Fix issues in merge operation.wip/visuallistmodel

Provide a way for internal items to be merged if possible, and
correctly remove the from item from the composite list.

4 files changed, 102 insertions, 25 deletions

diff --git a/examples/declarative/modelviews/visualdatamodel/visualdatamodel.qml b/examples/declarative/modelviews/visualdatamodel/visualdatamodel.qml
index 0374ac9da6..38f1e12604 100644
--- a/examples/declarative/modelviews/visualdatamodel/visualdatamodel.qml
+++ b/examples/declarative/modelviews/visualdatamodel/visualdatamodel.qml
@@ -76,7 +76,7 @@ Rectangle {
                         var message = visualModel.get(j)
                         if (!message.outbound)
                             continue;
-                        for (var k = inserts[i].start - 1 - delta; k >= 0; ++k) {
+                        for (var k = inserts[i].start - 1 - delta; k >= 0; --k) {
                             var existing = visualModel.get(k);
                             if (!existing.outbound)
                                 continue;
diff --git a/src/declarative/items/qsgvisualitemmodel.cpp b/src/declarative/items/qsgvisualitemmodel.cpp
index feecbe5b92..2447814565 100644
--- a/src/declarative/items/qsgvisualitemmodel.cpp
+++ b/src/declarative/items/qsgvisualitemmodel.cpp
@@ -347,6 +347,9 @@ protected:
                 *t = *f;
         }
     }
+
+    bool mergeInternalData(int from, int to);
+    bool mergeInternalData(int internalIndex, void *list, int index);
 };
 
 class QSGVisualDataParts;
@@ -497,6 +500,7 @@ public:
     }
 
     QSGVisualData *model() const { return m_model; }
+    void setModel(QSGVisualData *model, int index);
     QDeclarativeComponent *delegate() const { return m_delegate; }
 
     void ensureProperties();
@@ -532,6 +536,23 @@ QSGVisualModelData *QSGVisualModelPrivate::createScriptData(QDeclarativeComponen
     return data;
 }
 
+
+bool QSGVisualModelPrivate::mergeInternalData(int internalIndex, void *list, int index)
+{
+    if (children[internalIndex].data)
+        children[internalIndex].data->setModel(static_cast<QSGVisualData *>(list), index);
+    return true;
+}
+
+bool QSGVisualModelPrivate::mergeInternalData(int from, int to)
+{
+    Q_UNUSED(to);
+    if (children[to].data && children[from].data)
+        children[to].data->setModel(children[from].data->model(), children[from].data->index());
+    removeInternalData(from, 1);
+    return true;
+}
+
 QSGVisualModel::QSGVisualModel(QObject *parent)
     : QObject(*(new QSGVisualModelPrivate), parent)
 {
@@ -1019,14 +1040,17 @@ void QSGVisualModel::merge(int from, int to)
         return;
     if (!d->transaction)
         d->childrenChanged = false;
-    if (!d->merge(from, to)) {
+    int internalIndex = d->merge(from, to);
+    if (internalIndex == -1) {
         qmlInfo(this) << "Items cannot be merged" << from << to;
-    } else if (d->transaction) {
-        d->transactionChanges.insertRemove(from, 1);
     } else {
-        emit itemsRemoved(from, 1);
-        if (d->childrenChanged)
-            emit childrenChanged();
+        if (d->transaction) {
+            d->transactionChanges.insertRemove(from, from + 1);
+        } else {
+            emit itemsRemoved(from, 1);
+            if (d->childrenChanged)
+                emit childrenChanged();
+        }
     }
 }
 
@@ -1280,6 +1304,12 @@ void QSGVisualModelData::setIndex(int index)
     emit indexChanged();
 }
 
+void QSGVisualModelData::setModel(QSGVisualData *model, int index)
+{
+    m_model = model;
+    m_index = index;
+    emit indexChanged();
+}
 
 //---------------------------------------------------------------------------
 
diff --git a/src/declarative/util/qdeclarativelistcompositor.cpp b/src/declarative/util/qdeclarativelistcompositor.cpp
index b081549e59..6fba99fb99 100644
--- a/src/declarative/util/qdeclarativelistcompositor.cpp
+++ b/src/declarative/util/qdeclarativelistcompositor.cpp
@@ -521,7 +521,7 @@ void QDeclarativeListCompositor::move(int from, int to, int count)
     Q_ASSERT(qt_verifyIntegrity(ranges, absoluteCount, internalCount));
 }
 
