Refactor the doLayout() function; unify vertical and horizontal layout.

1 files changed, 72 insertions, 109 deletions

diff --git a/src/qgraphicslistview.cpp b/src/qgraphicslistview.cpp
index 3988bc8..f57956b 100644
--- a/src/qgraphicslistview.cpp
+++ b/src/qgraphicslistview.cpp
@@ -659,127 +659,90 @@ void QtGraphicsListView::doLayout()
 
     const QRectF area = boundingRect();
     const QSizeF constraint = area.size();
+    const int count = d->model ? d->model->count() : 0;
+    const bool vertical = (d->orientation == Qt::Vertical);
+    const qreal areaStart = (vertical ? area.y() : area.x());
+    const qreal areaEnd = (vertical ? area.bottom() : area.right());
+    const qreal offset = (vertical ? d->verticalOffset : d->horizontalOffset);
+    const qreal perpendicularOffset = (vertical ? d->horizontalOffset : d->verticalOffset);
+
+    qreal coordinate = -offset;
     int index = d->firstIndex;
-    int count = d->model ? d->model->count() : 0;
-    qreal x = -d->horizontalOffset;
-    qreal y = -d->verticalOffset;
 
     // find the visible items; caching helps us skip this most of the time
-    if (d->orientation == Qt::Vertical) {
-        if (y <= 0 && !d->items.isEmpty()) { // ###
-            // optimization: use the cached index and offset as starting points
-            // The cached values are offsets from the start of the _contents_
-            // and the to index found at that offset.
+    if (coordinate <= 0 && !d->items.isEmpty()) {
+        // optimization: use the cached index and offset as starting points
+        // The cached values are offsets from the start of the _contents_
+        // and the to index found at that offset.
 #if 0 // enable or disable the caching
-            index += d->cachedIndexOffset;
-            y += d->cachedCoordinateOffset;
+        index += d->cachedIndexOffset;
+        coordinate += d->cachedCoordinateOffset;
 #endif
-            // the visible area starts at y == 0
-            if (y < 0) { // the cached offset was above the visible area
-                while (index < count) {
-                    initStyleOption(&option, index);
-                    const qreal height = d->itemSizeHint(&option, index, constraint).height();
-                    if (y + height > area.y())
-                        break;
-                    y += height;
-                    ++index;
-                }
-            } else if (y > 0) { // the cached offset was below
-                while (index >= 0 && y > 0) {
-                    initStyleOption(&option, index);
-                    const qreal height = d->itemSizeHint(&option, index, constraint).height();
-                    y -= height;
-                    --index;
-                }
+        // the visible area starts at coordinate == 0
+        if (coordinate < 0) { // the cached offset was above or to the left of the visible area
+            while (index < count) {
+                initStyleOption(&option, index);
+                const QSizeF hint = d->itemSizeHint(&option, index, constraint);
+                const qreal size = vertical ? hint.height() : hint.width();
+                if (coordinate + size > areaStart)
+                    break;
+                coordinate += size;
+                ++index;
             }
-#if 0 // enable or disable the caching
-        d->cachedIndexOffset = index - d->firstIndex;
-        d->cachedCoordinateOffset = y + d->verticalOffset;
-#endif
-        }
-        // we are now at the visible items
-        const int firstVisibleIndex = index;
-        d->scrollItems(firstVisibleIndex);
-        // set existing item positions
-        for (int i = 0; i < d->items.count() && index < count && y < area.bottom(); ++i) {
-            QtGraphicsListViewItem *item = d->items.at(i);
-            const QSizeF size = item->size();
-            item->setPos(d->horizontalOffset, y);
-            y += size.height();
-            ++index;
-        }
-        // add more items and set geometry
-        while (index < count && y < area.bottom()) {
-            QtGraphicsListViewItem *item = d->creator->create(index, this);
-            d->items.append(item);
-            initStyleOption(&option, index);
-            const QSizeF size = item->sizeHint(index, &option, Qt::PreferredSize, constraint);
-            item->setGeometry(d->horizontalOffset, y, area.width(), size.height());
-            y += size.height();
-            ++index;
-        }
-        // remove unused items
-        const int visibleCount = index - firstVisibleIndex;
-        while (visibleCount < d->items.count())
