Remember the row- and column-information for visible items

Up to now KItemListView has not been aware to which column or row
an item belongs to. This has been handled internally in
KItemListViewLayouter. But for deciding whether a move-animation
might result in overlapping items it is mandatory to be aware about
the column/row. The current approach to guess a column/row change
by comparing the source- and target-rectangle works very well but
breaks on some corner-cases when e.g. zooming.

Now the layouter allows to access the information. This assures
that in the vertical alignment no move-animation is done between
rows and the in the horizontal alignment no move-animation is
done between the columns.

1 files changed, 59 insertions, 29 deletions

diff --git a/src/kitemviews/kitemlistviewlayouter.cpp b/src/kitemviews/kitemlistviewlayouter.cpp
index 14774c412..744914929 100644
--- a/src/kitemviews/kitemlistviewlayouter.cpp
+++ b/src/kitemviews/kitemlistviewlayouter.cpp
@@ -49,7 +49,7 @@ KItemListViewLayouter::KItemListViewLayouter(QObject* parent) :
     m_groupItemIndexes(),
     m_groupHeaderHeight(0),
     m_groupHeaderMargin(0),
-    m_itemRects()
+    m_itemInfos()
 {
 }
 
@@ -227,14 +227,14 @@ int KItemListViewLayouter::lastVisibleIndex() const
 QRectF KItemListViewLayouter::itemRect(int index) const
 {
     const_cast<KItemListViewLayouter*>(this)->doLayout();
-    if (index < 0 || index >= m_itemRects.count()) {
+    if (index < 0 || index >= m_itemInfos.count()) {
         return QRectF();
     }
 
     if (m_scrollOrientation == Qt::Horizontal) {
         // Rotate the logical direction which is always vertical by 90°
         // to get the physical horizontal direction
-        const QRectF& b = m_itemRects[index];
+        const QRectF& b = m_itemInfos[index].rect;
         QRectF bounds(b.y(), b.x(), b.height(), b.width());
         QPointF pos = bounds.topLeft();
         pos.rx() -= m_scrollOffset;
@@ -242,7 +242,7 @@ QRectF KItemListViewLayouter::itemRect(int index) const
         return bounds;
     }
 
-    QRectF bounds = m_itemRects[index];
+    QRectF bounds = m_itemInfos[index].rect;
     bounds.moveTo(bounds.topLeft() - QPointF(m_itemOffset, m_scrollOffset));
     return bounds;
 }
@@ -271,10 +271,10 @@ QRectF KItemListViewLayouter::groupHeaderRect(int index) const
         // Qt::Horizontal and m_itemRects is accessed directly,
         // the logical height represents the visual width.
         qreal width = minimumGroupHeaderWidth();
-        const qreal y = m_itemRects[index].y();
-        const int maxIndex = m_itemRects.count() - 1;
+        const qreal y = m_itemInfos[index].rect.y();
+        const int maxIndex = m_itemInfos.count() - 1;
         while (index <= maxIndex) {
-            QRectF bounds = m_itemRects[index];
+            QRectF bounds = m_itemInfos[index].rect;
             if (bounds.y() != y) {
                 break;
             }
@@ -291,6 +291,30 @@ QRectF KItemListViewLayouter::groupHeaderRect(int index) const
     return QRectF(pos, size);
 }
 
+int KItemListViewLayouter::itemColumn(int index) const
+{
+    const_cast<KItemListViewLayouter*>(this)->doLayout();
+    if (index < 0 || index >= m_itemInfos.count()) {
+        return -1;
+    }
+
+    return (m_scrollOrientation == Qt::Vertical)
+            ? m_itemInfos[index].column
+            : m_itemInfos[index].row; 
+}
+
+int KItemListViewLayouter::itemRow(int index) const
+{
+    const_cast<KItemListViewLayouter*>(this)->doLayout();
+    if (index < 0 || index >= m_itemInfos.count()) {
+        return -1;
+    }
+
+    return (m_scrollOrientation == Qt::Vertical)
+            ? m_itemInfos[index].row
+            : m_itemInfos[index].column; 
+}
+
 int KItemListViewLayouter::maximumVisibleItems() const
 {
     const_cast<KItemListViewLayouter*>(this)->doLayout();
@@ -371,10 +395,10 @@ void KItemListViewLayouter::doLayout()
             ++rowCount;
         }
 
