C# ASP.NET: adding width and height properties and scrollbars to web user control

Have you got mixed up and tried to subclass a user control rather than a web control.

Are you in fact after this:

public class ImageGenerator : System.Web.UI.WebControls.WebControl  

Oh and scrollbars - if you just contain the image in a div with a set height and width and set scrolling to automatic I think that will do it.

Thanks for response.

I'm creating custom control by right clicking on my project name and selecting add new web user control.
When I do that, it automaticaly inherits System.Web.UI.UserControl. Ascx file looks like this:

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="ImageGenerator.ascx.cs" Inherits="ImageGenerator" %>

When I manualy change it to inherit System.Web.UI.WebControls.WebControl, I get this error:

Make sure that the class defined in this code file matches the 'inherits' attribute, and that it extends the correct base class (e.g. Page or UserControl)

I tried googling about it and found that I should change 'CodeFile' attribute to 'CodeBehind', but then I get this error:

Could not load type 'ImageGenerator'.

I found sever articles saying this error happens when sollutions is not compiled, but I can't compile it becouse this error arrises when I try to build the sollution.

Ok well the first thing to clarify is whether you are wanting a user control or a custom control.  Do you know the difference and know which one it is that you want?

I'm mainly a desktop programmer. So I didn't know there is a difference.

I want to be able to create a control which already has all common properties and functionality like all other asp controls. (Width, height, style, tag,  CssClass, Visible, Enabled, etc.)

Just like user control in desktop application. You get empty background with everything you need to put it on the form. Then just extend it with functionality you need.

Thanks. I'll read it later today.
I'll post back when I decide what I actually need :)

I think I understand the difference.
I'd like to do it with user control, as it seems simpler. So this means I have to create a <div> element or something similar inside the control, and specify width and height of the div.

Example in the code section does all that, plus it has scroll bars when picturebox is larger that div.

But when I try to generate the image using code from my first post (in page_load event), it overwrites the entire contents of the web page. I can see only generated image.
This makes sense, because I'm writing directly to Response object.

I know this is not the main question of this post, but maybe you know the solution. (You'll get the points regardless if you answer this or not)
Is there a way to specify exactly where Response output will go (for example inside <div>) or is there another way to put System.Drawing.Bitmap on a web page without saving it on the file system first?

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="ImageGenerator.ascx.cs" Inherits="ImageGenerator" %>
<div style="width: 200px; height: 200px; overflow: scroll;">
    <asp:Image ID="Image1" runat="server" Width="300" Height="300" />
</div>

                                              

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Yep you can place a container in your control - eg an image control or a literal control and then manipulate that.  First though tell me where your image is coming from?

I'm generating it on the fly. In the page_load event. It's in the code snippet of my question, here it is again.

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.DesignMode)
        {
            Response.Clear();
            Response.ContentType = "image/jpeg";
 
            Bitmap b = new Bitmap(100, 100);
            Graphics g = Graphics.FromImage(b);
            g.DrawRectangle(Pens.Bisque, 10, 10, 90, 90);
 
            b.Save(Response.OutputStream, ImageFormat.Jpeg);
            Response.End();
        }
    }

                                              

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Ok thought it would be something like that.

I have done this kind of thing before and I think what you need to do is create a page whose sole job is the creation of images (Call it ImageFactory.aspx or somethign like that).  Parameters for which image to be created can be passed in as querystring parameters.

Then in your other page/control you place an image server control or even just a plain old html image tag but you set the src of the image to the url of the page(with querystring parameters if required).

Hope that make sense?

Yep.
It makes sense. In fact I was just reading an article I found which explains how something like this works.
Here's the link for future reference:

http://www.developerfusion.com/article/2569/creating-images-on-the-fly-with-aspnet/

Thanks again for your help.

Yep thats a good article but it doesn't mention how to then get it on a page as part of the page - fine if you just want the image on it's own of course but this isn't usually the case,