Simple C # image operations

Recently, You need to draw some labels (such as simple circular rectangular text) on an image that already exists on the server ). I have never done any graphic operations before, but I heard it is quite simple. Let's just ask, we will use the Graphics class.
Then, you can simply get the following code.

1 // get the image
2 System. Drawing. Image img = System. Drawing. Image. FromFile (this. TextBox1.Text );
3 Graphics g = Graphics. FromImage (img );
4 Pen p = new Pen (Color. White, 2 );
5g. DrawImage (img, 10, 10 );
6
7 // circle and text
8g. DrawEllipse (p, 10, 10, 5, 5 );
9g. DrawString ("here is the circle", new Font ("", 9), Brushes. White, new PointF (20, 20 ));
10
11 // fill in a circle
12g. FillEllipse (Brushes. White, 10, 10, 5, 5 );
13
14 // The file is not generated when it is displayed on the page
15 Response. ContentType = "image/gif ";
16 img. Save (Response. OutputStream, ImageFormat. Jpeg );

In this way, an image is displayed on the page. And draw a circle.

PS: Use a stupid method to merge Multiple Graphs into one graph: 1 // merge four images
2 // 96*96
3System. Drawing. Image imgBig = System. Drawing. Image. FromFile ("c: \ qcd_logo2.PNG ");
4 // 48*48
5System. Drawing. Image img = System. Drawing. Image. FromFile ("c: \ qcd_logo.bmp ");
6 Graphics g = Graphics. FromImage (imgBig );
7G. DrawImage (img, 0, 0 );
8g. DrawImage (img, 49, 0 );
9g. DrawImage (img, 0, 49 );
10g. DrawImage (img, 49, 49 );

PS2: extract the merged graph in one way. 1 // 144*144 Graph
2 System. Drawing. Image imgBig = System. Drawing. Image. FromFile ("c: \ qcd_logo2.PNG ");
3 // 48*48 Graph
4 System. Drawing. Image img = System. Drawing. Image. FromFile ("c: \ qcd_logo.bmp ");
5 Graphics g = Graphics. FromImage (imgBig );
6 Pen p = new Pen (Color. Red, 2 );
7 // merge all, that is, 3*3
8g. DrawImage (img, 0, 0 );
9g. DrawImage (img, 49, 0 );
10g. DrawImage (img, 0, 49 );
11g. DrawImage (img, 49, 49 );
12g. DrawImage (img, 97, 0 );
13g. DrawImage (img, 0, 97 );
14g. DrawImage (img, 97, 97 );
15g. DrawImage (img, 49, 97 );
16g. DrawImage (img, 97, 49 );
17g. DrawEllipse (p, 49, 49, 10, 10 );
18g. DrawString ("this is a circle", new Font ("", 9), Brushes. Red, new PointF (55, 55 ));
19
20 // switch to the thumbnail
21g = Graphics. FromImage (img );
22 // specifies the range of the captured image.
23 Rectangle rect = new Rectangle (49, 49, 48, 48 );
24 // capture a large image
25g. DrawImage (imgBig, 0, 0, rect, GraphicsUnit. Pixel );
26
27 // The file is not generated when it is displayed on the page
28 Response. ContentType = "image/gif ";
29 img. Save (Response. OutputStream, ImageFormat. Jpeg );