QAbstractScrollArea - add SizeAdjustPolicy and viewportSizeHint

This patch adds SizeAdjustPolicy to QAbstractScrollArea.
If it is set to AdjustToContents it will make use of the new
protected viewportSizeHint() (BC since it was reserved in Qt5).
This function returns a suggested size based on contents.

Change-Id: I5d8aa517e88b8b21c5712e62b4d574c3aad99d3b
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>

13 files changed, 206 insertions, 18 deletions

diff --git a/src/widgets/itemviews/qabstractitemview.cpp b/src/widgets/itemviews/qabstractitemview.cpp
index 70c8f44a73..b79525b9df 100644
--- a/src/widgets/itemviews/qabstractitemview.cpp
+++ b/src/widgets/itemviews/qabstractitemview.cpp
@@ -1108,6 +1108,7 @@ void QAbstractItemView::reset()
         QAccessible::updateAccessibility(&accessibleEvent);
     }
 #endif
+    d->updateGeometry();
 }
 
 /*!
@@ -1124,6 +1125,7 @@ void QAbstractItemView::setRootIndex(const QModelIndex &index)
     }
     d->root = index;
     d->doDelayedItemsLayout();
+    d->updateGeometry();
 }
 
 /*!
@@ -2668,8 +2670,10 @@ void QAbstractItemView::updateEditorGeometries()
 */
 void QAbstractItemView::updateGeometries()
 {
+    Q_D(QAbstractItemView);
     updateEditorGeometries();
-    d_func()->fetchMoreTimer.start(0, this); //fetch more later
+    d->fetchMoreTimer.start(0, this); //fetch more later
+    d->updateGeometry();
 }
 
 /*!
@@ -3231,6 +3235,7 @@ void QAbstractItemView::dataChanged(const QModelIndex &topLeft, const QModelInde
         QAccessible::updateAccessibility(&accessibleEvent);
     }
 #endif
+    d->updateGeometry();
 }
 
 /*!
@@ -3332,6 +3337,7 @@ void QAbstractItemViewPrivate::_q_rowsRemoved(const QModelIndex &index, int star
         QAccessible::updateAccessibility(&accessibleEvent);
     }
 #endif
+    updateGeometry();
 }
 
 /*!
@@ -3412,6 +3418,7 @@ void QAbstractItemViewPrivate::_q_columnsRemoved(const QModelIndex &index, int s
         QAccessible::updateAccessibility(&accessibleEvent);
     }
 #endif
+    updateGeometry();
 }
 
 
@@ -3435,6 +3442,7 @@ void QAbstractItemViewPrivate::_q_rowsInserted(const QModelIndex &index, int sta
         QAccessible::updateAccessibility(&accessibleEvent);
     }
 #endif
+    updateGeometry();
 }
 
 /*!
@@ -3459,6 +3467,7 @@ void QAbstractItemViewPrivate::_q_columnsInserted(const QModelIndex &index, int
         QAccessible::updateAccessibility(&accessibleEvent);
     }
 #endif
+    updateGeometry();
 }
 
 /*!
@@ -4084,7 +4093,14 @@ void QAbstractItemViewPrivate::interruptDelayedItemsLayout() const
     delayedPendingLayout = false;
 }
 
-
+void QAbstractItemViewPrivate::updateGeometry()
+{
+    Q_Q(QAbstractItemView);
+    if (sizeAdjustPolicy == QAbstractScrollArea::AdjustIgnored)
+        return;
+    if (sizeAdjustPolicy == QAbstractScrollArea::AdjustToContents || !shownOnce)
+        q->updateGeometry();
+}
 
 QWidget *QAbstractItemViewPrivate::editor(const QModelIndex &index,
                                           const QStyleOptionViewItem &options)
diff --git a/src/widgets/itemviews/qabstractitemview_p.h b/src/widgets/itemviews/qabstractitemview_p.h
index 86eab174ed..5da22615e2 100644
--- a/src/widgets/itemviews/qabstractitemview_p.h
+++ b/src/widgets/itemviews/qabstractitemview_p.h
@@ -127,6 +127,8 @@ public:
     void doDelayedItemsLayout(int delay = 0);
     void interruptDelayedItemsLayout() const;
 
