download generated images automatically multiple times - asp.net

Question

I am trying to download around 1000 images. For that first I am generating random number, converting this text to image. After this on button click, I am downloading this generated image. This is working fine. Now I want to run this loop for 1000 times so that I can download thousand images. The below code works fine when the loop is running once, but when the loop is running 1000 times, its not working as I am expecting.
Also, I want to change the destination folder where this images should be downloaded. How can I do that?
Below if I change value of variable i to 1000, the output is not what I am expecting
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
for (int i = 0; i < 1; i++)
{
CallBUttonClick();
}
}
protected void Button1_Click(object sender, EventArgs e)
{
var s = GenerateRandomCode();
RandomImage ci = new RandomImage(s.ToString(), 300, 75);
this.Response.Clear();
this.Response.ContentType = "image/jpeg";
Response.AppendHeader("Content-Disposition", "attachment; filename=downloadedFile.JPG");
ci.Image.Save(this.Response.OutputStream, ImageFormat.Jpeg);
ci.Dispose();
}
protected void CallBUttonClick()
{
Button1_Click(Button1, null);
}
private string GenerateRandomCode()
{
Random r = new Random();
string s = "";
for (int j = 0; j < 5; j++)
{
int i = r.Next(3);
int ch;
switch (i)
{
case 1:
ch = r.Next(0, 9);
s = s + ch.ToString();
break;
case 2:
ch = r.Next(65, 90);
s = s + Convert.ToChar(ch).ToString();
break;
case 3:
ch = r.Next(97, 122);
s = s + Convert.ToChar(ch).ToString();
break;
default:
ch = r.Next(97, 122);
s = s + Convert.ToChar(ch).ToString();
break;
}
r.NextDouble();
r.Next(100, 1999);
}
return s;
}
}
Adding RandomImage.cs class file
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing.Text;
using System;
public class RandomImage
{
//Default Constructor
public RandomImage() { }
//property
public string Text
{
get { return this.text; }
}
public Bitmap Image
{
get { return this.image; }
}
public int Width
{
get { return this.width; }
}
public int Height
{
get { return this.height; }
}
//Private variable
private string text;
private int width;
private int height;
private Bitmap image;
private Random random = new Random();
//Methods declaration
public RandomImage(string s, int width, int height)
{
this.text = s;
this.SetDimensions(width, height);
this.GenerateImage();
}
public void Dispose()
{
GC.SuppressFinalize(this);
this.Dispose(true);
}
protected virtual void Dispose(bool disposing)
{
if (disposing)
this.image.Dispose();
}
private void SetDimensions(int width, int height)
{
if (width <= 0)
throw new ArgumentOutOfRangeException("width", width,
"Argument out of range, must be greater than zero.");
if (height <= 0)
throw new ArgumentOutOfRangeException("height", height,
"Argument out of range, must be greater than zero.");
this.width = width;
this.height = height;
}
private void GenerateImage()
{
Bitmap bmp = new Bitmap(1, 1);
Graphics graphics = Graphics.FromImage(bmp);
Font font = new Font(FontFamily.GenericSansSerif, 28);
SizeF stringSize = graphics.MeasureString(this.text, font);
bmp = new Bitmap(bmp, (int)stringSize.Width+30, (int)stringSize.Height+30);
graphics = Graphics.FromImage(bmp);
graphics.DrawString(this.text, font, Brushes.White, 0, 0);
font.Dispose();
graphics.Flush();
graphics.Dispose();
this.image = bmp;
}
}

Answer 1

Hi you need to save you bitmap file on physcial folder. I have modified you code. Please see below code
private void GenerateImage()
{
Bitmap bmp = new Bitmap(1, 1);
Graphics graphics = Graphics.FromImage(bmp);
Font font = new Font(FontFamily.GenericSansSerif, 28);
SizeF stringSize = graphics.MeasureString(this.text, font);
bmp = new Bitmap(bmp, (int)stringSize.Width + 30, (int)stringSize.Height + 30);
graphics = Graphics.FromImage(bmp);
graphics.DrawString(this.text, font, Brushes.White, 0, 0);
font.Dispose();
graphics.Flush();
graphics.Dispose();
bmp.Save("C:\\" + this.text + ".jpg");
this.image = bmp;
}
I have also removed below code from button click and rested, it is working fine.
//this.Response.Clear();
//this.Response.ContentType = "image/jpeg";
//Response.AppendHeader("Content-Disposition", "attachment; filename=downloadedFile.JPG");
//ci.Image.Save(this.Response.OutputStream, ImageFormat.Jpeg);
//ci.Dispose();

Answer 2

That's not how the ASP.NET Page Life Cycle works. If you use the Response object to serve a download, you can serve ONE file.
You are approaching the problem from the wrong side; you say "I am trying to download around 1000 images". That is a process on the client side, on the browser if you will.
Yet you are trying to solve this on the server side.
You want 1000 downloads, so you have to initiate 1000 downloads from the client, and let the server side, the one Page you're writing for that, live through that 1000 times.
In other words, you cannot "push download" multiple files from the server, you have to request them one by one.