pdf文件显示

pdf文件显示

由于项目需要在.net下将pdf转换为普通图像格式，在网上搜了好久终于找到一个解决方案，于是采用拿来主义直接用。来源见代码中注释，感谢原作者。

1. usingSystem;
2. usingSystem.Collections.Generic;
3. usingSystem.Text;
4. usingSystem.Runtime.InteropServices;
5. usingSystem.Collections;
6. /**
7. ConvertPDFtoImageFormat(JPEG)usingGhostscriptAPI
9. convertapdftojpegusingghostscriptcommandline:
10. gswin32c-q-dQUIET-dPARANOIDSAFER-dBATCH-dNOPAUSE-dNOPROMPT-dMaxBitmap=500000000-dFirstPage=1-dAlignToPixels=0-dGridFitTT=0-sDEVICE=jpeg-dTextAlphaBits=4-dGraphicsAlphaBits=4-r100x100-sOutputFile=output.jpgtest.pdf
11. seealso:http://www.mattephraim.com/blog/2009/01/06/a-simple-c-wrapper-for-ghostscript/
12. and:http://www.codeproject.com/KB/cs/GhostScriptUseWithCSharp.aspx
13. Note:copygsdll32.dlltosystem32directorybeforeusingthisghostscriptwrapper.
14. *
15. */
16. namespaceConvertPDF
17. {
18. ///<summary>
19. ///
20. ///ClasstoconvertapdftoanimageusingGhostScriptDLL
21. ///Creditforthiscodegoto:RangelAvulso
22. ///ionlyfixalittlebugandrefactoralittle
23. ///http://www.hrangel.com.br/index.php/2006/12/04/converter-pdf-para-imagem-jpeg-em-c/
24. ///</summary>
25. ///<seealsocref="http://www.hrangel.com.br/index.php/2006/12/04/converter-pdf-para-imagem-jpeg-em-c/"/>
26. classPDFConvert
27. {
28. #regionGhostScriptImport
29. ///<summary>CreateanewinstanceofGhostscript.Thisinstanceispassedtomostothergsapifunctions.Thecaller_handlewillbeprovidedtocallbackfunctions.
30. ///Atthisstage,Ghostscriptsupportsonlyoneinstance.</summary>
31. ///<paramname="pinstance"></param>
32. ///<paramname="caller_handle"></param>
33. ///<returns></returns>
34. [DllImport("gsdll32.dll",EntryPoint="gsapi_new_instance")]
35. privatestaticexternintgsapi_new_instance(outIntPtrpinstance,IntPtrcaller_handle);
36. ///<summary>Thisistheimportantfunctionthatwillperformtheconversion</summary>
37. ///<paramname="instance"></param>
38. ///<paramname="argc"></param>
39. ///<paramname="argv"></param>
40. ///<returns></returns>
41. [DllImport("gsdll32.dll",EntryPoint="gsapi_init_with_args")]
42. privatestaticexternintgsapi_init_with_args(IntPtrinstance,intargc,IntPtrargv);
43. ///<summary>
44. ///Exittheinterpreter.Thismustbecalledonshutdownifgsapi_init_with_args()hasbeencalled,andjustbeforegsapi_delete_instance().
45. ///</summary>
46. ///<paramname="instance"></param>
47. ///<returns></returns>
48. [DllImport("gsdll32.dll",EntryPoint="gsapi_exit")]
49. privatestaticexternintgsapi_exit(IntPtrinstance);
50. ///<summary>
51. ///DestroyaninstanceofGhostscript.Beforeyoucallthis,Ghostscriptmusthavefinished.IfGhostscripthasbeeninitialised,youmustcallgsapi_exitbeforegsapi_delete_instance.
52. ///</summary>
53. ///<paramname="instance"></param>
54. [DllImport("gsdll32.dll",EntryPoint="gsapi_delete_instance")]
55. privatestaticexternvoidgsapi_delete_instance(IntPtrinstance);
56. #endregion
57. #regionVariables
58. privatestring_sDeviceFormat;
59. privateint_iWidth;
60. privateint_iHeight;
61. privateint_iResolutionX;
62. privateint_iResolutionY;
63. privateint_iJPEGQuality;
64. privateBoolean_bFitPage;
65. privateIntPtr_objHandle;
66. #endregion
67. #regionProprieties
68. publicstringOutputFormat
69. {
70. get{return_sDeviceFormat;}
71. set{_sDeviceFormat=value;}
72. }
73. publicintWidth
74. {
75. get{return_iWidth;}
76. set{_iWidth=value;}
77. }
78. publicintHeight
79. {
80. get{return_iHeight;}
81. set{_iHeight=value;}
82. }
83. publicintResolutionX
84. {
85. get{return_iResolutionX;}
86. set{_iResolutionX=value;}
87. }
88. publicintResolutionY
89. {
90. get{return_iResolutionY;}
91. set{_iResolutionY=value;}
92. }
93. publicBooleanFitPage
94. {
95. get{return_bFitPage;}
96. set{_bFitPage=value;}
97. }
98. ///<summary>QualityofcompressionofJPG</summary>
99. publicintJPEGQuality
100. {
101. get{return_iJPEGQuality;}
102. set{_iJPEGQuality=value;}
103. }
104. #endregion
105. #regionInit
106. publicPDFConvert(IntPtrobjHandle)
107. {
108. _objHandle=objHandle;
109. }
110. publicPDFConvert()
111. {
112. _objHandle=IntPtr.Zero;
113. }
114. #endregion
115. privatebyte[]StringToAnsiZ(stringstr)
116. {
117. //'ConvertaUnicodestringtoanullterminatedAnsistringforGhostscript.
118. //'Theresultisstoredinabytearray.Lateryouwillneedtoconvert
119. //'thisbytearraytoapointerwithGCHandle.Alloc(XXXX,GCHandleType.Pinned)
120. //'andGSHandle.AddrOfPinnedObject()
121. intintElementCount;
122. intintCounter;
123. byte[]aAnsi;
124. bytebChar;
125. intElementCount=str.Length;
126. aAnsi=newbyte[intElementCount+1];
127. for(intCounter=0;intCounter<intElementCount;intCounter++)
128. {
129. bChar=(byte)str[intCounter];
130. aAnsi[intCounter]=bChar;
131. }
132. aAnsi[intElementCount]=0;
133. returnaAnsi;
134. }
135. ///<summary>Convertthefile!</summary>
136. publicvoidConvert(stringinputFile,stringoutputFile,
137. intfirstPage,intlastPage,stringdeviceFormat,intwidth,intheight)
138. {
139. //Avoidtoworkwhenthefiledoesn'texist
140. if(!System.IO.File.Exists(inputFile))
141. {
142. System.Windows.Forms.MessageBox.Show(string.Format("Thefile:'{0}'doesn'texist",inputFile));
143. return;
144. }
145. intintReturn;
146. IntPtrintGSInstanceHandle;
147. object[]aAnsiArgs;
148. IntPtr[]aPtrArgs;
149. GCHandle[]aGCHandle;
150. intintCounter;
151. intintElementCount;
152. IntPtrcallerHandle;
153. GCHandlegchandleArgs;
154. IntPtrintptrArgs;
155. string[]sArgs=GetGeneratedArgs(inputFile,outputFile,
156. firstPage,lastPage,deviceFormat,width,height);
157. //ConverttheUnicodestringstonullterminatedANSIbytearrays
158. //thengetpointerstothebytearrays.
159. intElementCount=sArgs.Length;
160. aAnsiArgs=newobject[intElementCount];
161. aPtrArgs=newIntPtr[intElementCount];<