利用ACAD2000 ARX的AcGs类的AcGsView对象，编程实现对图纸空间和模型空间的PAN和ZOOM

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1. 
   
2. PAN & ZOOM USING ACGSVIEW
   
3. Product AUTOCAD  Author LEE,HENRY
   
4. Date 30-APR-99  Document ID 32452
   
5. Expiration date    Attachments 32452.zip
   
6. Keywords API_TAHOE_OK
   
7. 
   
8. Developer Consulting Group technical solution. Autodesk confidential, for ADN members only. Please read the disclaimer
   
9. 
   
10. Question
    
11. 
    
12. 
    
13. ObjectARX 2000 has AcGs classes specially the AcGsView object. Can I use
    
14. AcGsView to pan and zoom programmatically?
    
15. 
    
16. 
    
17. Answer
    
18. 
    
19. 
    
20. The key to the pan and zoom capability of AcGsView is to initialize the
    
21. object properly. There is a global function acgsGetGsView() which will help
    
22. you to do so. However, it is design to retrieve the persistently shaded
    
23. AcGsView associated with the specified viewport. This method will return NULL
    
24. if there is no such view unless the bCreateIfNone flag is set to true; in
    
25. this case, an AcGsView will be created and linked to the specified viewport.
    
26. 
    
27. Moreover, it is designed to work in 3D view. But, 2D view is just a special
    
28. case of 3D view. We can certainly mimic the 2D view situation.
    
29. 
    
30. So, the very first thing is asking AutoCAD to generate an AcGsView object
    
31. under all circumstances.
    
32. 
    
33. 
    
34. bool getGsViewObj(AcGsView*& pView, int& vportNum)
    
35. {
    
36.      struct resbuf rb;
    
37.      int rt = acedGetVar("CVPORT", &rb);
    
38.      if(rt != RTNORM)
    
39.      {
    
40.          acutPrintf("\nError acquiring sysvar "CVPORT" value.");
    
41.          return false;
    
42.      }
    
43. 
    
44.      vportNum = rb.resval.rint;
    
45.      pView = acgsGetGsView(vportNum, true);
    
46.      if(!pView)
    
47.      {
    
48.          acutPrintf("\nError obtaining AcGsView object.");
    
49.          return false;
    
50.      }
    
51.      return true;
    
52. }
    
53. 
    
54. 
    
55. Secondly, we need to verify if we are dealing with paper space or not. This
    
56. is mainly because, paper space is a 2D space.
    
57. 
    
58. 
    
59. //
    
60. // see solution 1881
    
61. //
    
62. bool purePaperSpace()
    
63. {
    
64.      struct resbuf rb;
    
65.      int nTileMode, nVport;
    
66.      acedGetVar("tilemode", &rb);
    
67.      nTileMode = rb.resval.rint;
    
68.      acedGetVar("cvport", &rb);
    
69.      nVport = rb.resval.rint;
    
70.      if(nTileMode == 0 && nVport == 1)
    
71.          return true;
    
72.      else
    
73.          return false;
    
74. }
    
75. 
    
76. 
    
77. In the case of panning, it is a matter of transforming the view target point
    
78. based on the user input.
    
79. 
    
80. 
    
81. void myPan()
    
82. {
    
83.      acedDwgPoint pt1, pt2;
    
84.      if(!get2Points(pt1, pt2, false))
    
85.          return;
    
86.      AcGsView* pView = NULL;
    
87.      int vportNum;
    
88.      if(!getGsViewObj(pView, vportNum))
    
89.          return;
    
90. 
    
91.      AcGePoint3d camaraPt = pView->position();
    
92.      AcGeVector3d upVector = pView->upVector();
    
93. 
    
94.      double fieldWd = pView->fieldWidth();
    
95.      double fieldHt = pView->fieldHeight();
    
96. 
    
97.      double xShift = pt1[X] - pt2[X];
    
98.      double yShift = pt1[Y] - pt2[Y];
    
99.      
    