+    void updateGeometry();
+
     void startAutoScroll()
     {   // ### it would be nice to make this into a style hint one day
         int scrollInterval = (verticalScrollMode == QAbstractItemView::ScrollPerItem) ? 150 : 50;
diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index edfbc5c8f1..0dbf0a6a76 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -550,6 +550,22 @@ QSize QHeaderView::sizeHint() const
 }
 
 /*!
+    \reimp
+*/
+
+void QHeaderView::setVisible(bool v)
+{
+    bool actualChange = (v != isVisible());
+    QAbstractItemView::setVisible(v);
+    if (actualChange) {
+        QAbstractScrollArea *parent = qobject_cast<QAbstractScrollArea*>(parentWidget());
+        if (parent)
+            parent->updateGeometry();
+    }
+}
+
+
+/*!
     Returns a suitable size hint for the section specified by \a logicalIndex.
 
     \sa sizeHint(), defaultSectionSize(), minimumSectionSize(),
@@ -918,6 +934,18 @@ void QHeaderView::resizeSection(int logical, int size)
         d->doDelayedResizeSections();
         r = d->viewport->rect();
     }
+
+    // If the parent is a QAbstractScrollArea with QAbstractScrollArea::AdjustToContents
+    // then we want to change the geometry on that widget. Not doing it at once can/will
+    // cause scrollbars flicker as they would be shown at first but then removed.
+    // In the same situation it will also allow shrinking the whole view when stretchLastSection is set
+    // (It is default on QTreeViews - and it wouldn't shrink since the last stretch was made before the
+    // viewport was resized)
+
+    QAbstractScrollArea *parent = qobject_cast<QAbstractScrollArea *>(parentWidget());
+    if (parent && parent->sizeAdjustPolicy() == QAbstractScrollArea::AdjustToContents)
+        parent->updateGeometry();
+
     d->viewport->update(r.normalized());
     emit sectionResized(logical, oldSize, size);
 }
diff --git a/src/widgets/itemviews/qheaderview.h b/src/widgets/itemviews/qheaderview.h
index 8fcd8d7a36..0b94eedf78 100644
--- a/src/widgets/itemviews/qheaderview.h
+++ b/src/widgets/itemviews/qheaderview.h
@@ -84,6 +84,7 @@ public:
     int offset() const;
     int length() const;
     QSize sizeHint() const;
+    void setVisible(bool v);
     int sectionSizeHint(int logicalIndex) const;
 
     int visualIndexAt(int position) const;
diff --git a/src/widgets/itemviews/qtableview.cpp b/src/widgets/itemviews/qtableview.cpp
index 573df1db6a..37c52948b0 100644
--- a/src/widgets/itemviews/qtableview.cpp
+++ b/src/widgets/itemviews/qtableview.cpp
@@ -1056,6 +1056,19 @@ QTableView::~QTableView()
 /*!
   \reimp
 */
+QSize QTableView::viewportSizeHint() const
+{
+    Q_D(const QTableView);
+    QSize result( (d->verticalHeader->isHidden() ? 0 : d->verticalHeader->width()) + d->horizontalHeader->length(),
+                  (d->horizontalHeader->isHidden() ? 0 : d->horizontalHeader->height()) + d->verticalHeader->length());
+    result += QSize(verticalScrollBar()->isVisible() ? verticalScrollBar()->width() : 0,
+                    horizontalScrollBar()->isVisible() ? horizontalScrollBar()->height() : 0);
+    return result;
+}
+
+/*!
+  \reimp
+*/
 void QTableView::setModel(QAbstractItemModel *model)
 {
     Q_D(QTableView);
diff --git a/src/widgets/itemviews/qtableview.h b/src/widgets/itemviews/qtableview.h
index 824348dbe8..db956480d6 100644
--- a/src/widgets/itemviews/qtableview.h
+++ b/src/widgets/itemviews/qtableview.h
@@ -118,6 +118,8 @@ public:
 
     void sortByColumn(int column, Qt::SortOrder order);
 
