Add proper abstractions to the grid layout engine.

The abstractions are needed so that they can work with both
QGraphicsLayouts and QtQuick.Layouts.

Since the plan is to move the engine to QtGui, this means that the
engine cannot have any references to anything in the QtWidgets module.

As a consequence of that several things had to be done:
* The style info object had to be redone with an abstraction layer
  to get rid of style and widget dependency. (Abstract class is
  called QAbstractLayoutStyleInfo)
* QGridLayoutEngine must be subclassed due to some specializations for
  QGraphicsLayoutItem, manifested as QGraphicsGridLayoutEngine.
* QGridLayoutItem must be subclassed due to some specializations for
  QGraphicsLayoutItem, manifested as QGraphicsGridLayoutEngineItem.

Did also some minor cleanups, reordered arguments so that all styleInfo
arguments are last in all function calls

This also fixes QTBUG-35099 (bug was spotted during this refactoring)

Task-number: QTBUG-35099

Change-Id: If49d40f71870dc8d99d2e145be158e3080b595fa
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

1 files changed, 25 insertions, 17 deletions

diff --git a/src/widgets/graphicsview/qgraphicslinearlayout.cpp b/src/widgets/graphicsview/qgraphicslinearlayout.cpp
index 00076502ea..f506148ea3 100644
--- a/src/widgets/graphicsview/qgraphicslinearlayout.cpp
+++ b/src/widgets/graphicsview/qgraphicslinearlayout.cpp
@@ -122,7 +122,8 @@
 #include "qgraphicslayoutitem.h"
 #include "qgraphicslinearlayout.h"
 #include "qgraphicswidget.h"
-#include "qgridlayoutengine_p.h"
+#include "qgraphicsgridlayoutengine_p.h"
+#include "qgraphicslayoutstyleinfo_p.h"
 #ifdef QT_DEBUG
 #include <QtCore/qdebug.h>
 #endif
@@ -132,16 +133,20 @@ QT_BEGIN_NAMESPACE
 class QGraphicsLinearLayoutPrivate : public QGraphicsLayoutPrivate
 {
 public:
-    QGraphicsLinearLayoutPrivate(Qt::Orientation orientation) : orientation(orientation) { }
+    QGraphicsLinearLayoutPrivate(Qt::Orientation orientation)
+        : orientation(orientation),
+          m_styleInfo(0)
+    { }
 
     void removeGridItem(QGridLayoutItem *gridItem);
-    QLayoutStyleInfo styleInfo() const;
+    QGraphicsLayoutStyleInfo *styleInfo() const;
     void fixIndex(int *index) const;
     int gridRow(int index) const;
     int gridColumn(int index) const;
 
     Qt::Orientation orientation;
-    QGridLayoutEngine engine;
+    mutable QGraphicsLayoutStyleInfo *m_styleInfo;
+    QGraphicsGridLayoutEngine engine;
 };
 
 void QGraphicsLinearLayoutPrivate::removeGridItem(QGridLayoutItem *gridItem)
@@ -172,13 +177,12 @@ int QGraphicsLinearLayoutPrivate::gridColumn(int index) const
     return int(qMin(uint(index), uint(engine.columnCount())));
 }
 
-Q_GLOBAL_STATIC(QWidget, globalStyleInfoWidget)
-
-QLayoutStyleInfo QGraphicsLinearLayoutPrivate::styleInfo() const
+QGraphicsLayoutStyleInfo *QGraphicsLinearLayoutPrivate::styleInfo() const
 {
-    QGraphicsItem *item = parentItem();
-    QStyle *style = (item && item->isWidget()) ? static_cast<QGraphicsWidget*>(item)->style() : QApplication::style();
-    return QLayoutStyleInfo(style, globalStyleInfoWidget());
+    if (!m_styleInfo)
+        m_styleInfo = new QGraphicsLayoutStyleInfo(this);
+    m_styleInfo->updateChanged(QAbstractLayoutStyleInfo::Unknown);
+    return m_styleInfo;
 }
 
