Introduce a Document QObject that composes DesignerScene + QUndoStack,
following "composition over inheritance" and unidirectional signal-slot
communication per Qt Graphics View Framework conventions.
New files:
- include/document.h — Document class declaration
- source/document.cpp — full implementation (~450 lines)
Core capabilities:
- JSON serialization/deserialization for rect, roundRect, polygon, group
(uses dynamic_cast dispatch since subclasses don't override type())
- Two-path dirty tracking:
1. QUndoStack::indexChanged for undoable ops (add/delete/group/ungroup)
2. Explicit markDirty() via DesignerScene::notifyDocumentModified()
called by selectors after successful move/scale/rotate/edit
- save()/saveAs()/load()/clear() with maybeSave() prompt on close
- File actions (New/Open/Save/Save As) wired to toolbar and File menu;
window title tracks filename + modified indicator
Integration changes:
- DrawingPanel now receives scene via setScene() instead of creating it
- CMainWindow routes all modifications through Document::execute()
- DesignerScene gains notifyDocumentModified() for selector dirty marking
- GraphicsRectItem gains isRound()/ratioX()/ratioY() accessors
- CreatingSelector: fix missing signalAddItem emit for polygon completion
- Scene lifecycle uses clear() instead of delete+recreate to avoid
dangling view pointer
Moved QUndoStack ownership from CMainWindow into Document.
Jesse Qu