider.BlinkRate = 1000
            favoriteColorErrorProvider.BlinkStyle = System.Windows.Forms.ErrorBlinkStyle.NeverBlink
        End Sub 'New
 
        Private Sub nameTextBox1_Validated(sender As Object, e As System.EventArgs) Handles nameTextBox1.Validated
            If IsNameValid() Then
                ' Clear the error, if any, in the error provider.
                nameErrorProvider.SetError(Me.nameTextBox1, "")
            Else
                ' Set the error if the name is not valid.
                nameErrorProvider.SetError(Me.nameTextBox1, "Name is required.")
            End If 
        End Sub 
              
        Private Sub ageUpDownPicker_Validated(sender As Object, e As System.EventArgs) Handles ageUpDownPicker.Validated
            If IsAgeTooYoung() Then
                ' Set the error if the age is too young.
                ageErrorProvider.SetError(Me.ageUpDownPicker, "Age not old enough")
            ElseIf IsAgeTooOld() Then
                ' Set the error if the age is too old.
                ageErrorProvider.SetError(Me.ageUpDownPicker, "Age is too old")
            Else
                ' Clear the error, if any, in the error provider.
                ageErrorProvider.SetError(Me.ageUpDownPicker, "")
            End If
        End Sub
         
        Private Sub favoriteColorComboBox_Validated(sender As Object, e As System.EventArgs) Handles favoriteColorComboBox.Validated
            If Not IsColorValid() Then
                ' Set the error if the favorite color is not valid.
                favoriteColorErrorProvider.SetError(Me.favoriteColorComboBox, "Must select a color.")            
            Else
                ' Clear the error, if any, in the error provider.
                favoriteColorErrorProvider.SetError(Me.favoriteColorComboBox, "")
            End If
        End Sub 

        ' Functions to verify data.
        Private Function IsNameValid() As Boolean
            ' Determine whether the text box contains a zero-length string.
            Return nameTextBox1.Text.Length > 0
        End Function 

        Private Function IsAgeTooYoung() As Boolean
            ' Determine whether the age value is less than three.
            Return ageUpDownPicker.Value < 3
        End Function 
        
        
        Private Function IsAgeTooOld() As Boolean
            ' Determine whether the age value is greater than five.
            Return ageUpDownPicker.Value > 5
        End Function 
                
        Private Function IsColorValid() As Boolean
            ' Determine whether the favorite color has a valid value.
            If Not (favoriteColorComboBox.SelectedItem Is Nothing) Then
                    If Not(favoriteColorComboBox.SelectedItem.ToString().Equals("None")) Then
                        Return true 
                    End If
            End If
            Return false
        End Function 

    End Class 'Form1
End Namespace 'ErrorProvider 

package ErrorProvider;

import System.*;
import System.Drawing.*;
import System.Windows.Forms.*;

public class Form1 extends System.Windows.Forms.Form
{
    private System.Windows.Forms.Label label1;
    private System.Windows.Forms.Label label2;
    private System.Windows.Forms.Label label4;
    private System.Windows.Forms.Label label5;
    private System.Windows.Forms.Label label6;
    private System.Windows.Forms.Label label3;
    private System.Windows.Forms.TextBox nameTextBox1;
    private System.Windows.Forms.NumericUpDown ageUpDownPicker;
    private System.Windows.Forms.ComboBox favoriteColorComboBox;
    private System.Windows.Forms.ErrorProvider ageErrorProvider;
    private System.Windows.Forms.ErrorProvider nameErrorProvider;
    private System.Windows.Forms.ErrorProvider favoriteColorErrorProvider;

