NET generate picture verification code--turn from lisliefor

At present, the machine identification verification code has been quite powerful, more common to avoid the machine recognition method, is to connect the verification code string together, so that the difficulty of recognition, after all, the machine does not have artificial intelligence. I looked for a lot of. NET Generate picture Verification code example, later after some modification and collation, almost satisfied my requirements: The picture has noise point, each character's font is random, the color is random, the character part overlaps.

So how does it work?

1. First, verify the Code picture label link to the ASPX page that generated the picture, such as:

[C-sharp]View Plaincopyprint?

1. <img src="identifyingcode.aspx" src= "identifyingcode.aspx" style= "Vertical-align:bottom; margin-bottom:1px; Cursor:pointer; "Style=" vertical-align:bottom; margin-bottom:1px; Cursor:pointer; "Alt=" click Refresh "onclick=" javascript:var time = new Date (). GetTime (); This.src=this.src + '? ' + Time; " >

The role of the OnClick event is that, after clicking, it will reload the page that generated the image because of the src change, in order to achieve the effect of updating the verification code.

2. Generate the Picture page code, the ASPX page does not need to add any code, Aspx.cs code, in the Pageload method, generate the picture.

[C-sharp]View Plaincopyprint?

2. Using System;
4. Using System.Data;
6. Using System.Configuration;
8. Using System.Collections;
10. Using System.Web;
12. Using System.Web.Security;
14. Using System.Web.UI;
16. Using System.Web.UI.WebControls;
18. Using System.Web.UI.WebControls.WebParts;
20. Using System.Web.UI.HtmlControls;
22. Using System.Drawing;
24. Using System.Drawing.Imaging;
26. Using System.IO;
32. Namespace ATA.OLSD.OrgMng.WebSite
34. {
36. Public partial class IdentifyingCode:System.Web.UI.Page
38. {
40. private void Page_Load (object sender, System.EventArgs e)
42. {
44. string randomcode = this .  Createrandomcode (4);
46. RESPONSE.COOKIES.ADD (new HttpCookie ("Checkcode", Randomcode));
48. //viewstate["Validatecode"] = Randomcode;//Session, Cookie, ViewState can be saved, according to the actual situation
50. This .  CreateImage (Randomcode);
54. }
58. // <summary>
60. // Generate random code
62. // </summary>
64. /// <param name= "Length" > Random code number </param>
66. // <returns></returns>
68. Private string createrandomcode (int length)
70. {
72. int Rand;
74. char code;
76. string randomcode = String.Empty;
80. //Generate a certain length of verification code
82. System.Random random = new Random ();
84. For (int i = 0; i < length; i++)
86. {
88. Rand = random. Next ();
92. if (rand% 3 = = 0)
94. {
96. Code = (char) (' A ' + (char) (rand% 26));
98. }
100. Else
102. {
104. Code = (char) (' 0 ' + (char) (rand% 10));
106. }
110. Randomcode + = code. ToString ();
112. }
114. return randomcode;
116. }
120. // <summary>
122. // Create random code images
124. // </summary>
126. /// <param name= "Randomcode" > Random code </param>
128. private void CreateImage (string randomcode)
130. {
132. int randangle = 45; //Random rotation angle
134. int mapwidth = (int) (Randomcode.  Length * 16);
136. Bitmap map = new Bitmap (Mapwidth, 28); //Create a picture background, set its length and width
138. Graphics graph = graphics.fromimage (map);
140. Graph. Clear (Color.aliceblue);
142. Graph. DrawRectangle (new Pen (color.black, 0), 0, 0, map. Width-1, map. HEIGHT-1); //Draw a border
146. Random rand = new Random ();
150. //Generate background noise
152. Pen Blackpen = New Pen (color.lightgray, 0);
154. For (int i = 0; i <; i++)
156. {
158. int x = rand. Next (0, map.  Width);
160. int y = rand. Next (0, map.  Height);
162. Graph. DrawRectangle (Blackpen, x, Y, 1, 1);
164. }
168. //Verification code rotation to prevent machine identification
170. char[] chars = Randomcode. ToCharArray (); //Break strings into single-character arrays
174. //Text spacing
176. StringFormat format = new StringFormat (Stringformatflags.noclip);
178. Format. Alignment = Stringalignment.center;
180. Format. LineAlignment = Stringalignment.center;
184. //define a random color list
186. Color[] C = {color.black, color.red, Color.darkblue, Color.green, Color.orange, Color.brown, Color.darkcyan, COLOR.PURPL e};
188. //define random font font
190. string[] Font = { "Verdana", "Microsoft Sans Serif", " Comic Sans MS", "Arial", "song Body"};
194. For (int i = 0; i < chars. Length; i++)
196. {
198. int cindex = rand.  Next (7);
200. int findex = rand.  Next (5);
204. Font f = new System.Drawing.Font (Font[findex], System.Drawing.FontStyle.Bold); //font style (parameter 2 is font size)
206. Brush B = new System.Drawing.SolidBrush (C[cindex]);
210. Point dot = new Point (11, 11); //The larger the value in parentheses, the greater the spacing between characters
212. float angle = rand.  Next (0, Randangle); //Rotation degree, if 0 is changed to-randangle, then the rotation angle is-45 degrees ~45 degrees
216. Graph. TranslateTransform (dot. X, Dot. Y);
218. Graph. RotateTransform (angle);
220. Graph. DrawString (Chars[i]. ToString (), F, B, 2, 6, format); //4th, 5 parameters control left and top spacing
222. Graph. RotateTransform (-angle);
224. Graph. TranslateTransform (2,-dot. Y);
226. }
230. //Generate pictures
232. System.IO.MemoryStream ms = new System.IO.MemoryStream ();
234. Map. Save (MS, SYSTEM.DRAWING.IMAGING.IMAGEFORMAT.GIF);
236. Response.clearcontent ();
238. Response.ContentType = "Image/gif";
240. Response.BinaryWrite (Ms. ToArray ());
242. Graph. Dispose ();
244. Map. Dispose ();
246. }
250. }
252. }

You can modify the character size, rotation angle, font, color, and so on for the verification code based on the comments. Each time you reload the page, you will receive a new verification code, saved in session or cookie, and read from the session or cookie at the time of verification.

The effect is as follows:

You can click Refresh.

NET generate picture verification code--turn from lisliefor