QHeaderView: fix restoreState() on a model with more columns

When saving state for a 3-columns headerview and then restoring that
state onto a 5-column headerview, the headerview shouldn't suddenly think
it has 3 columns.

Rather than making restoreState() fail, we adjust for the additional
columns, so that we can still apply the customizations from the user to
all other columns (hiding, moving, etc.).

Change-Id: I3f220aa322ea8b629d2fe345f8cde13e0ea615d6
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/src/widgets/itemviews/qheaderview.cpp b/src/widgets/itemviews/qheaderview.cpp
index 837383f016..1310a060ea 100644
--- a/src/widgets/itemviews/qheaderview.cpp
+++ b/src/widgets/itemviews/qheaderview.cpp
@@ -3857,6 +3857,20 @@ bool QHeaderViewPrivate::read(QDataStream &in)
     if (sectionItemsLengthTotal != lengthIn)
         return false;
 
+    const int currentCount = (orient == Qt::Horizontal ? model->columnCount(root) : model->rowCount(root));
+    if (newSectionItems.count() < currentCount) {
+        // we have sections not in the saved state, give them default settings
+        for (int i = newSectionItems.count(); i < currentCount; ++i) {
+            visualIndicesIn.append(i);
+            logicalIndicesIn.append(i);
+        }
+        const int insertCount = currentCount - newSectionItems.count();
+        const int insertLength = defaultSectionSizeIn * insertCount;
+        lengthIn += insertLength;
+        SectionItem section(defaultSectionSizeIn, globalResizeMode);
+        newSectionItems.insert(newSectionItems.count(), insertCount, section); // append
+    }
+
     orientation = static_cast<Qt::Orientation>(orient);
     sortIndicatorOrder = static_cast<Qt::SortOrder>(order);
     sortIndicatorSection = sortIndicatorSectionIn;