UWP KeyDown事件

Question

我在WPF中编写了一个应用，其中我的Keydown事件通过以下代码运行：

private void Form1_Load(object sender, EventArgs e)
    {
        this.KeyDown += new System.Windows.Forms.KeyEventHandler(Form1_KeyDown);
        this.KeyUp += new System.Windows.Forms.KeyEventHandler(Form1_KeyUp);
    }

    //Declare the comands for Rover control//
    private void Form1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.W)                                // Holding Keyboard Character "W" //
        {
            serialPort1.Write("F");                             // Passing command "Forward" thorugh letter "F" in arduino code //
        }

我正在尝试在UWP中复制此内容，但不确定我在做什么错。 根据到目前为止的研究，我了解到我必须在XAML部分的Grid中放置KeyDown =“ Grid_KeyDown”，并且我必须编写如下内容：

 private async void Grid_KeyDown(object sender, KeyRoutedEventArgs e)
    {
        //handling code here
        if (e.Key == Key.F)
        {
            string sendData = "F";
            if (string.IsNullOrEmpty(sendData))
            {
                errorStatus.Visibility = Visibility.Visible;
                errorStatus.Text = "Please specify the string you are going to send";
            }
            else
            {
                DataWriter dwriter = new DataWriter(streamSocket.OutputStream);
                UInt32 len = dwriter.MeasureString(sendData);
                dwriter.WriteUInt32(len);
                dwriter.WriteString(sendData);
                await dwriter.StoreAsync();
                await dwriter.FlushAsync();
            }
        }

但是，这不起作用。 有没有人有任何建议我如何使此Keydown正常工作，所以当我按F键时我想将其传递到串行端口并将其作为字符串“ F”发送到蓝牙设备？

好的，所以当我涉及if（e.Key == Windows.System.VirtualKey.F）时，代码工作如下：

private async void Grid_KeyDown(object sender, KeyRoutedEventArgs e)
    {

        //handling code here
        if (e.Key == Windows.System.VirtualKey.F)
        {
            string sendData = "F";
            if (string.IsNullOrEmpty(sendData))
            {
                errorStatus.Visibility = Visibility.Visible;
                errorStatus.Text = "Please specify the string you are going to send";
            }
            else
            {
                DataWriter dwriter = new DataWriter(streamSocket.OutputStream);
                UInt32 len = dwriter.MeasureString(sendData);
                dwriter.WriteUInt32(len);
                dwriter.WriteString(sendData);
                await dwriter.StoreAsync();
                await dwriter.FlushAsync();
            }
        }
    }

但是，我喜欢延迟。 正如我在使用serialPort1.Write的代码的第一部分中提到的那样，当我按下按钮时，蓝牙会立即将命令发送给机器人，而当我释放按钮时，蓝牙将立即停止。 因此，我必须像在以下WPF代码中所做的那样，加入类似于UWP的内容：

 private void Form1_Load(object sender, EventArgs e)
    {
        this.KeyDown += new System.Windows.Forms.KeyEventHandler(Form1_KeyDown);
        this.KeyUp += new System.Windows.Forms.KeyEventHandler(Form1_KeyUp);
    }

    //Declare the comands for Rover control//
    private void Form1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.W)                                // Holding Keyboard Character "W" //
        {
            serialPort1.Write("F");                             // Passing command "Forward" thorugh letter "F" in arduino code //
        }

谢谢

Answer 1

您是否尝试过使用如下所示的按键事件：

<Grid KeyUp="Grid_KeyUp">
  ...
</Grid>

void Grid_KeyUp(object sender, KeyRoutedEventArgs e)
{
    //handling code here
}

有关更多详细信息，请阅读此处的文档。

Answer 2

也许这会有所帮助！ 这就是我使用KeyUP的方式...

`private void Value1_KeyUp(object sender, KeyRoutedEventArgs e)
  {
    if (e.Key == VirtualKey.Enter)
    {
        string value = Value1.Text;
        PivotItem pi = MainPivot.SelectedItem;
        ((WebView)pi.Content).Navigate(new Uri(value,
        UriKind.Absolute));   
        MainPivot.SelectedItem = pi;
        TagTextBlock.Text = Value1.Text;
        pi.Header = ((WebView)pi.Content).DocumentTitle;
    }
}

`

Answer 3

也许您需要刷新DataWriter：

await dwriter.FlushAsync();