-bool QDeclarativeListCompositor::merge(int from, int to)
+int QDeclarativeListCompositor::merge(int from, int to)
 {
     int internalIndex = 0;
     int internalFrom = 0;
@@ -544,8 +544,10 @@ bool QDeclarativeListCompositor::merge(int from, int to)
             internalFrom = internalIndex;
             if (range->internal())
                 internalFrom += relativeFrom;
-            relativeTo -= from - relativeFrom;
-            internalIndex -= 1;
+            if (from > to)
+                relativeTo -= to - relativeFrom;
+            else
+                relativeTo -= from - relativeFrom;
             break;
         }
         if (range->internal())
@@ -575,16 +577,44 @@ bool QDeclarativeListCompositor::merge(int from, int to)
 
     if (fromRange == ranges.end()
             || toRange == ranges.end()
-            || fromRange->list
-            || !toRange->list
-            || toRange->internal()) {
-        return false;
+            || (!fromRange->internal() && !toRange->internal())
+            || (fromRange->list && toRange->list)) {
+        return -1;
+    } else if (fromRange->internal() && toRange->internal()) {
+        if (!mergeInternalData(internalFrom, internalTo))
+            return -1;
+    } else if (fromRange->internal()) {
+        if (!mergeInternalData(internalTo, toRange->list, toRange->index + relativeTo))
+            return -1;
+    } else if (toRange->internal()) {
+        if (!mergeInternalData(internalTo, fromRange->list, fromRange->index + relativeFrom))
+            return -1;
     }
 
-    fromRange->count -= 1;
+    void *toList = fromRange->list;
+    int toIndex = fromRange->index + relativeFrom;
 
-    if (fromRange->count == 0)
-        ranges.erase(fromRange);
+    fromRange->count -= 1;
+    int removeFrom = fromRange->index + relativeFrom;
+    if (relativeFrom > 0) {
+        int splitOffset = relativeFrom;
+        if (fromRange->list)
+            splitOffset += 1;
+        if (splitOffset < fromRange->count) {
+            fromRange = insert(fromRange, QDeclarativeCompositeRange(
+                    fromRange->list, fromRange->index, relativeFrom, fromRange->flags & ~Append));
+            fromRange->index += splitOffset;
+            fromRange->count -= splitOffset;
+        } else {
+            fromRange->index += relativeFrom;
+        }
+    } else if (fromRange->list) {
+        fromRange->index += 1;
+    }
+    if (fromRange->prepend()) {
+        fromRange = insert(fromRange, QDeclarativeCompositeRange(
+                fromRange->list, removeFrom, 1, Null | Prepend));
+    }
 
     if (relativeTo > 0) {
         toRange = ++ranges.insert(toRange, QDeclarativeCompositeRange(
@@ -595,19 +625,25 @@ bool QDeclarativeListCompositor::merge(int from, int to)
 
     if (toRange->count == 1 && !toRange->append()) {
         toRange->flags |= Internal;
+        if (!toRange->list) {
+            toRange->list = toList;
+            toRange->index = toIndex;
+        }
     } else {
-        toRange = ++ranges.insert(toRange, QDeclarativeCompositeRange(
-                toRange->list, toRange->index, 1, (toRange->flags | Internal) & ~Append));
+        if (toRange->list) {
+            toRange = ++ranges.insert(toRange, QDeclarativeCompositeRange(
+                    toRange->list, toRange->index, 1, (toRange->flags | Internal) & ~Append));
+        } else {
+            toRange = ++ranges.insert(toRange, QDeclarativeCompositeRange(
+                    toList, toIndex, 1, Internal));
+        }
         toRange->index += 1;
         toRange->count -= 1;
     }
 
-    if (internalFrom != internalTo)
-        moveInternalData(internalFrom, internalTo, 1);
-
     absoluteCount -= 1;
 
-    return true;
+    return internalTo;
 }
 
 void QDeclarativeListCompositor::clear()
@@ -985,6 +1021,16 @@ void QDeclarativeListCompositor::listItemsChanged(void *list, int start, int end
     }
 }
 
+bool QDeclarativeListCompositor::mergeInternalData(int, int)
+{
+    return false;
+}
+
+bool QDeclarativeListCompositor::mergeInternalData(int, void *, int)
+{
+    return false;
+}
+
 void QDeclarativeListCompositor::compress()
 {
 }
diff --git a/src/declarative/util/qdeclarativelistcompositor_p.h b/src/declarative/util/qdeclarativelistcompositor_p.h
index 2d2123ad8c..e3220f1466 100644
--- a/src/declarative/util/qdeclarativelistcompositor_p.h
+++ b/src/declarative/util/qdeclarativelistcompositor_p.h
@@ -106,7 +106,7 @@ public:
     void removeAt(int index, int count);
     void removeList(void *list, QVector<QDeclarativeChangeSet::Remove> *changes);
     void move(int from, int to, int count);
-    bool merge(int from, int to);
+    int merge(int from, int to);
     void clear();
     void clearData(int internalIndex, int count);
 
@@ -128,7 +128,8 @@ protected:
     virtual void replaceInternalData(int index, const void *data) = 0;
     virtual void removeInternalData(int index, int count) = 0;
     virtual void moveInternalData(int from, int to, int count) = 0;
-
+    virtual bool mergeInternalData(int from, int to);
+    virtual bool mergeInternalData(int internalIndex, void *list, int range);
 
 private:
     int absoluteCount;