textarea自适应高度

<!--textarea自适应高度-->
<textarea style='border: 1px solid #94BBE2;width:100%;' rows=15 onpropertychange='this.style.posHeight=this.scrollHeight' id=textarea onfocus='textarea.style.posHeight=this.scrollHeight'>
</textarea>

 

<textarea name="textarea" cols="70" style="overflow-y:visible"> </textarea>

自动适应输入内容高度的TextBox控件

Code
附 AutoTextBox 控件源码#region 附 AutoTextBox 控件源码 
using System; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.ComponentModel; 
 
namespace WebExcel.UI.WebControls 
{ 
    /**//**//**//// <summary> 
    /// Summary description for AutoLengthTextBox. 
    /// </summary> 
    [DefaultProperty("Text"),  
        ToolboxData("<{0}:AutoTextArea runat=server></{0}:AutoTextArea>")] 
    public class AutoTextArea : System.Web.UI.WebControls.TextBox 
    { 
        [DefaultValue(200)] 
        public int MaxHeight 
        { 
            get 
            { 
                object obj = ViewState["MaxHeight"]; 
                return obj == null ? 200 : (int)obj; 
            } 
            set 
            { 
                ViewState["MaxHeight"] = value; 
            } 
        } 
 
        [DefaultValue(60)] 
        public int MinHeight 
        { 
            get 
            { 
                object obj = ViewState["MinHeight"]; 
                return obj == null ? 60 : (int)obj; 
            } 
            set 
            { 
                ViewState["MinHeight"] = value; 
            } 
        } 
 
        protected override void OnPreRender(EventArgs e) 
        { 
            this.Attributes["minHeight"] = this.MinHeight.ToString(); 
            if ( this.Height == Unit.Empty ) 
            { 
                this.Height = this.MinHeight; 
            } 
            else 
            { 
                this.Height = (int)Math.Max(this.MinHeight, this.Height.Value); 
            } 
            base.OnPreRender (e); 
        } 
 
        /**//**//**//// <summary>  
        /// Render this control to the output parameter specified. 
        /// </summary> 
        /// <param name="output"> The HTML writer to write out to </param> 
        protected override void Render(HtmlTextWriter output) 
        { 
            string strCode; 
            if ( this.MaxHeight <= 0 ) 
            { 
                strCode = "this.style.height=Math.max(this.minHeight,this.scrollHeight)+(this.offsetHeight-this.clientHeight)"; 
            } 
            else 
            { 
                strCode = "this.style.height=(this.scrollHeight>200)?200:Math.max(this.minHeight,this.scrollHeight)+(this.offsetHeight-this.clientHeight)"; 
            } 
            base.Attributes["onpropertychange"] = strCode; 
            // base.Attributes["onfocus"] = "this.height=this.height"; 
            if ( base.Rows == 0 ) 
            { 
                base.Rows = 1; 
            } 
            base.TextMode = TextBoxMode.MultiLine; 
            base.Render(output); 
        } 
    } 
} 
#endregion