Hello all,

I've been trying for hours to get this QTreeView / QAbstractItemModel code snippet to work with Qt4.4 and VC++ 2008 Express. When I expand the nested items twice, Qt fails with the assert "ASSERT: "i > -1" in file itemviews\qtreeview.cpp, line 3013". Am I doing something wrong?

Qt Code: 
  1. #include <QtGui>
  2. class TestModel;
  3.  
  4. class SceneTest : public QDialog {
  5. public:
  6.     SceneTest();
  7. protected:
  8.     QTreeView *tree;
  9.     TestModel *model;
  10. };
  11.  
  12. class InternalItem {
  13. public:
  14.     InternalItem() {
  15.         parent = NULL;
  16.     }
  17.     ~InternalItem() {qDeleteAll(children);}
  18.     int row() {
  19.         if (parent) {
  20.             return parent->children.indexOf(this);
  21.         } else {
  22.             return 0;
  23.         }
  24.     }
  25.     InternalItem *append(InternalItem *iitem) {children.append(iitem); return (iitem->parent = this);}
  26.     InternalItem *parent;
  27.     QList < InternalItem * > children;
  28. };
  29.  
  30. class TestModel : public QAbstractItemModel {
  31. public:
  32.     TestModel();
  33.     QVariant data(const QModelIndex &index, int role) const;
  34.     Qt::ItemFlags flags(const QModelIndex &index) const;
  35.     QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const;
  36.     int rowCount(const QModelIndex &parent = QModelIndex()) const;
  37.     int columnCount(const QModelIndex &parent) const;
  38.     QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const;
  39.     QModelIndex parent(const QModelIndex &) const;
  40. protected:
  41.     InternalItem *root;
  42. };
  43.  
  44. TestModel::TestModel() {
  45.     root = new InternalItem();
  46.     root->append(new InternalItem());
  47.     root->append(new InternalItem());
  48.     root->children[1]->append(new InternalItem());
  49.     root->children[1]->children[0]->append(new InternalItem());
  50.     root->children[1]->children[0]->children[0]->append(new InternalItem());
  51. }
  52.  
  53. Qt::ItemFlags TestModel::flags(const QModelIndex &index) const {
  54.     return index.isValid() ? (Qt::ItemIsEnabled | Qt::ItemIsSelectable) : 0;
  55. }
  56.  
  57. QVariant TestModel::data(const QModelIndex &index, int role) const {
  58.     if (!index.isValid() || index.column() >= 1)
  59.         return QVariant();
  60.     if (role == Qt::DisplayRole) {
  61.         InternalItem *iitem = static_cast < InternalItem * >(index.internalPointer());
  62.         if (index.column() == 0) {
  63.             return (long)iitem;
  64.         }
  65.     }
  66.     return QVariant();
  67. }
  68.  
  69. QModelIndex TestModel::index(int row, int column, const QModelIndex &parent) const {
  70.     if (!hasIndex(row, column, parent)) {
  71.         return QModelIndex();
  72.     }
  73.     InternalItem *parentItem = NULL;
  74.     if (!parent.isValid()) {
  75.         parentItem = root;
  76.     } else {
  77.         parentItem = static_cast<InternalItem*>(parent.internalPointer());
  78.     }
  79.     InternalItem *child = parentItem->children[row];
  80.     if (child) {
  81.         return createIndex(row, column, child);
  82.     } else {
  83.         return QModelIndex();
  84.     }
  85. }
  86.  
  87. QModelIndex TestModel::parent(const QModelIndex &index) const {
  88.     if (!index.isValid()) return QModelIndex();
  89.     InternalItem *iindex = static_cast < InternalItem * >(index.internalPointer());
  90.     if (!iindex->parent || iindex->parent == root) {
  91.         return QModelIndex();
  92.     }  else {
  93.         return createIndex(iindex->row(), 0, iindex->parent);
  94.     }
  95. }
  96.  
  97. QVariant TestModel::headerData(int section, Qt::Orientation orientation, int role) const {
  98.     if (section == 0 && role == Qt::DisplayRole) {
  99.         return QString("A");
  100.     } else {
  101.         return QVariant();
  102.     }
  103. }
  104.  
  105. int TestModel::rowCount(const QModelIndex &parent) const {
  106.     if (parent.column() > 0) return 0;
  107.     if (parent.isValid()) {
  108.         return static_cast < InternalItem * >(parent.internalPointer())->children.size();
  109.     } else {
  110.         return root->children.size();
  111.     }
  112. }
  113.  
  114. int TestModel::columnCount(const QModelIndex &parent) const {
  115.     return 1;
  116. }
  117.  
  118. SceneTest::SceneTest() : QDialog(NULL) {
  119.     model = new TestModel();
  120.     tree = new QTreeView(this);
  121.     tree->setModel(model);
  122.     QBoxLayout *layout = new QHBoxLayout(this);
  123.     layout->addWidget(tree);
  124. }
To copy to clipboard, switch view to plain text mode