论Web控件开发 - 树状控件（二）

介绍完基础类及WinPop控件后下面开始介绍第一个控件DropDownTree。首先我先对该控件的功能作个介绍：

其界面如下：

其功能如下：

    1.支持从DataTable中载入数据
    2.支持验证器控件
    3.支持不同级别显示样式
    4.支持仅针对叶子节点的数据选择验证

其开发原刑如下：



其中DropDownTree中含有两个集合属性，一个Items一个ItemStyles，Items中用来保存树状结构中的节点信息，而ItemStyles则保存不同级别的节点样式，在每一个Item中也会有一个ItemStyle属性，当Item的ItemStyle不为空时，系统才会取在DropDownTree中ItemStyles集合中的样式来绘制节点。而ItemStyles集合中根据集合中的索引来决定绘制级别的样式，如绘制根节点时将会取在ItemStyles[0]中的样式，而当节点级别大于ItemStyles集合中的条目时将取最后一个为绘制样式。另外在Item中也会有一个Items集合属性以此来实现树状结构。

以下是DropDownTreeItemStyle和DropDownTreeItemStyleCollection的源代码，他们的实现和WinPopItem和WinPopItemCollection的实现基本相同。

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.Design;
using System.Drawing.Design;
using System.Drawing;

using System.ComponentModel;
using System.ComponentModel.Design;

namespace Keyss.WebControls
{    
    [TypeConverter(typeof(ExpandableObjectConverter))]
    public class DropDownTreeItemStyle:ViewStatePartBase
{

        public const string ForeColorKey = "A";
        public const string BackColorKey = "B";
        #endregion

        [
        Bindable(true),
        Category("Appearance"),
        DefaultValue(typeof(System.Drawing.Color),""),
        NotifyParentProperty(true),
        TypeConverter(typeof(WebColorConverter))
        ]
        public  System.Drawing.Color ForeColor 
{
            get
{
                object o = ViewState[ForeColorKey];
                return(o==null)? System.Drawing.Color.Empty:(System.Drawing.Color)o;
            }
            set
{
                ViewState[ForeColorKey] = value;
            }
        }
        [
        Bindable(true),
        Category("Appearance"),
        DefaultValue(typeof(System.Drawing.Color),""),
        NotifyParentProperty(true),
        TypeConverter(typeof(WebColorConverter))
        ]
        public  System.Drawing.Color BackColor 
{
            get
{
                object o = ViewState[BackColorKey];
                return(o==null)? System.Drawing.Color.Empty:(System.Drawing.Color)o;
            }
            set
{
                ViewState[BackColorKey] = value;
            }
        }
        #endregion

        public virtual void AddAttributesToRender(HtmlTextWriter writer)
{
            if(this.ForeColor!=Color.Empty)
{
                writer.AddStyleAttribute(HtmlTextWriterStyle.Color,ColorTranslator.ToHtml(this.ForeColor));
            }
            if(this.BackColor!=Color.Empty)
{
                writer.AddStyleAttribute(HtmlTextWriterStyle.BackgroundColor,ColorTranslator.ToHtml(this.BackColor));
            }
        }
        #endregion

        [EditorBrowsable(EditorBrowsableState.Never)]
        public virtual void CopyFrom(DropDownTreeItemStyle s)
{    
            base.CopyFrom(s);
        }
        [EditorBrowsable(EditorBrowsableState.Never)]
        public virtual void MergeWith(DropDownTreeItemStyle s)
{
            base.MergeWith(s);
        }
        #endregion
    }
}

其中由于Style经常要作些Copy、Merge的操作因此重载了基类的MergeWith和CopyFrom方法，而为了方便样式的使用，系统定义了另外一个方法AddAttributesToRender，当在绘制Item时可以调用此方法来实现样式属性的输出。

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.Design;
using System.Drawing.Design;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;

namespace Keyss.WebControls
{
    [ 
    PersistenceMode(PersistenceMode.InnerProperty),
    ] 
    public class DropDownTreeItemStyleCollection:ViewStatePartCollectionBase
{

        public int Add(DropDownTreeItemStyle item)
{
            return base.AddItem(item);
        }
        public DropDownTreeItemStyle this[int index]
{
            get 
{
                if(index >= Count || index < 0)
{
                    return null;
                }
                return (DropDownTreeItemStyle)this.InnerList[index];
            }
        }
        protected override ViewStatePartBase NewItem()
{
            return new DropDownTreeItemStyle();
        }