-        m_itemRects.reserve(itemCount);
+        m_itemInfos.reserve(itemCount);
 
         qreal y = m_headerHeight + itemMargin.height();
-        int rowIndex = 0;
+        int row = 0;
 
         int index = 0;
         while (index < itemCount) {
@@ -419,10 +443,16 @@ void KItemListViewLayouter::doLayout()
                 }
 
                 const QRectF bounds(x, y, itemSize.width(), requiredItemHeight);
-                if (index < m_itemRects.count()) {
-                    m_itemRects[index] = bounds;
+                if (index < m_itemInfos.count()) {
+                    m_itemInfos[index].rect = bounds;
+                    m_itemInfos[index].column = column;
+                    m_itemInfos[index].row = row;
                 } else {
-                    m_itemRects.append(bounds);
+                    ItemInfo itemInfo;
+                    itemInfo.rect = bounds;
+                    itemInfo.column = column;
+                    itemInfo.row = row;
+                    m_itemInfos.append(itemInfo);
                 }
 
                 if (grouped && horizontalScrolling) {
@@ -457,21 +487,21 @@ void KItemListViewLayouter::doLayout()
             }
 
             y += maxItemHeight + itemMargin.height();
-            ++rowIndex;
+            ++row;
         }
-        if (m_itemRects.count() > itemCount) {
-            m_itemRects.erase(m_itemRects.begin() + itemCount,
-                              m_itemRects.end());
+        if (m_itemInfos.count() > itemCount) {
+            m_itemInfos.erase(m_itemInfos.begin() + itemCount,
+                              m_itemInfos.end());
         }
-
+        
         if (itemCount > 0) {
             // Calculate the maximum y-range of the last row for m_maximumScrollOffset
-            m_maximumScrollOffset = m_itemRects.last().bottom();
-            const qreal rowY = m_itemRects.last().y();
+            m_maximumScrollOffset = m_itemInfos.last().rect.bottom();
+            const qreal rowY = m_itemInfos.last().rect.y();
 
-            int index = m_itemRects.count() - 2;
-            while (index >= 0 && m_itemRects.at(index).bottom() >= rowY) {
-                m_maximumScrollOffset = qMax(m_maximumScrollOffset, m_itemRects.at(index).bottom());
+            int index = m_itemInfos.count() - 2;
+            while (index >= 0 && m_itemInfos[index].rect.bottom() >= rowY) {
+                m_maximumScrollOffset = qMax(m_maximumScrollOffset, m_itemInfos[index].rect.bottom());
                 --index;
             }
 
@@ -515,7 +545,7 @@ void KItemListViewLayouter::updateVisibleIndexes()
     int mid = 0;
     do {
         mid = (min + max) / 2;
-        if (m_itemRects[mid].top() < m_scrollOffset) {
+        if (m_itemInfos[mid].rect.top() < m_scrollOffset) {
             min = mid + 1;
         } else {
             max = mid - 1;
@@ -525,13 +555,13 @@ void KItemListViewLayouter::updateVisibleIndexes()
     if (mid > 0) {
         // Include the row before the first fully visible index, as it might
         // be partly visible
-        if (m_itemRects[mid].top() >= m_scrollOffset) {
+        if (m_itemInfos[mid].rect.top() >= m_scrollOffset) {
             --mid;
-            Q_ASSERT(m_itemRects[mid].top() < m_scrollOffset);
+            Q_ASSERT(m_itemInfos[mid].rect.top() < m_scrollOffset);
         }
 
-        const qreal rowTop = m_itemRects[mid].top();
-        while (mid > 0 && m_itemRects[mid - 1].top() == rowTop) {
+        const qreal rowTop = m_itemInfos[mid].rect.top();
+        while (mid > 0 && m_itemInfos[mid - 1].rect.top() == rowTop) {
             --mid;
         }
     }
@@ -548,14 +578,14 @@ void KItemListViewLayouter::updateVisibleIndexes()
     max = maxIndex;
     do {
         mid = (min + max) / 2;
-        if (m_itemRects[mid].y() <= bottom) {
+        if (m_itemInfos[mid].rect.y() <= bottom) {
             min = mid + 1;
         } else {
             max = mid - 1;
         }
     } while (min <= max);
 
-    while (mid > 0 && m_itemRects[mid].y() > bottom) {
+    while (mid > 0 && m_itemInfos[mid].rect.y() > bottom) {
         --mid;
     }
     m_lastVisibleIndex = mid;