Details view: Improve performance

When inserting items or when updating the item-roles there is no
need to recalculate the column-widths for all items to get an
optimized column-width.

1 files changed, 32 insertions, 17 deletions

diff --git a/src/kitemviews/kfileitemlistview.cpp b/src/kitemviews/kfileitemlistview.cpp
index 50f28fe5b..f1594b10b 100644
--- a/src/kitemviews/kfileitemlistview.cpp
+++ b/src/kitemviews/kfileitemlistview.cpp
@@ -167,31 +167,42 @@ QSizeF KFileItemListView::itemSizeHint(int index) const
     return QSize();
 }
 
-QHash<QByteArray, QSizeF> KFileItemListView::visibleRolesSizes() const
+QHash<QByteArray, QSizeF> KFileItemListView::visibleRolesSizes(const KItemRangeList& itemRanges) const
 {
     QElapsedTimer timer;
     timer.start();
 
     QHash<QByteArray, QSizeF> sizes;
 
-    const int itemCount = model()->count();
-    for (int i = 0; i < itemCount; ++i) {
-        foreach (const QByteArray& visibleRole, visibleRoles()) {
-            QSizeF maxSize = sizes.value(visibleRole, QSizeF(0, 0));
-            const QSizeF itemSize = visibleRoleSizeHint(i, visibleRole);
-            maxSize = maxSize.expandedTo(itemSize);
-            sizes.insert(visibleRole, maxSize);
-        }
+    int calculatedItemCount = 0;
+    bool maxTimeExceeded = false;
+    foreach (const KItemRange& itemRange, itemRanges) {
+        const int startIndex = itemRange.index;
+        const int endIndex = startIndex + itemRange.count - 1;
+
+        for (int i = startIndex; i <= endIndex; ++i) {
+            foreach (const QByteArray& visibleRole, visibleRoles()) {
+                QSizeF maxSize = sizes.value(visibleRole, QSizeF(0, 0));
+                const QSizeF itemSize = visibleRoleSizeHint(i, visibleRole);
+                maxSize = maxSize.expandedTo(itemSize);
+                sizes.insert(visibleRole, maxSize);
+            }
 
-        if (i > 100 && timer.elapsed() > 200) {
-            // When having several thousands of items calculating the sizes can get
-            // very expensive. We accept a possibly too small role-size in favour
-            // of having no blocking user interface.
-            #ifdef KFILEITEMLISTVIEW_DEBUG
-                kDebug() << "Timer exceeded, stopped after" << i << "items";
-            #endif
+            if (calculatedItemCount > 100 && timer.elapsed() > 200) {
+                // When having several thousands of items calculating the sizes can get
+                // very expensive. We accept a possibly too small role-size in favour
+                // of having no blocking user interface.
+                #ifdef KFILEITEMLISTVIEW_DEBUG
+                    kDebug() << "Timer exceeded, stopped after" << calculatedItemCount << "items";
+                #endif
+                maxTimeExceeded = true;
+                break;
+            }
+        }
+        if (maxTimeExceeded) {
             break;
         }
+        ++calculatedItemCount;
     }
 
     // Stretch the width of the first role so that the full visible view-width
@@ -213,7 +224,11 @@ QHash<QByteArray, QSizeF> KFileItemListView::visibleRolesSizes() const
     }
 
 #ifdef KFILEITEMLISTVIEW_DEBUG
-    kDebug() << "[TIME] Calculated dynamic item size for " << itemCount << "items:" << timer.elapsed();
+    int rangesItemCount = 0;
+    foreach (const KItemRange& itemRange, itemRanges) {
+        rangesItemCount += itemRange.count;
+    }
+    kDebug() << "[TIME] Calculated dynamic item size for " << rangesItemCount << "items:" << timer.elapsed();
 #endif
     return sizes;
 }