Asp, net C# download image frome bitmap

Question

1.00/5 (2 votes)

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I have a picture on the server is a generous certificate of appreciation when the student searches with a number the student's data is written on the image and without saving it on the server the student protects it on his machine
I got the code to write on the image, but it saves it on the server. Please help me. Instead of saving on the server, the downloader works for the student.
This is the writing code

<pre>Bitmap bitMapImage = new Bitmap(Server.MapPath("img1.jpg"));
            Graphics graphicImage = Graphics.FromImage(bitMapImage);
            graphicImage.DrawString("testing 1 2 3",
            new Font("Arial", 20, FontStyle.Bold),
            SystemBrushes.WindowText, new Point(0, 0));
                    //  I want to replace this by downloading it to the student machine //instead of saving it to the server          bitMapImage.Save(Server.MapPath("~/Images")+"newImage.jpg" , ImageFormat.Jpeg);
            graphicImage.Dispose();

bitMapImage.Dispose();

What I have tried:

i

tried

download image to client pc

Posted 25-Jun-20 0:37am

Saeeed Sayed

Updated 25-Jun-20 1:08am

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Comments

Richard MacCutchan 25-Jun-20 7:00am

You cannot download files to the user's PC, it would be a major security breach. Only they can do it by requesting a download. What you must do is to create a file which they can then download through their browser.

2 solutions

Solution 2

1. Create a MemoryStream and "save" the image to that.
2. Write the above MemoryStream as the response

Will look something like this

C#

Bitmap bitMapImage = new Bitmap(Server.MapPath("img1.jpg"));
Graphics graphicImage = Graphics.FromImage(bitMapImage);
graphicImage.DrawString("testing 1 2 3",
new Font("Arial", 20, FontStyle.Bold),
SystemBrushes.WindowText, new Point(0, 0));
        
// I want to replace this by downloading it to the student machine 
// instead of saving it to the server
// bitMapImage.Save(Server.MapPath("~/Images")+"newImage.jpg" , ImageFormat.Jpeg);

MemoryStream memoryStream = new MemoryStream();
bitmap.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Jpeg);

byte[] bytesInStream = memoryStream.ToArray();
memoryStream.Close(); 

Response.Clear();
Response.ContentType = "image/jpeg";
Response.AddHeader("content-disposition", "attachment; newImage.jpg");
Response.BinaryWrite(bytesInStream);

graphicImage.Dispose();
bitMapImage.Dispose();

Response.End();

Helpful info:
c# - Saving a bitmap into a MemoryStream - Stack Overflow[^]
c# - How to download memorystream to a file? - Stack Overflow[^]

Posted 25-Jun-20 1:08am

MadMyche

Comments

Saeeed Sayed 25-Jun-20 7:49am

I tried it but it doesn't download the image but it download the page by name with ex aspx

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OriginalGriff · Accepted Answer · 2020-06-25T01:01:00

Solution 1

Convert the image to a byte array, then use BinaryWrite to send it to the client as a file:

C#

Response.AddHeader("Cache-Control", "no-cache, must-revalidate, post-check=0, pre-check=0");
Response.AddHeader("Pragma", "no-cache");
Response.AddHeader("Content-Description", "File Download");
Response.AddHeader("Content-Type", "application/force-download");
Response.AddHeader("Content-Transfer-Encoding", "binary\n");
Response.AddHeader("content-disposition", "attachment;filename=" + fileName);
Response.BinaryWrite(data);
Response.End();

Posted 25-Jun-20 1:01am

OriginalGriff

Comments

Richard MacCutchan 25-Jun-20 7:36am

Dumb question but ... can the server force that without the user's intervention?

OriginalGriff 25-Jun-20 7:58am

Yes.
It's up to the user what happens to it though, and Chrome at least will warn you about zip, exe, and suchlike.

Richard MacCutchan 25-Jun-20 8:15am

Thanks, wasn't aware of that.