Here is a sample code to synchronize the view parameters between two model space viewports. For simplicity, this sample code assumes that the drawing already has two vertically split model space viewports of equal width. If the model space viewports are manually resized to different widths, the code resizes them to be of equal width before synchronizing the view parameters.
To get view change notification, the sample code uses the “AcEditorReactor::viewChanged” event handler. Because a view changed notification by pan or mouse wheel does not fire the “viewChanged” notification, we also need to monitor mouse related windows messages using a message filter. After the view change occurs, we will sync the view parameters at the next right oppurtunity by waiting for AutoCAD to reach its quiescent state.
Here are the relevant code snippets. The full sample project is available for download here :
// Command to sync the model space viewport parameters
static void AdskMyTestSyncVTR()
{
// Get the VTR updated
acedVports2VportTableRecords();
// We will update the other VTR only if
// view parameters change
Adesk::Boolean updateNeeded = Adesk::kFalse;
Acad::ErrorStatus es;
AcDbDatabase *pDb
= acdbHostApplicationServices()->workingDatabase();
AcApDocument *pDoc = acDocManager->document(pDb);
if ( pDoc == NULL )
return ;
es = acDocManager->lockDocument(pDoc);
// This code at present can only deal with 2 Modelspace
// viewports split vertically in half
if (pDb->tilemode() == Adesk::kFalse)
{
struct resbuf rb;
if (ads_getvar(_T("cvport" ), &rb) != RTNORM)
{
acutPrintf(_T("\nError using ads_getvar().\n" ));
return ;
}
if (rb.resval.rint == 1)
{
// Can only work with model space viewports.
return ;
}
}
AcDbViewportTable *pVT = NULL;
pDb->getViewportTable(pVT,AcDb::kForRead);
// Identify the left and right modelspace viewports
AcDbViewportTableRecord *pLeftVTR = NULL;
AcDbViewportTableRecord *pRightVTR = NULL;
AcDbViewportTableIterator *pIter = NULL;
es = pVT->newIterator(pIter);
if (es == Acad::eOk)
{
for (;!pIter->done();pIter->step())
{
AcDbViewportTableRecord *pVTR = NULL;
es = pIter->getRecord(pVTR, AcDb::kForRead);
if (es == Acad::eOk)
{
AcGePoint2d ll = pVTR->lowerLeftCorner();
AcGePoint2d ur = pVTR->upperRightCorner();
if (ll.isEqualTo(AcGePoint2d(0, 0)))
{// Left modelspace viewport
pLeftVTR = pVTR;
}
else if (ur.isEqualTo(AcGePoint2d(1.0, 1.0)))
{// Right modelspace viewport
pRightVTR = pVTR;
}
else
pVTR->close();
}
}
// If for some reason, we did not have
// two modelspace viewports, lets stop here.
if (pLeftVTR == NULL)
{
if (pRightVTR != NULL)
pRightVTR->close();
return ;
}
if (pRightVTR == NULL)
{
if (pLeftVTR != NULL)
pLeftVTR->close();
return ;
}
// Ensure that the two viewports are split
// vertically in half.
// If not, the view parameters when applied
// from one to another may not apply directly
// using this code.
// If the viewports were resized manually,
// we will set them right.
AcGePoint2d ll1 = pLeftVTR->lowerLeftCorner();
AcGePoint2d ur1 = pLeftVTR->upperRightCorner();
AcGePoint2d ll2 = pRightVTR->lowerLeftCorner();
AcGePoint2d ur2 = pRightVTR->upperRightCorner();
if (ll1.isEqualTo(AcGePoint2d(0.0, 0.0)) == false )
{
if (! pLeftVTR->isWriteEnabled())
pLeftVTR->upgradeOpen();
pLeftVTR->setLowerLeftCorner
(AcGePoint2d(0.0, 0.0));
}
if (ur1.isEqualTo(AcGePoint2d(0.5, 1.0)) == false )
{
if (! pLeftVTR->isWriteEnabled())
pLeftVTR->upgradeOpen();
pLeftVTR->setUpperRightCorner
(AcGePoint2d(0.5, 1.0));
}
if (ll2.isEqualTo(AcGePoint2d(0.5, 0.0)) == false )
{
if (! pRightVTR->isWriteEnabled())
pRightVTR->upgradeOpen();
pRightVTR->setLowerLeftCorner
(AcGePoint2d(0.5, 0.0));
}
if (ur2.isEqualTo(AcGePoint2d(1.0, 1.0)) == false )
{
if (! pRightVTR->isWriteEnabled())
pRightVTR->upgradeOpen();
pRightVTR->setUpperRightCorner
(AcGePoint2d(1.0, 1.0));
}
// Get the active model space viewport
struct resbuf res;
acedGetVar(L"CVPORT" , &res);
short vpnumber = res.resval.rint;
// Identify the model space viewports from/to which
// settings will be copied.
