C#用户控件设置自定义属性的选项列表

Question

我正在尝试为我的一个项目创建一个自定义折叠面板。我已经设置好显示哪些边框可以折叠，并且它接受一个字符串输入{"None", "Up", "Right", "Down", "Left", "All"}。

以下是我目前的代码：

public partial class CollapsiblePanel : UserControl
{
    # region Collapse Direction
    List<string> DirectionOptions = new List<string> { "None", "Up", "Right", "Down", "Left", "All" };
    [Browsable(true), DefaultValue("All"), Description("Direction panel collapses. 0-none, 1-up, 2-right, 3-down, 4-left, 5-all")]
    [ListBindable(true), Editor(typeof(ComboBox), typeof(UITypeEditor))]
    private string _direction = "All";
    public List<string> Direction
    {
        get { return DirectionOptions; }
        set
        {
            DirectionOptions = value;
            callCollapseDirectionChanged();
        }
    }

    public event Action CollapseDirectionChanged;
    protected void callCollapseDirectionChanged()
    {
        Action handler = CollapseDirectionChanged;
        DisplayButtons();
        if (handler != null)
        {
            handler();
        }
    }
    # endregion

    public CollapsiblePanel()
    {
        InitializeComponent();
    }

    private void DisplayButtons()
    {
        switch (_direction)
        {
            case "None":
                buttonDown.Visible = false;
                buttonUp.Visible = false;
                buttonRight.Visible = false;
                buttonLeft.Visible = false;
                break;

            case "Up":
                buttonDown.Visible = false;
                buttonUp.Visible = true;
                buttonRight.Visible = false;
                buttonLeft.Visible = false;
                break;

            case "Right":
                buttonDown.Visible = false;
                buttonUp.Visible = false;
                buttonRight.Visible = true;
                buttonLeft.Visible = false;
                break;

            case "Down":
                buttonDown.Visible = true;
                buttonUp.Visible = false;
                buttonRight.Visible = false;
                buttonLeft.Visible = false;
                break;

            case "Left":
                buttonDown.Visible = false;
                buttonUp.Visible = false;
                buttonRight.Visible = false;
                buttonLeft.Visible = true;
                break;

            case "All":
                buttonDown.Visible = true;
                buttonUp.Visible = true;
                buttonRight.Visible = true;
                buttonLeft.Visible = true;
                break;
        }
    }
}

有人能向我解释一下如何让设计师将DirectionOptions列表作为可能的值提供给用户吗？他们可以选择任意一个字符串作为值。

- Chris

Answer 1

用户应该只能选择一个选项还是可以选择多个选项？

如果只能选择一个选项，则属性应该是枚举而不是列表。

像这样的代码应该可以工作：

public partial class CollapsiblePanel : UserControl
{
    public enum CollapseDirection
    {
        None,
        Up,
        Right,
        Down,
        Left,
        All
    }

    # region Collapse Direction

    [Browsable(true), DefaultValue("All"), Description("Direction panel collapses. 0-none, 1-up, 2-right, 3-down, 4-left, 5-all")]
    [ListBindable(true), Editor(typeof(ComboBox), typeof(UITypeEditor))]
    private CollapseDirection _direction = CollapseDirection.All;
    public CollapseDirection Direction
    {
        get { return _direction; }
        set
        {
            _direction = value;
            callCollapseDirectionChanged();
        }
    }

    public event Action CollapseDirectionChanged;
    protected void callCollapseDirectionChanged()
    {
        Action handler = CollapseDirectionChanged;
        DisplayButtons();
        if (handler != null)
        {
            handler();
        }
    }
    # endregion

    public CollapsiblePanel()
    {
        InitializeComponent();
    }

    private void DisplayButtons()
    {
        switch (_direction)
        {
            case CollapseDirection.None:
                buttonDown.Visible = false;
                buttonUp.Visible = false;
                buttonRight.Visible = false;
                buttonLeft.Visible = false;
                break;

            case CollapseDirection.Up:
                buttonDown.Visible = false;
                buttonUp.Visible = true;
                buttonRight.Visible = false;
                buttonLeft.Visible = false;
                break;

            case CollapseDirection.Right:
                buttonDown.Visible = false;
                buttonUp.Visible = false;
                buttonRight.Visible = true;
                buttonLeft.Visible = false;
                break;

            case CollapseDirection.Down:
                buttonDown.Visible = true;
                buttonUp.Visible = false;
                buttonRight.Visible = false;
                buttonLeft.Visible = false;
                break;

            case CollapseDirection.Left:
                buttonDown.Visible = false;
                buttonUp.Visible = false;
                buttonRight.Visible = false;
                buttonLeft.Visible = true;
                break;

            case CollapseDirection.All:
                buttonDown.Visible = true;
                buttonUp.Visible = true;
                buttonRight.Visible = true;
                buttonLeft.Visible = true;
                break;
        }
    }
}

• 注意 - 这是一份指导 - 我没有测试过这段代码，但它应该能让你朝着想要实现的方向前进。

- Richard Seal

---

非常感谢。这正是我需要的。 - Chris

除了 public event Action CollapseDirectionChanged; 这个部分，我对这里的所有内容都理解。在 void 方法之前，它实际上是做什么的？如果没有它，你能让这段代码工作吗？ - IneffaWolf