    }
}

DropDownTreeItemStyleCollection的实现和WinPopItemCollection的实现基本一样。

以下是DropDownTreeItem的实现

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.Design;
using System.Drawing.Design;
using System.Drawing;

using System.ComponentModel;
using System.ComponentModel.Design;

namespace Keyss.WebControls
{
    public class DropDownTreeItem:ViewStatePartBase
{

        public const string TextKey = "A";
        public const string ValueKey = "B";
        #endregion

        [
        NotifyParentProperty(true), 
        Bindable(true),
        Category("Appearance"),
        DefaultValue("")
        ]
        public string Text 
{ 
            get 
{ 
                object o = ViewState[TextKey]; 
                return (o == null)?string.Empty : (string)o; 
            } 
            set 
{ 
                ViewState[TextKey] = value;
            } 
        }
        [
        NotifyParentProperty(true), 
        Bindable(true),
        Category("Appearance"),
        DefaultValue("")
        ]
        public string Value 
{ 
            get 
{ 
                object o = ViewState[ValueKey];
                return (o == null)?string.Empty:(string)o;
            } 
            set 
{ 
                ViewState[ValueKey] = value; 
            } 
        }

        #endregion

        protected DropDownTreeItemStyle _style;
        [
        NotifyParentProperty(true),
        PersistenceMode(PersistenceMode.Attribute),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Content),
        TypeConverter(typeof(ExpandableObjectConverter))
        ]
        public virtual DropDownTreeItemStyle Style 
{ 
            get 
{ 
                if(_style == null) 
{
                    _style = new DropDownTreeItemStyle();
                    if(_isTrackingViewState)
                        _style.TrackViewState();
                }
                return _style; } 
        }
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        protected virtual DropDownTreeItemStyle RenderStyle
{
            get
{
                if(!DropDownTree.ItemStyles.IsEmpty)
{
                    DropDownTreeItemStyle tmpStyle = new DropDownTreeItemStyle();
                    int tmpLevel = this.Level;

                    if(tmpLevel < DropDownTree.ItemStyles.Count)
{
                        tmpStyle.CopyFrom(DropDownTree.ItemStyles[tmpLevel]);
                    }
                    else
{
                        tmpStyle.CopyFrom(this.DropDownTree.ItemStyles[DropDownTree.ItemStyles.Count - 1]);
                    }
                    if(!Style.IsEmpty)
{
                        tmpStyle.CopyFrom(this.Style);
                    }
                    return tmpStyle;
                }
                else
                    return this.Style;
            }
        }
        #endregion

        protected DropDownTree _dropDownTree;
        protected DropDownTreeItem _owner;
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        public DropDownTreeItem Owner
{


        }
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        public DropDownTree DropDownTree
{


        }
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        public int Level
{
            get 
{
                int i = 0;
                DropDownTreeItem tmpOwner = this._owner;
                while(tmpOwner != null)
{
                    tmpOwner = tmpOwner.Owner;
                    i++;
                }
                return i;
            }
        }
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        public int Index
{
            get 
{
                if(this.Level != 0)
                    return this.Owner.Items.IndexOf(this);
                else
                    return this.DropDownTree.Items.IndexOf(this);
            }
        }
        #endregion

        private DropDownTreeItemCollection _items;
        [
        NotifyParentProperty(true),
        PersistenceMode(PersistenceMode.InnerProperty),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Content),
        ]
        public DropDownTreeItemCollection Items
{
            get 
{
                if(_items == null) 
{
                    _items = new DropDownTreeItemCollection();
                    if(this._isTrackingViewState)
                        _items.TrackViewState();
                }
                return _items;
            }
        }
        #endregion        

