Zooming, panning and orbiting the current AutoCAD view using ObjectARX

By Xiaodong Liang

Our colleauge Kean has produced a blog on zooming, panning, orbiting the current view in .NET. I am writing the code in ObjectARX. The basic workflow for zooming, panning, orbiting is similar:

1. get he current view record

2. adjust its parameters. e.g.

   zooming: adjust height and width with a factor

   panning: adjust the view center

   orbiting: adjust the view direction along an axis.

1. update the current view with the updated view record.

static void panView()
{
    AcDbDatabase *pDb = 
        acdbHostApplicationServices()->workingDatabase();
        
    acedVports2VportTableRecords();
    
    //get the active viewport object
    AcDbViewportTable *pVpT = NULL;
    AcDbViewportTableRecord *pActVp = NULL;
    
    //get the *Active view port
    pDb->getViewportTable(pVpT,AcDb::kForRead);
    pVpT->getAt(_T("*Active"),pActVp,AcDb::kForWrite);
    pVpT->close();
    
    //get the view center point
    //assume we need to pan the view along X & Y in 10
    double panStep = 10;
    AcGePoint2d mCentPt = pActVp->centerPoint();
    mCentPt.x += panStep;
    mCentPt.y += panStep;
    
    //set the view center
    pActVp->setCenterPoint(mCentPt);
    
    //close the Active viewport
    pActVp->close();
    
    //update the viewport
    acedVportTableRecords2Vports();
}
    
static void zoomView()
{
    AcDbDatabase *pDb = 
        acdbHostApplicationServices()->workingDatabase();
        
    acedVports2VportTableRecords();
    
    //get the active viewport object
    AcDbViewportTable *pVpT = NULL;
    AcDbViewportTableRecord *pActVp = NULL;
    
    //get the *Active view port
    pDb->getViewportTable(pVpT,AcDb::kForRead);
    pVpT->getAt(_T("*Active"),pActVp,AcDb::kForWrite);
    pVpT->close();
    
    //assume we need to zoom the view out in scaling 10
    double zoomFactor = 10;
    
    pActVp->setHeight(pActVp->height() * zoomFactor);
    pActVp->setWidth(pActVp->width() * zoomFactor);
    
    //close the Active viewport
    pActVp->close();
    
    //update the viewport
    acedVportTableRecords2Vports();
}
    
static void orbitView()
{
    AcDbDatabase *pDb = 
        acdbHostApplicationServices()->workingDatabase();
        
    acedVports2VportTableRecords();
    
    //get the active viewport object
    AcDbViewportTable *pVpT = NULL;
    AcDbViewportTableRecord *pActVp = NULL;
    
    //get the *Active view port
    pDb->getViewportTable(pVpT,AcDb::kForRead);
    pVpT->getAt(_T("*Active"),pActVp,AcDb::kForWrite);
    pVpT->close();
    
    //assume we need to orbit the view direction
    // along (1,0,0) in angle 30 degree.
    AcGeVector3d oOldDir = pActVp->viewDirection();
    AcGeMatrix3d oM;
    oM.setToRotation(30 * 3.1415926 / 180,AcGeVector3d(1,0,0),AcGePoint3d::kOrigin);
    oOldDir.transformBy(oM);
    pActVp->setViewDirection(oOldDir);
    
    //close the Active viewport
    pActVp->close();
    
    //update the viewport
    acedVportTableRecords2Vports();
}