Hi,
nachfolgend eine Demo in VB.NET und MVVM. Einfach alles in ein leeres Projekt kopieren und dann mit Button-Klick Bild aus Dateisystem auswählen.
XAML:
<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WpfApp1"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.DataContext>
<local:ViewModel/>
</Window.DataContext>
<StackPanel>
<RibbonButton Content="Test Button"
SmallImageSource="{Binding Bild}"/>
<Button Content="Bild laden" Command="{Binding Cmd}"/>
</StackPanel>
</Window>
Und die genutzten Klassen:
Imports System.ComponentModel
Imports System.Runtime.CompilerServices
Imports Microsoft.Win32
Public Class ViewModel
Implements INotifyPropertyChanged
Public Property Bild As ImageSource
Public Property Cmd As ICommand = New RelayCommand(Sub(state)
Dim ofd As New OpenFileDialog
If ofd.ShowDialog Then
Try
Bild = New BitmapImage(New Uri(ofd.FileName))
OnPropChanged(NameOf(Bild))
Catch ex As Exception
MsgBox(ex.Message)
End Try
End If
End Sub)
#Region " PropertyChanged"
Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
Friend Sub OnPropChanged(<CallerMemberName> Optional propName As String = "")
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propName))
End Sub
#End Region
End Class
''' <summary>
''' Eine das ICommand-Interface implementierende Klasse, deren Ziel es ist,
''' über Delegates die Funktionalität an andere Objekte zu übertragen.
''' CanExecute ist standardmäßig "True".
''' </summary>
Public Class RelayCommand
Implements ICommand
#Region "Fields"
' der Delegate, der auszuführen ist
Private ReadOnly _execute As Action(Of Object)
Private ReadOnly _canExecute As Predicate(Of Object)
#End Region ' Fields
#Region "Constructors"
''' <summary>
''' Neuen Befehl (Command) erzeugen, der immer ausgefühert werden kann
''' </summary>
''' <param name="execute">The execution logic.</param>
Public Sub New(ByVal execute As Action(Of Object))
Me.New(execute, Nothing)
End Sub
''' <summary>
''' Neuen Befehl (Command) erzeugen mit zum Befehl gehörenden Methoden,
''' die die dazugehörenden Kriterien prüfen
''' </summary>
''' <param name="execute">The execution logic.</param>
''' <param name="canExecute">The execution status logic.</param>
Public Sub New(ByVal execute As Action(Of Object), ByVal canExecute As Predicate(Of Object))
If execute Is Nothing Then Throw New ArgumentNullException("execute")
Me._execute = execute
Me._canExecute = canExecute
End Sub
#End Region ' Constructors
#Region "ICommand Members"
<DebuggerStepThrough()>
Public Function CanExecute(ByVal parameter As Object) As Boolean Implements ICommand.CanExecute
' ohne Kriterien wird True geliefert, sonst werden Kriterien geprüft
Return If(Me._canExecute Is Nothing, True, Me._canExecute(parameter))
End Function
Public Custom Event CanExecuteChanged As EventHandler Implements ICommand.CanExecuteChanged
AddHandler(ByVal value As EventHandler)
AddHandler CommandManager.RequerySuggested, value
End AddHandler
RemoveHandler(ByVal value As EventHandler)
RemoveHandler CommandManager.RequerySuggested, value
End RemoveHandler
RaiseEvent(ByVal sender As Object, ByVal e As EventArgs)
End RaiseEvent
End Event
Public Sub Execute(ByVal parameter As Object) Implements ICommand.Execute
Me._execute(parameter)
End Sub
#End Region ' ICommand Members
End Class
--
Best Regards / Viele Grüße
Peter Fleischer (former MVP for Developer Technologies)
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