100.      AcGePoint3d targetOrinPt = pView->target();
     
101.      AcGePoint3d targetPt(targetOrinPt.x + xShift,
     
102.          targetOrinPt.y + yShift, targetOrinPt.z);
     
103.      AcGsView::Projection projType = pView->isPerspective() ?     
     
104.          AcGsView::Projection::kPerspective :
     
105. AcGsView::Projection::kParallel;
     
106.      pView->setView(camaraPt, targetPt, upVector, fieldWd, fieldHt,
     
107. projType);
     
108.      pView->update();
     
109.      
     
110.      if(purePaperSpace())
     
111.      {
     
112.          tweakToUpdateWindow();
     
113.          acgsSetViewParameters(vportNum, pView, false, true);
     
114.      }
     
115.      else
     
116.          acgsSetViewParameters(vportNum, pView, true, true);
     
117. }
     
118. 
     
119. 
     
120. In the case of zooming, it is a matter of resetting the view target point and
     
121. also the view window size based on the use input.
     
122. 
     
123. 
     
124. void myZoom()
     
125. {
     
126.      acedDwgPoint pt1, pt2;
     
127.      if(!get2Points(pt1, pt2, true))
     
128.          return;
     
129.      AcGsView* pView = NULL;
     
130.      int vportNum;
     
131.      if(!getGsViewObj(pView, vportNum))
     
132.          return;
     
133. 
     
134.      AcGePoint3d camaraPt = pView->position();
     
135.      AcGeVector3d upVector = pView->upVector();
     
136.      double xMin = min(pt1[X], pt2[X]);
     
137.      double xMax = max(pt1[X], pt2[X]);
     
138.      double yMin = min(pt1[Y], pt2[Y]);
     
139.      double yMax = max(pt1[Y], pt2[Y]);
     
140.      double fieldWd = xMax - xMin;
     
141.      double fieldHt = yMax - yMin;
     
142.      AcGePoint3d targetPt(xMin+fieldWd/2, yMin+fieldHt/2, 0);
     
143.      AcGsView::Projection projType = pView->isPerspective() ?         
     
144.   
     
145.          AcGsView::Projection::kPerspective :
     
146. AcGsView::Projection::kParallel;
     
147.      pView->setView(camaraPt, targetPt, upVector, fieldWd, fieldHt,
     
148. projType);
     
149.      pView->update();
     
150.      
     
151.      if(purePaperSpace())
     
152.      {
     
153.          tweakToUpdateWindow();
     
154.          acgsSetViewParameters(vportNum, pView, false, true);
     
155.      }
     
156.      else
     
157.          acgsSetViewParameters(vportNum, pView, true, true);
     
158. }
     
159. 
     
160. 
     
161. You probably wondering at this point, why there is a tweakToUpdateWindow();
     
162. function call if it is paper space?
     
163. 
     
164. Well, that is where the limitation of AcGsView generated from the
     
165. acgsGetGsView() coming in. The view parameters are calculated properly, but
     
166. the view is not update by the setView(), update() and
     
167. acgsSetViewParameters(). Nor it will be updated by acedUpdateDisplay(). So
     
168. the workaround that I can come up with, is to calculated the view window
     
169. client area size and move the window just slightly to force AutoCAD to update
     
170. the paper space viewport.
     
171. 
     
172. 
     
173. void tweakToUpdateWindow()
     
174. {
     
175.      CView* pActiveView =
     
176. acedGetAcadFrame()->GetActiveFrame()->GetActiveView();
     
177.      CRect rect;
     
178.      pActiveView->GetClientRect(&rect);
     
179.      rect.InflateRect(1,0,16,0);
     
180.      pActiveView->MoveWindow(rect, TRUE);
     
181. }
     
182. 
     
183. 
     
184. Please find the attached project for all the related code in its entirety.
     
185. 
     
186. See also,
     
187. solution 8781 - HOW TO SIMULATE ZOOM WINDOW IN OBJECTARX WITHOUT
     
188. ADS_COMMAND()
     
189. solution 1881 - HOW DO I KNOW I'M IN PAPERSPACE FOR SURE  
     

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