Adjust the layout if a QGraphicsWidget is explicitly hidden

Since layout items can now be hidden, this also makes sure we respect
the QSizePolicy::retainSizeWhenHidden

Task-number: QTBUG-20132
Change-Id: Iab59fc9b61d4ca1bb2208c479a027da6eb0283a9
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

src/gui/util/qgridlayoutengine.cpp

@@ -1289,7 +1289,7 @@ void QGridLayoutEngine::fillRowData(QGridLayoutRowData *rowData,
             if (rowIsIdenticalToPrevious && item != itemAt(row - 1, column, orientation))
                 rowIsIdenticalToPrevious = false;
 
-            if (item)
+            if (item && !item->isIgnored())
                 rowIsEmpty = false;
         }
 

src/gui/util/qgridlayoutengine_p.h

@@ -295,6 +295,7 @@ public:
 
     virtual QLayoutPolicy::Policy sizePolicy(Qt::Orientation orientation) const = 0;
     virtual QSizeF sizeHint(Qt::SizeHint which, const QSizeF &constraint) const = 0;
+    virtual bool isIgnored() const { return false; }
 
     virtual void setGeometry(const QRectF &rect) = 0;
     /*

src/widgets/graphicsview/qgraphicsgridlayoutengine.cpp

@@ -38,9 +38,29 @@
 #include "qgraphicslayoutitem_p.h"
 #include "qgraphicslayout_p.h"
 #include "qgraphicswidget.h"
+#include <private/qgraphicswidget_p.h>
 
 QT_BEGIN_NAMESPACE
 
+bool QGraphicsGridLayoutEngineItem::isHidden() const
+{
+    if (QGraphicsItem *item = q_layoutItem->graphicsItem())
+        return QGraphicsItemPrivate::get(item)->explicitlyHidden;
+    return false;
+}
+
+/*!
+  \internal
+
+  If this returns true, the layout will arrange just as if the item was never added to the layout.
+  (Note that this shouldn't lead to a "double spacing" where the item was hidden)
+  ### Qt6: Move to QGraphicsLayoutItem and make virtual
+*/
+bool QGraphicsGridLayoutEngineItem::isIgnored() const
+{
+    return isHidden() && !q_layoutItem->sizePolicy().retainSizeWhenHidden();
+}
+
 /*
   returns \c true if the size policy returns \c true for either hasHeightForWidth()
   or hasWidthForHeight()

src/widgets/graphicsview/qgraphicsgridlayoutengine_p.h

@@ -82,6 +82,10 @@ public:
         return q_layoutItem->effectiveSizeHint(which, constraint);
     }
 
+    bool isHidden() const;
+
+    virtual bool isIgnored() const Q_DECL_OVERRIDE;
+
     virtual void setGeometry(const QRectF &rect) Q_DECL_OVERRIDE
     {
          q_layoutItem->setGeometry(rect);

src/widgets/graphicsview/qgraphicswidget.cpp

@@ -1137,6 +1137,10 @@ QVariant QGraphicsWidget::itemChange(GraphicsItemChange change, const QVariant &
                 setAttribute(Qt::WA_Resized, false);
             }
         }
+
+        // layout size hint only changes if an item changes from/to explicitly hidden state
+        if (value.toBool() || d->explicitlyHidden)
+            updateGeometry();
         break;
     case ItemVisibleHasChanged:
         if (!value.toBool()) {

tests/auto/widgets/graphicsview/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp

@@ -124,6 +124,7 @@ private slots:
     void heightForWidthWithSpanning();
     void stretchAndHeightForWidth();
     void testDefaultAlignment();
+    void hiddenItems();
 };
 
 class RectWidget : public QGraphicsWidget
@@ -3485,6 +3486,94 @@ void tst_QGraphicsGridLayout::testDefaultAlignment()
     QCOMPARE(w->geometry(), QRectF(0,0,50,50));
     QCOMPARE(w2->geometry(), QRectF(0,50,100,100));
 }
+
+static RectWidget *addWidget(QGraphicsGridLayout *grid, int row, int column)
+{
+    RectWidget *w = new RectWidget;
+    w->setPreferredSize(20, 20);
+    grid->addItem(w, row, column);
+    return w;
+}
+
+static void setVisible(bool visible, QGraphicsWidget **widgets)
+{
+    for (int i = 0; i < 3; ++i)
+        if (widgets[i]) widgets[i]->setVisible(visible);
+}
+
+static void setRetainSizeWhenHidden(bool retainSize, QGraphicsWidget **widgets)
+{
+    QSizePolicy sp = widgets[0]->sizePolicy();
+    sp.setRetainSizeWhenHidden(retainSize);
+    for (int i = 0; i < 3; ++i)
+        if (widgets[i]) widgets[i]->setSizePolicy(sp);
+}
+
+void tst_QGraphicsGridLayout::hiddenItems()
+{
+    QGraphicsWidget *widget = new QGraphicsWidget;
+    QGraphicsGridLayout *layout = new QGraphicsGridLayout(widget);
+    layout->setContentsMargins(0, 0, 0, 0);
+    layout->setSpacing(2);
+
+    // Create a 3x3 layout
+    addWidget(layout, 0, 0);
+    RectWidget *w01 = addWidget(layout, 0, 1);
+    addWidget(layout, 0, 2);
+    RectWidget *w10 = addWidget(layout, 1, 0);
+    RectWidget *w11 = addWidget(layout, 1, 1);
+    RectWidget *w12 = addWidget(layout, 1, 2);
+    addWidget(layout, 2, 0);
+    RectWidget *w21 = addWidget(layout, 2, 1);
+    addWidget(layout, 2, 2);
+
+    QGraphicsWidget *middleColumn[] = {w01, w11, w21 };
+    QGraphicsWidget *topTwoOfMiddleColumn[] = {w01, w11, 0 };
+
+    // hide and show middle column
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+    setVisible(false, middleColumn);   // hide middle column
+    QCOMPARE(layout->preferredWidth(), qreal(42));
+    setVisible(true, middleColumn);    // show middle column
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+    setRetainSizeWhenHidden(true, middleColumn);
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+    setVisible(false, middleColumn);   // hide middle column
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+    setRetainSizeWhenHidden(false, middleColumn);
+    QCOMPARE(layout->preferredWidth(), qreal(42));
+    setVisible(true, middleColumn);
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+
+    // Hide only two items, => column should not collapse
+    setVisible(false, topTwoOfMiddleColumn);
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+
+
+    QGraphicsWidget *middleRow[] = {w10, w11, w12 };
+    QGraphicsWidget *leftMostTwoOfMiddleRow[] = {w10, w11, 0 };
+
+    // hide and show middle row
+    QCOMPARE(layout->preferredHeight(), qreal(64));
+    setVisible(false, middleRow);
+    QCOMPARE(layout->preferredHeight(), qreal(42));
+    setVisible(true, middleRow);
+    QCOMPARE(layout->preferredHeight(), qreal(64));
+    setRetainSizeWhenHidden(true, middleColumn);
+    QCOMPARE(layout->preferredHeight(), qreal(64));
+    setVisible(false, middleRow);
+    QCOMPARE(layout->preferredHeight(), qreal(64));
+    setRetainSizeWhenHidden(false, middleRow);
+    QCOMPARE(layout->preferredHeight(), qreal(42));
+    setVisible(true, middleRow);
+    QCOMPARE(layout->preferredHeight(), qreal(64));
+
+    // Hide only two items => row should not collapse
+    setVisible(false, leftMostTwoOfMiddleRow);
+    QCOMPARE(layout->preferredHeight(), qreal(64));
+
+}
+
 QTEST_MAIN(tst_QGraphicsGridLayout)
 #include "tst_qgraphicsgridlayout.moc"
 

