C # general types of perfect verification codes written

1. Using System;
2. Using System. Collections;
3. Using System. ComponentModel;
4. Using System. Data;
5. Using System. Drawing;
6. Using System. Web;
7. Using System. Web. SessionState;
8. Using System. Web. UI;
9. Using System. Web. UI. WebControls;
10. Using System. Web. UI. HtmlControls;
11. Namespace WebApplication1. Verification Code
12. {
13. /// <Summary>
14. /// Perfect Random verification code 0.10
15. /// Verion: 0.10
16. /// Description: The verification code is randomly generated and rotated to a certain angle. The font color is different.
17. /// </Summary>
18. Public class ValidateCode: System. Web. UI. Page
19. {
20. Private void Page_Load (object sender, System. EventArgs e)
21. {
22. String randomcode = this. CreateRandomCode (4 );
23. Session ["ValidateCode"] = randomcode;
24. // ViewState ["ValidateCode"] = randomcode;
25. This. CreateImage (randomcode );
26. }
27. /// <Summary>
28. /// Generate random code
29. /// </Summary>
30. /// <Param name = "length"> Number of random codes </param>
31. /// <Returns> </returns>
32. Private string CreateRandomCode (int length)
33. {
34. Int rand;
35. Char code;
36. String randomcode = String. Empty;
37. // Generate a verification code of a certain length
38. System. Random random = new Random ();
39. For (int I = 0; I <length; I ++)
40. {
41. Rand = random. Next ();
42. If (rand % 3 = 0)
43. {
44. Code = (char) (A + (char) (rand % 26 ));
45. }
46. Else
47. {
48. Code = (char) (0 + (char) (rand % 10 ));
49. }
50. Randomcode + = code. ToString ();
51. }
52. Return randomcode;
53. }
54. /// <Summary>
55. /// Create a random Image
56. /// </Summary>
57. /// <Param name = "randomcode"> Random Code </param>
58. Private void CreateImage (string randomcode)
59. {
60. Int randAngle = 45; // random Rotation Angle
61. Int mapwidth = (int) (randomcode. Length * 23 );
62. Bitmap map = new Bitmap (mapwidth, 28); // creates an image background.
63. Graphics graph = Graphics. FromImage (map );
64. Graph. Clear (Color. AliceBlue); // Clear the screen and fill in the background.
65. Graph. DrawRectangle (new Pen (Color. Black, 0), 0, 0, map. Width-1, map. Height-1); // draw a border
66. // Graph. SmoothingMode = System. Drawing. Drawing2D. SmoothingMode. AntiAlias; // Mode
67. Random rand = new Random ();
68. // Generate background noise
69. Pen blackPen = new Pen (Color. LightGray, 0 );
70. For (int I = 0; I <50; I ++)
71. {
72. Int x = rand. Next (0, map. Width );
73. Int y = rand. Next (0, map. Height );
74. Graph. DrawRectangle (blackPen, x, y, 1, 1 );
75. }
76. // Rotate the verification code to prevent Machine recognition
77. Char [] chars = randomcode. ToCharArray (); // split the string into a single character array
78. // Text distance
79. StringFormat format = new StringFormat (StringFormatFlags. NoClip );
80. Format. Alignment = StringAlignment. Center;
81. Format. LineAlignment = StringAlignment. Center;
82. // Define the color
83. Color [] c = {Color. Black, Color. Red, Color. DarkBlue, Color. Green, Color. Orange, Color. Brown, Color. DarkCyan, Color. Purple };
84. // Define the font
85. String [] font = {"Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", ""};
86. For (int I = 0; I <chars. Length; I ++)
87. {
88. Int cindex = rand. Next (7 );
89. Int findex = rand. Next (5 );
90. Font f = new System. Drawing. Font (font [findex], 13, System. Drawing. FontStyle. Bold); // Font style (parameter 2 indicates the Font size)
91. Brush B = new System. Drawing. SolidBrush (c [cindex]);
92. Point dot = new Point (16, 16 );
93. // Graph. DrawString (dot. X. ToString (), fontstyle, new SolidBrush (Color. Black), 10,150); // test the display spacing of X coordinates.
94. Float angle = rand. Next (-randAngle, randAngle); // degrees of Rotation
95. Graph. TranslateTransform (dot. X, dot. Y); // move the cursor to the specified position
96. Graph. RotateTransform (angle );
97. Graph. DrawString (chars [I]. ToString (), f, B, 1, 1, format );
98. // Graph. DrawString (chars [I]. ToString (), fontstyle, new SolidBrush (Color. Blue), 1, 1, format );
99. Graph. RotateTransform (-angle); // go back
100. Graph. TranslateTransform (2,-dot. Y); // move the cursor to the specified position
101. }
102. // Graph. DrawString (randomcode, fontstyle, new SolidBrush (Color. Blue), 2, 2); // standard random code
103. // Generate an image
104. System. IO. MemoryStream MS = new System. IO. MemoryStream ();
105. Map. Save (MS, System. Drawing. Imaging. ImageFormat. Gif );
106. Response. ClearContent ();
107. Response. ContentType = "image/gif ";
108. Response. BinaryWrite (ms. ToArray ());
109. Graph. Dispose ();
110. Map. Dispose ();
111. }
112. # Code generated by region Web Form Designer
113. Override protected void OnInit (EventArgs e)
114. {
115. //
116. // CODEGEN: & n