c# - webbrowser 不导航，如果你不看它

Question

我遇到了一个奇怪的问题。我有一个 tabcontrol 和 3 个选项卡。在每个选项卡上，我都有一个网络浏览器控件。他们都导航到一个网站。但它只有在您实际查看网络浏览器控件时才会导航。因此，将它在任务栏或系统托盘上最小化，不会使其导航到网站。

这是为什么呢？我怎样才能改变这种行为？

[编辑]

这似乎只在我启动应用程序时发生。在获得“关注”或“查看”后，这种情况就不会再发生了。

更多信息，导航发生在与 UI 线程不同的线程中。[/编辑]

[第三次编辑]

这是一个测试用例:

XAML 代码:

<Window x:Class="WPFWebbrowserFocusTest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="453" Width="755">
<Grid>
    <TabControl Height="390" HorizontalAlignment="Left" Margin="12,12,0,0" Name="tabControl1" VerticalAlignment="Top" Width="709">
        <TabItem Header="tabItem1" Name="tabItem1">
            <Grid>
                <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="18,17,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
            </Grid>
        </TabItem>
        <TabItem Header="tabItem2" Name="tabItem2">
            <Grid>
                <WebBrowser Height="352" HorizontalAlignment="Left" Margin="0,6,0,0" Name="webBrowser1" VerticalAlignment="Top" Width="693" Navigated="webbrowser_Navigated" LoadCompleted="webbrowser_LoadCompleted" />
            </Grid>
        </TabItem>
        <TabItem Header="tabItem3" Name="tabItem3">
            <Grid>
                <WebBrowser Height="346" HorizontalAlignment="Left" Margin="6,6,0,0" Name="webBrowser2" VerticalAlignment="Top" Width="687" Navigated="webbrowser_Navigated" LoadCompleted="webbrowser_LoadCompleted" />
            </Grid>
        </TabItem>
        <TabItem Header="tabItem4" Name="tabItem4">
            <Grid>
                <WebBrowser Height="346" HorizontalAlignment="Left" Margin="10,10,0,0" Name="webBrowser3" VerticalAlignment="Top" Width="687" Navigated="webbrowser_Navigated" LoadCompleted="webbrowser_LoadCompleted" />
            </Grid>
        </TabItem>
        <TabItem Header="tabItem5" Name="tabItem5">
            <Grid>
                <WebBrowser Height="346" HorizontalAlignment="Left" Margin="10,10,0,0" Name="webBrowser4" VerticalAlignment="Top" Width="687" Navigated="webbrowser_Navigated" LoadCompleted="webbrowser_LoadCompleted" />
            </Grid>
        </TabItem>
    </TabControl>
</Grid>

这是文件背后的代码:

public MainWindow()
{
   InitializeComponent();
}

private void webbrowser_Navigated(object sender, NavigationEventArgs e)
{ 
   this.SuppressScriptErrors((WebBrowser)sender, true);
}

private void webbrowser_LoadCompleted(object sender, NavigationEventArgs e)
{
    WebBrowser wb = (WebBrowser)sender;

    if (e.Uri.AbsoluteUri != wb.Source.AbsoluteUri)
        return;
}

public void SuppressScriptErrors(System.Windows.Controls.WebBrowser wb, bool Hide)
{
    FieldInfo fi = typeof(System.Windows.Controls.WebBrowser).GetField(
            "_axIWebBrowser2", BindingFlags.Instance | BindingFlags.NonPublic);

    if (fi != null)
    {
        object browser = fi.GetValue(wb);

        if (browser != null)
        {
            browser.GetType().InvokeMember("Silent", BindingFlags.SetProperty, null, browser, new object[] { Hide });
        }
    }
}

private void button1_Click(object sender, RoutedEventArgs e)
{
    this.webBrowser1.Navigate("http://www.google.com");
    this.webBrowser2.Navigate("http://www.google.com");
    this.webBrowser3.Navigate("http://www.google.com");
    this.webBrowser4.Navigate("http://www.google.com");
}

如何重现:

在 webbrowser_LoadCompleted 中放置一个断点。然后按下位于 tabcontrol 的第一个 tabpage 上的按钮。

先不要进入下一个标签页，等待几秒钟，比如 15 秒左右。

然后转到 tabitem2 或 3/4/5。您会看到页面刚刚加载，webbrowser_LoadCompleted 事件被触发。

Answer 1

这是 WPF 中有效的代码片段。单击该按钮后，它会最小化应用程序，并在 2 秒后调用导航到所有浏览器，同时窗口最小化。无论窗口状态或选项卡焦点如何，页面都会加载到所有选项卡中。确保在 Dispatcher.Invoke 中调用 Navigate。除非调用调度程序，否则不能从不同的线程在 WPF 中更改 UI。那可能是个问题。我下面的示例从不同的线程调用导航。

<Window x:Class="WpfApplication3.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        DataContext="{Binding RelativeSource={RelativeSource Self}}"
        Title="MainWindow" Height="350" Width="525"
        StateChanged="Window_StateChanged">
    <Grid>
        <TabControl Height="225" HorizontalAlignment="Left" Margin="12,12,0,0" Name="tabControl1" VerticalAlignment="Top" Width="491">
            <TabItem Header="tabItem1">
                <WebBrowser Height="189" Name="webBrowser1" Width="479" />
            </TabItem>
            <TabItem Header="tabItem2">
                <WebBrowser Height="185" Name="webBrowser2" Width="466" />
            </TabItem>
            <TabItem Header="tabItem3">
                <WebBrowser Height="187" Name="webBrowser3" Width="434" />
            </TabItem>
        </TabControl>
        <Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="116,268,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" />
        <TextBox Height="23" HorizontalAlignment="Left" Margin="236,268,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" />
    </Grid>
</Window>

private void button1_Click(object sender, RoutedEventArgs e)
{
    this.WindowState = System.Windows.WindowState.Minimized;
}

private void Window_StateChanged(object sender, EventArgs e)
{
    if (this.WindowState == System.Windows.WindowState.Minimized)
    {
        new Thread((state) =>
        {
            Thread.Sleep(TimeSpan.FromSeconds(2));

            this.Dispatcher.Invoke(new Action(() =>
            {
                webBrowser1.Navigate(textBox1.Text);
                webBrowser2.Navigate(textBox1.Text);
                webBrowser3.Navigate(textBox1.Text);
            }), null);

        }).Start();
    }
}