QGraphicsView::render() paints only what the scene draws, so a scene
without a background brush left the off-screen buffer uninitialized
and the inversion turned that memory into noise. The buffer is now
filled white first, which the inversion turns into the Base color.
listenToScene() connected a new receiver on every setScene() call and
never dropped the previous scene's. It now keeps a single connection
and replaces it.
Test in tst_qetpalette: paletteViewFillsWhatTheSceneLeavesBlank.
After a live light/dark switch only the sheet changed colors; the
viewport around it kept the previous palette. Qt repaints a widget on
an application palette change only when the widget's own palette
changed with it, and under the folio tab widget's style sheet it does
not, so the only repaints came from the scene and covered the scene
rectangle alone. PaletteGraphicsView now watches the application
object for ApplicationPaletteChange, the one receiver Qt always
notifies, and repaints its whole viewport.
The test paletteViewFollowsTheApplicationUnderAStyleSheet now also
requires a full-viewport repaint after each switch, before anything
asks the view for a rendering.
The folio tab widget carries a style sheet, and QStyleSheetStyle pins
the palette of every widget under it to the application palette in
force when the sheet was applied. After a live light/dark switch the
view's own palette() is therefore stale: the folio kept its dark sheet
after a switch to light, and kept its white sheet after a switch to
dark. PaletteGraphicsView now reads the application palette both for
the decision to invert and for the sheet and ink colors.
Test in tst_qetpalette: paletteViewFollowsTheApplicationUnderAStyleSheet
puts the view in a tab widget with a style sheet and switches the
application palette to dark and back.
The inverted painting, the rubber band replay and the changed()
receiver lived in DiagramView, which the unit tests cannot link, so the
update-flag regression was only covered through a stand-in view. They
now live in PaletteGraphicsView, a QGraphicsView subclass with no
other dependency, and DiagramView derives from it. The view tells a
subclass through paintingInverted(bool) when it renders for an
inverted display; DiagramView forwards that to the diagram. The grid
dot rule moves out of Diagram::drawBackground into
QET::Palette::gridDotColor().
tst_qetpalette now links the real class: gridDotColorSoftensInvertedDots,
paletteViewFollowsThePalette (light sheet, dark sheet at text contrast
with a red box still red and the paintingInverted calls in order, back
to light), paletteViewKeepsSceneUpdatesFlowing (three whole-scene
updates and a selection each repaint, scene set after construction),
paletteViewDrawsTheRubberBand.
Laurent Trinques