WPF (vb.net) Text from web page to label/text block-CodePudding

I want to read and display a text from my HTML Page into a Label or TextBlock in my WPF application. How do I do that?

With Windows Forms I have done it this way:

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    WebBrowser1.Navigate("C:\Users\Test\Desktop\Webseite\test.htm")
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click


    Dim ImageInhalt As String
    Label1.Text = WebBrowser1.Document.GetElementById("mytext").GetAttribute("value")

    ImageInhalt = WebBrowser1.Document.GetElementById("mytext2").GetAttribute("value")

    If ImageInhalt.Contains("STOP") Then
        PictureBox1.Image = My.Resources._stop
    End If

End Sub
End Class

HTML Page (test.htm)

<input type="text" name="userInfoNav" value="Hallo"/><br/>"

Many thanks now for the help

CodePudding user response：

You must load the HTML content of an URL or file into a mshtml.HTMLDocument. You can then process the DOM object in a JavaScript like syntax.

Requires reference to Microsoft.mshtml.dll.

partial class MainWindow : Window
{
  private mshtml.HTMLDocument HtmlDocument { get; set; }

  public async Task SetTextBoxTextAsync(string filePath, string id)
  {
    await UpdateHtmlDocumentAsync(filePath);
    string value = GetHtmlElementValueById(id);
    this.TextBlock.Text = value;
  }

  private async Task UpdateHtmlDocumentAsync(string filePath)
  {
    string htmlContent = await File.ReadAllLinesAsync(filePath);
    this.HtmlDocument = new HTMLDocument();
    (this.HtmlDocument as IHTMLDocument2).write(htmlContent);
  }

  private string GetHtmlElementValueById(string elementId)
    => this.HtmlDocument.getElementById(elementId).innerText;
}

VB.NET

Partial Class MainWindow
    Inherits Window

    Private Property HtmlDocument As mshtml.HTMLDocument

    Private Async Function SetTextBoxTextAsync(ByVal filePath As String, ByVal id As String) As Task
        Await UpdateHtmlDocumentAsync(filePath)
        Dim value As String = GetHtmlElementValueById(id)
        Me.TextBlock.Text = value
    End Function

    Public Async Function UpdateHtmlDocumentAsync(ByVal filePath As String) As Task
        Dim htmlContent As String = Await File.ReadAllLinesAsync(filePath)
        Me.HtmlDocument = New HTMLDocument()
        (TryCast(Me.HtmlDocument, IHTMLDocument2)).write(htmlContent)
    End Function

    Public Function GetHtmlElementValueById(ByVal elementId As String) As String
        Return Me.HtmlDocument.getElementById(elementId).innerText
    End Function
End Class

Remarks

If you are interested in rendering the content, then use the WebBrowser control. It has a Document property that you can cast to a mshtml.HTMLDocument. Since the WebBrowser is a heavy instance, you should only use it if your intend is to render the HTML. Otherwise constuct the mshtml.HTMLDocument manually like shown above.

CodePudding user response：

You can load the html into a TextBlock like this:

TextBlock1.Text = System.IO.File.ReadAllText("C:\Users\Test\Desktop\Webseite\test.htm")

I assume that the TextBlock is named: TextBlock1.