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Layer and technology editing

The layer-and-technology panel groups two related jobs into the end of the right-hand side panel: an upgraded layer manager for arranging and styling the layer table, and a technology editor for viewing and changing the process description that drives the whole document. Its window-free logic lives in the tech_editor module and the layer state lives in layers, so the interesting behavior is unit-tested without a GPU or a window; the panel itself is thin glue that binds widgets to that logic.

Layer manager

The layer manager is a view over the app’s layer state, the same table the canvas consults when it culls hidden layers. Every action here is a cheap, view-only change: it never mutates the document and never lands on the undo stack.

  • Reorder. The up and down arrows move a layer one position earlier or later in the table. The first row cannot move up and the last cannot move down. Reordering keeps the layer table’s internal id-to-index lookup in sync, so visibility and name queries keep resolving to the right rows after a move.
  • Recolor. The color button opens a picker seeded with the layer’s current color. Choosing a new color repacks it into the layer’s 0xRRGGBBAA value; the canvas palette re-reads layer colors, so the change shows up on the next scene rebuild.
  • Fill style. Each layer carries a fill style (solid, hatch, or outline) chosen from a small drop-down. Fill style is display metadata for the manager preview and the legend; it stays inside the app and does not change the geometry.
  • Solo. Solo shows only the chosen layer and hides every other, the fast way to isolate one layer. Soloing an unknown layer is a no-op rather than a blank canvas, so a stale id never hides everything.
  • Show all / Hide all flip every layer visible or hidden at once, and the per-row checkbox toggles a single layer.

Technology editor

The technology editor edits a working draft of the document’s technology: the database resolution (dbu_per_micron), the layer table, and the DRC rule thresholds. The draft is seeded from the live document the first time the panel is shown, and from then on it is yours to edit; nothing touches the document until you press Apply.

You can edit the technology name and resolution, recolor and renumber layers or rename them, and adjust each rule’s threshold value. The rule rows show each rule’s kind and its layer (or layer pair) for context, with the threshold as the editable field, because retuning a value is the common change.

Validation

Apply validates the whole draft before it commits, and if anything is wrong it applies nothing and lists every problem inline. The checks are the invariants the DRC engine and the file format assume but the in-memory type does not enforce on its own:

  • the resolution must be positive,
  • every rule threshold must be non-negative, and a length-style rule (width, spacing, enclosure, extension, notch) or an area rule must be strictly positive, so a negative or zero width is rejected,
  • a two-layer rule kind (spacing, enclosure, extension) must carry a second layer and a single-layer kind must not, and
  • every physical-stack entry’s thickness must be positive.

Only a clean draft reaches the document. Revert throws the draft away and reloads it from the current document, discarding any in-progress edits.

How the change reaches the document

Setting a technology is not one of the document’s undoable edits: the edit vocabulary is geometry-only (add and remove shapes, cells, instances, and labels), and the undo/redo log records only those. So a validated technology is applied directly to the document rather than pushed onto the undo stack. The document revision still advances, which is what the retained renderer keys its cache invalidation on, so the canvas re-reads the new technology. The practical consequence is that a technology change is not itself undoable, and it leaves the existing shape-edit history intact: undoing a shape edit made before the technology change still works.

Technology file round-trip

The editor round-trips the draft through the line-oriented technology-file text format described in File formats. The collapsible Technology file (text) panel shows the draft serialized to that format; Refresh from draft re-serializes the current draft, and Load from text parses the text box back into the draft, reporting a parse error instead of loading a malformed file.

Serialization is canonical and byte-stable rather than a verbatim copy. Parsing discards comments, blank lines, token spacing, keyword case, and any 0x or # color prefix, so those cannot survive a load; the serializer emits one directive per line in a fixed order, with colors as eight uppercase hex digits. The guarantee the editor relies on is a fixpoint: parsing the serialized draft yields an equal technology, and re-serializing it reproduces the same bytes. Re-saving a file the editor wrote gives back exactly that file; a hand-authored file with comments comes back in canonical form without them.