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Run-time Image in ASP.NET using GDI+

, 12 Jun 2012
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How to make a dynamic/embedded image at run-time for an ASP.NET application using GDI+.

Sample Image

Introduction

This tip explains how to make a dynamic/embedded image at run-time for an ASP.NET application using GDI+.

Background

I searched around in Google and the only answer I could find was to make an ASPX page, hijack the Response.OutputStream, and change the Response.ContentType. This approach I think is far easier to work with, although older browser compatibility issues may come into play. Read about embedded image data and dataURI here: Wiki - Data_URI_scheme. There is also a Microsoft disclaimer for using GDI+ within ASP.NET. Anyway...

Using the code

Here is the code for the ASP.NET 'UserControl'. There is no mark-up code, and below is the code-behind.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;
using System.IO;

public partial class UserControls_ImageRender : System.Web.UI.UserControl
{   

    protected override void Render(HtmlTextWriter writer)
    {    
        writer.Write(@"<img src=""data:image/jpeg;base64,{0}"">", Data64);
    }

    public Bitmap bitmap
    {
        set
        {
            MemoryStream ms = new MemoryStream();
            value.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            Data64 = Convert.ToBase64String(ms.ToArray());
        }
    }

    private string Data64
    {
        get
        {
            string s = ViewState["Data64"] as string;
            return (s == null) ? string.Empty : s;
        }
        set
        { ViewState["Data64"] = value; }
    }
}

Register your control in web.config:

<add tagPrefix="ctl" src="~/UserControls/ImageRender.ascx" tagName="ImageRender"/>

Add an example to use on your form:

<ctl:ImageRender id="Image1" runat="server"/>

Use this Control, by setting the bitmap property.

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        Image1.bitmap = MakeImage();
    }
}
	
// make your own GDI+ image here. Here is my example...
public Bitmap MakeImage()
{
    DateTime dt = DateTime.Now;
    string sHeading1 = "asd";
    string sMachineSerial = "asdasd";
    string sText1 = "rtu";
    string sText2 = "uiouiouio";
    string sText3 = "dfgbftyfy";

    Bitmap bitmap = new System.Drawing.Bitmap(400, 200);
    Graphics g = System.Drawing.Graphics.FromImage(bitmap);
    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

    System.Drawing.Font drawFontAGBoldSmall = new System.Drawing.Font("Arial", 8);
    System.Drawing.Font drawFontAGBold = new System.Drawing.Font("Arial", 12);
    System.Drawing.Font drawFontAGBook = new System.Drawing.Font("Arial", 12, FontStyle.Bold);
    System.Drawing.Font drawFontAGBookDate = new System.Drawing.Font("Arial", 24);
    System.Drawing.Font drawFontAGBookHeading = new System.Drawing.Font("Arial", 16, FontStyle.Bold);
    System.Drawing.Font drawFontArial = new System.Drawing.Font("Arial", 12, FontStyle.Bold);

    Color myColor = ColorTranslator.FromHtml(@"#F0F0F0");
    System.Drawing.SolidBrush drawBrush = new System.Drawing.SolidBrush(myColor);

    System.Drawing.StringFormat drawFormat = new System.Drawing.StringFormat();
    System.Drawing.StringFormat drawCentreFormat = 
           new System.Drawing.StringFormat(StringFormatFlags.NoWrap);
    drawCentreFormat.Alignment = StringAlignment.Center;

    Pen drawPen = new Pen(drawBrush);

    g.DrawRectangle(drawPen, new Rectangle(0, 0, bitmap.Width - 1, bitmap.Height - 1));

    g.DrawString(dt.ToShortDateString(), drawFontAGBookDate, drawBrush, 
                 new Rectangle(0, 36, 400, 40), drawCentreFormat);
    g.DrawString(sHeading1, drawFontAGBookHeading, drawBrush, new Rectangle(4, 0, 392, 26), drawFormat);
    g.DrawString(sMachineSerial, drawFontAGBoldSmall, drawBrush, new Rectangle(8, 22, 392, 14), drawFormat);
    g.DrawString(sText1, drawFontAGBold, drawBrush, new Rectangle(8, 80, 192, 20), drawFormat);
    g.DrawString(sText2, drawFontAGBold, drawBrush, new Rectangle(8, 101, 192, 20), drawFormat);
    g.DrawString(sText3, drawFontAGBold, drawBrush, new Rectangle(8, 122, 192, 20), drawFormat);

    drawFontAGBook.Dispose();
    drawFontAGBold.Dispose();
    drawFontArial.Dispose();
    drawBrush.Dispose();
    drawPen.Dispose();
    g.Dispose();

    return bitmap;
}

End

All done! As my son would write, thanks for listening!

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Richard Leiser
Web Developer
Switzerland Switzerland
No Biography provided

Comments and Discussions

 
Questionhello Pinmemberbeleshi3-Jun-12 23:44 

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