Fixed a bug where spans across empty cells got broken.

If a row/column is only used only because of the spanning of an item,
the cell should be treated as it didn't exist. We keep track of this
with the "ignore" bit array.

The old code would always start from the row/column at position 1.
In the attached testcase this made the effectiveRowSpan become larger
than actually needed.

Task-number: QTBUG-30255

Change-Id: Ief0e7018ee8e5ee36272ce075a43312ffeac7b91
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/auto/widgets/graphicsview/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp b/tests/auto/widgets/graphicsview/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
index 41e5ed466c..9f10d72f4e 100644
--- a/tests/auto/widgets/graphicsview/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
+++ b/tests/auto/widgets/graphicsview/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
@@ -126,6 +126,7 @@ private slots:
     void spanningItem2x3_data();
     void spanningItem2x3();
     void spanningItem();
+    void spanAcrossEmptyRow();
     void heightForWidth();
     void widthForHeight();
     void heightForWidthWithSpanning();
@@ -3352,6 +3353,33 @@ void tst_QGraphicsGridLayout::spanningItem()
     QCOMPARE(layout->maximumSize(), QSizeF(160,80));
 }
 
+void tst_QGraphicsGridLayout::spanAcrossEmptyRow()
+{
+    QGraphicsWidget *form = new QGraphicsWidget(0, Qt::Window);
+    QGraphicsGridLayout *layout = new QGraphicsGridLayout(form);
+    layout->setContentsMargins(0, 0, 0, 0);
+    layout->setSpacing(0);
+    RectWidget *w1 = new RectWidget;
+    RectWidget *w2 = new RectWidget;
+    RectWidget *w3 = new RectWidget;
+
+    QSizeF size(10, 10);
+    for (int i = 0; i < 3; ++i) {
+        w1->setSizeHint((Qt::SizeHint)i, size);
+        w2->setSizeHint((Qt::SizeHint)i, size);
+        w3->setSizeHint((Qt::SizeHint)i, size);
+        size+=size;                 //[(10,10), (20,20), (40,40)]
+    }
+    layout->addItem(w1, 0, 0, 1, 1);
+    layout->addItem(w2, 0, 1, 1, 2);
+    layout->addItem(w3, 0, 99, 1, 1);
+
+    form->resize(60,20);
+    QCOMPARE(w1->geometry(), QRectF( 0, 0, 20, 20));
+    QCOMPARE(w2->geometry(), QRectF(20, 0, 20, 20));
+    QCOMPARE(w3->geometry(), QRectF(40, 0, 20, 20));
+}
+
 void tst_QGraphicsGridLayout::stretchAndHeightForWidth()
 {
     QGraphicsWidget *widget = new QGraphicsWidget(0, Qt::Window);