        public virtual void Render(System.Web.UI.HtmlTextWriter writer)
{
            writer.WriteLine();
            this.AddAttributesToRender(writer);
            writer.RenderBeginTag(HtmlTextWriterTag.Option);
            this.RenderContent(writer);
            writer.RenderEndTag();
            writer.WriteLine();
            this.Items.Render(writer);
        }
        protected virtual void AddAttributesToRender(System.Web.UI.HtmlTextWriter writer)
{
            this.RenderStyle.AddAttributesToRender(writer);
            string tvalue = this.Value;
            if(this.DropDownTree.SelectLeafOnly&&(!this.Items.IsEmpty))
                tvalue = string.Empty;
            if(tvalue!= string.Empty)
                writer.AddAttribute(HtmlTextWriterAttribute.Value,tvalue);
            if(this.DropDownTree.SelectedValue == this.Value)
                writer.AddAttribute(HtmlTextWriterAttribute.Selected,"true");
        }
        protected virtual void RenderContent(System.Web.UI.HtmlTextWriter writer)
{    
            writer.Write(string.Format("{0} {1}", this.GetTabText() + this.GetPreText(), this.Text));    
        }
        protected virtual string GetTabText()
{
            if(this.Level == 0) return string.Empty;
            DropDownTreeItem pItem = this.Owner;
            DropDownTreeItemCollection p_pItems;
            if(this.Level > 1)
                p_pItems = pItem.Owner.Items;
            else
                p_pItems = this.DropDownTree.Items;
            if(pItem.Index == p_pItems.Count-1)
                return string.Format("{0}{1}",pItem.GetTabText(), "&nbsp;&nbsp;&nbsp;&nbsp;" + this.DropDownTree.TabString);
            else
                return string.Format("{0}{1}",pItem.GetTabText(), "┃" + this.DropDownTree.TabString);
        }
        protected virtual string GetPreText()
{
            int l = this.Level;
            int i = this.Index;

            DropDownTreeItemCollection pItems;
            if(l == 0)
                pItems = this.DropDownTree.Items;
            else
                pItems = this.Owner.Items;

            if((l == 0)&&(pItems.Count == 1))
                return "┣";

            if((l == 0) && (i == 0) && (pItems.Count > 1))
                return "┏";

            if(i == (pItems.Count-1))
                return "┗";
            else
                return "┣";
        }
        #endregion


        public override void SetDirty()
{
            base.SetDirty ();
            Style.SetDirty();
            Items.SetDirty();
        }
        #endregion
        public override void TrackViewState()
{
            base.TrackViewState();
            Style.TrackViewState();
            Items.TrackViewState();
        }
        public override object SaveViewState()
{
            object[] savedState = new object[3];
            savedState[0] = base.SaveViewState();
            savedState[1] = Style.SaveViewState();
            savedState[2] = Items.SaveViewState();
            for(int i=0;i<savedState.Length;i++)
{
                if(savedState[i] != null)
                    return savedState;
            }
            return null;
        }
        public override void LoadViewState(object state)
{
            if(state !=null)
{
                object[] savedState = (object[])state;

                if(savedState[0] != null)
                    base.LoadViewState(savedState[0]);
                if(savedState[1] != null)
                    Style.LoadViewState(savedState[1]);
                if(savedState[2] != null)
                    Items.LoadViewState(savedState[2]);
            }    
        }
        #endregion

        public virtual void Init()
{
            this.Items.Owner = this;
            this.Items.DropDownTree = this.DropDownTree;
            this.Items.Init();
        }
        #endregion

        public virtual void LoadFromDataRow(System.Data.DataRow row)
{
            System.Data.DataTable table = row.Table;

            if(table.Columns.Contains("Text"))
{
                this.Text = row["Text"].ToString();
            }
            if(table.Columns.Contains("Value"))
{
                this.Value = row["Value"].ToString();
            }
        }
        #endregion
    }
}

以下是DropDownTreeItemCollection的源代码

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.Design;
using System.Drawing.Design;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design;
namespace Keyss.WebControls
{
    public class DropDownTreeItemCollection:ViewStatePartCollectionBase
{

        protected DropDownTree _dropDownTree;
        protected DropDownTreeItem _owner;
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        public DropDownTreeItem Owner
{


        }
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        public DropDownTree DropDownTree
{


        }
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        public int Level
{
            get 
{
                int i = 0;
                DropDownTreeItem tmpOwner = this._owner;
                while(tmpOwner != null)
{
                    tmpOwner = tmpOwner.Owner;
                    i++;
                }
                return i;
            }
        }
        #endregion

        public int Add(DropDownTreeItem item)
{    
            return this.AddItem(item);
        }
        protected override int AddItem(ViewStatePartBase item)
{        
            DropDownTreeItem mItem = (DropDownTreeItem)item;
            mItem.DropDownTree = this.DropDownTree;
            mItem.Owner = this.Owner;
            mItem.Init();
            return base.AddItem(mItem);
        }
        public DropDownTreeItem this[int index]
{
            get 
{
                if(index >= Count || index < 0)
{
                    return null;
                }
                return (DropDownTreeItem)this.InnerList[index];
            }
        }
        public int IndexOf(DropDownTreeItem item)
{
            return this.InnerList.IndexOf(item);
        }
        public DropDownTreeItem GetItemByValue(string _value)
{
            if(!IsEmpty)
{
                foreach(DropDownTreeItem item in this.InnerList)
{
                    if(item.Value==_value)
                        return item;
                    else
{
                        DropDownTreeItem item1 = item.Items.GetItemByValue(_value);
                        if(item1!=null)
                            return item1;
                    }
                }
            }
            return null;
        }
        #endregion

