In this article I will explain with an example, how to convert
WebGrid to Image using HTML5 canvas in ASP.Net Core (.Net Core) MVC.
Here
MVC6 Grid library is use for implementing
WebGrid.
html2canvas plugin
Please refer the following link for documentation for the
jQuery html2canvas plugin.
Database
Here I am making use of Microsoft’s Northwind Database. You can download it from here.
Database Context
Once the
Entity Framework is configured and connected to the database table, the Database Context will look as shown below.
using Microsoft.EntityFrameworkCore;
using WebGrid_Export_Image_Core.Models;
namespace WebGrid_Export_Image_Core.Models
{
public class DBCtx : DbContext
{
public DBCtx(DbContextOptions<DBCtx> options) : base(options)
{
}
public DbSet<Customer> Customers { get; set; }
}
}
Model
The Model class consists of following properties.
public class Customer
{
public string CustomerID { get; set; }
public string ContactName { get; set; }
public string City { get; set; }
public string Country { get; set; }
}
Controller
The Controller consists of following Action method.
Action method for handling GET operation
Inside this Action method, the Top 10 records are fetched from the Customers table using Database Context and returned to the View.
public class HomeController:Controller
{
private DBCtx Context { get; }
public HomeController(DBCtx _context)
{
this.Context = _context;
}
public IActionResult Index()
{
return View(this.Context.Customers.Take(10).ToList());
}
}
View
HTML Markup
Inside the View, in the very first line the Customer class is declared as Model for the View.
The
WebGrid is initialized with the Model i.e.
IEnumerable collection of
Customer class objects as source.
Below the MVC6 WebGrid, there is an HTML Form created with following ASP.Net Tag Helpers attributes.
asp-action – Name of the Action. In this case the name is Export.
asp-controller – Name of the Controller. In this case the name is Home.
method – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
The View also consists of an HTML INPUT Button.
Inside the View, the following script file is inherited:
1. jquery.min.js
2. html2canvas.min.js
Converting GridView to Image using HTML5 Canvas
Inside the
jQuery document ready event handler, the INPUT Button has been assigned with a click event handler.
Inside this function, the
html2canvas method accepts reference of the
WebGrid and then using
toDataURL method of canvas object of
html2canvas library the BASE64 string is determined.
Then, an Anchor element is created and its href property is set with the BASE64 string determined earlier and target and download properties are also set.
Finally, the click function is called which initiates the file download operation.
@model IEnumerable<WebGrid_Export_Image_Core.Models.Customer>
@addTagHelper*, Microsoft.AspNetCore.Mvc.TagHelpers
@using NonFactors.Mvc.Grid;
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>Index</title>
</head>
<body>
<div id="Grid">
@(Html.Grid(Model).Build(columns =>
{
columns.Add(model => model.CustomerID).Titled("Customer Id");
columns.Add(model => model.ContactName).Titled("ContactName");
columns.Add(model => model.City).Titled("City");
columns.Add(model => model.Country).Titled("Country");
})
)
</div>
<br />
<input type="button" id="btnExport" value="Export to Image"/>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/html2canvas/1.4.1/html2canvas.min.js"></script>
<script type="text/javascript">
$(function () {
$("#btnExport").click(function () {
html2canvas($("#Grid")[0]).then(function (canvas) {
var base64 = canvas.toDataURL();
var lnkDownload = document.createElement('a');
document.body.appendChild(lnkDownload);
lnkDownload.href = base64;
lnkDownload.target = "_self";
lnkDownload.download = "Grid.png";
lnkDownload.click();
document.body.removeChild(lnkDownload);
});
});
});
</script>
</body>
</html>
Screenshots
Exported Image
Downloads