[教学]：创建图纸空间“viewport”，附代码

XDSoft

Create Paper Space Viewports  
ID    8784  
Applies to:    AutoCAD 2000
AutoCAD 2000I
AutoCAD 2002

This document is part of    Viewport   ObjectARX   AcDb (AutoCAD Database)     


Question
How can I create a new viewport in paper space and activate it? I want to let
the user specify a rectangle (like the MVIEW command) and an existing view name.
With this data I want to create a new viewport.
Answer
To create a new viewport in paper space, perform the following steps:

1. Create a new object of type AcDbViewport.
2. Set the view coordinates (with setWidth(), setHeight() and setCenterPoint()).
3. Append the new viewport to the paper space.
4. Get the view the user specified (AcDbViewTableRecord).
5. Set this view on the new viewport with acdbSetCurrentView().
6. Activate the viewport with AcDbViewport::setOn().

NOTE: The AcDbViewport::setOn() function only works if your command has been
registered without the ACRX_CMD_TRANSPARENT flag. If this flag is set,
AcDbViewport::setOn() returns with eCommandWasInProgress and you cannot activate
the viewport until you set tilemode to 1 and back to 0.

The following code demonstrates how to do this:

1. 
   
2. void fCreateViewPort()
   
3. {
   
4.   // Only works in paperspace
   
5.   AcDbObjectId mCurViewportId = acedGetCurViewportObjectId();
   
6. 
   
7. 
   
8.   if (mCurViewportId == AcDbObjectId::kNull)
   
9.   {
   
10.     acutPrintf("\nCommand only works in paperspace.");
    
11.     return;
    
12.   }
    
13. 
    
14. 
    
15.   AcDbViewport *pCurViewport;
    
16.   if (Acad::eOk != acdbOpenObject(pCurViewport,mCurViewportId,AcDb::kForRead))
    
17.   {
    
18.     acutPrintf("\nCannot get active viewport.");
    
19.     return;
    
20.   }
    
21. 
    
22. 
    
23.   if (pCurViewport->number() != 1)
    
24.   {
    
25.     acutPrintf("\nCommand only works in paperspace.");
    
26.     pCurViewport->close();
    
27.     return;
    
28.   }
    
29.   pCurViewport->close();
    
30. 
    
31. 
    
32.   // Ask for the position
    
33.   ads_point pt1,pt2;
    
34. 
    
35. 
    
36.   if (RTNORM != acedGetPoint(NULL, "\nSelect first corner: ", pt1))
    
37.     return;
    
38. 
    
39. 
    
40.   if (RTNORM != acedGetCorner(pt1, "\nSelect second corner: ", pt2))
    
41.     return;
    
42. 
    
43. 
    
44.   // Ask for the view to use
    
45.   char mViewName[133];
    
46. 
    
47. 
    
48.   if (RTNORM != acedGetString(0, "\nEnter name of view to use: ", mViewName))
    
49.     return;
    
50. 
    
51. 
    
52. 
    
53.   // Create new viewport
    
54. 
    
55. 
    
56.   AcDbViewport *pViewport = new AcDbViewport;
    
57. 
    
58. 
    
59.   pViewport->setWidth(fabs(pt2[X] - pt1[X]));
    
60.   pViewport->setHeight(fabs(pt2[Y] - pt1[Y]));
    
61.   pViewport->setCenterPoint(AcGePoint3d(pt1[X] + (pt2[X] - pt1[X]) / 2,
    
62.       pt1[Y] + (pt2[Y] - pt1[Y]) / 2,
    
63.       pt1[Z]));
    
64. 
    
65. 
    
66.   // Append new viewport to paper space
    
67.   AcDbBlockTable *pTable;
    
68.   AcDbBlockTableRecord *pPsBTR;
    
69. 
    
70. 
    
71.   if (Acad::eOk != acdbHostApplicationServices()->workingDatabase()->getBlockTable(pTable, AcDb::kForRead))
    
72.   {
    
73.     acutPrintf("\nCannot get block table.");
    
74.     delete pViewport;
    
75.     return;
    
76.   }
    
77. 
    
78. 
    
79.   if (Acad::eOk != pTable->getAt(ACDB_PAPER_SPACE, pPsBTR, AcDb::kForWrite))
    
80.   {
    
81.     acutPrintf("\nCannot access paper space.");
    
82.     pTable->close();
    
83.     delete pViewport;
    
84.     return;
    
85.   }
    
86.   pTable->close();
    
87. 
    
88. 
    
89.   AcDbObjectId mViewPortId;
    
90.   if (Acad::eOk != pPsBTR->appendAcDbEntity(mViewPortId, pViewport))
    
91.   {
    
92.     acutPrintf("\nCannot append viewport to paper space.");
    
93.     pPsBTR->close();
    
94.     delete pViewport;
    
95.     return;
    
96.   }
    
97. 
    
98. 
    
99.   pPsBTR->close();
    
100. 
     
101. 
     
102.   pViewport->setOn();
     
103. 
     
104. 
     
105.   // Set the view
     
106.   AcDbViewTable *pViewTable;
     
107.   AcDbViewTableRecord *pViewTR;
     
108. 
     
109. 
     
110.   if (Acad::eOk != acdbHostApplicationServices()->workingDatabase()->getViewTable(pViewTable, AcDb::kForRead))
     
111.   {
     
112.     acutPrintf("\nCannot get view table.");
     
113.     pViewport->close();
     
114.     return;
     
115.   }
     
116. 
     
117. 
     
118.   if (Acad::eOk != pViewTable->getAt(mViewName, pViewTR, AcDb::kForRead))
     
119.   {
     
120.     acutPrintf("\nCannot access view '%s'.", mViewName);
     
121.     pViewport->close();
     
122.     pViewTable->close();
     
123.     return;
     
124.   }
     
125.   pViewTable->close();
     
126. 
     
127. 
     
128.   if (acedSetCurrentView(pViewTR, pViewport)!=Acad::eOk)
     
129.    acutPrintf("\nFailed to set view");
     
130. 
     
131. 
     
132. 
     
133.   // Close the objects
     
134.   pViewTR->close();
     
135.   pViewport->close();
     
136. }
     

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