How to thaw one layer in one viewport?

[sonny3g]

I have been trying to figure out how to make sure a specific layer is thawed in the current viewport.  My program makes sure a layer is thawed when in the model tab.  But, I cannot seem to get it to work when in a viewport.  I did figure out how to test if my layer is frozen in the viewport but cannot seem to get the layer thawed.  

The goal is to take a given layer and create a sibling layer if the sibling layer does not exist.  My code is below:

 //***************************************************************************************************************************
        /// <summary>
        /// Takes selected block layer and creates required sibling layer if it does
        /// not exist and makes it the current layer.
        /// </summary>
        /// <param name="blkLyrName"></param>
        /// <returns></returns>
        public string MakeSiblingLayer(string blkLyrName)
        {
            // Intialize the sibling layer namve variable.
            string sibLyrName;
            try
            {
                // Creates new layer name string for sibling layer.
                if (blkLyrName.EndsWith("_CONV"))
                {
                    int cnt = blkLyrName.Length - 5;
                    sibLyrName = blkLyrName.Remove(cnt, 5) + "_DIM_EL";
                }
                else
                {
                    sibLyrName = blkLyrName + "_DIM_EL";
                }
            }
            catch (Autodesk.AutoCAD.Runtime.Exception a6)
            {
                System.Windows.Forms.MessageBox.Show("ERROR:\n" + a6.ToString());
                return null;
            }
            catch
            {
                System.Windows.Forms.MessageBox.Show("ERROR:\n PROGRAM WILL EXIT!");
                return null;
            }
            // Checks for the existence of the sibling layer and creates the new sibling layer if it does not exist.
            using (Transaction mklyrTrans = db.TransactionManager.StartTransaction())
            {
                LayerTable sibLyrTable = mklyrTrans.GetObject(db.LayerTableId, OpenMode.ForWrite) as LayerTable;
                LayerTableRecord sibLTRec = mklyrTrans.GetObject(db.Clayer, OpenMode.ForWrite) as LayerTableRecord;
                try
                {
                    // Thaws the existing sibling layer if it is frozen and it already exists.
                    if (sibLyrTable.Has(sibLyrName) == true)
                    {
                        using (Transaction frznTrans = db.TransactionManager.StartTransaction())
                        {
                            try
                            {
                                LayerTableRecord frznRec;
                                frznRec = frznTrans.GetObject(sibLyrTable[sibLyrName], OpenMode.ForRead) as LayerTableRecord;
                                if (db.TileMode)
                                {
                                    if (frznRec.IsFrozen == true)
                                    {
                                        frznRec.UpgradeOpen();
                                        frznRec.IsFrozen = false;
                                        frznTrans.Commit();
                                    }
                                    else
                                    {
                                        frznTrans.Dispose();
                                    }
                                }
                                else
                                {
                                    Viewport vp = (Viewport)ed.ActiveViewportId.GetObject(OpenMode.ForRead);

                                    if (vp.IsLayerFrozenInViewport(frznRec.Id))
                                    {
                                       frznRec.UpgradeOpen();
                                       vp.;
                                    }
                                }
                            }
                            catch (Autodesk.AutoCAD.Runtime.Exception fl)
                            {
                                System.Windows.Forms.MessageBox.Show("FROZEN LAYER ERROR:\n" + fl.ToString());
                                return null;
                            }
                            catch
                            {
                                System.Windows.Forms.MessageBox.Show("ERROR:\n PROGRAM WILL EXIT!");
                                return null;
                            }
                        }
                        db.Clayer = sibLyrTable[sibLyrName];
                    }// end if sibLyrTable exists make it current layer
                     // Creates the sibling layer if it does not exist already.
                    else
                    {
                        sibLTRec = mklyrTrans.GetObject(sibLyrTable[blkLyrName], OpenMode.ForWrite).Clone() as LayerTableRecord;
                        sibLTRec.Name = sibLyrName;
                        sibLTRec.Color = Color.FromColorIndex(ColorMethod.ByAci, 7);
                        sibLyrTable.Add(sibLTRec);
                        mklyrTrans.AddNewlyCreatedDBObject(sibLTRec, true);
                        db.Clayer = sibLyrTable[sibLyrName];
                    }// end clone layer if sibling layer does not exist and make new sibling layer the current layer
                }
                catch (Autodesk.AutoCAD.Runtime.Exception a7)
                {
                    System.Windows.Forms.MessageBox.Show("ERROR:\n" + a7.ToString());
                    return null;
                }
                catch
                {
                    System.Windows.Forms.MessageBox.Show("ERROR:\n PROGRAM WILL EXIT!");
                    return null;
                }
                // Commits the transaction to add the sibling layer.
                mklyrTrans.Commit();
            }// end the mklyrTrans transaction
            // Returns the new sibling layer name to the calling program.
            return sibLyrName;
        }
        //***************************************************************************************************************************

