设计时自定义控制控件大小和移动

做一个类似于TextBox一样在设计时只能调整位置和宽度，不能修改它的高度，请使用下面的方法：

假定我的控件名称为PopupCheckedList，高度只能是21像素。

首先，需要与控件对应的一个Desinger类，名为<PopupCheckedListDesigner>，代码如下：

    public class PopupCheckedListDesigner : System.Windows.Forms.Design.ControlDesigner
    {
        public override System.Windows.Forms.Design.SelectionRules SelectionRules
        {
            get
            {
                return System.Windows.Forms.Design.SelectionRules.LeftSizeable |
                    System.Windows.Forms.Design.SelectionRules.RightSizeable
                    | System.Windows.Forms.Design.SelectionRules.Moveable;
            }
        }

    }

这里面的SelectionRules就是控制了设计时可以执行的选中操作，定义如下，大家一看就明白了：

    // Summary:
    //     Defines identifiers that are used to indicate selection rules for a component.
    [Flags]
    public enum SelectionRules
    {
        // Summary:
        //     Indicates the component is locked to its container. Overrides the System.Windows.Forms.Design.SelectionRules.Moveable,
        //     System.Windows.Forms.Design.SelectionRules.AllSizeable, System.Windows.Forms.Design.SelectionRules.BottomSizeable,
        //     System.Windows.Forms.Design.SelectionRules.LeftSizeable, System.Windows.Forms.Design.SelectionRules.RightSizeable,
        //     and System.Windows.Forms.Design.SelectionRules.TopSizeable bit flags of this
        //     enumeration.
        Locked = -2147483648,
        //
        // Summary:
        //     Indicates no special selection attributes.
        None = 0,
        //
        // Summary:
        //     Indicates the component supports resize from the top.
        TopSizeable = 1,
        //
        // Summary:
        //     Indicates the component supports resize from the bottom.
        BottomSizeable = 2,
        //
        // Summary:
        //     Indicates the component supports resize from the left.
        LeftSizeable = 4,
        //
        // Summary:
        //     Indicates the component supports resize from the right.
        RightSizeable = 8,
        //
        // Summary:
        //     Indicates the component supports sizing in all directions.
        AllSizeable = 15,
        //
        // Summary:
        //     Indicates the component supports a location property that allows it to be
        //     moved on the screen.
        Moveable = 268435456,
        //
        // Summary:
        //     Indicates the component has some form of visible user interface and the selection
        //     service is drawing a selection border around this user interface. If a selected
        //     component has this rule set, you can assume that the component implements
        //     System.ComponentModel.IComponent and that it is associated with a corresponding
        //     designer instance.
        Visible = 1073741824,
    }

第二步，对控件类应用特性标记，标识它的Designer类。

 [DesignerAttribute(typeof(PopupCheckedListDesigner))]
 public partial class PopupCheckedList : DevExpress.XtraEditors.XtraUserControl

第三部，在构造函数中，将高度修改为默认的21.

public PopupCheckedList()
{
    InitializeComponent();
    base.Height = popupContainerEdit1.Height;
    base.Width = 150;
    this.checkedListBoxControl1.ItemCheck += new DevExpress.XtraEditors.Controls.ItemCheckEventHandler(checkedListBoxControl1_ItemCheck);
}

注意，一定要在InitializeComponent函数调用之后。

这样已经OK了，我们看看在设计时，控件的选中状态吧。

这个控件在选中时，就没有可以上下拖动的锚点，一看就让使用着知道高度是不可更改的。

当然手工代码还是可以修改这个控件的高度，比如修改Control.height属性，那怎么办哪？

你就需要额外的写点东西了，第一覆盖常用的Height属性和Size属性，使用自定义的代码逻辑，禁止外部修改它的高度。

比如下面的代码段，去掉了Height的Set方法。

public new int Height
{
       get { return base.Height; }
 }

同样，还需要在Resize事件中进行判断，如果高度不是21的话，就强制修改为21，以防止其他方式修改了控件的Height。