    /** @attribute STAThread()
     */
    public static void main(String[] args)
    {
        Application.Run(new Form1());
    } //main

    public Form1()
    {
        this.nameTextBox1 = new System.Windows.Forms.TextBox();
        this.label1 = new System.Windows.Forms.Label();
        this.label2 = new System.Windows.Forms.Label();
        this.ageUpDownPicker = new System.Windows.Forms.NumericUpDown();
        this.favoriteColorComboBox = new System.Windows.Forms.ComboBox();
        this.label3 = new System.Windows.Forms.Label();
        this.label4 = new System.Windows.Forms.Label();
        this.label5 = new System.Windows.Forms.Label();
        this.label6 = new System.Windows.Forms.Label();
        // Name Label
        this.label1.set_Location(new System.Drawing.Point(56, 32));
        this.label1.set_Size(new System.Drawing.Size(40, 23));
        this.label1.set_Text("Name:");
        // Age Label
        this.label2.set_Location(new System.Drawing.Point(40, 64));
        this.label2.set_Size(new System.Drawing.Size(56, 23));
        this.label2.set_Text("Age (3-5)");
        // Favorite Color Label
        this.label3.set_Location(new System.Drawing.Point(24, 96));
        this.label3.set_Size(new System.Drawing.Size(80, 24));
        this.label3.set_Text("Favorite color");
        // ErrorBlinkStyle.AlwaysBlink Label
        this.label4.set_Location(new System.Drawing.Point(264, 32));
        this.label4.set_Size(new System.Drawing.Size(160, 23));
        this.label4.set_Text("ErrorBlinkStyle.AlwaysBlink");
        // ErrorBlinkStyle.BlinkIfDifferentError Label
        this.label5.set_Location(new System.Drawing.Point(264, 64));
        this.label5.set_Size(new System.Drawing.Size(200, 23));
        this.label5.set_Text("ErrorBlinkStyle.BlinkIfDifferentError");
        // ErrorBlinkStyle.NeverBlink Label
        this.label6.set_Location(new System.Drawing.Point(264, 96));
        this.label6.set_Size(new System.Drawing.Size(200, 23));
        this.label6.set_Text("ErrorBlinkStyle.NeverBlink");
        // Name TextBox
        this.nameTextBox1.set_Location(new System.Drawing.Point(112, 32));
        this.nameTextBox1.set_Size(new System.Drawing.Size(120, 20));
        this.nameTextBox1.set_TabIndex(0);
        this.nameTextBox1.add_Validated(new System.EventHandler(
            this.nameTextBox1_Validated));
        // Age NumericUpDown
        this.ageUpDownPicker.set_Location(new System.Drawing.Point(112, 64));
        this.ageUpDownPicker.set_Maximum(new System.Decimal(new int[] {
            150, 0, 0, 0 }));
        this.ageUpDownPicker.set_TabIndex(4);
        this.ageUpDownPicker.add_Validated(new System.EventHandler(
            this.ageUpDownPicker_Validated));
        // Favorite Color ComboBox
        this.favoriteColorComboBox.get_Items().AddRange(new Object[] { 
            "None", "Red", "Yellow", "Green", "Blue", "Purple" });
        this.favoriteColorComboBox.set_Location(
            new System.Drawing.Point(112, 96));
        this.favoriteColorComboBox.set_Size(new System.Drawing.Size(120, 21));
        this.favoriteColorComboBox.set_TabIndex(5);
        this.favoriteColorComboBox.add_Validated(new System.EventHandler(
            this.favoriteColorComboBox_Validated));
        // Set up how the form should be displayed and add the controls to 
        // the form.
        this.set_ClientSize(new System.Drawing.Size(464, 150));
        this.get_Controls().AddRange(new System.Windows.Forms.Control[] { 
            this.label6, this.label5, this.label4, this.label3, 
            this.favoriteColorComboBox, this.ageUpDownPicker, this.label2, 
            this.label1, this.nameTextBox1 });
        this.set_Text("Error Provider Example");
        // Create and set the ErrorProvider for each data entry control.
        nameErrorProvider = new System.Windows.Forms.ErrorProvider();
        nameErrorProvider.SetIconAlignment(this.nameTextBox1, 
            ErrorIconAlignment.MiddleRight);
        nameErrorProvider.SetIconPadding(this.nameTextBox1, 2);
        nameErrorProvider.set_BlinkRate(1000);
        nameErrorProvider.set_BlinkStyle(
            System.Windows.Forms.ErrorBlinkStyle.AlwaysBlink);
        nameErrorProvider.set_ContainerControl(this);

