Empty layers referenced in a block

I have written a function to set all objects in a drawing, that I get from the city, to bylayer. At the same time creating a layer matching the properties that the entity was. Basically, if a line was on the layer 30 with the color red and linetype hidden, the function would make a layer called 30-1-hidden, color red and linetype hidden and place the line on that layer. I do all this so that when I xref the drawing into my own, I can change layer colors without changing the basic layer structure of the original. What I'm coming across is, there are about 50 blocks with layers empty layers referenced to them, so I cant purge them. The blocks were probably created with that layer, and not layer 0 as the current layer (poor drafting). How do I get VBA to find these layers and delete them or merge them to layer 0?

Here is my code so far. Feel free to bash my methods, thats the only way to learn.

Sub Citysitefix()
Dim entcol As String, entlay As String, entline As String
Dim blkcol As String, blklay As String, blkline As String
Dim OldLayer As AcadLayer, laycol As New AcadAcCmColor, layname As String
Dim oLayer As AcadLayer, oLayername As Variant
For Each blk In ThisDrawing.Blocks
For Each ent In blk
entcol = ent.color
entlay = ent.Layer
entline = ent.Linetype
If entcol = 256 Then
Set OldLayer = ThisDrawing.Layers(entlay)
entcol = OldLayer.color
End If
If entline = "Bylayer" Then
Set OldLayer = ThisDrawing.Layers(entlay)
entline = OldLayer.Linetype
End If
laycol.ColorIndex = entcol
layname = entlay & "-" & entcol & "-" & entline
Set oLayer = ThisDrawing.Layers.Add(layname)
oLayer.Plottable = False
oLayer.TrueColor = laycol
oLayer.Linetype = entline
oLayername = oLayer.Name
ent.Layer = oLayername
ent.color = acByLayer
ent.Linetype = "Bylayer"
ent.Lineweight = Bylayer
Next
Next
ThisDrawing.PurgeAll
End Sub

 

You can't purge them because they are still be in use - blocks *cannot*
contain empty layers. You need to re-look at the file and determine what is
actually on these layers. My guess is the blocks were created with their
own layers [instead of 0] and then inserted onto a layer, lets call it "X".
"X" cannot be deleted because it has the poorly created blocks on it and
there is no way you can tell unless you specifcally select one of those
blocks and check its layer - remember, visually you'll never "see" it since
the block is displaying the property's of its nested layering, NOT its host
layer.

-- Mike
___________________________
Mike Tuersley
CADalyst's CAD Clinic
Rand IMAGINiT Technologies
___________________________
the trick is to realize that there is no spoon...

 

I may be misreading or misunderstanding something in the code
but I would think his code would find those insertions when it iterates the
modelspace block
it would put them on his newly named layer and set its' properties to by
layer.
That would clear the insertions off that original layer.
Also when he iterates each block def, each object is likewise 're-layered'.
So when he's done all the 'direct' entities should be on newly named layers.

so that would leave sequends, frozen vplayers, dictionary references or
xdata or any other kind of reference to the layer object which that code
won't pick up and which might also hang onto the layer and prevent it's
deletion would they not???

and as a side issue, is a block which contains items on multiple layers
really "poorly created"?
I use many blocks which need various lineweights and linetypes and since
everything is bylayer, they have multiple layers. Is that considered
universally wrong?
Do you put everything in every block on layer "0"? and then override
lineweight and linetype to get it to plot correctly?

 

Well, I didn't read his code just the premise as I said, blocks cannot
contain empty layers ALL of the things you mentioned are are objects and,
therefore, the layers are not empty. As for "poorly created" the generally
accepted practice states "yes" - blocks should not contain layers in most
cases. For lineweights and colors, the entities should be created using
BYBLOCK properties for those values. Most cad users have no clue what
BYBLOCK means. Of course, it all boils down to personal preference and
doing whatever it takes to get it out the door. For you specifically, since
you are writing apps, I'd start looking into byblock properties.

-- Mike
___________________________
Mike Tuersley
CADalyst's CAD Clinic
Rand IMAGINiT Technologies
___________________________
the trick is to realize that there is no spoon...