[_gile]

You should be able to get some inspiration from this snippet (assuming layers is an IEnumerable of string containing the layer names to freeze in the viewport)

                using (Transaction tr = db.TransactionManager.StartTransaction())
                {
                    // open the viewport for write
                    Viewport vp = (Viewport)tr.GetObject(vpId, OpenMode.ForWrite);

                    // get the viewport layer
                    LayerTable lt = (LayerTable)tr.GetObject(db.LayerTableId, OpenMode.ForRead);
                    LayerTableRecord ltr = (LayerTableRecord)tr.GetObject(lt[vp.Layer], OpenMode.ForRead);

                    // unlock the viewport layer if needed
                    bool locked = ltr.IsLocked;
                    if (locked)
                    {
                        ltr.UpgradeOpen();
                        ltr.IsLocked = false;
                    }

                    // freeze the layers in the viewport
                    ObjectIdCollection ids = new ObjectIdCollection();
                    foreach (string layer in layers)
                    {
                        if (lt.Has(layer))
                        {
                            ids.Add(lt[layer]);
                        }
                    }
                    vp.FreezeLayersInViewport(ids.GetEnumerator());

                    // reset the lock state of the viewport layer
                    if (locked)
                        ltr.IsLocked = true;
                    tr.Commit();
                }

[sonny3g]

To clarify, I cannot thaw a specific layer for which I already have the name and ID inside of a viewport unless I create a objectId collection for that viewport and step through the collection to find the enumerator for the layer?

[_gile]

This is the way the Viewport.FreezeLayersInViewport() method works.

[_gile · Accepted solution]

You can build some extension methods to freeze or thaw a single in a viewport by passing a layer name or ObjectId

    public static class Extension
    {
        public static void FreezeLayer(this Viewport vp, string layerName)
        {
            var layerTable = (LayerTable)vp.Database.LayerTableId.GetObject(OpenMode.ForRead);
            vp.FreezeLayer(layerTable[layerName]);
        }

        public static void FreezeLayer(this Viewport vp, ObjectId layerId)
        {
            if (!layerId.IsNull)
            {
                var ids = new ObjectIdCollection();
                ids.Add(layerId);
                vp.FreezeLayersInViewport(ids.GetEnumerator());
            }
        }

        public static void ThawLayer(this Viewport vp, string layerName)
        {
            var layerTable = (LayerTable)vp.Database.LayerTableId.GetObject(OpenMode.ForRead);
            vp.ThawLayer(layerTable[layerName]);
        }

        public static void ThawLayer(this Viewport vp, ObjectId layerId)
        {
            if (!layerId.IsNull)
            {
                var ids = new ObjectIdCollection();
                ids.Add(layerId);
                vp.ThawLayersInViewport(ids.GetEnumerator());
            }
        }
    }

[sonny3g]

Thank you Giles.  That was exactly what I needed. 

My list of subjects to study and learn is getting longer the more I try to write code.

I am grateful for forums with people who are willing to share their knowledge with the rest of us.

Sonny