Fix a crash when undoing form layout

In a rare case when breaking a layout might
make widgets overlap, the internal heuristic
failed when recreating an original layout during undo.
Some widgets were removed from the grid.
The patch fixes this heuristic (makes sure
we don't remove other widgets). Creating
a form layout from overlapping widgets works
better now.

Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Task-number: QTCREATORBUG-3616

2 files changed, 15 insertions, 10 deletions

diff --git a/tools/designer/src/lib/shared/layout.cpp b/tools/designer/src/lib/shared/layout.cpp
index c9ffe71..9fe438b 100644
--- a/tools/designer/src/lib/shared/layout.cpp
+++ b/tools/designer/src/lib/shared/layout.cpp
@@ -996,13 +996,23 @@ bool Grid::shrinkFormLayoutSpans()
     for (WidgetSet::const_iterator it = widgets.constBegin(); it != cend ; ++it) {
         QWidget *w = *it;
         int row, col,  rowspan, colspan;
-        locateWidget(w, row, col, rowspan, colspan);
+        if (!locateWidget(w, row, col, rowspan, colspan))
+            qDebug("ooops, widget '%s' does not fit in layout", w->objectName().toUtf8().constData());
         const int maxColSpan = col == 0 ? 2 : 1;
         const int newColSpan = qMin(colspan, maxColSpan);
         const int newRowSpan = qMin(rowspan, maxRowSpan);
         if (newColSpan != colspan || newRowSpan != rowspan) {
-            setCells(QRect(col, row, colspan, rowspan), 0);
-            setCells(QRect(col, row, newColSpan, newRowSpan), w);
+            // in case like this:
+            // W1 W1
+            // W1 W2
+            // do:
+            // W1 0
+            // 0  W2
+            for (int i = row; i < row + rowspan - 1; i++)
+                for (int j = col; j < col + colspan - 1; j++)
+                    if (i > row + newColSpan - 1 || j > col + newRowSpan - 1)
+                        if (cell(i, j) == w)
+                            setCell(i, j, 0);
             shrunk = true;
         }
     }
@@ -1177,11 +1187,7 @@ void GridLayout<GridLikeLayout, LayoutType, GridMode>::doLayout()
             if (const Spacer *spacer = qobject_cast<const Spacer*>(w))
                 alignment = spacer->alignment();
 
-            if (rs * cs == 1) {
-                addWidgetToGrid(layout, w, r, c, 1, 1, alignment);
-            } else {
-                addWidgetToGrid(layout, w, r, c, rs, cs, alignment);
-            }
+            addWidgetToGrid(layout, w, r, c, rs, cs, alignment);
 
             w->show();
         } else {
diff --git a/tools/designer/src/lib/shared/qlayout_widget.cpp b/tools/designer/src/lib/shared/qlayout_widget.cpp
index 20db606..4debb5e 100644
--- a/tools/designer/src/lib/shared/qlayout_widget.cpp
+++ b/tools/designer/src/lib/shared/qlayout_widget.cpp
@@ -1181,8 +1181,7 @@ QRect LayoutHelper::itemInfo(QLayout *lt, const QWidget *widget) const
             } else {
                 for (int c = 0; c < FormLayoutColumns; c++) {
                     const QFormLayout::ItemRole role = c == 0 ? QFormLayout::LabelRole : QFormLayout::FieldRole;
-                    if (widgets[c]) {
-                        Q_ASSERT(BoxLayoutHelper::findItemOfWidget(items, widgets[c]));
+                    if (widgets[c] && BoxLayoutHelper::findItemOfWidget(items, widgets[c])) {
                         formLayout->setWidget(r, role, widgets[c]);
                     } else {
                         formLayout->setItem(r, role, createFormSpacer());