C # preview the complete source code of a DWG file (without the need for an AutoCAD environment)

1. Using system;
2. Using system. drawing;
3. Using system. collections;
4. Using system. componentmodel;
5. Using system. Windows. forms;
6. Using system. Data;
7. Using system. IO;
8. Namespace windowsapplication3
9. {
10. /// <Summary>
11. /// Summary of form1.
12. /// </Summary>
13. Public class form1: system. Windows. Forms. Form
14. {
15. Private system. Windows. Forms. Timer timer1;
16. Private system. Windows. Forms. picturebox picturebox1;
17. Private system. componentmodel. icontainer components;
18. Public form1 ()
19. {
20. //
21. // Required for Windows Form Designer support
22. //
23. Initializecomponent ();
24. //
25. // Todo: add Any constructor code after initializecomponent calls
26. //
27. }
28. /// <Summary>
29. /// Clear all resources in use.
30. /// </Summary>
31. Protected override void dispose (bool disposing)
32. {
33. If (disposing)
34. {
35. If (components! = NULL)
36. {
37. Components. Dispose ();
38. }
39. }
40. Base. Dispose (disposing );
41. }
42. # Region windows Form Designer generated code
43. /// <Summary>
44. /// The designer supports the required methods-do not use the code editor to modify
45. /// Content of this method.
46. /// </Summary>
47. Private void initializecomponent ()
48. {
49. This. components = new system. componentmodel. Container ();
50. This. timer1 = new system. Windows. Forms. Timer (this. components );
51. This. picturebox1 = new system. Windows. Forms. picturebox ();
52. This. suspendlayout ();
53. //
54. // Picturebox1
55. //
56. This. picturebox1.location = new system. Drawing. Point (16, 16 );
57. This. picturebox1.name = "picturebox1 ";
58. This. picturebox1.size = new system. Drawing. Size (416,272 );
59. This. picturebox1.tabindex = 0;
60. This. picturebox1.tabstop = false;
61. //
62. // Form1
63. //
64. This. autoscalebasesize = new system. Drawing. Size (6, 14 );
65. This. clientsize = new system. Drawing. Size (472,310 );
66. This. Controls. addrange (new system. Windows. Forms. Control [] {
67. This. picturebox1 });
68. This. Name = "form1 ";
69. This. Text = "form1 ";
70. This. Load + = new system. eventhandler (this. form#load );
71. This. resumelayout (false );
72. }
73. # Endregion
74. /// <Summary>
75. /// Main entry point of the application.
76. /// </Summary>
77. [Stathread]
78. Static void main ()
79. {
80. Application. Run (New form1 ());
81. }
82. Private void form1_load (Object sender, system. eventargs E)
83. {
84. Viewdwg = new viewdwg ();
85. Picturebox1.image = viewdwg. getdwgimage ("C :\\\ 1.dwg ");
86. }
87. }
88. Class viewdwg
89. {
90. Struct bitmapfileheader
91. {
92. Public short bftype;
93. Public int bfsize;
94. Public short bfreserved1;
95. Public short bfreserved2;
96. Public int bfoffbits;
97. }
98. Public Image getdwgimage (string filename)
99. {
100. If (! (File. exists (filename )))
101. {
102. Throw new filenotfoundexception ("file not found ");
103. }
104. Filestream dwgf; // file stream
105. Int possentinel; // file description block location
106. Binaryreader BR; // read binary files
107. Int typepreview; // thumbnail format
108. Int posbmp; // The Position of the thumbnail.
109. Int lenbmp; // The thumbnail size.
110. Short bibitcount; // The bitdepth of the thumbnail.
111. Bitmapfileheader BiH; // BMP file header. the DWG file does not contain the bitmap file header.
112. Byte [] BMP Info; // The BMP file body contained in the DWG File
113. Memorystream bmp f = new memorystream (); // stores the bitmap memory file stream
114. Binarywriter BMP r = new binarywriter (bmp f); // write binary file class
115. Image myimg = NULL;
116. Try
117. {
118. Dwgf = new filestream (filename, filemode. Open, fileaccess. Read); // file stream
119. BR = new binaryreader (dwgf );
120. Dwgf. Seek (13, seekorigin. Begin); // read from 13th bytes
121. Possentinel = Br. readint32 (); // 13th to 17 bytes indicate the location of the thumbnail description block
122. Dwgf. Seek (possentinel + 30, seekorigin. Begin); // move the pointer to 31st bytes of the thumbnail description block
123. Typepreview = Br. readbyte (); // 31st bytes indicates the thumbnail format, 2 indicates the BMP format, and 3 indicates the WMF Format.
124. If (typepreview = 1)
125. {
126. }
127. Else if (typepreview = 2 | typepreview = 3)
128. {
129. Posbmp = Br. readint32 (); // location of the saved bitmap of the DWG File
130. Lenbmp = Br. readint32 (); // bitmap size
131. Dwgf. Seek (posbmp + 14, seekorigin. Begin); // move the pointer to the position graph block.
132. Bibitcount = Br. readint16 (); // read the bit depth
133. Dwgf. Seek (posbmp, seekorigin. Begin); // read all bitmap content from the beginning of the bitmap block.
134. BMP info = Br. readbytes (lenbmp); // bitmap information that does not contain the file header
135. BR. Close ();
136. Dwgf. Close ();
137. BiH. bftype = 19778; // create a bitmap file header
138. If (bibitcount <9)
139. {
140. BiH. bfsize = 54 + 4 * (INT) (math. Pow (2, bibitcount) + lenbmp;
141. }
142. Else
143. {
144. BiH. bfsize = 54 + lenbmp;
145. }
146. BiH. bfreserved1 = 0; // reserved bytes
147. BiH. bfreserved2 = 0; // reserved bytes
148. BiH. bfoffbits = 14 + 40 + 1024; // image data offset
149. // Write the following Bitmap File Header
150. Bmp r. Write (BIH. bftype); // file type
151. Bmp r. Write (BIH. bfsize); // File Size
152. Bmp r. Write (BIH. bfreserved1); // 0
153. Bmp r. Write (BIH. bfreserved2); // 0
154. Bmp r. Write (BIH. bfoffbits); // image data offset
155. Bmp r. Write (BMP info); // write a bitmap
156. Bmp f. Seek (0, seekorigin. Begin); // move the pointer to the beginning of the file
157. Myimg = image. fromstream (bmp f); // create a bitmap object
158. Bmp r. Close ();
159. Bmp f. Close ();
160. }
161. Return myimg;
162. }
163. Catch (exception ex)
164. {
165. Throw new exception (ex. Message );
166. }
167. }
168. }
169. }