Fix tab widget painting in QGtkStyle with reverse

This also adds QStyleOptionTabWidgetFrameV2 so that we do not have
to do ugly hacks in the style to obtain it.

Task-number: QTBUG-5187
Reviewed-by: ogoffart

6 files changed, 166 insertions, 28 deletions

diff --git a/src/gui/styles/qgtkstyle.cpp b/src/gui/styles/qgtkstyle.cpp
index d315c98..a7c291b 100644
--- a/src/gui/styles/qgtkstyle.cpp
+++ b/src/gui/styles/qgtkstyle.cpp
@@ -1004,32 +1004,27 @@ void QGtkStyle::drawPrimitive(PrimitiveElement element,
             gtkPainter.setAlphaSupport(false);
             GtkShadowType shadow = GTK_SHADOW_OUT;
             GtkStateType state = GTK_STATE_NORMAL; // Only state supported by gtknotebook
-            if (const QTabWidget *tabwidget = qobject_cast<const QTabWidget*>(widget)) {
-                // We should introduce QStyleOptionTabWidgetFrameV2 to obtain this information
-                // No gap if we do not show the actual tabs
-                QTabBar *tabBar = tabwidget->findChild<QTabBar*>();
-                if (tabwidget->count() > 0 && tabBar->isVisible()) {
-                    QRect tabRect = tabBar->tabRect(tabBar->currentIndex());
-                    int begin = 0, size = 0;
-                    GtkPositionType frameType = GTK_POS_TOP;
-                    QTabBar::Shape shape = frame->shape;
-                    if (shape == QTabBar::RoundedNorth || shape == QTabBar::RoundedSouth) {
-                        begin = option->direction == Qt::LeftToRight ?
-                                frame->leftCornerWidgetSize.width() + tabRect.left() :
-                                frame->rect.width() - frame->tabBarSize.width() + tabRect.left()
-                                - frame->rightCornerWidgetSize.width();
-                        size = tabRect.width();
-                        frameType = (shape == QTabBar::RoundedNorth) ? GTK_POS_TOP : GTK_POS_BOTTOM;
-                    } else {
-                        begin = frame->leftCornerWidgetSize.height() + tabRect.top();
-                        size = tabRect.height();
-                        frameType = (shape == QTabBar::RoundedWest) ? GTK_POS_LEFT : GTK_POS_RIGHT;
-                    }
-                    gtkPainter.paintBoxGap(gtkNotebook, "notebook",  option->rect, state, shadow, frameType,
-                                            begin, size, style);
-                    break; // done
+            bool reverse = (option->direction == Qt::RightToLeft);
+            QGtk::gtk_widget_set_direction(gtkNotebook, reverse ? GTK_TEXT_DIR_RTL : GTK_TEXT_DIR_LTR);
+            if (const QStyleOptionTabWidgetFrameV2 *tabframe = qstyleoption_cast<const QStyleOptionTabWidgetFrameV2*>(option)) {
+                GtkPositionType frameType = GTK_POS_TOP;
+                QTabBar::Shape shape = frame->shape;
+                int gapStart = 0;
+                int gapSize = 0;
+                if (shape == QTabBar::RoundedNorth || shape == QTabBar::RoundedSouth) {
+                    frameType = (shape == QTabBar::RoundedNorth) ? GTK_POS_TOP : GTK_POS_BOTTOM;
+                    gapStart = tabframe->selectedTabRect.left();
+                    gapSize = tabframe->selectedTabRect.width();
+                } else {
+                    frameType = (shape == QTabBar::RoundedWest) ? GTK_POS_LEFT : GTK_POS_RIGHT;
+                    gapStart = tabframe->selectedTabRect.y();
+                    gapSize = tabframe->selectedTabRect.height();
                 }
+                gtkPainter.paintBoxGap(gtkNotebook, "notebook",  option->rect, state, shadow, frameType,
+                                        gapStart, gapSize, style);
+                break; // done
             }
+
             // Note this is only the fallback option
             gtkPainter.paintBox(gtkNotebook, "notebook",  option->rect, state, shadow, style);
         }
diff --git a/src/gui/styles/qstyleoption.cpp b/src/gui/styles/qstyleoption.cpp
index 061afcc..f5a2b94 100644
--- a/src/gui/styles/qstyleoption.cpp
+++ b/src/gui/styles/qstyleoption.cpp
@@ -4654,6 +4654,119 @@ QStyleOptionTabWidgetFrame::QStyleOptionTabWidgetFrame(int version)
 
