[Qt-interest] Styling QStyledItemDelegate checkboxes in a QAbstractItemView with Qt Style Sheets

[RJ Ryan]

Pradeep,

That worked perfectly. Thank you!

RJ Ryan

On Tue, Nov 30, 2010 at 11:57 AM, Pradeep K Vijayan <
pradeep.vijayan at gmail.com> wrote:

> Hi Ryan,
>
> If you are still looking for an answer, I managed to make it work with:
>
> QTableView::indicator:checked
> {
>     background: url(":checkbox/checked");
> }
>
> QTableView::indicator:unchecked
> {
>     background: url(":checkbox/unchecked");
> }
>
> Cheers,
> Pradeep
> --
> Pradeep K Vijayan
> EditShare EMEA
> United Kingdom
> www.editshare.co.uk
>
> On 22/10/2010 09:37, RJ Ryan wrote:
> > Hello all,
> >
> > I have a QTableView in which I use the Qt::CheckStateRole to show
> > checkboxes in one of the columns. How can I style these checkboxes with
> > Qt style sheets?
> >
> > I have tried the following selectors:
> > - QCheckBox::indicator
> > - QTableView QCheckBox::indicator
> > - QTableView::item QCheckBox::indicator
> > - QTableView::item::indicator
> >
> > Once I select the indicator, I give it a rule like so:
> >
> > {
> >    image: url(:/foo.png);
> > }
> >
> > None of the above selectors work. I've confirmed that the same settings
> > work fine on a regular QCheckBox that is not in my table.
> >
> > I've tried to dig through the Qt source to find out how the checkbox is
> > being rendered. It looks to me like QStyledItemDelegate checks for the
> > flags to see if Qt::ItemIsUserCheckable, and then checks the
> > Qt::CheckStateRole of the cells. If it turns out the item is checkable,
> > then it paints the widget like so:
> >
> > qstyleditemdelegate.cpp:422
> > const QWidget *widget = QStyledItemDelegatePrivate::widget(option);
> > QStyle *style = widget ? widget->style() : QApplication::style();
> > style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget);
> >
> > Looking at QStyleSheetStyle::drawControl, I can see that
> > QStyle::CE_ItemViewItem is handled like so:
> >
> > qstylesheetstyle.cpp:3952
> > QRenderRule subRule = renderRule(w, opt, PseudoElement_ViewItem);
> > if (subRule.hasDrawable() || hasStyleRule(w, PseudoElement_Indicator)) {
> >      QStyleOptionViewItemV4 optCopy(*vopt);
> >      subRule.configurePalette(&optCopy.palette, vopt->state &
> > QStyle::State_Selected ? QPalette::HighlightedText : QPalette::Text,
> >                               vopt->state & QStyle::State_Selected ?
> > QPalette::Highlight : QPalette::Base);
> >      QWindowsStyle::drawControl(ce, &optCopy, p, w);
> > } else {
> >      QStyleOptionViewItemV4 voptCopy(*vopt);
> >      subRule.configurePalette(&voptCopy.palette, QPalette::Text,
> > QPalette::NoRole);
> >      baseStyle()->drawControl(ce, &voptCopy, p, w);
> > }
> >
> >  From this, it appears that the QAbstractItemView::item is checked for a
> > drawable (e.g. background-image?) and also if the widget itself has an
> > ::indicator style, then it is passed through
> > QWindowsStyle::drawControl(), while otherwise it is passed through
> > baseStyle()->drawControl().
> >
> > Since no other styles (on my platform) handle CE_ItemViewItem, this
> > makes it to QCommonStyle. The handling for CE_ItemViewItem in
> > QCommonStyle draws the check-box like this:
> >
> > proxy()->drawPrimitive(QStyle::PE_IndicatorViewItemCheck, &option, p,
> > widget);
> >
> > I don't know this code so well, so I'm assuming proxy() goes right back
> > to the top of the chain of styles, back to QStyleSheetStyle.
> > drawPrimitive() for QStyleSheetStyle with PE_IndicatorViewItemCheck sets
> > pseudoElement to PseudoElement_ViewItemIndicator and then does this:
> >
> >
> > qstylesheetstyle.cpp:4398
> > if (pseudoElement != PseudoElement_None) {
> >      QRenderRule subRule = renderRule(w, opt, pseudoElement);
> >      if (subRule.hasDrawable()) {
> >          subRule.drawRule(p, rect);
> >      } else {
> >          baseStyle()->drawPrimitive(pe, opt, p, w);
> >      }
> > }
> >
> > So it looks to me like this checkbox should be rendered with the rule
> > indicated by PseudoElement_ViewItemIndicator. From the PseudoElement
> > info structure, I can tell that the selector for this is "indicator".
> > This leads me to believe that a selector like these should work:
> >
> > QTableView::item::indicator
> > or
> > QTableView::item::indicator::checked
> >
> > I've tried these and none of them seem to work. I'm using Qt 4.6.2 on
> > Ubuntu 10.04, so I'm not sure if this is a bug or not. I've reached the
> > limit of my knowledge of how QStyle works, so it'd be really helpful if
> > someone who knows what is going on here could help me out.
> >
> > Thanks for your time,
> > RJ Ryan
> >
> >
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