+    QSize viewportSizeHint() const;
+
 public Q_SLOTS:
     void selectRow(int row);
     void selectColumn(int column);
diff --git a/src/widgets/itemviews/qtreeview.cpp b/src/widgets/itemviews/qtreeview.cpp
index 70523815e8..962ed97762 100644
--- a/src/widgets/itemviews/qtreeview.cpp
+++ b/src/widgets/itemviews/qtreeview.cpp
@@ -335,6 +335,7 @@ void QTreeView::setHeader(QHeaderView *header)
             this, SLOT(updateGeometries()));
 
     setSortingEnabled(d->sortingEnabled);
+    d->updateGeometry();
 }
 
 /*!
@@ -2619,6 +2620,35 @@ void QTreeView::selectAll()
 }
 
 /*!
+  \reimp
+*/
+QSize QTreeView::viewportSizeHint() const
+{
+    Q_D(const QTreeView);
+    d->executePostedLayout(); // Make sure that viewItems are up to date.
+
+    if (d->viewItems.size() == 0)
+        return QAbstractItemView::viewportSizeHint();
+
+    // Get rect for last item
+    const QRect deepestRect = visualRect(d->viewItems.last().index);
+
+    if (!deepestRect.isValid())
+        return QAbstractItemView::viewportSizeHint();
+
+    QSize result = QSize(d->header->length(), deepestRect.bottom() + 1);
+
+    // add size for header
+    result += QSize(0, d->header->isVisible() ? d->header->height() : 0);
+
+    // add size for scrollbars
+    result += QSize(verticalScrollBar()->isVisible() ? verticalScrollBar()->width() : 0,
+                    horizontalScrollBar()->isVisible() ? horizontalScrollBar()->height() : 0);
+
+    return result;
+}
+
+/*!
   \since 4.2
   Expands all expandable items.
 
diff --git a/src/widgets/itemviews/qtreeview.h b/src/widgets/itemviews/qtreeview.h
index 73f11f1a48..fae814c6f6 100644
--- a/src/widgets/itemviews/qtreeview.h
+++ b/src/widgets/itemviews/qtreeview.h
@@ -144,6 +144,8 @@ public:
     void dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles = QVector<int>());
     void selectAll();
 
+    QSize viewportSizeHint() const;
+
 Q_SIGNALS:
     void expanded(const QModelIndex &index);
     void collapsed(const QModelIndex &index);
diff --git a/src/widgets/widgets/qabstractscrollarea.cpp b/src/widgets/widgets/qabstractscrollarea.cpp
index 900e95f4da..e7827055fb 100644
--- a/src/widgets/widgets/qabstractscrollarea.cpp
+++ b/src/widgets/widgets/qabstractscrollarea.cpp
@@ -167,6 +167,7 @@ QT_BEGIN_NAMESPACE
 
 QAbstractScrollAreaPrivate::QAbstractScrollAreaPrivate()
     :hbar(0), vbar(0), vbarpolicy(Qt::ScrollBarAsNeeded), hbarpolicy(Qt::ScrollBarAsNeeded),
+     shownOnce(false), sizeAdjustPolicy(QAbstractScrollArea::AdjustIgnored),
      viewport(0), cornerWidget(0), left(0), top(0), right(0), bottom(0),
      xoffset(0), yoffset(0), viewportFilter(0)
 #ifdef Q_WS_WIN
@@ -527,6 +528,19 @@ void QAbstractScrollAreaPrivate::layoutChildren()
 }
 
 /*!
+    \enum QAbstractScrollArea::SizeAdjustPolicy
+    \since 5.2
+
+    This enum specifies how the size hint of the QAbstractScrollArea should
+    adjust when the size of the viewport changes.
+
+    \value AdjustIgnored                 The scroll area will behave like before - and not do any adjust.
+    \value AdjustToContents              The scroll area will always adjust to the viewport
+    \value AdjustToContentsOnFirstShow   The scroll area will adjust to its viewport the first time it is shown.
+*/
+
+
+/*!
     \internal
 