     The default value is QSize(-1, -1), i.e. an invalid size.
 */
+
+
+/*!
+
+    \class QStyleOptionTabWidgetFrameV2
+    \brief The QStyleOptionTabWidgetFrameV2 class is used to describe the
+    parameters for drawing the frame around a tab widget.
+
+    QStyleOptionTabWidgetFrameV2 contains all the information that
+    QStyle functions need to draw the frame around QTabWidget.
+
+    For performance reasons, the access to the member variables is
+    direct (i.e., using the \c . or \c -> operator). This low-level feel
+    makes the structures straightforward to use and emphasizes that
+    these are simply parameters used by the style functions.
+
+    For an example demonstrating how style options can be used, see
+    the \l {widgets/styles}{Styles} example.
+
+    \sa QStyleOption, QTabWidget
+*/
+
+
+/*!
+    \variable QStyleOptionTabWidgetFrameV2::tabBarRect
+    \brief the rectangle containing all the tabs
+
+    The default value is a null rectangle, i.e. a rectangle with both
+    the width and the height set to 0.
+*/
+
+/*!
+    \variable QStyleOptionTabWidgetFrameV2::selectedTabRect
+    \brief the rectangle containing the selected tab
+
+    This rectangle is contained within the tabBarRect. The default
+    value is a null rectangle, i.e. a rectangle with both the width
+    and the height set to 0.
+*/
+
+
+/*!
+    Constructs a QStyleOptionTabWidgetFrameV2, initializing the members
+    variables to their default values.
+*/
+
+QStyleOptionTabWidgetFrameV2::QStyleOptionTabWidgetFrameV2()
+    : QStyleOptionTabWidgetFrame(Version)
+{
+}
+
+
+/*! \internal */
+QStyleOptionTabWidgetFrameV2::QStyleOptionTabWidgetFrameV2(int version)
+    : QStyleOptionTabWidgetFrame(version)
+{
+}
+
+
+/*!
+    Constructs a QStyleOptionTabWidgetFrameV2 copy of the \a other style option
+    which can be either of the QStyleOptionTabWidgetFrameV2 or
+    QStyleOptionTabWidgetFrame types.
+
+    If the \a other style option's version is 1, the new style option's \l
+    selectedTabRect and tabBarRect will contain null rects
+
+    \sa version
+*/
+QStyleOptionTabWidgetFrameV2::QStyleOptionTabWidgetFrameV2(const QStyleOptionTabWidgetFrame &other)
+{
+    QStyleOptionTabWidgetFrameV2::operator=(other);
+
+}
+
+
+/*!
+    Assigns the \a other style option to this style option. The \a
+    other style option can be either of the QStyleOptionFrameV2 or
+    QStyleOptionFrame types.
+
+    If the \a{other} style option's version is 1, this style option's
+    \l FrameFeature value is set to \l QStyleOptionFrameV2::None. If
+    its version is 2, its \l FrameFeature value is simply copied to
+    this style option.
+*/
+QStyleOptionTabWidgetFrameV2 &QStyleOptionTabWidgetFrameV2::operator=(const QStyleOptionTabWidgetFrame &other)
+{
+    QStyleOptionTabWidgetFrame::operator=(other);
+    if (const QStyleOptionTabWidgetFrameV2 *f2 = qstyleoption_cast<const QStyleOptionTabWidgetFrameV2 *>(&other)) {
+        selectedTabRect = f2->selectedTabRect;
+        tabBarRect = f2->tabBarRect;
+    }
+    return *this;
+}
+
+
+/*!
+    \enum QStyleOptionTabWidgetFrameV2::StyleOptionVersion
+
+    This enum is used to hold information about the version of the style option, and
+    is defined for each QStyleOption subclass.
+
+    \value Version 2
+
+    The version is used by QStyleOption subclasses to implement
+    extensions without breaking compatibility. If you use
+    qstyleoption_cast(), you normally do not need to check it.
+
+    \sa StyleOptionType
+*/
+
+
 #endif // QT_NO_TABWIDGET
 