        public virtual void Render(System.Web.UI.HtmlTextWriter writer)
{
            if(!IsEmpty)
{
                for(int i=0;i<this.Count;i++)
{
                    this[i].Render(writer);
                }
            }
        }
        #endregion

        public virtual void Init()
{
            for(int i = 0; i < this.Count; i ++)
{
                this[i].DropDownTree = this.DropDownTree;
                this[i].Owner = this.Owner;
                this[i].Init();
            }
        }
        #endregion

        protected override ViewStatePartBase NewItem()
{
            return new DropDownTreeItem();
        }
        #endregion
    }
}

最后是DropDownTree的代码

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;

namespace Keyss.WebControls
{
    [
    ParseChildren(true),
    ValidationPropertyAttribute("SelectedValue"),
    PersistChildren(false),
    DefaultProperty("Items"),
    ToolboxData("<{0}:DropDownTree runat=server></{0}:DropDownTree>")]
    public class DropDownTree : System.Web.UI.WebControls.WebControl,IPostBackDataHandler
{

        public virtual void LoadFromTable(System.Data.DataTable table,bool isStr, string idField, string parentIDField)
{
            try
{
                this.Items.Clear();
                System.Data.DataRow[] rows = table.Select(string.Format("{0} is null",parentIDField));
                foreach(System.Data.DataRow row in rows)
{
                    Keyss.WebControls.DropDownTreeItem item = new Keyss.WebControls.DropDownTreeItem();
                    item.LoadFromDataRow(row);
                    this.Items.Add(item);
                    LoadItemsFromTable(item, row[idField], table, isStr, idField, parentIDField);
                }
            }
            catch
{
                throw new ArgumentException("Table or filed name error!",table.TableName);
            }
        }
        protected virtual void LoadItemsFromTable(DropDownTreeItem item, object idValue, System.Data.DataTable table,bool isStr,string idField, string parentIDField)
{
            string selectStr;
            if(isStr)
{
                selectStr = "{0} = '{1}'";
            }
            else
{
                selectStr = "{0} = {1}";
            }

            try
{
                System.Data.DataRow[] rows = table.Select(string.Format(selectStr,parentIDField,idValue));
                foreach(System.Data.DataRow row in rows)
{
                    Keyss.WebControls.DropDownTreeItem item1 = new Keyss.WebControls.DropDownTreeItem();
                    item1.LoadFromDataRow(row);
                    item.Items.Add(item1);
                    LoadItemsFromTable(item1, row[idField], table, isStr, idField, parentIDField);
                }
            }
            catch
{
                throw new ArgumentException("Table or filed name error!",table.TableName);
            }
        }
        #endregion

        [
        Bindable(true),
        Category("Appearance"),
        DefaultValue("&nbsp;&nbsp;&nbsp;")
        ]
        public string TabString 
{ 
            get 
{ 
                object o = ViewState["tabString"];
                return (o == null)?"&nbsp;&nbsp;&nbsp;":(string)o;
            } 
            set 
{ 
                ViewState["tabString"] = value; 
            }
        }
        [
        Bindable(true),
        Category("Appearance"),
        DefaultValue("")
        ]
        public string SelectedValue 
{
            get 
{ 
                object o = ViewState["selectedValue"];
                return (o == null)?"":(string)o;
            } 
            set 
{ 
                ViewState["selectedValue"] = value; 
            }
        }
        [
        DefaultValue(false),
        NotifyParentProperty(true), 
        ]
        public bool AutoPostBack 
{ 
            get 
{ 
                object o = ViewState["autoPostBack"];
                return (o == null)?false:(bool)o;
            } 
            set 
{ 
                ViewState["autoPostBack"] = value; 
            } 
        }
        [
        DefaultValue(false),
        NotifyParentProperty(true), 
        ]
        public bool SelectLeafOnly
{ 
            get 
{ 
                object o = ViewState["selectLeafOnly"];
                return (o == null)?false:(bool)o;
            } 
            set 
{ 
                ViewState["selectLeafOnly"] = value; 
            } 
        }
        [
        DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden),
        Browsable(false),
        ]
        public DropDownTreeItem SelectedItem
{

