具有自动刷新功能的Web浏览器的PowerShell表单

Question

I'm trying to create a simple form in PowerShell in a small window that always stays on top other windows and just contains a web browser object that automatically refreshes every 10 seconds. I've been searching online and trying various options but nothing seems to work. Almost every example I come across has the form or web browser refresh happen on a button press, but I need the web browser to automatically refresh on its own without any user interaction. From what I've been reading it sounds like WPF (Windows Presentation Foundation) with XAML (Extensible Application Markup Language) is the way to go, since WinForms is limited into a single thread, which makes refreshing the form more difficult or perhaps impossible to accomplish effectively.

For now this is what I have (testing with google) without the automatic refresh:

[void][System.Reflection.Assembly]::LoadWithPartialName('presentationframework')
[xml]$XAML = @'
<Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="PowerShell HTML GUI" WindowStartupLocation="Manual">
    <Grid>
        <WebBrowser
            HorizontalAlignment="Left"
            Width="415"
            Height="340"
            Margin="10,10,0,0"
            VerticalAlignment="Top"
            Name="WebBrowser"
        />
    </Grid>
</Window>
'@
$reader = New-Object System.Xml.XmlNodeReader($xaml)
$Form = [Windows.Markup.XamlReader]::Load($reader)
$Form.Width = 415
$Form.Height = 340
$Form.Topmost = $True
$WebBrowser = $Form.FindName('WebBrowser')
$WebBrowser.add_Loaded({$this.Navigate('http://www.google.com')})
$Form.ShowDialog()

I tried adding the following loop at the end of the code to replace $Form.ShowDialog() , but obviously this isn't going to work.

While (1) {
    Start-Sleep -seconds 10
    $WebBrowser.Refresh()
    $Form.ShowDialog()
}

I think I need to use the System.Windows.Forms.Timer class, but I'm not sure how to implement that into this example without any user interaction.

Anyone able to figure this out?

Answer 1

我从Reddit的一个用户那里得到了帮助，因为这里提供的当前答案（特别是答案的第一部分）只会让我更加困惑。

Answer 2

Yes, you are going to have to use a timer.

See the example in this article for more details. No, it's not talking to the web control directly, but the same approach could get you there.

Weekend Scripter: Create a Holiday Greeting Using PowerShell and WPF

The final interesting piece of code is how we can update the content of a WPF object continually. The script uses this ability to display the number of days, hours, minutes & seconds until the New Year. To do this, we create a $countDownUpdate scriptblock that contains a New-Timespan cmdlet. This calculates the difference between now and midnight on 31st December 2010, then sets this value on the content property of a label control.

# scriptblock that gets called every second by the timer object
# updates the 'content' property of the countdownlabel
$countDownUpdate = {
    $ts = New-TimeSpan -Start $([datetime]::now) -End $([datetime]"12/31/2010 00:00:00")

    # find the countdown label control
    $lbl = $objCanvas.FindName("countDown")
    $lbl.content = "$($ts.Days) . $($ts.Hours) : $($ts.Minutes) : $($ts.Seconds)"
}

See also this example:

A PowerShell clock

I ended up using Windows Presentation Foundation

## Create a script block which will update the UI            
 $counter = 0;            
 $updateBlock = {            
    # Update the clock            
    $clock.Resources["Time"] = [DateTime]::Now.ToString("T")            
 }            

## Hook up some event handlers             
$clock.Add_SourceInitialized( {            
    ## Before the window's even displayed ...            
    ## We'll create a timer            
    $timer = new-object System.Windows.Threading.DispatcherTimer            
    ## Which will fire 4 times every second            
    $timer.Interval = [TimeSpan]"0:0:0.25"            
    ## And will invoke the $updateBlock            
    $timer.Add_Tick( $updateBlock )            
    ## Now start the timer running            
    $timer.Start()            
    if( $timer.IsEnabled ) {            
       Write-Host "Clock is running. Don't forget: RIGHT-CLICK to close it."            
    } else {            
       $clock.Close()            
       Write-Error "Timer didn't start"            
    }            
 } )