     Creates a new QAbstractScrollAreaPrivate, \a dd with the given \a parent.
@@ -983,6 +997,13 @@ bool QAbstractScrollArea::event(QEvent *e)
     case QEvent::Resize:
             d->layoutChildren();
             break;
+    case QEvent::Show:
+        if (!d->shownOnce && d->sizeAdjustPolicy == QAbstractScrollArea::AdjustToContentsOnFirstShow) {
+            d->sizeHint = QSize();
+            updateGeometry();
+        }
+        d->shownOnce = true;
+        return QFrame::event(e);
     case QEvent::Paint: {
         QStyleOption option;
         option.initFrom(this);
@@ -1533,17 +1554,70 @@ QSize QAbstractScrollArea::minimumSizeHint() const
 }
 
 /*!
+    Returns the sizeHint property of the scroll area. The size is determined by using
+    viewportSizeHint() plus some extra space for scroll bars, if needed.
     \reimp
 */
 QSize QAbstractScrollArea::sizeHint() const
 {
-    return QSize(256, 192);
-#if 0
     Q_D(const QAbstractScrollArea);
-    int h = qMax(10, fontMetrics().height());
-    int f = 2 * d->frameWidth;
-    return QSize((6 * h) + f, (4 * h) + f);
-#endif
+    if (d->sizeAdjustPolicy == QAbstractScrollArea::AdjustIgnored)
+        return QSize(256, 192);
+
+    if (!d->sizeHint.isValid() || d->sizeAdjustPolicy == QAbstractScrollArea::AdjustToContents) {
+        const int f = 2 * d->frameWidth;
+        const QSize frame( f, f );
+        const QSize scrollbars(d->vbarpolicy == Qt::ScrollBarAlwaysOn ? d->vbar->sizeHint().width() : 0,
+                               d->hbarpolicy == Qt::ScrollBarAlwaysOn ? d->hbar->sizeHint().height() : 0);
+        d->sizeHint = frame + scrollbars + viewportSizeHint();
+    }
+    return d->sizeHint;
+}
+
+/*!
+   \since 5.2
+   Returns the recommended size for the viewport.
+   The default implementation returns viewport()->sizeHint().
+   Note that the size is just the viewport's size, without any scroll bars visible.
+ */
+QSize QAbstractScrollArea::viewportSizeHint() const
+{
+    Q_D(const QAbstractScrollArea);
+    if (d->viewport) {
+        const QSize sh = d->viewport->sizeHint();
+        if (sh.isValid()) {
+            return sh;
+        }
+    }
+    const int h = qMax(10, fontMetrics().height());
+    return QSize(6 * h, 4 * h);
+}
+
+/*!
+    \since 5.2
+    \property QAbstractScrollArea::sizeAdjustPolicy
+    This property holds the policy describing how the size of the scroll area changes when the
+    size of the viewport changes.
+
+    The default policy is QAbstractScrollArea::AdjustIgnored.
+    Changing this property might actually resize the scrollarea.
+*/
+
+QAbstractScrollArea::SizeAdjustPolicy QAbstractScrollArea::sizeAdjustPolicy() const
+{
+    Q_D(const QAbstractScrollArea);
+    return d->sizeAdjustPolicy;
+}
+
+void QAbstractScrollArea::setSizeAdjustPolicy(SizeAdjustPolicy policy)
+{
+    Q_D(QAbstractScrollArea);
+    if (d->sizeAdjustPolicy == policy)
+        return;
+
+    d->sizeAdjustPolicy = policy;
+    d->sizeHint = QSize();
+    updateGeometry();
 }
 
 /*!
@@ -1559,16 +1633,6 @@ void QAbstractScrollArea::setupViewport(QWidget *viewport)
     Q_UNUSED(viewport);
 }
 
-/*!
-    \internal
-
-    This method is reserved for future use.
-*/
-QSize QAbstractScrollArea::viewportSizeHint() const
-{
-    return QSize();
-}
-
 QT_END_NAMESPACE
 
