Layermanager in C++

[Tom]

Hi Readers,

I'm a newbie in QCAD, but not in CAD Developement. So I try port some old and tested Features like a Layer Manager to QCAD. At first I want get a feeling for the system, specifically the Transaction system. I wrote this code:

RDocumentInterface *di = RMainWindow::getDocumentInterfaceStatic();
   if(di)
   {
      RDocument &document = di->getDocument();

      QSet<RLayer::Id> LayerSet = document.queryAllLayers();

      foreach(RLayer::Id theLayerID, LayerSet)
      {
         QSharedPointer<RLayer> theLayer = document.queryLayer(theLayerID);
         if(!theLayer.isNull())
         {
            // For testing I pick a layer, but on the end I want traverse the whole layer tabel
            if(Globals::getLyrNmSeamData() == theLayer->getName())
            {
               RTransaction theTransaction(document.getStorage(), QObject::tr("Set layer properties"), false);

               theLayer->setFrozen(false);
               theLayer->setLocked(false);

               theTransaction.addObject(theLayer, false);  // true hasn't any effect in this kind
               theTransaction.end();

               document.setCurrentLayer(theLayerID);

               break;
            }
         }
      }

      di->regenerateScenes() ; // Important if you want see the changes on the screen
   }

A lot work. The Current Layer was changed. I can draw entities and can see them. But the old entities was not shown, even during I draw a new line, too. I try call methods from notify system but no effect. I search in internet an look in this board. Then I found the reason as I inspect the DocumentInterface class. I'm sure before that I have to find a method for rebuild the internal display lists. A call of regenerateScenes() was the solution.

[andrew]

Transactions are usually only used on a lower level in QCAD (a transaction records all changes on a set of objects caused by an operation, i.e. when adding, deleting or modifying objects).

Operations are the concept used for more comfortable, higher level modifications:

RModifyObjectsOperation op;
op.addObject(layer);
di->applyOperation(&op);

This will update the document and also the views, layer lists, etc. accordingly. A transaction object is returned by applyOperation which contains information about objects that were changed.