#include <QAbstractItemView>
#include <QClipboard>
#include <QColor>
+#include <QListView>
#include <QPainter>
#include <QScrollBar>
#include <QIcon>
+/**
+ * If the passed item view is an instance of QListView, expensive
+ * layout operations are blocked in the constructor and are unblocked
+ * again in the destructor.
+ *
+ * This helper class is a workaround for the following huge performance
+ * problem when having directories with several 1000 items:
+ * - each change of an icon emits a dataChanged() signal from the model
+ * - QListView iterates through all items on each dataChanged() signal
+ * and invokes QItemDelegate::sizeHint()
+ * - the sizeHint() implementation of KFileItemDelegate is quite complex,
+ * invoking it 1000 times for each icon change might block the UI
+ *
+ * QListView does not invoke QItemDelegate::sizeHint() when the
+ * uniformItemSize property has been set to true, so this property is
+ * set before exchanging a block of icons. It is important to reset
+ * it again before the event loop is entered, otherwise QListView
+ * would not get the correct size hints after dispatching the layoutChanged()
+ * signal.
+ */
+class LayoutBlocker {
+public:
+ LayoutBlocker(QAbstractItemView* view) :
+ m_uniformSizes(false),
+ m_view(qobject_cast<QListView*>(view))
+ {
+ if (m_view != 0) {
+ m_uniformSizes = m_view->uniformItemSizes();
+ m_view->setUniformItemSizes(true);
+ }
+ }
+
+ ~LayoutBlocker()
+ {
+ if (m_view != 0) {
+ m_view->setUniformItemSizes(m_uniformSizes);
+ }
+ }
+
+private:
+ bool m_uniformSizes;
+ QListView* m_view;
+};
+
IconManager::IconManager(QAbstractItemView* parent, DolphinSortFilterProxyModel* model) :
QObject(parent),
m_showPreview(false),
dispatchCount = previewsCount;
}
+ LayoutBlocker blocker(m_view);
for (int i = 0; i < dispatchCount; ++i) {
const ItemInfo& preview = m_previews.first();
replaceIcon(preview.url, preview.pixmap);
// Order the items in a way that the preview for the visible items
// is generated first, as this improves the feeled performance a lot.
//
- // Implementation note: using KDirModel::itemForUrl() would lead to a more
- // readable code, but it is slower as iterating all model indicess
- // and checking whether the index is part of 'items'.
+ // Implementation note: 2 different algorithms are used for the sorting.
+ // Algorithm 1 is faster when having a lot of items in comparison
+ // to the number of rows in the model. Algorithm 2 is faster
+ // when having quite less items in comparison to the number of rows in
+ // the model. Choosing the right algorithm is important when having directories
+ // with several hundreds or thousands of items.
const int itemCount = items.count();
- const QRect visibleArea = m_view->viewport()->rect();
-
const int rowCount = m_proxyModel->rowCount();
- for (int row = 0; row < rowCount; ++row) {
- const QModelIndex proxyIndex = m_proxyModel->index(row, 0);
- const QRect itemRect = m_view->visualRect(proxyIndex);
- const QModelIndex dirIndex = m_proxyModel->mapToSource(proxyIndex);
+ const QRect visibleArea = m_view->viewport()->rect();
- KFileItem item = m_dolphinModel->itemForIndex(dirIndex); // O(1)
- const KUrl url = item.url();
+ if (itemCount * 10 > rowCount) {
+ // Algorithm 1: The number of items is > 10 % of the row count. Parse all rows
+ // and check whether the received row is part of the item list.
+ for (int row = 0; row < rowCount; ++row) {
+ const QModelIndex proxyIndex = m_proxyModel->index(row, 0);
+ const QRect itemRect = m_view->visualRect(proxyIndex);
+ const QModelIndex dirIndex = m_proxyModel->mapToSource(proxyIndex);
+
+ KFileItem item = m_dolphinModel->itemForIndex(dirIndex); // O(1)
+ const KUrl url = item.url();
+
+ // check whether the item is part of the item list 'items'
+ int index = -1;
+ for (int i = 0; i < itemCount; ++i) {
+ if (items[i].url() == url) {
+ index = i;
+ break;
+ }
+ }
- // check whether the item is part of the item list 'items'
- int index = -1;
- for (int i = 0; i < itemCount; ++i) {
- if (items[i].url() == url) {
- index = i;
- break;
+ if ((index > 0) && itemRect.intersects(visibleArea)) {
+ // The current item is (at least partly) visible. Move it
+ // to the front of the list, so that the preview is
+ // generated earlier.
+ items.removeAt(index);
+ items.insert(0, item);
}
}
-
- if ((index > 0) && itemRect.intersects(visibleArea)) {
- // The current item is (at least partly) visible. Move it
- // to the front of the list, so that the preview is
- // generated earlier.
- items.removeAt(index);
- items.insert(0, item);
+ } else {
+ // Algorithm 2: The number of items is <= 10 % of the row count. In this case iterate
+ // all items and receive the corresponding row from the item.
+ for (int i = 0; i < itemCount; ++i) {
+ const QModelIndex dirIndex = m_dolphinModel->indexForItem(items[i]); // O(n) (n = number of rows)
+ const QModelIndex proxyIndex = m_proxyModel->mapFromSource(dirIndex);
+ const QRect itemRect = m_view->visualRect(proxyIndex);
+
+ if (itemRect.intersects(visibleArea)) {
+ // The current item is (at least partly) visible. Move it
+ // to the front of the list, so that the preview is
+ // generated earlier.
+ items.insert(0, items[i]);
+ items.removeAt(i + 1);
+ }
}
}
}
projects / dolphin.git / blobdiff