 #include "moc_qabstractscrollarea.cpp"
diff --git a/src/widgets/widgets/qabstractscrollarea.h b/src/widgets/widgets/qabstractscrollarea.h
index ccf16b5e5c..fb9562db1b 100644
--- a/src/widgets/widgets/qabstractscrollarea.h
+++ b/src/widgets/widgets/qabstractscrollarea.h
@@ -56,13 +56,22 @@ class QAbstractScrollAreaPrivate;
 class Q_WIDGETS_EXPORT QAbstractScrollArea : public QFrame
 {
     Q_OBJECT
+
+    Q_ENUMS(SizeAdjustPolicy)
     Q_PROPERTY(Qt::ScrollBarPolicy verticalScrollBarPolicy READ verticalScrollBarPolicy WRITE setVerticalScrollBarPolicy)
     Q_PROPERTY(Qt::ScrollBarPolicy horizontalScrollBarPolicy READ horizontalScrollBarPolicy WRITE setHorizontalScrollBarPolicy)
+    Q_PROPERTY(SizeAdjustPolicy sizeAdjustPolicy READ sizeAdjustPolicy WRITE setSizeAdjustPolicy)
 
 public:
     explicit QAbstractScrollArea(QWidget* parent=0);
     ~QAbstractScrollArea();
 
+    enum SizeAdjustPolicy {
+        AdjustIgnored,
+        AdjustToContentsOnFirstShow,
+        AdjustToContents
+    };
+
     Qt::ScrollBarPolicy verticalScrollBarPolicy() const;
     void setVerticalScrollBarPolicy(Qt::ScrollBarPolicy);
     QScrollBar *verticalScrollBar() const;
@@ -89,6 +98,9 @@ public:
 
     virtual void setupViewport(QWidget *viewport);
 
+    SizeAdjustPolicy sizeAdjustPolicy() const;
+    void setSizeAdjustPolicy(SizeAdjustPolicy policy);
+
 protected:
     QAbstractScrollArea(QAbstractScrollAreaPrivate &dd, QWidget *parent = 0);
     void setViewportMargins(int left, int top, int right, int bottom);
diff --git a/src/widgets/widgets/qabstractscrollarea_p.h b/src/widgets/widgets/qabstractscrollarea_p.h
index 34d767fe29..3093c2f812 100644
--- a/src/widgets/widgets/qabstractscrollarea_p.h
+++ b/src/widgets/widgets/qabstractscrollarea_p.h
@@ -75,6 +75,10 @@ public:
     QScrollBar *hbar, *vbar;
     Qt::ScrollBarPolicy vbarpolicy, hbarpolicy;
 
+    bool shownOnce;
+    mutable QSize sizeHint;
+    QAbstractScrollArea::SizeAdjustPolicy sizeAdjustPolicy;
+
     QWidget *viewport;
     QWidget *cornerWidget;
     QRect cornerPaintingRect;
diff --git a/src/widgets/widgets/qscrollarea.cpp b/src/widgets/widgets/qscrollarea.cpp
index 93c335c56b..2a6d4620d7 100644
--- a/src/widgets/widgets/qscrollarea.cpp
+++ b/src/widgets/widgets/qscrollarea.cpp
@@ -407,6 +407,18 @@ QSize QScrollArea::sizeHint() const
     return sz.boundedTo(QSize(36 * h, 24 * h));
 }
 
+/*!
+    \reimp
+ */
+QSize QScrollArea::viewportSizeHint() const
+{
+    Q_D(const QScrollArea);
+    if (d->widget) {
+        return d->resizable ? d->widget->sizeHint() : d->widget->size();
+    }
+    const int h = fontMetrics().height();
+    return QSize(6 * h, 4 * h);
+}
 
 
 /*!
diff --git a/src/widgets/widgets/qscrollarea.h b/src/widgets/widgets/qscrollarea.h
index 576c9bc9e0..70af5fbbd7 100644
--- a/src/widgets/widgets/qscrollarea.h
+++ b/src/widgets/widgets/qscrollarea.h
@@ -69,6 +69,8 @@ public:
     void setWidgetResizable(bool resizable);
 
     QSize sizeHint() const;
+    QSize viewportSizeHint() const;
+
     bool focusNextPrevChild(bool next);
 
     Qt::Alignment alignment() const;