-            d->creator->destroy(d->items.takeLast());
-    } else { // Horizontal
-        if (x <= 0 && !d->items.isEmpty()) {
-            // optimization: use the cached index and offset as starting points
-#if 0 // enable or disable the caching
-            index += d->cachedIndexOffset;
-            x += d->cachedCoordinateOffset;
-#endif
-            // the visible area starts at x == 0
-            if (x < 0) { // the cached offset was left of the visible area
-                while (index < count) {
-                    initStyleOption(&option, index);
-                    const qreal width = d->itemSizeHint(&option, index, constraint).width();
-                    if (x + width > area.x())
-                        break;
-                    x += width;
-                    ++index;
-                }
-            } else if (x > 0) { // the cached offset was to the right
-                while (index >= 0 && x > 0) {
-                    initStyleOption(&option, index);
-                    const qreal width = d->itemSizeHint(&option, index, constraint).width();
-                    x -= width;
-                    --index;
-                }
+        } else if (coordinate > 0) { // the cached offset was below or to the right
+            while (index >= 0 && coordinate > 0) {
+                initStyleOption(&option, index);
+                const QSizeF hint = d->itemSizeHint(&option, index, constraint);
+                const qreal size = vertical ? hint.height() : hint.width();
+                coordinate -= size;
+                --index;
             }
+        }
 #if 0 // enable or disable the caching
-            d->cachedIndexOffset = index - d->firstIndex;
-            d->cachedCoordinateOffset = x + d->horizontalOffset;
+    d->cachedIndexOffset = index - d->firstIndex;
+    d->cachedCoordinateOffset = coordinate + offset;
 #endif
+    }
+
+    // shuffle the existing items around
+    const int firstVisibleIndex = index;
+    d->scrollItems(firstVisibleIndex);
+
+    // set existing item positions
+    for (int i = 0; i < d->items.count() && index < count && coordinate < areaEnd; ++i) {
+        QtGraphicsListViewItem *item = d->items.at(i);
+        const QSizeF size = item->size();
+        if (vertical) {
+            item->setPos(perpendicularOffset, coordinate);
+            coordinate += size.height();
+        } else {
+            item->setPos(coordinate, perpendicularOffset);
+            coordinate += size.width();
         }
-        // we are now at the visible items
-        const int firstVisibleIndex = index;
-        d->scrollItems(firstVisibleIndex);
-        // set existing item positions
-        for (int i = 0; i < d->items.count() && index < count && x < area.right(); ++i) {
-            QtGraphicsListViewItem *item = d->items.at(i);
-            const QSizeF size = item->size();
-            item->setPos(x, d->verticalOffset);
-            x += size.width();
-            ++index;
-        }
-        // add more items and set geometry
-        while (index < count && x < area.right()) {
-            QtGraphicsListViewItem *item = d->creator->create(index, this);
-            d->items.append(item);
-            initStyleOption(&option, index);
-            const QSizeF size = item->sizeHint(index, &option, Qt::PreferredSize, constraint);
-            item->setGeometry(x, d->verticalOffset, size.width(), area.height());
-            x += size.width();
-            ++index;
+        ++index;
+    }
+
+    // add more items and set geometry
+    while (index < count && coordinate < areaEnd) {
+        QtGraphicsListViewItem *item = d->creator->create(index, this);
+        d->items.append(item);
+        initStyleOption(&option, index);
+        const QSizeF size = item->sizeHint(index, &option, Qt::PreferredSize, constraint);
+        if (vertical) {
+            item->setGeometry(perpendicularOffset, coordinate, area.width(), size.height());
+            coordinate += size.height();
+        } else {
+            item->setGeometry(coordinate, perpendicularOffset, size.width(), area.height());
+            coordinate += size.width();
         }
-        // remove unused items
-        const int visibleCount = index - firstVisibleIndex;
-        while (visibleCount < d->items.count())
-            d->creator->destroy(d->items.takeLast());
+        ++index;
     }
-    // done
-    emit layoutChanged();
+
+    // remove unused items
+    const int visibleCount = index - firstVisibleIndex;
+    while (visibleCount < d->items.count())
+        d->creator->destroy(d->items.takeLast());
+
 }
 
 /*!