c# - 如何在 ViewModel 类中执行 ComboboxSelectionChanged 方法

Question

我的 xaml 文件中有 2 个组合框。基本上，当我们双击 xaml 文件中的组合框时，它会在 xaml.cs 文件中创建一个 combobox_selectionchanged 事件。我已经这样做了:

查看类(class):

<ComboBox Height="23" ItemsSource="{Binding BusRateList}" SelectedItem="{Binding SelectedBusRateItem}" SelectedIndex="2"  Name="comboBox2" SelectionChanged="comboBox2_SelectionChanged" />

<ComboBox Height="23" ItemsSource="{Binding BaudRateList}" SelectedItem="{Binding SelectedBaudRateItem}" SelectedIndex="6" Name="comboBox3" SelectionChanged="comboBox3_SelectionChanged" />

查看.xaml.cs 文件:

private void comboBox2_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        int id = Convert.ToInt32(comboBox2.SelectedIndex);            
        int speed = mI2c._busRate[id]; //mI2C is object of viewmodel class

        sendBuf[0] = Convert.ToByte((speed & 0xFF000000) >> 24);
        sendBuf[1] = Convert.ToByte((speed & 0x00FF0000) >> 16);
        sendBuf[2] = Convert.ToByte((speed & 0x0000FF00) >> 8);
        sendBuf[3] = Convert.ToByte(speed & 0x000000FF);

        cmd = (256 << 8 | 0x00);
        mCom.WriteInternalCommand(cmd, 4, ref sendBuf);

        ReadBusAndBaudRate();            
    }


private void comboBox3_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        int id = Convert.ToInt32(comboBox3.SelectedIndex);            
        int speed = mI2c._baudRate[id]; //mI2C is object of viewmodel class
        sendBuf[0] = Convert.ToByte((speed & 0xFF000000) >> 24);
        sendBuf[1] = Convert.ToByte((speed & 0x00FF0000) >> 16);
        sendBuf[2] = Convert.ToByte((speed & 0x0000FF00) >> 8);
        sendBuf[3] = Convert.ToByte(speed & 0x000000FF);

        cmd = (256 << 8 | 0x00);
        mCom.WriteInternalCommand(cmd, 4, ref sendBuf);

        ReadBusAndBaudRate();
    }

public void ReadBusAndBaudRate()
    {          

        int speed = 100;

        // Some Code

        textBox1.Text = speed.ToString();

        textBox2.Text = speed.ToString();

        // Update message in Output Window as Effective Baud Rate
    }

ViewModel 类:

public ObservableCollection<int> _busRate;
public ObservableCollection<int> BusRateList
    {
        get { return _busRate; }
        set
        {
            _busRate = value;
            NotifyPropertyChanged("BusRateList");
        }
    }

    private int _selectedBusRate;
    public int SelectedBusRateItem
    {
        get { return _selectedBusRate; }
        set
        {
            _selectedBusRate = value;
            NotifyPropertyChanged("SelectedBusRateItem");
        }
    }      

    public ObservableCollection<int> _baudRate;
    public ObservableCollection<int> BaudRateList
    {
        get { return _baudRate; }
        set
        {
            _baudRate = value;
            NotifyPropertyChanged("BusRateList");
        }
    }

    private int _selectedBaudRate;
    public int SelectedBaudRateItem
    {
        get { return _selectedBaudRate; }
        set
        {
            _selectedBaudRate = value;
            NotifyPropertyChanged("SelectedBaudRateItem");
        }
    }

我在 viewmodel 构造函数的两个组合框中添加了大约 8 个项目。

现在使用上述属性，我想在 viewmodel 类中执行组合框选择更改事件，该事件应该执行在我的 .cs 文件中完成的所有语句。

请帮忙!!!

Answer 1

如果您希望用户界面在没有选择更改事件的情况下更新您的 View 模型，只需将双向绑定(bind)添加到您的选定项。这将使您进入具有您想要使用的值的 View 模型。这是一个例子:

<ComboBox Height="23" ItemsSource="{Binding BusRateList}" SelectedItem="{Binding SelectedBusRateItem,Mode=TwoWay}" SelectedIndex="2"  Name="comboBox2"  /> 

编辑:您要执行的语句将在您的属性中，因此在 SelectedBusRate 中调用 SetBusRate()，如果 Busrate 可能受到影响，则调用 SelectedBaudRate。