Python » ROOM » Cell

Cell Class

Named design cell. Python counterpart of C++ room::Cell. More…

Import:	`import room`
Obtain:	`db.find_cell(name)` / `db.get_or_create_cell(name)` / `db.cells()`
C++:	`room::Cell`

Notation: name() with parentheses = method (call it). A bare name without () would mean an attribute — Cell has none of those; use cell.name(), not cell.name.

Public API

`name()`	Cell name (str).
`contents()`	All view bodies as `list[CellContent]`.
`content(view=None)`	Existing view or `None` (C++ `findContent`). No arg / `None`: sole content when the cell has exactly one view.
`ensure_content(view="layout", dbu_per_micron=1000.0)`	Get or create view (C++ `getOrCreateContent`).
`layout()`	Shortcut for `content("layout")`.
`properties()`	not yet exposed

Detailed Description

A cell is a named design unit inside the library. It holds zero or more CellContent entries (layout, schematic, symbol, abstract). Names must be unique within the parent library.

Accessors match the C++ method style: call cell.name(), not cell.name.

Member documentation

name() → str

Returns the cell name (C++ Cell::name()).

Returns: Name assigned at creation or read from a file.

contents() → list[CellContent]

Returns all view data attached to this cell (C++ contents()).

Returns: List of CellContent handles (may be empty).

content(view=None) → CellContent | None

Looks up view data (C++ findContent). With no argument (or None), if the cell has exactly one content — typical for a single *.schematic.room / *.layout.room file — that body is returned. If there are zero or several views, returns None; pass an explicit view type instead.

Parameter	Description
`view`	Optional. `None` (default) = auto when unique; otherwise `ViewType`, int, or string (`"layout"`, `"schematic"`, `"symbol"`, `"abstract"`, `"emmodel"`).

Returns: Matching content, or None.

cxt = cell.content()                 # sole view
cxt = cell.content("schematic")      # explicit
lay = cell.layout()                  # layout only

ensure_content(view="layout", dbu_per_micron=1000.0) → CellContent

Returns existing view data or creates a new entry (C++ getOrCreateContent).

Parameter	Description
`view`	View type to retrieve or create.
`dbu_per_micron`	Used only when a new content entry is created.

layout() → CellContent | None

Convenience alias for content(ViewType.LAYOUT).

CellContent Class

One view body of a cell. Counterpart of C++ room::CellContent. Block topology (shapes / instances / bbox) is exposed directly on this object (there is no separate block() step in Python).

Obtain:	`cell.content(...)` / `cell.ensure_content(...)` / `cell.layout()`
C++:	`room::CellContent` + `block()`

Public API

`view()`	`ViewType` (C++ `viewType()`).
`dbu_per_micron()`	float (C++ `dbuPerMicron()`).
`bbox()`	Box (C++ `block().bbox()`).
`shapes()`	Geometry list — see Shape.
`instances()`	`list[Instance]`.
`add_rect(...)`	Append a rectangle; returns index.
`add_instance(...)`	Append a child placement; returns index.
`properties()` / `sourceInfo()` / `nets()`	not yet exposed

view() → ViewType

Returns the view kind of this content (C++ viewType()).

dbu_per_micron() → float

DBU per micron for layout views (C++ dbuPerMicron()). Typically 1000 for GDS imports.

bbox() → Box

Cached axis-aligned bounding box of the block (C++ block().bbox()).

shapes() → list[Rect | dict]

Geometry in this view (C++ block().shapes()). Rectangles become room.Rect; other kinds are {"type", "index"} dicts until fully decoded.

instances() → list[Instance]

Child cell placements (C++ block().instances()).

add_rect(layer_id, llx, lly, urx, ury) → int

Appends a rectangle shape. layer_id indexes into db.layers().

add_instance(cell_name, x=0, y=0, orient=Orient.R0, mag=1.0) → int

Appends a child placement referencing another cell by name.

Example

import room

db = room.open("design.room")
cell = db.find_cell("INVX1")
print(cell.name())                 # 'INVX1'

layout = cell.ensure_content("layout")
print(layout.view(), layout.dbu_per_micron())
print(layout.bbox(), len(layout.shapes()), len(layout.instances()))