[c#] How can I determine browser window size on server side C#

How can I get the exact height and width of the currently open browser screen window?

There is a solution to solve page_onload problem (can't get size until page load complete) : Create a userControl :

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="ClientSizeDetector.ascx.vb"    Inherits="Project_UserControls_ClientSizeDetector" %>
<%If (IsFirstTime) Then%>
<script type="text/javascript">
var pageURL = window.location.href.search(/\?/) > 0 ? "&" : "?";
window.location.href = window.location.href + pageURL + "clientHeight=" + window.innerHeight + "&clientWidth=" + window.innerWidth;
</script>
<%End If%>

Code behind :

 Private _isFirstTime As Boolean = False
 Private _clientWidth As Integer = 0
 Private _clientHeight As Integer = 0

 Public Property ClientWidth() As Integer
    Get
        Return _clientWidth
    End Get
    Set(value As Integer)
        _clientWidth = value
    End Set
End Property

Public Property ClientHeight() As Integer
    Get
        Return _clientHeight
    End Get
    Set(value As Integer)
        _clientHeight = value
    End Set
End Property

public Property IsFirstTime() As Boolean 
    Get
        Return _isFirstTime
    End Get
    Set(value As Boolean)
        _isFirstTime = value
    End Set
End Property



Protected Overrides Sub OnInit(e As EventArgs)

    If (String.IsNullOrEmpty(Request.QueryString("clientHeight")) Or String.IsNullOrEmpty(Request.QueryString("clientWidth"))) Then
        Me._isFirstTime = True
    Else
        Integer.TryParse(Request.QueryString("clientHeight").ToString(), ClientHeight)
        Integer.TryParse(Request.QueryString("clientWidth").ToString(), ClientWidth)
        Me._isFirstTime = False
    End If
End Sub

So after, you can call your control properties

Here's an Ajax, asxh handler and session variables approach:

Handler:

using System;
using System.Web;

public class windowSize : IHttpHandler , System.Web.SessionState.IRequiresSessionState  {

    public void ProcessRequest (HttpContext context) {
        context.Response.ContentType = "application/json";

        var json = new System.Web.Script.Serialization.JavaScriptSerializer();
        var output = json.Serialize(new { isFirst = context.Session["BrowserWidth"] == null });
        context.Response.Write(output);

        context.Session["BrowserWidth"] =  context.Request.QueryString["Width"]; 
        context.Session["BrowserHeight"] = context.Request.QueryString["Height"];
    }

    public bool IsReusable
    {
        get { throw new NotImplementedException(); }
    }
}

Javascript:

window.onresize = function (event) {
    SetWidthHeight();
}
function SetWidthHeight() {
    var height = $(window).height();
    var width = $(window).width();
    $.ajax({
        url: "windowSize.ashx",
        data: {
            'Height': height,
            'Width': width
        },
        contentType: "application/json; charset=utf-8",
        dataType: "json"
    }).done(function (data) {     
        if (data.isFirst) {
            window.location.reload();
        };
    }).fail(function (xhr) {
        alert("Problem to retrieve browser size.");
    });

}
$(function () {
    SetWidthHeight();
});

On aspx file:

...
<script src="Scripts/jquery-1.9.1.min.js"></script>
<script src="Scripts/BrowserWindowSize.js"></script>
...
<asp:Label ID="lblDim" runat="server" Text=""></asp:Label>
...

Code behind:

protected void Page_Load(object sender, EventArgs e)
  {
      if (Session["BrowserWidth"] != null)
      {
          // Do all code here to avoid double execution first time
          // ....
          lblDim.Text = "Width: " + Session["BrowserWidth"] + " Height: " + Session["BrowserHeight"];
      }
  }

Source: https://techbrij.com/browser-height-width-server-responsive-design-asp-net

Here how I solved it using Cookies:

First of all, inside the website main script:

var browserWindowSize = getCookie("_browserWindowSize");
var newSize = $(window).width() + "," + $(window).height();
var reloadForCookieRefresh = false;

if (browserWindowSize == undefined || browserWindowSize == null || newSize != browserWindowSize) {
    setCookie("_browserWindowSize", newSize, 30);
    reloadForCookieRefresh = true;
}

if (reloadForCookieRefresh)
    window.location.reload();

function setCookie(name, value, days) {
    var expires = "";
    if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
        expires = "; expires=" + date.toUTCString();
    }
    document.cookie = name + "=" + (value || "") + expires + "; path=/";
}

function getCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for (var i = 0; i < ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0) == ' ') c = c.substring(1, c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length);
    }
    return null;
}

And inside MVC action filter:

public class SetCurrentRequestDataFilter : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        // currentRequestService is registered per web request using IoC
        var currentRequestService = iocResolver.Resolve<ICurrentRequestService>();

        if (filterContext.HttpContext.Request.Cookies.AllKeys.Contains("_browserWindowSize"))
        {
            var browserWindowSize = filterContext.HttpContext.Request.Cookies.Get("_browserWindowSize").Value.Split(',');
            currentRequestService.browserWindowWidth = int.Parse(browserWindowSize[0]);
            currentRequestService.browserWindowHeight = int.Parse(browserWindowSize[1]);
        }

    }
}

So here is how you will do it.

Write a javascript function which fires whenever the window is resized.

window.onresize = function(event) {
    var height=$(window).height();
    var width=$(window).width();
    $.ajax({
     url: "/getwindowsize.ashx",
     type: "POST",
     data : { Height: height, 
              Width:width, 
              selectedValue:selectedValue },
     contentType: "application/json; charset=utf-8",
     dataType: "json",
     success: function (response) { 
           // do stuff
     }

}

Codebehind of Handler:

 public class getwindowsize : IHttpHandler {

public void ProcessRequest (HttpContext context) {
    context.Response.ContentType = "application/json";
     string Height = context.Request.QueryString["Height"]; 
     string Width = context.Request.QueryString["Width"]; 
    }

I went with using the regex from detectmobilebrowser.com to check against the user-agent string. Even tho it says it was last updated in 2014 it was accurate on the devices I tested.

Here is the C# code I got from them at the time of submitting this answer:

<%@ Page Language="C#" %> 
<%@ Import Namespace="System.Text.RegularExpressions" %>
<%
    string u = Request.ServerVariables["HTTP_USER_AGENT"];
    Regex b = new Regex(@"(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|mobile.+firefox|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows ce|xda|xiino", RegexOptions.IgnoreCase | RegexOptions.Multiline);
    Regex v = new Regex(@"1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-", RegexOptions.IgnoreCase | RegexOptions.Multiline);
    if ((b.IsMatch(u) || v.IsMatch(u.Substring(0, 4)))) {
        Response.Redirect("http://detectmobilebrowser.com/mobile");
    }
%>