4 使用自定義樣式

在上一節中，我們通過集成TableStyle完成了RegistControlStyle類。現在我們需要在RegisterControl中使用自定義的RegistControlStyle。

使用自定義樣式，首先復寫RegistControl的CreatedControlStyle()方法，代碼如下所示：

protected override Style CreateControlStyle()

{

return new RegisterControlStyle(this.ViewState);

}

為什么需要復寫CreatedControlStyle屬性呢？因為RegisteControl繼承與WebControl，所有擁有ControlStyle屬性。在WebControl基類中，ControlStyle屬性的源代碼如下所示：

private Style controlStyle;

public Style ControlStyle

{

get

{

if (this.controlStyle == null)

{

this.controlStyle= this.CreateControlStyle();

}

return this.controlStyle;

}

}

由于自定義控件的ControlStyle屬性是通過CreatedControlStyle方法創建的，所以我們需要復寫CreatedControlStyle方法，覆蓋原有的ControlStyle屬性。

現在還需要復寫AddAttributeToRender方法，代碼如下所示：

[System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]

protected override void AddAttributesToRender(HtmlTextWriter writer)

{

base.AddAttributesToRender(writer);

writer.AddAttribute(HtmlTextWriterAttribute.Id,this.ClientID);

writer.AddAttribute(HtmlTextWriterAttribute.Accesskey,this.AccessKey);

if (!this.Enabled)

{

writer.AddAttribute(HtmlTextWriterAttribute.Disabled,"disabled");

}

writer.AddAttribute(HtmlTextWriterAttribute.Tabindex,this.TabIndex.ToString());

writer.AddAttribute(HtmlTextWriterAttribute.Title,this.ToolTip.ToString());

this.ControlStyle.AddAttributesToRender(writer,this);

IEnumerator item = this.Attributes.Keys.GetEnumerator();

while (item.MoveNext())

{

string key = item.Current.ToString();

writer.AddAttribute(key,this.Attributes[key]);

}

}

公開所有我們需要使用的自定義控件的樣式屬性，代碼如下所示：

public virtual BackImageRepeat BackImageRepeat

{

get

{

RegisterControlStyle rs = this.ControlStyle as RegisterControlStyle;

return rs.BackImageRepeat;

}

set

{

RegisterControlStyle rs = this.ControlStyle as RegisterControlStyle;

rs.BackImageRepeat = value;

}

}

public new BorderStyle BorderStyle

{

get { return (this.ControlStyle as RegisterControlStyle).BorderStyle; }

set { (this.ControlStyle as RegisterControlStyle).BorderStyle = value; }

}

public new System.Web.UI.WebControls.Unit BorderWidth

{

get { return (this.ControlStyle as RegisterControlStyle).BorderWidth; }

set { (this.ControlStyle as RegisterControlStyle).BorderWidth = value; }

}

public int CellPadding

{

get { return (this.ControlStyle as RegisterControlStyle).CellPadding; }

set { (this.ControlStyle as RegisterControlStyle).CellPadding = value; }

}

public int CellSpacing

{

get { return (this.ControlStyle as RegisterControlStyle).CellSpacing; }

set { (this.ControlStyle as RegisterControlStyle).CellSpacing = value; }

}

public string BackImageUrl

{

get { return (this.ControlStyle as RegisterControlStyle).BackImageUrl; }

set { (this.ControlStyle as RegisterControlStyle).BackImageUrl = value; }

}

注意：所有的自定義樣式都需要在自定義控件中進行公開，才能被設計器識別。特別需要注意的是，基于自定義樣式的屬性都要進行轉換并且來自于ControlStyle屬性。

修改RenderBeginTag()方法，以便使用所有我們公開的自定義控件樣式屬性。代碼如下所示：

public override void RenderBeginTag(HtmlTextWriter writer)

{

writer.RenderBeginTag(HtmlTextWriterTag.Table);

writer.AddAttribute(HtmlTextWriterAttribute.Id,"RegisterTable");

writer.AddStyleAttribute(HtmlTextWriterStyle.Width,"auto");

writer.AddStyleAttribute(HtmlTextWriterStyle.Height, "auto");

writer.AddStyleAttribute(HtmlTextWriterStyle.BackgroundColor,System.Drawing.
ColorTranslator.ToHtml(this.BackColor));

writer.AddStyleAttribute(HtmlTextWriterStyle.BorderColor, 
System.Drawing.ColorTranslator.ToHtml(this.BorderColor));

writer.AddStyleAttribute(HtmlTextWriterStyle.BorderStyle,this.BorderStyle.ToString());

writer.AddStyleAttribute(HtmlTextWriterStyle.BorderWidth,this.BorderWidth.ToString());

writer.AddAttribute("cellpadding",this.CellPadding.ToString());

writer.AddAttribute("cellspacing", this.CellSpacing.ToString());

writer.AddStyleAttribute(HtmlTextWriterStyle.FontFamily,this.ControlStyle.Font.Name);

writer.AddStyleAttribute(HtmlTextWriterStyle.BackgroundImage,
 (this.ControlStyle as RegisterControlStyle).BackImageUrl);

writer.AddStyleAttribute(this.BackImageRepeat.ToString(),this.
BackImageRepeat.ToString());

}

現在我們重新生成解決方案，重新再頁面上拖入RegistControl，設定樣式屬性，效果如圖4.1所示：

圖4.1 使用自定樣式屬性控制自定義控件樣式