Using the Callback control framework with a map resource

re: Using the Callback control framework with a map resource

Mohamed Moustafa — Tue, 26 Dec 2006 10:29:01 GMT

please where i can find callback control framework ?

re: Using the Callback control framework with a map resource

Bryan Baker — Wed, 27 Dec 2006 19:01:26 GMT

The CallbackResult class is part of the Web ADF. It builds on the client callback framework that is part of ASP.NET 2.0. It makes transferring information between server and browser easier.

The WebControl abstract class, in the ESRI.ArcGIS.Web.UI.WebControls assembly, extends the ASP.NET WebControl class by adding the CallbackResults property. So any control that extends the Web ADF's WebControl can take advantage of the CallbackResults to send data.

re: Using the Callback control framework with a map resource

David Jones — Mon, 08 Jan 2007 14:37:45 GMT

This method works fine against the map control, but against other controls, it doesn't work. For instance, the scalebar control, lets say you update the units from miles to kilometers in code. That doesn't produce item in the callbacklist on the scalebar, so there is no way of causing it to redraw without having something happen to the map (such as zoom in in, which does cause a item to be added to the scalebars callbackresults list). Perhaps I am wrong, but I would think that updating the units would then create a call back result because the scalebar would need to be redrawn. Code: protected void CallbackButton1_Clicked(object sender, EventArgs args) { ScaleBar1.BarUnits = ScaleBarUnits.Kilometers; ScaleBar1.BarColor = System.Drawing.Color.BlueViolet; ScaleBar1.BarHeight = 50; ScaleBar1.Refresh(); CallbackButton1.CallbackResults.CopyFrom(ScaleBar1.CallbackResults); //doesn't do anything, no call back result on scalebar. }

re: Using the Callback control framework with a map resource

Ryan Olson — Mon, 08 Jan 2007 19:34:45 GMT

That is a good find. We have logged a bug for this problem in the ScaleBar.Refresh() method. There are 2 things you need to do to work around this problem. First of all, you need to call InitializeFunctionalities() on the Map control you are working with. This is because the ScaleBar.Refresh() checks to see if there are functionalities associated with the map and it assumes they will be initialized first. This will allow the scalebar image to refresh in a callback. The second thing you should do to workaround the background color is use a similar method for refreshing a control’s html when working with non-ADF controls.

Here is such a method:

private CallbackResult RefreshControlHtml(Control control)

    {
        System.IO.StringWriter sw = new System.IO.StringWriter();
        HtmlTextWriter writer = new HtmlTextWriter(sw);

control.RenderControl(writer);

string htmlContent = sw.ToString();

sw.Close();

return new CallbackResult(control, "content", htmlContent);

}

You should add this result to the callback results of your ScaleBar. Note, you can use the RefreshControlHtml function with many different controls, like GridView, etc. Your code will end up looking something like this:

protected void CallbackButton1_Clicked(object sender, EventArgs args)

{

Map1.InitializeFunctionalities();

ScaleBar1.BackColor = System.Drawing.Color.Lime;

ScaleBar1.BarUnits = ESRI.ArcGIS.ADF.Web.ScaleBarUnits.Feet;

// the following line is necessary to change the back color because that is not part of the image

CallbackButton1.CallbackResults.Add(RefreshControlHtml(ScaleBar1));

ScaleBar1.Refresh();

CallbackButton1.CallbackResults.CopyFrom(ScaleBar1.CallbackResults);

}

private CallbackResult RefreshControlHtml(Control control)

{

System.IO.StringWriter sw = new System.IO.StringWriter();

HtmlTextWriter writer = new HtmlTextWriter(sw);

control.RenderControl(writer);

string htmlContent = sw.ToString();

sw.Close();

return new CallbackResult(control, "content", htmlContent);

}

re: Using the Callback control framework with a map resource

karimhamdy — Wed, 10 Jan 2007 08:53:52 GMT

This method works fine with the map control only if i made a sipmle proccessing at the server ,but if i made something which takes time (5 sec) or i made a big change to the map sometimes it dosen't work.

my case is generating a service area which takes about 3 or 4 sec but most probably it dosen't work "no change in the map unless i made any action on it like zomming "