[开源]FreeSCADA的通道数据与控件属性关联以及自动刷新机制研究

1. 几个重要的类列表：

a) Designer工程下的CommonBindingDialog.cs：

b) Designer工程下的NumericBindingPanel.cs（或者StringBindingPanel.cs）：

2. 通道数据与控件属性关联（以及自动刷新机制）：

a) 通道数据与控件属性绑定：

CommonBindingDialog.cs中的事件响应方法（Create association按钮被按下）：

private void CreateAssociationButton_Click(object sender, EventArgs e)
{
    SavePanelStateAndClose();

    if (propertyList.SelectedIndex >= 0 && bindingTypes.SelectedIndex >= 0)
    {
        BaseBindingPanelFactory factory = (BaseBindingPanelFactory)bindingTypes.SelectedItem; // factory在这里执行过后，就是NumericBindingPanel.cs里定义的NumericBindingPanelFactory类型了
        bindingPanel = factory.CreateInstance(); // bindingPanel的具体类型是NumericBindingPanel还是StringBindingPanel，在这里得到了重新定义（不再是基类的BaseBindingPanel类型了）
        bindingPanel.Initialize(element, propertyList.SelectedItem as PropertyWrapper, null);
        bindingPanel.Parent = panel1;
        bindingPanel.Dock = DockStyle.Fill;
        CreateAssociationButton.Enabled = false;
        bindingTypes.Enabled = false;
    }
}

CommonBindingDialog.cs中的事件响应方法（Save按钮被按下）：

private void saveButton_Click(object sender, EventArgs e)
{
    SavePanelStateAndClose();
    if (activeBindings.Count > 0)
    {
        foreach (PropertyWrapper key in activeBindings.Keys)
        {
            DependencyObject depObj;
            DependencyProperty depProp;
            System.Windows.Data.BindingBase binding = activeBindings[key];

            if (key.GetWpfObjects(out depObj, out depProp) && binding != null)
                BindingOperations.SetBinding(depObj, depProp, binding);
        }
    }
    DialogResult = DialogResult.OK;
    Close();
}

继续来看SavePanelStateAndClose方法的实现：

private void SavePanelStateAndClose()
{
    if (bindingPanel != null)
    {
        BindingBase binding = bindingPanel.Save(); // 见NumericBindingPanel类的Save()定义
        if (binding != null)
            activeBindings[bindingPanel.Property] = binding; // activeBindings为Dictionary<PropertyWrapper, BindingBase>，bindingPanel.Property为PropertyWrapper

        bindingPanel.Dispose();
        bindingPanel = null;
    }
}

我们再继续深入NumericBindingPanel.cs里面定义的Save方法：

public override System.Windows.Data.BindingBase Save()
{
    if (channel != null)
    {
        System.Windows.Data.Binding bind = new System.Windows.Data.Binding("Value");
        ChannelDataProvider cdp = new ChannelDataProvider();
        cdp.ChannelName = channel.PluginId + "." + channel.Name;
        bind.Source = cdp; // 绑定的源数据为通道数据
        bind.UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged;
        cdp.Refresh();

        ComposingConverter conv = new ComposingConverter();
        if (checkBox1.Checked)
        {
            RangeConverter rc = new RangeConverter();
            rc.Min = Decimal.ToDouble(minEdit.Value);
            rc.Max = Decimal.ToDouble(maxEdit.Value);
            conv.Converters.Add(rc);
        }

        conv.Converters.Add(new Kent.Boogaart.Converters.TypeConverter(cdp.Channel.Type, Property.PropertyType));
        bind.Converter = conv;

        bind.Mode = BindingMode.TwoWay;

        DependencyObject depObj;
        DependencyProperty depProp;
        if (Property.GetWpfObjects(out depObj, out depProp))
            bind.FallbackValue = depObj.GetValue(depProp);

        return bind;
    }
    else
        return base.Save();
}