Best pratices to create and edit layer

[seabrahenrique]

Hello everyone!

I face two options here to create/edit layers in AutoCAD using C#. Which one is the better thinking about the good practices:

Access my LayerTable direct for write, like this:

LayerTable lytab = trans.GetObject(db.LayerTableId, OpenMode.ForWrite) as LayerTable;

....Create or update my layer

Or access my LaterTable for read, and use the instruction lytab.UpgradeOpen(), like this:

LayerTable lytab = trans.GetObject(db.LayerTableId, OpenMode.ForRead) as LayerTable;

lytab.UpgradeOpen();

....Create or update my layer

I know that result of both is equals, but one is better of other? (thinking about erros, performance and etc...)

Thanks in advance.

[seabrahenrique]

And a complementar question:

I really need this foreach simply to find a layer in my LayerTable?

                    LayerTable lytb = trans.GetObject(db.LayerTableId, OpenMode.ForRead) as LayerTable;

                    foreach (ObjectId LyId in lytb)
                    {
                        LayerTableRecord ltbr = trans.GetObject(LyId, OpenMode.ForRead) as LayerTableRecord;

                        if (ltbr.Name == "Teste")
                        {
                            ltbr.UpgradeOpen(); 

                            ltbr.Color = Color.FromColorIndex(ColorMethod.ByLayer, 3);

                            LinetypeTable lttb = trans.GetObject(db.LinetypeTableId, OpenMode.ForRead) as LinetypeTable;
                            if (lttb.Has("Hidden"))
                            {
                                ltbr.LinetypeObjectId = lttb["Hidden"];
                            }

                            trans.Commit();
                            doc.Editor.WriteMessage("\nLayer alterado");
                            break;

                        }

Or is there another simple way to set a layer in my LayerTableRecord if i know that name?

For example, in VBA i can do:

Dim MyLayer as AcadLayer
MyLayer = ThisDrawing.Layer("NameOfLayer")

Can i do something similar in C# .NET to set a layer in a LayerTableRecord ltr, if i already know the name of layer is "NameOfLayer", for example?

Thanks again.

[hippe013]

The get the layer objectId by name use the following:

(Sorry its in vb.net)

Dim lyrTbl As LayerTable = tr.GetObject(curDb.LayerTableId, OpenMode.ForRead)
Dim lyrId As ObjectId = lyrTbl.Item("MyLayer")

[norman.yuan]

I am not sure what your were thinking of "best practice" with this code, where you have already known LayerTable.Has() method:

LayerTable lytb = trans.GetObject(db.LayerTableId, OpenMode.ForRead) as LayerTable;

                    foreach (ObjectId LyId in lytb)
                    {
                        LayerTableRecord ltbr = trans.GetObject(LyId, OpenMode.ForRead) as LayerTableRecord;

                        if (ltbr.Name == "Teste")
                        {
                            ltbr.UpgradeOpen(); 

                            ltbr.Color = Color.FromColorIndex(ColorMethod.ByLayer, 3);

                            LinetypeTable lttb = trans.GetObject(db.LinetypeTableId, OpenMode.ForRead) as LinetypeTable;
                            if (lttb.Has("Hidden"))
                            {
                                ltbr.LinetypeObjectId = lttb["Hidden"];
                            }

                            trans.Commit();
                            doc.Editor.WriteMessage("\nLayer alterado");
                            break;

                        }

if you already know a block name ("Teste"), you simply do:

var layerTable=(LayerTable)tran.GetObject(db.LayerTableId, OpenMode.ForRead);

LayerTableRecord layer;

if (!layerTable.Has("Teste")

{

    layerTable.UpgradeOpen();

    layer=new LayerTableRecord();

    layer.Name="Teste";

    layerTable.Add(layer);

    tran.AddNewlyCreatedDBObject(....);

}

else

{

    layer=(LayerTableRecord)tran.GetObject(layerTable["Teste", OpenMode.ForWrite);

}

// Change/Set layer's properties here

layer.Color=...;

layer.LineType=....;

Because of the method Has(), there is no need to loop through LayerTable for each LayerTableRecord and test its name in order to find the layer in interest.

[seabrahenrique]

Thanks for the collaboration, guys!

I already found watt i need here.

[hippe013]

If you found what you needed please mark the appropriate reply as the accepted solution. It helps others know that a solution has been found. 

[MarkJamesRogolino]

Pls try this.

var documentManager = Application.DocumentManager;
            var currentDocument = documentManager.MdiActiveDocument;
            var database = currentDocument.Database;
            ObjectId layerId = ObjectId.Null;
            using (DocumentLock docLock = currentDocument.LockDocument())
            {
                using (Transaction acTrans = database.TransactionManager.StartTransaction())
                {
                    // Open the Layer table for read
                    LayerTable acLyrTbl;
                    acLyrTbl = acTrans.GetObject(database.LayerTableId,
                                                 OpenMode.ForRead) as LayerTable;
                            LayerTableRecord acLyrTblRec = new LayerTableRecord();
                            acLyrTblRec.Name = "somename";
                            LinetypeTable acLinTbl;
                            acLinTbl = acTrans.GetObject(database.LinetypeTableId,
                                                               OpenMode.ForRead) as LinetypeTable;
                            acLyrTbl.UpgradeOpen();
                            acLyrTbl.Add(acLyrTblRec);
                            acTrans.AddNewlyCreatedDBObject(acLyrTblRec, true);
                    acTrans.Commit();
                }
            }

[kerry_w_brown]

@MarkJamesRogolino 

Have you tested this code ?

what will happen if it's run twice ??

[seabrahenrique]

Sorry, but i can't use your suggestion, see:

The LayerTable object here does not have the .Item method... Again, someone know how can i get a layer by a name in C#?

In VBA i used to do this:

Dim MyLayer as AcadLayer
MyLayer = ThisDrawing.Layer("NameOfLayer")

Is there a way to do something similar in .NET? I mean, if i already have the name of layer or block, can i access that using this name?

[kerry_w_brown]

Perhaps something like this :

public void GetLayerByName( )
{            
    var db = Application.DocumentManager.MdiActiveDocument.Database;
    var layerName = "MyLayer";

    using (var tr = db.TransactionManager.StartTransaction())
    {
        var layerTable = (LayerTable)tr.GetObject(
                        db.LayerTableId, OpenMode.ForRead);

        var layerRecord = (LayerTableRecord)tr.GetObject( 
                            layerTable[layerName], OpenMode.ForRead);

        // if you really want the ObjectID  ??

        var layerRecordOid = layerRecord.ObjectId;
                
        // . . . . 

    } 
}

Regards,

[kerry_w_brown · Accepted solution]

Of course, we should check that the LayerTable actually does have a Layer of that name  🙂

. . . or this will happen :

public void GetLayerByName( )
{
    var db = Application.DocumentManager.MdiActiveDocument.Database;
    var layerName = "MyLayer_DoesNotExist";

    using ( var tr = db.TransactionManager.StartTransaction( ) )
    {
        var layerTable = (LayerTable)tr.GetObject(
                db.LayerTableId, OpenMode.ForRead);

        // ensure the layer exists !!
        if ( !layerTable.Has( layerName ) )
        {
            // show a message to the user.
            // then :
            return;
        }
        var layerRecord = (LayerTableRecord)tr.GetObject(
                    layerTable[layerName], OpenMode.ForRead);

        // if you really want the ObjectID  ??

        var layerRecordOid = layerRecord.ObjectId;

        // . . . .                 

    }
}

[kerry_w_brown]

For what it's worth ;

This is about 17 years old and posted more as proof of concept than professional code.

Making Layers with Particular Linetypes 

Regards,