Adds two QetGraphicsHandlerItem grip handles at the left/right edges of a
selected DynamicElementTextItem's frameRect(), reusing the exact same
handle class, scene-event-filter wiring, and live-drag-then-undo-on-release
pattern QetShapeItem already uses for its own diagram-level resize handles
(sources/qetgraphicsitem/qetshapeitem.cpp).
- Handles are created/destroyed on ItemSelectedHasChanged, matching
QetShapeItem's convention (and ElementPrimitiveDecorator's, for the
element editor's own primitives).
- Position is recomputed in paint() rather than hooked to specific
mutators, since textWidth/font/text/rotation can all move frameRect()
and there's no single itemChange notification that covers all of them.
- The drag delta is resolved through mapFromScene() into the item's own
local coordinates, so a rotated text box still resizes along its own
baseline rather than along the scene's x-axis.
- setTextWidth() is called live during the drag for immediate visual
feedback (matching how QetShapeItem's handlerMouseMoveEvent live-updates
geometry); only on release is a QPropertyUndoCommand pushed -- the exact
same command the properties-panel width spinbox already uses
(sources/ui/dynamicelementtextmodel.cpp), so no new undo-command class
or XML was needed.
- The original textWidth() value is preserved as-is (including -1, the
"auto" sentinel) for the undo command's old_value, separately from the
concrete baseline used for the live drag's delta math -- otherwise an
undo would replace "auto width" with a synthesized fixed width instead
of actually restoring the auto-sizing state.
Scoped to DynamicElementTextItem per the discussion's phase 1 (the
buildable, no-new-XML piece); IndependentTextItem and the element editor's
PartText/PartDynamicTextField have no serialized width property to resize
yet and are left as explicitly out-of-scope follow-ups.
Verified headlessly (Xvfb + xdotool + scrot): selecting an element's
label text shows the two handles, dragging one live-resizes the text
(confirmed via the properties panel's width field updating in real time),
and undo/redo correctly restores the exact original width including the
auto-width (-1) case.
ispyisail
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