Calculate all item size hints at once.

The speed up is really small, but theses changes are mostly straightforward and make the code a bit nicer - break
the KStandardItemListWidgetInformant::itemSizeHint beast into three smaller functions.

FIXED-IN: 4.13
REVIEW: 112979

4 files changed, 24 insertions, 12 deletions

diff --git a/src/kitemviews/private/kitemlistsizehintresolver.cpp b/src/kitemviews/private/kitemlistsizehintresolver.cpp
index 0e2286b45..029beddf9 100644
--- a/src/kitemviews/private/kitemlistsizehintresolver.cpp
+++ b/src/kitemviews/private/kitemlistsizehintresolver.cpp
@@ -23,7 +23,8 @@
 
 KItemListSizeHintResolver::KItemListSizeHintResolver(const KItemListView* itemListView) :
     m_itemListView(itemListView),
-    m_sizeHintCache()
+    m_sizeHintCache(),
+    m_needsResolving(false)
 {
 }
 
@@ -31,14 +32,10 @@ KItemListSizeHintResolver::~KItemListSizeHintResolver()
 {
 }
 
-QSizeF KItemListSizeHintResolver::sizeHint(int index) const
+QSizeF KItemListSizeHintResolver::sizeHint(int index)
 {
-    QSizeF size = m_sizeHintCache.at(index);
-    if (size.isEmpty()) {
-        size = m_itemListView->itemSizeHint(index);
-        m_sizeHintCache[index] = size;
-    }
-    return size;
+    updateCache();
+    return m_sizeHintCache.at(index);
 }
 
 void KItemListSizeHintResolver::itemsInserted(const KItemRangeList& itemRanges)
@@ -77,6 +74,8 @@ void KItemListSizeHintResolver::itemsInserted(const KItemRangeList& itemRanges)
         }
     }
 
+    m_needsResolving = true;
+
     Q_ASSERT(m_sizeHintCache.count() == m_itemListView->model()->count());
 }
 
@@ -135,9 +134,20 @@ void KItemListSizeHintResolver::itemsChanged(int index, int count, const QSet<QB
         ++index;
         --count;
     }
+
+    m_needsResolving = true;
 }
 
 void KItemListSizeHintResolver::clearCache()
 {
     m_sizeHintCache.fill(QSizeF());
+    m_needsResolving = true;
+}
+
+void KItemListSizeHintResolver::updateCache()
+{
+    if (m_needsResolving) {
+        m_itemListView->calculateItemSizeHints(m_sizeHintCache);
+        m_needsResolving = false;
+    }
 }
diff --git a/src/kitemviews/private/kitemlistsizehintresolver.h b/src/kitemviews/private/kitemlistsizehintresolver.h
index 486f9b631..86580bf7b 100644
--- a/src/kitemviews/private/kitemlistsizehintresolver.h
+++ b/src/kitemviews/private/kitemlistsizehintresolver.h
@@ -36,7 +36,7 @@ class LIBDOLPHINPRIVATE_EXPORT KItemListSizeHintResolver
 public:
     KItemListSizeHintResolver(const KItemListView* itemListView);
     virtual ~KItemListSizeHintResolver();
-    QSizeF sizeHint(int index) const;
+    QSizeF sizeHint(int index);
 
     void itemsInserted(const KItemRangeList& itemRanges);
     void itemsRemoved(const KItemRangeList& itemRanges);
@@ -44,10 +44,12 @@ public:
     void itemsChanged(int index, int count, const QSet<QByteArray>& roles);
 
     void clearCache();
+    void updateCache();
 
 private:
     const KItemListView* m_itemListView;
     mutable QVector<QSizeF> m_sizeHintCache;
+    bool m_needsResolving;
 };
 
 #endif
diff --git a/src/kitemviews/private/kitemlistviewlayouter.cpp b/src/kitemviews/private/kitemlistviewlayouter.cpp
index 90e8a6d0f..73f3d6182 100644
--- a/src/kitemviews/private/kitemlistviewlayouter.cpp
+++ b/src/kitemviews/private/kitemlistviewlayouter.cpp
@@ -209,7 +209,7 @@ const KItemModelBase* KItemListViewLayouter::model() const
     return m_model;
 }
 
-void KItemListViewLayouter::setSizeHintResolver(const KItemListSizeHintResolver* sizeHintResolver)
+void KItemListViewLayouter::setSizeHintResolver(KItemListSizeHintResolver* sizeHintResolver)
 {
     if (m_sizeHintResolver != sizeHintResolver) {
         m_sizeHintResolver = sizeHintResolver;
diff --git a/src/kitemviews/private/kitemlistviewlayouter.h b/src/kitemviews/private/kitemlistviewlayouter.h
index 19b14796d..5ae472411 100644
--- a/src/kitemviews/private/kitemlistviewlayouter.h
+++ b/src/kitemviews/private/kitemlistviewlayouter.h
@@ -103,7 +103,7 @@ public:
     void setModel(const KItemModelBase* model);
     const KItemModelBase* model() const;
 
-    void setSizeHintResolver(const KItemListSizeHintResolver* sizeHintResolver);
+    void setSizeHintResolver(KItemListSizeHintResolver* sizeHintResolver);
     const KItemListSizeHintResolver* sizeHintResolver() const;
 
     /**
@@ -205,7 +205,7 @@ private:
     QSizeF m_itemMargin;
     qreal m_headerHeight;
     const KItemModelBase* m_model;
-    const KItemListSizeHintResolver* m_sizeHintResolver;
+    KItemListSizeHintResolver* m_sizeHintResolver;
 
     qreal m_scrollOffset;
     qreal m_maximumScrollOffset;