Asp.Net Core Generate Image file dynamically

Question

How is it possible to generate an image all in the controller and return it as an image file? For example if link is:

www.test.com/generate?width=100&height=50&color=red

This shall generate 100x50 red image and return it, and if I set this link as a source of Image View on front, it shall draw that image. It shall work as a service which does not have any connection to UI either HTML or other platforms like iOS UIImageView and Android ImageView.

@Mat thanks but the question seems ok for me and I answered my question, and when someone googles same problem, he may find this 'downvoted' question useful — mister_giga
– mister_giga, Commented Dec 31, 2017 at 10:39

Kirk Woll · Accepted Answer · 2018-12-19 15:29:55Z

14

I managed to draw using System.Drawing and System.Drawing.Drawing2D - Graphics class

Bitmap bitmap = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);

Graphics graphics = Graphics.FromImage(bitmap);

var pen = new Pen(lineColor, widthLine);

graphics.FillRectangle(new SolidBrush(bgColor), new Rectangle(0, 0, width, height));

and graphics has all necessary methods for drawing, after drawing finished use the bitmap to create image file and return HttpResponseMessage from ASP net action

using (MemoryStream ms = new MemoryStream())
{
    bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
    HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
    result.Content = new ByteArrayContent(ms.ToArray());
    result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
    return result;
}

This was all I wanted and not the useless down votes :)

edited Dec 19, 2018 at 15:29

Kirk Woll

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answered Dec 31, 2017 at 10:38

mister_giga

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1 Comment

Kirk Woll Over a year ago

In a new .net core web app, I also had to install System.Drawing.Common Also, don't forget to dispose of all those resources (Bitmap, Graphics, Pen, SolidBrush)

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