        ageErrorProvider = new System.Windows.Forms.ErrorProvider();
        ageErrorProvider.SetIconAlignment(this.ageUpDownPicker, 
            ErrorIconAlignment.MiddleRight);
        ageErrorProvider.SetIconPadding(this.ageUpDownPicker, 2);
        ageErrorProvider.set_BlinkStyle(
            System.Windows.Forms.ErrorBlinkStyle.BlinkIfDifferentError);
        ageErrorProvider.set_ContainerControl(this);

        favoriteColorErrorProvider = new System.Windows.Forms.ErrorProvider();
        favoriteColorErrorProvider.SetIconAlignment(this.favoriteColorComboBox, 
            ErrorIconAlignment.MiddleRight);
        favoriteColorErrorProvider.SetIconPadding(this.favoriteColorComboBox, 2);
        favoriteColorErrorProvider.set_BlinkRate(1000);
        favoriteColorErrorProvider.set_BlinkStyle(
            System.Windows.Forms.ErrorBlinkStyle.NeverBlink);
        favoriteColorErrorProvider.set_ContainerControl(this);
    } //Form1
    
    private void nameTextBox1_Validated(Object sender, System.EventArgs e)
    {
        if (IsNameValid()) {
            // Clear the error, if any, in the error provider.
            nameErrorProvider.SetError(this.nameTextBox1, "");
        }
        else {
            // Set the error if the name is not valid.
            nameErrorProvider.SetError(this.nameTextBox1, "Name is required.");
        }
    } //nameTextBox1_Validated

    private void ageUpDownPicker_Validated(Object sender, System.EventArgs e)
    {
        if (IsAgeTooYoung()) {
            // Set the error if the age is too young.
            ageErrorProvider.SetError(this.ageUpDownPicker, 
                "Age not old enough");
        }
        else {
            if (IsAgeTooOld()) {
                // Set the error if the age is too old.
                ageErrorProvider.SetError(this.ageUpDownPicker, 
                    "Age is too old");
            }
            else {
                // Clear the error, if any, in the error provider.
                ageErrorProvider.SetError(this.ageUpDownPicker, "");
            }
        }
    } //ageUpDownPicker_Validated

    private void favoriteColorComboBox_Validated(Object sender, 
        System.EventArgs e)
    {
        if (!(IsColorValid())) {
            // Set the error if the favorite color is not valid.
            favoriteColorErrorProvider.SetError(this.favoriteColorComboBox, 
                "Must select a color.");
        }
        else {
            // Clear the error, if any, in the error provider.
            favoriteColorErrorProvider.SetError(
                this.favoriteColorComboBox, "");
        }
    } //favoriteColorComboBox_Validated

    // Functions to verify data.
    private boolean IsNameValid()
    {
        // Determine whether the text box contains a zero-length string.
        return ((nameTextBox1.get_Text().get_Length()) > 0);
    } //IsNameValid

    private boolean IsAgeTooYoung()
    {
        // Determine whether the age value is less than three.
        return (System.Convert.ToInt32(ageUpDownPicker.get_Value()) < 3);
    } //IsAgeTooYoung

    private boolean IsAgeTooOld()
    {
        // Determine whether the age value is greater than five.
        return (System.Convert.ToInt32(ageUpDownPicker.get_Value()) > 5);
    } //IsAgeTooOld

    private boolean IsColorValid()
    {
        // Determine whether the favorite color has a valid value.
        return (favoriteColorComboBox.get_SelectedItem() != null) 
            && (!(favoriteColorComboBox.get_SelectedItem().
            ToString().Equals("None")));
    } //IsColorValid
} //Form1

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

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