 /*!
@@ -281,7 +285,8 @@ void QGraphicsLinearLayout::insertItem(int index, QGraphicsLayoutItem *item)
     Q_ASSERT(item);
     d->fixIndex(&index);
     d->engine.insertRow(index, d->orientation);
-    new QGridLayoutItem(&d->engine, item, d->gridRow(index), d->gridColumn(index), 1, 1, 0, index);
+    QGraphicsGridLayoutEngineItem *gridEngineItem = new QGraphicsGridLayoutEngineItem(item, d->gridRow(index), d->gridColumn(index), 1, 1, 0);
+    d->engine.insertItem(gridEngineItem, index);
     invalidate();
 }
 
@@ -309,7 +314,7 @@ void QGraphicsLinearLayout::insertStretch(int index, int stretch)
 void QGraphicsLinearLayout::removeItem(QGraphicsLayoutItem *item)
 {
     Q_D(QGraphicsLinearLayout);
-    if (QGridLayoutItem *gridItem = d->engine.findLayoutItem(item)) {
+    if (QGraphicsGridLayoutEngineItem *gridItem = d->engine.findLayoutItem(item)) {
         item->setParentLayoutItem(0);
         d->removeGridItem(gridItem);
         delete gridItem;
@@ -330,7 +335,8 @@ void QGraphicsLinearLayout::removeAt(int index)
         qWarning("QGraphicsLinearLayout::removeAt: invalid index %d", index);
         return;
     }
-    if (QGridLayoutItem *gridItem = d->engine.itemAt(index)) {
+
+    if (QGraphicsGridLayoutEngineItem *gridItem = static_cast<QGraphicsGridLayoutEngineItem*>(d->engine.itemAt(index))) {
         if (QGraphicsLayoutItem *layoutItem = gridItem->layoutItem())
             layoutItem->setParentLayoutItem(0);
         d->removeGridItem(gridItem);
@@ -365,7 +371,7 @@ void QGraphicsLinearLayout::setSpacing(qreal spacing)
 qreal QGraphicsLinearLayout::spacing() const
 {
     Q_D(const QGraphicsLinearLayout);
-    return d->engine.spacing(d->styleInfo(), d->orientation);
+    return d->engine.spacing(d->orientation, d->styleInfo());
 }
 
 /*!
@@ -485,7 +491,7 @@ QGraphicsLayoutItem *QGraphicsLinearLayout::itemAt(int index) const
         return 0;
     }
     QGraphicsLayoutItem *item = 0;
-    if (QGridLayoutItem *gridItem = d->engine.itemAt(index))
+    if (QGraphicsGridLayoutEngineItem *gridItem = static_cast<QGraphicsGridLayoutEngineItem *>(d->engine.itemAt(index)))
         item = gridItem->layoutItem();
     return item;
 }
@@ -512,7 +518,7 @@ void QGraphicsLinearLayout::setGeometry(const QRectF &rect)
         dump(1);
     }
 #endif
-    d->engine.setGeometries(d->styleInfo(), effectiveRect);
+    d->engine.setGeometries(effectiveRect, d->styleInfo());
 #ifdef QT_DEBUG
     if (qt_graphicsLayoutDebug()) {
         qDebug() << "post dump";
@@ -530,7 +536,7 @@ QSizeF QGraphicsLinearLayout::sizeHint(Qt::SizeHint which, const QSizeF &constra
     qreal left, top, right, bottom;
     getContentsMargins(&left, &top, &right, &bottom);
     const QSizeF extraMargins(left + right, top + bottom);
-    return d->engine.sizeHint(d->styleInfo(), which , constraint - extraMargins) + extraMargins;
+    return d->engine.sizeHint(which , constraint - extraMargins, d->styleInfo()) + extraMargins;
 }
 
 /*!
@@ -540,6 +546,8 @@ void QGraphicsLinearLayout::invalidate()
 {
     Q_D(QGraphicsLinearLayout);
     d->engine.invalidate();
+    if (d->m_styleInfo)
+        d->m_styleInfo->invalidate();
     QGraphicsLayout::invalidate();
 }