 #ifndef QT_NO_TABBAR
diff --git a/src/gui/styles/qstyleoption.h b/src/gui/styles/qstyleoption.h
index bf8b479..abd52bf 100644
--- a/src/gui/styles/qstyleoption.h
+++ b/src/gui/styles/qstyleoption.h
@@ -192,8 +192,28 @@ public:
 protected:
     QStyleOptionTabWidgetFrame(int version);
 };
+
+class Q_GUI_EXPORT QStyleOptionTabWidgetFrameV2 : public QStyleOptionTabWidgetFrame
+{
+public:
+    enum StyleOptionVersion { Version = 2 };
+
+    QRect tabBarRect;
+    QRect selectedTabRect;
+
+    QStyleOptionTabWidgetFrameV2();
+    QStyleOptionTabWidgetFrameV2(const QStyleOptionTabWidgetFrameV2 &other) :
+            QStyleOptionTabWidgetFrame(Version) { *this = other; }
+    QStyleOptionTabWidgetFrameV2(const QStyleOptionTabWidgetFrame &other);
+    QStyleOptionTabWidgetFrameV2 &operator=(const QStyleOptionTabWidgetFrame &other);
+
+protected:
+    QStyleOptionTabWidgetFrameV2(int version);
+};
+
 #endif
 
+
 #ifndef QT_NO_TABBAR
 class Q_GUI_EXPORT QStyleOptionTabBarBase : public QStyleOption
 {
diff --git a/src/gui/styles/qstylesheetstyle.cpp b/src/gui/styles/qstylesheetstyle.cpp
index 2d90aa1..ae1d33a 100644
--- a/src/gui/styles/qstylesheetstyle.cpp
+++ b/src/gui/styles/qstylesheetstyle.cpp
@@ -4325,7 +4325,7 @@ void QStyleSheetStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *op
             QRenderRule subRule = renderRule(w, opt, PseudoElement_TabWidgetPane);
             if (subRule.hasNativeBorder()) {
                 subRule.drawBackground(p, opt->rect);
-                QStyleOptionTabWidgetFrame frmCopy(*frm);
+                QStyleOptionTabWidgetFrameV2 frmCopy(*frm);
                 subRule.configurePalette(&frmCopy.palette, QPalette::WindowText, QPalette::Window);
                 baseStyle()->drawPrimitive(pe, &frmCopy, p, w);
             } else {
diff --git a/src/gui/styles/qwindowsxpstyle.cpp b/src/gui/styles/qwindowsxpstyle.cpp
index b5dc647..9fd9ce9 100644
--- a/src/gui/styles/qwindowsxpstyle.cpp
+++ b/src/gui/styles/qwindowsxpstyle.cpp
@@ -1582,7 +1582,7 @@ case PE_Frame:
                 // This should work, but currently there's an error in the ::drawBackgroundDirectly()
                 // code, when using the HDC directly..
                 if (useGradient) {
-                    QStyleOptionTabWidgetFrame frameOpt = *tab;
+                    QStyleOptionTabWidgetFrameV2 frameOpt = *tab;
                     frameOpt.rect = widget->rect();
                     QRect contentsRect = subElementRect(SE_TabWidgetTabContents, &frameOpt, widget);
                     QRegion reg = option->rect;
diff --git a/src/gui/widgets/qtabwidget.cpp b/src/gui/widgets/qtabwidget.cpp
index 0c89a72..d22bd54 100644
--- a/src/gui/widgets/qtabwidget.cpp
+++ b/src/gui/widgets/qtabwidget.cpp
@@ -313,7 +313,16 @@ void QTabWidget::initStyleOption(QStyleOptionTabWidgetFrame *option) const
                                                         : QTabBar::TriangularEast;
         break;
     }
+
     option->tabBarSize = t;
+
+    if (QStyleOptionTabWidgetFrameV2 *tabframe = qstyleoption_cast<QStyleOptionTabWidgetFrameV2*>(option)) {
+        QRect tbRect = tabBar()->geometry();
+        QRect selectedTabRect = tabBar()->tabRect(tabBar()->currentIndex());
+        tabframe->tabBarRect = tbRect;
+        selectedTabRect.moveTopLeft(selectedTabRect.topLeft() + tbRect.topLeft());
+        tabframe->selectedTabRect = selectedTabRect;
+    }
 }
 
 /*!
@@ -756,7 +765,7 @@ void QTabWidget::setUpLayout(bool onlyCheck)
     if (onlyCheck && !d->dirty)
         return; // nothing to do
 
-    QStyleOptionTabWidgetFrame option;
+    QStyleOptionTabWidgetFrameV2 option;
     initStyleOption(&option);
 
     // this must be done immediately, because QWidgetItem relies on it (even if !isVisible())
@@ -1186,7 +1195,8 @@ void QTabWidget::paintEvent(QPaintEvent *)
         return;
     }
     QStylePainter p(this);
-    QStyleOptionTabWidgetFrame opt;
+
+    QStyleOptionTabWidgetFrameV2 opt;
     initStyleOption(&opt);
     opt.rect = d->panelRect;
     p.drawPrimitive(QStyle::PE_FrameTabWidget, opt);