// The active modelspace viewport is the viewport
// from which settings will be copied
AcDbViewportTableRecord *pFromVTR = NULL;
AcDbViewportTableRecord *pToVTR = NULL;
if (pLeftVTR->number() == vpnumber)
{
pFromVTR = pLeftVTR;
pToVTR = pRightVTR;
}
if (pRightVTR->number() == vpnumber)
{
pFromVTR = pRightVTR;
pToVTR = pLeftVTR;
}
// Sorry, we did not identify the active viewport
// from which settings need to be copied.
if (pFromVTR == NULL || pToVTR == NULL)
return ;
// Copy the VTR settings from one modelspace viewport
// to another only if they are different. We will use
// a tolerance to ensure very small differences do not
// get us in a soup. I meant loop :)
AcGeTol newTol;
newTol.setEqualPoint (0.00001);
newTol.setEqualVector(0.00001);
// ViewDirection
AcGeVector3d fromViewDir = pFromVTR->viewDirection();
AcGeVector3d toViewDir = pToVTR->viewDirection();
if (pFromVTR->viewDirection().isEqualTo(
pToVTR->viewDirection(), newTol) == false )
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setViewDirection(
pFromVTR->viewDirection());
updateNeeded = Adesk::kTrue;
}
// ViewTwist
if (abs(pFromVTR->viewTwist()
- pToVTR->viewTwist()) > 0.01)
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setViewTwist(pFromVTR->viewTwist());
updateNeeded = Adesk::kTrue;
}
// Target
if (pFromVTR->target().isEqualTo(
pToVTR->target(), newTol) == false )
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setTarget(pFromVTR->target());
updateNeeded = Adesk::kTrue;
}
// BackClipEnabled
if (pFromVTR->backClipEnabled()
!= pToVTR->backClipEnabled())
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setBackClipEnabled(
pFromVTR->backClipEnabled());
updateNeeded = Adesk::kTrue;
}
// BackClipDistance
if (abs(pFromVTR->backClipDistance()
- pToVTR->backClipDistance()) > 0.01)
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setBackClipDistance(
pFromVTR->backClipDistance());
updateNeeded = Adesk::kTrue;
}
// FrontClipEnabled
if (pFromVTR->frontClipEnabled()
!= pToVTR->frontClipEnabled())
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setFrontClipEnabled(
pFromVTR->frontClipEnabled());
updateNeeded = Adesk::kTrue;
}
// FrontClipDistance
if (abs(pFromVTR->frontClipDistance()
- pToVTR->frontClipDistance()) > 0.01)
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setFrontClipDistance(
pFromVTR->frontClipDistance());
updateNeeded = Adesk::kTrue;
}
// Elevation
if (abs(pFromVTR->elevation()
- pToVTR->elevation()) > 0.01)
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setElevation(pFromVTR->elevation());
updateNeeded = Adesk::kTrue;
}
// centerPoint
if (pFromVTR->centerPoint().isEqualTo(
pToVTR->centerPoint(), newTol) == false )
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setCenterPoint(pFromVTR->centerPoint());
updateNeeded = Adesk::kTrue;
}
// Height
if (abs(pFromVTR->height() - pToVTR->height()) > 0.01)
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setHeight(pFromVTR->height());
updateNeeded = Adesk::kTrue;
}
// Width
if (abs(pFromVTR->width() - pToVTR->width()) > 0.01)
{
if (! pToVTR->isWriteEnabled())
pToVTR->upgradeOpen();
pToVTR->setWidth(pFromVTR->width());
updateNeeded = Adesk::kTrue;
}
// Done with the VTR
pLeftVTR->close();
pRightVTR->close();
delete pIter;
}
es = pVT->close();
es = acDocManager->unlockDocument(pDoc);
// Update the Vports if we did change any of
// the VTR parameters
if (updateNeeded)
{
acedVportTableRecords2Vports();
}
}
// Viewchanged notification is not received during
// a pan or zoom using mouse wheel.
// So identify those using WM messages.
BOOL WinCallBack(MSG *pMsg)
{
if ( pMsg->message == WM_VSCROLL ||
pMsg->message == WM_HSCROLL ||
pMsg->message == WM_MOUSEWHEEL ||
pMsg->message == WM_MBUTTONUP)
{
// Sync the modelspace viewports
acDocManager->sendStringToExecute(
acDocManager->mdiActiveDocument(),
ACRX_T("SyncVTR " ),
false , true , false );
}
return FALSE;
}
// Setting up reactors and message filter
virtual AcRx::AppRetCode On_kInitAppMsg (void *pkt)
{
AcRx::AppRetCode retCode
= AcRxArxApp::On_kInitAppMsg (pkt) ;
// Editor reactor to receive to ViewChanged notification
pEditorReactor = new AcMyEditorReactor(true );
// InputContext reactor to receive quiescent state
// change notification
pInputContextReactor = new AcMyInputContextReactor();
// Viewchanged notification is not received during a
// pan or zoom using mouse wheel.
// So identify those using WM messages.
acedRegisterFilterWinMsg(WinCallBack);
return (retCode);
}
// Cleanup of the reactors and message filter
virtual AcRx::AppRetCode On_kUnloadAppMsg (void *pkt)
{
AcRx::AppRetCode retCode
=AcRxArxApp::On_kUnloadAppMsg (pkt) ;
// cleanup
if (pEditorReactor)
{
delete pEditorReactor;
pEditorReactor = NULL;
}
if (pInputContextReactor)
{
delete pInputContextReactor;
pInputContextReactor = NULL;
}
acedRemoveFilterWinMsg(WinCallBack);
return (retCode);
}
// Overridden beginQuiescentState method to initiate a sync
void AcMyInputContextReactor::beginQuiescentState()
{
// See if the view has changed
if (_viewChanged)
{
// Sync the view once
_viewChanged = false ;
// Send a command to Sync the modelspace viewports
acDocManager->sendStringToExecute(
acDocManager->mdiActiveDocument(),
ACRX_T("SyncVTR " ),
false , true , false );
}
}
// Overridden viewChanged method to know if the view changed
void AcMyEditorReactor::viewChanged()
{
// View changed notification is received several times
// and we only want to sync the view parameters when
// AutoCAD attains a quiescent state next time.
// So only flaggin to sync in
// InputContextReactor::beginQuiescentState event handler.
AcMyInputContextReactor::_viewChanged = true ;
}
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