tests/auto/widgets/graphicsview/qgraphicslayout/tst_qgraphicslayout.cpp

@@ -50,6 +50,7 @@ private slots:
     void compressLayoutRequest();
     void automaticReparenting();
     void verifyActivate();
+    void sizeHintOfHiddenLayout();
     void invalidate();
     void constructors();
     void alternativeLayoutItems();
@@ -279,6 +280,30 @@ void tst_QGraphicsLayout::verifyActivate()
 
 }
 
+
+void tst_QGraphicsLayout::sizeHintOfHiddenLayout()
+{
+    QGraphicsScene scene;
+    QGraphicsView view(&scene);
+
+    QGraphicsWidget *window = new QGraphicsWidget(0, Qt::Window);
+    scene.addItem(window);
+    TestLayout *lout = new TestLayout(window);
+    lout->setContentsMargins(1,2,2,1);
+    QGraphicsWidget *w = new QGraphicsWidget;
+    w->setPreferredSize(20, 20);
+    w->setMaximumSize(50, 50);
+    lout->addItem(w);
+    window->setLayout(lout);
+
+    for (int pass = 0; pass < 3; ++pass) {
+        QCOMPARE(lout->sizeHint(Qt::MinimumSize), QSizeF(3,3));
+        QCOMPARE(lout->sizeHint(Qt::PreferredSize), QSizeF(23,23));
+        QCOMPARE(lout->sizeHint(Qt::MaximumSize), QSizeF(53,53));
+        window->setVisible(pass % 2);
+    }
+}
+
 static void clearAllCounters(TestGraphicsWidget *widget)
 {
     if (!widget)

tests/auto/widgets/graphicsview/qgraphicslinearlayout/tst_qgraphicslinearlayout.cpp

@@ -103,6 +103,7 @@ private slots:
     void testOffByOneInLargerLayout();
     void testDefaultAlignment();
     void combineSizePolicies();
+    void hiddenItems();
 
     // Task specific tests
     void task218400_insertStretchCrash();
@@ -1721,6 +1722,41 @@ void tst_QGraphicsLinearLayout::combineSizePolicies()
     QCOMPARE(layout->maximumHeight(), qreal(200));
 }
 
+void tst_QGraphicsLinearLayout::hiddenItems()
+{
+    QGraphicsWidget *widget = new QGraphicsWidget;
+    QGraphicsLinearLayout *layout = new QGraphicsLinearLayout(Qt::Horizontal, widget);
+    layout->setContentsMargins(0, 0, 0, 0);
+    layout->setSpacing(2);
+
+    RectWidget *w1 = new RectWidget;
+    w1->setPreferredSize(QSizeF(20, 20));
+    layout->addItem(w1);
+
+    RectWidget *w2 = new RectWidget;
+    w2->setPreferredSize(QSizeF(20, 20));
+    layout->addItem(w2);
+
+    RectWidget *w3 = new RectWidget;
+    w3->setPreferredSize(QSizeF(20, 20));
+    layout->addItem(w3);
+
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+    w2->hide();
+    QCOMPARE(layout->preferredWidth(), qreal(42));
+    w2->show();
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+    QSizePolicy sp = w2->sizePolicy();
+    sp.setRetainSizeWhenHidden(true);
+    w2->setSizePolicy(sp);
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+    w2->hide();
+    QCOMPARE(layout->preferredWidth(), qreal(64));
+    sp.setRetainSizeWhenHidden(false);
+    w2->setSizePolicy(sp);
+    QCOMPARE(layout->preferredWidth(), qreal(42));
+}
+
 QTEST_MAIN(tst_QGraphicsLinearLayout)
 #include "tst_qgraphicslinearlayout.moc"