How to Access WPF controls using ElementHost?-CodePudding

I'm building an Add-in for Excel. I wanted to use WPF controls, so I followed this tutorial https://learn.microsoft.com/en-us/visualstudio/vsto/using-wpf-controls-in-office-solutions?view=vs-2022 I added some tab controls to get my feet wet, I particularly wanted to programmatically go to a tab item if some condition was met upon clicking a button in the Ribbon, I was able to access the header text of the tab item, but I was not able to modify it or set it to isSelected.

This is the code that I'm using:

Imports Microsoft.Office.Tools
Imports Microsoft.Office.Tools.Ribbon

Public Class Ribbon1
    Private myUserControl1 As MyUserControl
    Private myCustomTaskPane As CustomTaskPane

    Private Sub btnCheck_Click(sender As Object, e As RibbonControlEventArgs) Handles btnCheck.Click
        ' Show the taskpane
        myUserControl1 = New MyUserControl
        myCustomTaskPane = Globals.ThisAddIn.CustomTaskPanes.Add(myUserControl1, "Test addin")
        myCustomTaskPane.Width = 500
        myCustomTaskPane.Visible = True
        Dim uc As New UserControl1

        ' Check if there's a table
        If isThereATable() Then
            MsgBox("There is")
            MsgBox(uc.Tab2.Header) ' works
            uc.Tab2.Header = "new header" ' does not work

        Else
            MsgBox("There is not")
        End If

    End Sub
End Class

And this is the markup code:

<UserControl x:Class="UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:AutoTable"
             mc:Ignorable="d" 
             d:DesignHeight="450" Width="500">
    <Grid Width="500">
        <TabControl BorderThickness="1" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" HorizontalAlignment="Left" Width="500" Name="MainTab">
            <TabItem Header="Init" Name="Tab1" >
                <Grid Background="#FFE5E5E5" Margin="0">
                    <TextBlock HorizontalAlignment="Left" TextWrapping="Wrap" Text="The following button should create a table." VerticalAlignment="Top" FontSize="16" Margin="10,10,0,0"/>
                    <Button Content="Create table" HorizontalAlignment="Left" Margin="5,60,0,0" VerticalAlignment="Top" Width="100" Click="Button_Click" Height="30" FontSize="14"/>
                </Grid>
            </TabItem>
            <TabItem Header="CC" Name="Tab2" >
                <Grid Background="#FFE5E5E5"/>
            </TabItem>
        </TabControl>
    </Grid>
</UserControl>

I have called the tab control "MainTab", and the two tab items "Tab1" and "Tab2", I can not manipulate any of them with my current code.

UPDATE:

In order to use WPF controls in an Excel Add-In, the WPF User Control must be hosted by a Windows Forms UI Element, according to the docs. In this case, the WPF User Control is inside a Windows Forms User Control. The link above explains how this is done. In the code above, I was using variable names provided by microsoft's tutorial, but by using arguably better variable names, this piece of code would clarify the approach I was following and its solution:

Public Class Ribbon1
    Private ThisUserControl As UserControlWF
    Private ThisTaskPane As Microsoft.Office.Tools.CustomTaskPane

    Private Sub ShowTaskPane_Click(sender As Object, e As RibbonControlEventArgs) Handles ShowTaskPane.Click
        ThisUserControl = New UserControlWF

        'CustomTaskPanes can only add Windows Forms UI elements, a WPF User Control throws an error
        ThisTaskPane = Globals.ThisAddIn.CustomTaskPanes.Add(ThisUserControl, "Title")
        ThisTaskPane.Width = 510
        ThisTaskPane.Visible = True

        ' Just to test if a condition is true after it loads the task pane
        If isThereATable() Then
            MsgBox("There is a table")
            ThisUserControl.UserControlWPF1.Tab2.Header = "Different Header" 'Original header name is "TabItem2"
            ThisUserControl.UserControlWPF1.Tab2.IsSelected = True 'Tab1 is selected by default

            ' In my first approach, I was initializing another instance of the WPF control
            ' instead of using the one that was already initialized:
            ' Dim uc As New UserControlWPF
            ' MsgBox(uc.Tab2.Header) ' <- it worked
            ' uc.Tab2.Header = "Different Header" ' <- it did not work
            ' That's why I was able to access the Header from the class, but I couldn't
            ' modify the header that was already loaded
        Else
            MsgBox("There is no table")
        End If
    End Sub
End Class

CodePudding user response：

You are setting the Header property of the TabItem in uc, which is a new control that you create without adding it to the add-in.

I guess you should set it in myUserControl1:

Private Sub btnCheck_Click(sender As Object, e As RibbonControlEventArgs) Handles btnCheck.Click
    ' Show the taskpane
    myUserControl1 = New MyUserControl
    myCustomTaskPane = Globals.ThisAddIn.CustomTaskPanes.Add(myUserControl1, "Test addin")
    myCustomTaskPane.Width = 500
    myCustomTaskPane.Visible = True

    ' Check if there's a table
    If isThereATable() Then
        MsgBox("There is")
        MsgBox(myUserControl1.Tab2.Header) ' works
        myUserControl1.Tab2.Header = "new header" ' does not work

    Else
        MsgBox("There is not")
    End If

End Sub

Or you should add uc to Globals.ThisAddIn.CustomTaskPanes to be able to see the change.