Lesson 23: Creating a Web Browser in VB2022

Private Sub BtnGo_Click(sender As Object, e As EventArgs) Handles BtnGo.Click
    If Not String.IsNullOrWhiteSpace(TxtUrl.Text) Then
        Try
            ' Ensure URL has proper protocol
            Dim url As String = TxtUrl.Text
            If Not url.StartsWith("http://") AndAlso Not url.StartsWith("https://") Then
                url = "https://" & url
            End If
            
            wbMain.Navigate(url)
        Catch ex As Exception
            MessageBox.Show("Error navigating to URL: " & ex.Message, "Navigation Error", 
                            MessageBoxButtons.OK, MessageBoxIcon.Error)
        End Try
    End If
End Sub

Private Sub BtnBack_Click(sender As Object, e As EventArgs) Handles BtnBack.Click
    If wbMain.CanGoBack Then
        wbMain.GoBack()
    End If
End Sub

Private Sub BtnForward_Click(sender As Object, e As EventArgs) Handles BtnForward.Click
    If wbMain.CanGoForward Then
        wbMain.GoForward()
    End If
End Sub

Private Sub BtnRefresh_Click(sender As Object, e As EventArgs) Handles BtnRefresh.Click
    wbMain.Refresh()
End Sub

Private Sub BtnHome_Click(sender As Object, e As EventArgs) Handles BtnHome.Click
    wbMain.GoHome()
End Sub

' In settings form
Private Sub BtnSave_Click(sender As Object, e As EventArgs) Handles BtnSave.Click
    Dim homeUrl As String = TxtHomeUrl.Text
    
    ' Validate URL format
    If Uri.TryCreate(homeUrl, UriKind.Absolute, Nothing) Then
        My.Settings.HomePage = homeUrl
        My.Settings.Save()
        MessageBox.Show("Home page saved successfully!")
    Else
        MessageBox.Show("Please enter a valid URL")
    End If
End Sub

' In main browser form
Private Sub BrowserForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    If String.IsNullOrEmpty(My.Settings.HomePage) Then
        My.Settings.HomePage = "https://www.vbtutor.net"
        My.Settings.Save()
    End If
    
    wbMain.GoHome()
End Sub

Private Sub wbMain_GoHome(sender As Object, e As EventArgs) Handles wbMain.GoHome
    wbMain.Navigate(My.Settings.HomePage)
End Sub

Private Sub BtnAddBookmark_Click(sender As Object, e As EventArgs) Handles BtnAddBookmark.Click
    Dim title As String = wbMain.DocumentTitle
    Dim url As String = wbMain.Url.ToString()
    
    If Not String.IsNullOrEmpty(title) AndAlso Not String.IsNullOrEmpty(url) Then
        ' Add to bookmarks menu
        Dim bookmarkItem As New ToolStripMenuItem(title)
        bookmarkItem.Tag = url
        AddHandler bookmarkItem.Click, AddressOf BookmarkItem_Click
        BookmarksMenu.DropDownItems.Add(bookmarkItem)
        
        ' Save to settings
        My.Settings.Bookmarks.Add($"{title}|{url}")
        My.Settings.Save()
    End If
End Sub

Private Sub BookmarkItem_Click(sender As Object, e As EventArgs)
    Dim item As ToolStripMenuItem = CType(sender, ToolStripMenuItem)
    wbMain.Navigate(CStr(item.Tag))
End Sub

Private Sub LoadBookmarks()
    For Each bookmark As String In My.Settings.Bookmarks
        Dim parts() As String = bookmark.Split("|")
        If parts.Length = 2 Then
            Dim bookmarkItem As New ToolStripMenuItem(parts(0))
            bookmarkItem.Tag = parts(1)
            AddHandler bookmarkItem.Click, AddressOf BookmarkItem_Click
            BookmarksMenu.DropDownItems.Add(bookmarkItem)
        End If
    Next
End Sub

Private Sub wbMain_FileDownload(sender As Object, e As EventArgs) Handles wbMain.FileDownload
    ' Prevent automatic download handling
    e.Cancel = True
    
    Dim url As String = wbMain.StatusText
    
    If Not String.IsNullOrEmpty(url) Then
        Dim saveDialog As New SaveFileDialog()
        saveDialog.FileName = IO.Path.GetFileName(url)
        
        If saveDialog.ShowDialog() = DialogResult.OK Then
            Dim downloadPath As String = saveDialog.FileName
            Dim webClient As New Net.WebClient()
            
            ' Add to downloads list
            Dim listItem As New ListViewItem(IO.Path.GetFileName(url))
            listItem.SubItems.Add(url)
            listItem.SubItems.Add("0%")
            listItem.SubItems.Add("Downloading...")
            ListViewDownloads.Items.Add(listItem)
            
            ' Start download in background
            webClient.DownloadFileAsync(New Uri(url), downloadPath)
            
            ' Track progress
            AddHandler webClient.DownloadProgressChanged, Sub(s, args)
                listItem.SubItems(2).Text = $"{args.ProgressPercentage}%"
            End Sub
            
            AddHandler webClient.DownloadFileCompleted, Sub(s, args)
                listItem.SubItems(3).Text = If(args.Error Is Nothing, "Completed", "Error")
            End Sub
        End If
    End If
End Sub