How to lock the cell placement

The Virtuoso layout editor does not offer a built-in way to lock the placement of a cell. I think you can lock placements when using VXL, but the locking is only going to work as long as the design is opened in VXL. The best way we found to lock cell placements was to make cells unselectable. Cadence provides a trigger function that will call a function that you define to determine if an object is selectable or not. You could then define a property on an instance or cell to indicate if the cell is locked. Your function would then return nil to the selection trigger and make your cell/instance unselectable. If it can't be selected, then the Cadence move and stretch commands can't grab it. Here is what you need:

leRegUserObjectSelectionFilter("myFilterFunction")

procedure(myFilterFunction(obj)
    if(obj~>objType == "inst" && obj~>myFixedProperty then
        return()
    else
        return(t)
    )
)

;This will disable the filter
;leUnregUserObjectSelectionFilter()

This routine needs to be efficient because it is run constantly as you move your cursor around the layout. If you have "Dynamic Hilight" turned on in the Layout Display Options form, then you normally see a yellow dotted outline around selectable objects when you move your cursor. If you register this selection filter, then the dynamic hilight will not display for instances that are not selecatble according to the above filter. You would be responsible for adding the "myFixedProperty" of t on instances that you wish to be fixed. If this property is not defined, then nil will be returned by default and thus the instance will remain selectable.

This filter can also be setup for shapes if you have a need to do so. You could also modify the "myFilterFunction" to lock by cellName rather than by individual instances. It is up to you to decide what is unselectable and when.

-Derek

The Virtuoso layout editor does not offer a built-in way to lock the placement of a cell. I think you can lock placements when using VXL, but the locking is only going to work as long as the design is opened in VXL. The best way we found to lock cell placements was to make cells unselectable. Cadence provides a trigger function that will call a function that you define to determine if an object is selectable or not. You could then define a property on an instance or cell to indicate if the cell is locked. Your function would then return nil to the selection trigger and make your cell/instance unselectable. If it can't be selected, then the Cadence move and stretch commands can't grab it. Here is what you need:

leRegUserObjectSelectionFilter("myFilterFunction")

procedure(myFilterFunction(obj)
    if(obj~>objType == "inst" && obj~>myFixedProperty then
        return()
    else
        return(t)
    )
)

;This will disable the filter
;leUnregUserObjectSelectionFilter()

This routine needs to be efficient because it is run constantly as you move your cursor around the layout. If you have "Dynamic Hilight" turned on in the Layout Display Options form, then you normally see a yellow dotted outline around selectable objects when you move your cursor. If you register this selection filter, then the dynamic hilight will not display for instances that are not selecatble according to the above filter. You would be responsible for adding the "myFixedProperty" of t on instances that you wish to be fixed. If this property is not defined, then nil will be returned by default and thus the instance will remain selectable.

This filter can also be setup for shapes if you have a need to do so. You could also modify the "myFilterFunction" to lock by cellName rather than by individual instances. It is up to you to decide what is unselectable and when.

-Derek