Make sure that widgets are initialized when changing the view mode

The problem was that DolphinItemListView overrides the virtual function
onItemLayoutChanged() without calling the base class implementation.
Therefore, KStandardItemListView::updateLayoutOfVisibleItems(), which
calls initializeItemListWidget(), is never called.

This patch refactors the "change item layout"/"supports item expanding"
code a bit to make it more robust and fix the problem that the view
looks "messed up" when switching from Details View without expandable
folders to Icons View.

I'm only pushing this patch to master (going to be KDE 4.12).
The patch is a bit too intrusive for the KDE/4.11 branch for my taste
at this point of the release cycle, and the bug is not a real
showstopper. If it works well in master, one could consider backporting
it to a 4.11.x bug fix release.

Thanks to Emmanuel Pescosta for helping to analyze this issue.

BUG: 302703
REVIEW: 111632
FIXED-IN: 4.12.0

src/kitemviews/kfileitemlistview.cpp

@@ -213,12 +213,6 @@ void KFileItemListView::onPreviewsShownChanged(bool shown)
 
 void KFileItemListView::onItemLayoutChanged(ItemLayout current, ItemLayout previous)
 {
-    if (previous == DetailsLayout || current == DetailsLayout) {
-        // The details-layout requires some invisible roles that
-        // must be added to the model if the new layout is "details".
-        // If the old layout was "details" the roles will get removed.
-        applyRolesToModel();
-    }
     KStandardItemListView::onItemLayoutChanged(current, previous);
     triggerVisibleIndexRangeUpdate();
 }

src/kitemviews/kstandarditemlistview.cpp

@@ -48,23 +48,8 @@ void KStandardItemListView::setItemLayout(ItemLayout layout)
     const ItemLayout previous = m_itemLayout;
     m_itemLayout = layout;
 
-    switch (layout) {
-    case IconsLayout:
-        setScrollOrientation(Qt::Vertical);
-        setSupportsItemExpanding(false);
-        break;
-    case DetailsLayout:
-        setScrollOrientation(Qt::Vertical);
-        setSupportsItemExpanding(true);
-        break;
-    case CompactLayout:
-        setScrollOrientation(Qt::Horizontal);
-        setSupportsItemExpanding(false);
-        break;
-    default:
-        Q_ASSERT(false);
-        break;
-    }
+    setSupportsItemExpanding(itemLayoutSupportsItemExpanding(layout));
+    setScrollOrientation(layout == CompactLayout ? Qt::Horizontal : Qt::Vertical);
 
     onItemLayoutChanged(layout, previous);
 
@@ -117,6 +102,11 @@ bool KStandardItemListView::itemSizeHintUpdateRequired(const QSet<QByteArray>& c
     return false;
 }
 
+bool KStandardItemListView::itemLayoutSupportsItemExpanding(ItemLayout layout) const
+{
+    return layout == DetailsLayout;
+}
+
 void KStandardItemListView::onItemLayoutChanged(ItemLayout current, ItemLayout previous)
 {
     Q_UNUSED(current);

src/kitemviews/kstandarditemlistview.h

@@ -63,6 +63,7 @@ protected:
     virtual KItemListGroupHeaderCreatorBase* defaultGroupHeaderCreator() const;
     virtual void initializeItemListWidget(KItemListWidget* item);
     virtual bool itemSizeHintUpdateRequired(const QSet<QByteArray>& changedRoles) const;
+    virtual bool itemLayoutSupportsItemExpanding(ItemLayout layout) const;
     virtual void onItemLayoutChanged(ItemLayout current, ItemLayout previous);
     virtual void onScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous);
     virtual void onSupportsItemExpandingChanged(bool supportsExpanding);

src/views/dolphinitemlistview.cpp

@@ -89,10 +89,7 @@ void DolphinItemListView::readSettings()
     beginTransaction();
 
     setEnabledSelectionToggles(GeneralSettings::showSelectionToggle());
-
-    const bool expandableFolders = (itemLayout() == KFileItemListView::DetailsLayout) &&
-                                   DetailsModeSettings::expandableFolders();
-    setSupportsItemExpanding(expandableFolders);
+    setSupportsItemExpanding(itemLayoutSupportsItemExpanding(itemLayout()));
 
     updateFont();
     updateGridSize();
@@ -119,19 +116,19 @@ KItemListWidgetCreatorBase* DolphinItemListView::defaultWidgetCreator() const
     return new KItemListWidgetCreator<DolphinFileItemListWidget>();
 }
 
+bool DolphinItemListView::itemLayoutSupportsItemExpanding(ItemLayout layout) const
+{
+    return layout == DetailsLayout && DetailsModeSettings::expandableFolders();
+}
+
 void DolphinItemListView::onItemLayoutChanged(ItemLayout current, ItemLayout previous)
 {
-    Q_UNUSED(previous);
-
-    if (current == DetailsLayout) {
-        setSupportsItemExpanding(DetailsModeSettings::expandableFolders());
-        setHeaderVisible(true);
-    } else {
-        setHeaderVisible(false);
-    }
+    setHeaderVisible(current == DetailsLayout);
 
     updateFont();
     updateGridSize();
+
+    KFileItemListView::onItemLayoutChanged(current, previous);
 }
 
 void DolphinItemListView::onPreviewsShownChanged(bool shown)

src/views/dolphinitemlistview.h

@@ -50,6 +50,7 @@ public:
 
 protected:
     virtual KItemListWidgetCreatorBase* defaultWidgetCreator() const;
+    virtual bool itemLayoutSupportsItemExpanding(ItemLayout layout) const;
     virtual void onItemLayoutChanged(ItemLayout current, ItemLayout previous);
     virtual void onPreviewsShownChanged(bool shown);
     virtual void onVisibleRolesChanged(const QList<QByteArray>& current,