本人正尝试做一自定义webcontrol,用于显示一个界面，不知怎样render?

[shibill]

本人正在尝试做一自定义webcontrol,用于显示一个界面，原理是先设置一个控件大小的Bitmap,然后再Bitmap上画，画完后输出，不知怎样render? 请指教

Private m_Image As Bitmap
m_Image = New Bitmap(Me.Width, Me.Height)
//下面在Bitmap对象上开画
。。。
画完后该怎么Render呢？
Protected Overrides Sub Render(ByVal output As System.Web.UI.HtmlTextWriter)
'output.Write(m_Value.ToString) ？？？？？
End Sub
请大家指点交流一下，另外谁有这方面的例子也请提供一个，多谢了

[shibill]

怎么没人懂吗？悲凉

[styker]

正确的应该是该类继承自WebControl，然后重载下面函数
protected override void CreateChildControls()
{
ErrorLabel = new Label();
ErrorLabel.Visible = false;
Controls.Add(ErrorLabel);

CustomerIdChooser = new DropDownList();
CustomerIdChooser.Load += new EventHandler(CustomerIdLoad);
CustomerIdChooser.SelectedIndexChanged +=
new EventHandler(CustomerIdChanged);
Controls.Add(CustomerIdChooser);

}
protected override void RenderWebPart(HtmlTextWriter output)
{
EnsureChildControls();
if (ErrorLabel.Visible == false)
{

output.AddAttribute(HtmlTextWriterAttribute.Cellpadding, "2px");
output.RenderBeginTag("div");
output.RenderBeginTag(HtmlTextWriterTag.Div);
output.AddAttribute(HtmlTextWriterAttribute.Width, "400px");
output.AddAttribute(HtmlTextWriterAttribute.Cellpadding, "2px");
output.AddAttribute(HtmlTextWriterAttribute.Cellspacing, "1px");
output.RenderBeginTag("table");
output.RenderBeginTag("tr");
output.AddStyleAttribute(HtmlTextWriterStyle.FontWeight, "bold");
output.AddStyleAttribute(HtmlTextWriterStyle.Width, "200px");
output.RenderBeginTag("td");
output.Write("<nobr>Customer ID:</nobr>");

output.RenderEndTag(); //td
output.AddAttribute("width", "200px");
output.RenderBeginTag("td");
this.CustomerIdChooser.RenderControl(output);
output.RenderEndTag(); //td
}
else // (ErrorLabel.Visible == true)
{
ErrorLabel.RenderControl(output);
}
}

[bflovesnow]

mark

[saucer]

why in Render? you realize the image only works for <img src="display.aspx">, right?

see

Create Snazzy Web Charts and Graphics On the Fly with the .NET Framework
http://msdn.microsoft.com/msdnmag/issues/02/02/ASPDraw/

Creating Dynamic Graphs in ASP.NET using GDI+
http://www.codeproject.com/aspnet/gdiGraph.asp

[yingshis]

up

[shibill]

感谢思归，你提供的对我帮助很大，我看了那个例子，它的方法是将Bitmap对象在服务器保存成一个JPG文件，然后再Render输出，不知道不这样做行不行，能不能直接输出Bitmap对象，因为保存文件太麻烦了，还要自己经常删掉不用的文件

[saucer]

you don't need a temporary jpg file

<img src="displayimage.aspx">

in displayimage.aspx:

Response.ContentType="image/jpeg";
...
//save your bitmap to Response.OutputStream

Response.End();

see
http://weblogs.asp.net/jrule/archive/2004/08/16/215393.aspx

[cnblackhawk]

up