自定义控件开发5--自定义属性编辑器(Modal,DropDown)

要实现这样的效果,我们只需要做2件事情。

1. 在控件类库中,添加一个WindowForm类,然后编辑相应的界面,并初始化

因为默认情况下 控件在designer.cs中定义为private,所以我们将他改为Public。

 public partial class CategoryWindow : Form
    {
        public CategoryWindow()
        {
            InitializeComponent();
            SetSelectData();
        }
        public void SetSelectData()
        {
            try
            {
                this.comboBox1.Items.Add("水果");
                this.comboBox1.Items.Add("蔬菜");
                this.comboBox1.Items.Add("肉类");
                this.comboBox1.Items.Add("蛋类");
                this.comboBox1.Items.Add("面食");
                this.comboBox1.SelectedItem = comboBox1.Items[0];
            }
            catch (Exception eee)
            {
                throw eee;
            }
            finally
            {
            }
        }
    }

2. 定制自己的UITypeEditor类。

 public class CategoryModalEditor : System.Drawing.Design.UITypeEditor
    {
        public CategoryModalEditor()
        {
        }
        public override System.Drawing.Design.UITypeEditorEditStyle GetEditStyle(System.ComponentModel.ITypeDescriptorContext context)
        {
            return UITypeEditorEditStyle.Modal;
        }
        public override object EditValue(System.ComponentModel.ITypeDescriptorContext context, 
            System.IServiceProvider provider, object value)
        {
            IWindowsFormsEditorService service = 
                (IWindowsFormsEditorService)provider.GetService(typeof(IWindowsFormsEditorService));
            if (service == null)
            {
                return null;
            }
            CategoryWindow form = new CategoryWindow();
            if (service.ShowDialog(form) == DialogResult.OK)
            {
                return form.comboBox1.SelectedItem;
            }
            return value;
        }
    }

 2. 属性下拉编辑器.

1.在ClassLibrary中,新建一个UserControl(CategoryDorpDown.cs).

2.实现自定义UITypeEditor.

3.因为WindowForm里的控件在Designer.cs声明为Private,如果声明为Public,则在自定义UITypeEditor中引用不到控件,所以我们需要

ComboBox obj = dropform.Controls[2] as ComboBox;需要找到下拉控件 并根据Value 参数赋值,但我们要判断是否控件为NULL和是否为"".

赋值为obj.Text=value as string.

 public class CategoryDropDownEditor : System.Drawing.Design.UITypeEditor
    {
        public CategoryDropDownEditor()
        {
        }
        public override System.Drawing.Design.UITypeEditorEditStyle
            GetEditStyle(System.ComponentModel.ITypeDescriptorContext context)
        {
            //指定编辑样式为下拉形状, 且基于Control 类型
            return UITypeEditorEditStyle.DropDown;
        }
        public override object EditValue(System.ComponentModel.ITypeDescriptorContext context, 
            System.IServiceProvider provider, object value)
        {
            //取得编辑器服务对象
            IWindowsFormsEditorService service = 
                (IWindowsFormsEditorService)provider.GetService(typeof(IWindowsFormsEditorService));
            if (service == null)
            {
                return null;
            }
      
            //定义一个用户控件对象
            string original = string.Empty;
            string strReturn = string.Empty;
            CategoryDorpDown dropform = new CategoryDorpDown(service);
            ComboBox obj = dropform.Controls[2] as ComboBox;
            if (obj != null)
            {
                if (value != null&&value.ToString()!="")
                {
                    obj.Text= (string)value;
                }
            }
            service.DropDownControl(dropform);
            strReturn = dropform.strReturnValue;
            if (strReturn + String.Empty != String.Empty)
            {
                return strReturn;
            }
            return (string)value;
        }
    }

 3.

 

在这个自定义属性中,我继承StringConverter并通过返回一个string数组来实现下拉：

    public class CustomCollectionPropertyConverter : StringConverter
    {
        public override bool GetStandardValuesSupported(ITypeDescriptorContext
context)
        {
            return true;
        }
        public override bool GetStandardValuesExclusive(ITypeDescriptorContext
        context)
        {
            return false;
        }
        public override StandardValuesCollection
        GetStandardValues(ITypeDescriptorContext context)
        {
            string[] strArray = new string[] { "水果", "蔬菜", "肉食", "面食", "蛋类" };
            StandardValuesCollection returnStandardValuesCollection = new
            StandardValuesCollection(strArray);
            return returnStandardValuesCollection;
        }
    }

没有特别之处,只是当我们重写GetStandardValuesExclusive为true是，我们就不能手动输入字符串，只能根据下拉选择值.