在WPF对话框中如何验证用户提供的数据

using System.Globalization;
using System.Windows.Controls;

namespace SDKSample
{
public class MarginValidationRule : ValidationRule
{
double minMargin;
double maxMargin;

public double MinMargin
{
get { return this.minMargin; }
set { this.minMargin = value; }
}

public double MaxMargin
{
get { return this.maxMargin; }
set { this.maxMargin = value; }
}

public override ValidationResult Validate(object value, CultureInfo cultureInfo)
{
double margin;

// Is a number?
if (!double.TryParse((string)value, out margin))
{
return new ValidationResult(false, "Not a number.");
}

// Is in range?
if ((margin < this.minMargin) || (margin > this.maxMargin))
{
string msg = string.Format("Margin must be between {0} and {1}.", this.minMargin, this.maxMargin);
return new ValidationResult(false, msg);
}

// Number is valid
return new ValidationResult(true, null);
}
}
}

Imports System.Globalization
Imports System.Windows.Controls

Namespace SDKSample

Public Class MarginValidationRule
Inherits ValidationRule

Private _maxMargin As Double
Private _minMargin As Double

Public Property MaxMargin() As Double
Get
Return Me._maxMargin
End Get
Set(ByVal value As Double)
Me._maxMargin = value
End Set
End Property

Public Property MinMargin() As Double
Get
Return Me._minMargin
End Get
Set(ByVal value As Double)
Me._minMargin = value
End Set
End Property

Public Overrides Function Validate(ByVal value As Object, ByVal cultureInfo As CultureInfo) As ValidationResult

Dim margin As Double

' Is a number?
If Not Double.TryParse(CStr(value), margin) Then
Return New ValidationResult(False, "Not a number.")
End If

' Is in range?
If ((margin < Me.MinMargin) OrElse (margin > Me.MaxMargin)) Then
Dim msg As String = String.Format("Margin must be between {0} and {1}.", Me.MinMargin, Me.MaxMargin)
Return New ValidationResult(False, msg)
End If

' Number is valid
Return New ValidationResult(True, Nothing)

End Function

End Class

End Namespace

<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Class="SDKSample.MarginsDialogBox"
xmlns:local="clr-namespace:SDKSample"
Title="Margins"
Height="190"
Width="300"
MinHeight="10"
MinWidth="300"
ResizeMode="CanResizeWithGrip"
ShowInTaskbar="False"
WindowStartupLocation="CenterOwner"
FocusManager.FocusedElement="{Binding ElementName=leftMarginTextBox}">

<Grid>

...

<Label Grid.Column="0" Grid.Row="0">Left Margin:</Label>
<TextBox Name="leftMarginTextBox" Grid.Column="1" Grid.Row="0">
<TextBox.Text>
<Binding Path="Left" UpdateSourceTrigger="PropertyChanged">
<Binding.ValidationRules>
<local:MarginValidationRule MinMargin="0" MaxMargin="10" />
</Binding.ValidationRules>
</Binding>
</TextBox.Text>
</TextBox>

...

</Window>

using System.Windows; // Window, RoutedEventArgs, IInputElement, DependencyObject
using System.Windows.Controls; // Validation
using System.Windows.Input; // Keyboard

namespace SDKSample
{
public partial class MarginsDialogBox : Window
{

...

void okButton_Click(object sender, RoutedEventArgs e)
{
// Don't accept the dialog box if there is invalid data
if (!IsValid(this)) return;

...

}

// Validate all dependency objects in a window
bool IsValid(DependencyObject node)
{
// Check if dependency object was passed
if (node != null)
{
// Check if dependency object is valid.
// NOTE: Validation.GetHasError works for controls that have validation rules attached
bool isValid = !Validation.GetHasError(node);
if (!isValid)
{
// If the dependency object is invalid, and it can receive the focus,
// set the focus
if (node is IInputElement) Keyboard.Focus((IInputElement)node);
return false;
}
}

// If this dependency object is valid, check all child dependency objects
foreach (object subnode in LogicalTreeHelper.GetChildren(node))
{
if (subnode is DependencyObject)
{
// If a child dependency object is invalid, return false immediately,
// otherwise keep checking
if (IsValid((DependencyObject)subnode) == false) return false;
}
}

// All dependency objects are valid
return true;
}
}
}

Imports System.Windows ' Window, RoutedEventArgs, IInputElement, DependencyObject
Imports System.Windows.Controls ' Validation
Imports System.Windows.Input ' Keyboard

Namespace SDKSample

Public Class MarginsDialogBox
Inherits Window

...

Private Sub okButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
' Don't accept the dialog box if there is invalid data
If Not Me.IsValid(Me) Then Return

...

End Sub

' Validate all dependency objects in a window
Private Function IsValid(ByVal node As DependencyObject) As Boolean

' Check if dependency object was passed and if dependency object is valid.
' NOTE: Validation.GetHasError works for controls that have validation rules attached
If ((Not node Is Nothing) AndAlso Validation.GetHasError(node)) Then
' If the dependency object is invalid, and it can receive the focus,
' set the focus
If TypeOf node Is IInputElement Then
Keyboard.Focus(DirectCast(node, IInputElement))
End If
Return False
End If

' If this dependency object is valid, check all child dependency objects
Dim subnode As Object
For Each subnode In LogicalTreeHelper.GetChildren(node)
If (TypeOf subnode Is DependencyObject AndAlso Not Me.IsValid(DirectCast(subnode, DependencyObject))) Then
' If a child dependency object is invalid, return false immediately,
' otherwise keep checking
Return False
End If
Next

' All dependency objects are valid
Return True

End Function

End Class

End Namespace