        }
        #endregion

        private DropDownTreeItemStyleCollection _itemStyles;
        [
        NotifyParentProperty(true),
        PersistenceMode(PersistenceMode.InnerProperty),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Content),
        ]
        public DropDownTreeItemStyleCollection ItemStyles
{
            get 
{
                if(_itemStyles==null) 
{
                    _itemStyles = new DropDownTreeItemStyleCollection();
                    if(this.IsTrackingViewState)
                        _itemStyles.TrackViewState();
                }
                return _itemStyles;
            }
        }
        #endregion

        private DropDownTreeItemCollection _items;
        [
        NotifyParentProperty(true),
        PersistenceMode(PersistenceMode.InnerProperty),
        DesignerSerializationVisibility(DesignerSerializationVisibility.Content),
        ]
        public DropDownTreeItemCollection Items
{
            get 
{
                if(this._items ==null) 
{
                    _items = new DropDownTreeItemCollection();
                    if(this.IsTrackingViewState)
                        _items.TrackViewState();
                }
                return _items;
            }
        }
        #endregion

        protected override void Render(HtmlTextWriter writer)
{
            if(Page != null)
                Page.VerifyRenderingInServerForm(this);

            if(!Items.IsEmpty)
{
                base.Render(writer);
            }
            else
{
                if((this.Site!=null)&&this.Site.DesignMode)
                    writer.WriteLine(this.ID);
            }
        }
        protected override void RenderContents(HtmlTextWriter writer)
{
            foreach(DropDownTreeItem item in this.Items)
{
                item.Render(writer);
            }

        }

        protected override HtmlTextWriterTag TagKey
{
            get
{
                return HtmlTextWriterTag.Select;
            }
        }
        protected override void AddAttributesToRender(HtmlTextWriter writer)
{
            base.AddAttributesToRender (writer);
            writer.AddAttribute(HtmlTextWriterAttribute.Name,this.UniqueID);
            if(this.AutoPostBack)
{
                writer.AddAttribute("language","javascript");
                writer.AddAttribute("onchange",this.Page.GetPostBackClientEvent(this,string.Empty));
            }

        }

        #endregion

        protected override void LoadViewState(object state)
{
            if(state !=null)
{
                object[] savedState = (object[])state;
                if(savedState[0] != null)
                    base.LoadViewState(savedState[0]);
                if(savedState[1] != null)
                    ItemStyles.LoadViewState(savedState[1]);
                if(savedState[2] != null)
                    Items.LoadViewState(savedState[2]);
            }    

        }
        protected override object SaveViewState()
{
            object[] savedState = new object[3];
            savedState[0] = base.SaveViewState ();
            savedState[1] = this.ItemStyles.SaveViewState();
            savedState[2] = this.Items.SaveViewState();
            for(int i=0;i<savedState.Length;i++)
{
                if(savedState[i] != null)
                    return savedState;
            }
            return null;
        }
        protected override void TrackViewState()
{
            base.TrackViewState();
            ItemStyles.TrackViewState();
            Items.TrackViewState();
        }
        #endregion

        protected override void OnInit(EventArgs e)
{
            base.OnInit (e);
            this.Items.Owner = null;
            this.Items.DropDownTree = this;
            this.Items.Init();
        }
        #endregion

        protected static readonly object EventSelectedIndexChanged = new object();
        public event System.EventHandler SelectedIndexChanged
{
            add
{
                Events.AddHandler(EventSelectedIndexChanged, value);
            }
            remove
{
                Events.RemoveHandler(EventSelectedIndexChanged, value);
            }
        }
        protected virtual void OnSelectedIndexChanged(System.EventArgs e)
{
            EventHandler selectedIndexChangedHandler = (EventHandler)Events[EventSelectedIndexChanged];
            if(selectedIndexChangedHandler!=null)
{
                selectedIndexChangedHandler(this,e);
            }
        }
        #endregion


        public void RaisePostDataChangedEvent()
{
            OnSelectedIndexChanged(System.EventArgs.Empty);
        }
        public bool LoadPostData(string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
{
            String presentValue = this.SelectedValue;
            String postedValue = postCollection[this.UniqueID];

            if (presentValue == null || !presentValue.Equals(postedValue))
{
                this.SelectedValue = postedValue;
                return true;
            }
            return false;
        }
        #endregion
    }
}

由于时间有限，今天先把代码贴上以后有空再加注解：），你们如果哪些看不懂可以帮我留言：）