Add custom model for tree view in Database Structure tab

Use a custom model for the tree view in the "Database Structure" tab in
the main window, i.e. change from a QTreeWidget to a QTreeView and do
all the item management stuff manually. This might add some code and
complexity but also offers some more flexibility for us.

src/DbStructureModel.cpp

@@ -0,0 +1,155 @@
+#include "DbStructureModel.h"
+#include "sqlitedb.h"
+#include <QTreeWidgetItem>
+
+DbStructureModel::DbStructureModel(QObject* parent)
+    : QAbstractItemModel(parent)
+{
+    // Create root item and use its columns to store the header strings
+    QStringList header;
+    header << tr("Name") << tr("Object") << tr("Type") << tr("Schema");
+    rootItem = new QTreeWidgetItem(header);
+}
+
+DbStructureModel::~DbStructureModel()
+{
+    delete rootItem;
+}
+
+int DbStructureModel::columnCount(const QModelIndex&) const
+{
+    return rootItem->columnCount();
+}
+
+QVariant DbStructureModel::data(const QModelIndex& index, int role) const
+{
+    if(!index.isValid())
+        return QVariant();
+
+    // Get the item the index points at
+    QTreeWidgetItem* item = static_cast<QTreeWidgetItem*>(index.internalPointer());
+
+    // Depending on the role either return the text or the icon
+    if(role == Qt::DisplayRole)
+        return item->text(index.column());
+    else if(role == Qt::DecorationRole)
+        return item->icon(index.column());
+    else
+        return QVariant();
+}
+
+Qt::ItemFlags DbStructureModel::flags(const QModelIndex &index) const
+{
+    if(!index.isValid())
+        return 0;
+
+    return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
+}
+
+QVariant DbStructureModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+    // Get the header string from the root item
+    if(orientation == Qt::Horizontal && role == Qt::DisplayRole)
+        return rootItem->data(section, role);
+
+    return QVariant();
+}
+
+QModelIndex DbStructureModel::index(int row, int column, const QModelIndex& parent) const
+{
+    if(!hasIndex(row, column, parent))
+        return QModelIndex();
+
+    QTreeWidgetItem *parentItem;
+    if(!parent.isValid())
+        parentItem = rootItem;
+    else
+        parentItem = static_cast<QTreeWidgetItem*>(parent.internalPointer());
+
+    QTreeWidgetItem* childItem = parentItem->child(row);
+    if(childItem)
+        return createIndex(row, column, childItem);
+    else
+        return QModelIndex();
+}
+
+QModelIndex DbStructureModel::parent(const QModelIndex& index) const
+{
+    if(!index.isValid())
+        return QModelIndex();
+
+    QTreeWidgetItem* childItem = static_cast<QTreeWidgetItem*>(index.internalPointer());
+    QTreeWidgetItem* parentItem = childItem->parent();
+
+    if(parentItem == rootItem)
+        return QModelIndex();
+    else
+        return createIndex(0, 0, parentItem);
+}
+
+int DbStructureModel::rowCount(const QModelIndex& parent) const
+{
+    if(parent.column() > 0)
+        return 0;
+
+    if(!parent.isValid())
+        return rootItem->childCount();
+    else
+        return static_cast<QTreeWidgetItem*>(parent.internalPointer())->childCount();
+}
+
+void DbStructureModel::reloadData(DBBrowserDB* db)
+{
+    // Remove all data except for the root item
+    while(rootItem->childCount())
+    {
+        delete rootItem->child(0);
+        rootItem->removeChild(rootItem->child(0));
+    }
+
+    // Create the nodes for tables, indices, views and triggers
+    QMap<QString, QTreeWidgetItem*> typeToParentItem;
+    QTreeWidgetItem* itemTables = new QTreeWidgetItem(rootItem);
+    itemTables->setIcon(0, QIcon(QString(":/icons/table")));
+    itemTables->setText(0, tr("Tables (%1)").arg(db->objMap.values("table").count()));
+    typeToParentItem.insert("table", itemTables);
+    QTreeWidgetItem* itemIndices = new QTreeWidgetItem(rootItem);
+    itemIndices->setIcon(0, QIcon(QString(":/icons/index")));
+    itemIndices->setText(0, tr("Indices (%1)").arg(db->objMap.values("index").count()));
+    typeToParentItem.insert("index", itemIndices);
+    QTreeWidgetItem* itemViews = new QTreeWidgetItem(rootItem);
+    itemViews->setIcon(0, QIcon(QString(":/icons/view")));
+    itemViews->setText(0, tr("Views (%1)").arg(db->objMap.values("view").count()));
+    typeToParentItem.insert("view", itemViews);
+    QTreeWidgetItem* itemTriggers = new QTreeWidgetItem(rootItem);
+    itemTriggers->setIcon(0, QIcon(QString(":/icons/trigger")));
+    itemTriggers->setText(0, tr("Triggers (%1)").arg(db->objMap.values("trigger").count()));
+    typeToParentItem.insert("trigger", itemTriggers);
+
+    // Add the actual table objects
+    for(objectMap::ConstIterator it=db->objMap.begin();it!=db->objMap.end();++it)
+    {
+        // Object node
+        QTreeWidgetItem *tableItem = new QTreeWidgetItem(typeToParentItem.value((*it).gettype()));
+        tableItem->setIcon(0, QIcon(QString(":/icons/%1").arg((*it).gettype())));
+        tableItem->setText(0, (*it).getname());
+        tableItem->setText(1, (*it).gettype());
+        tableItem->setText(3, (*it).getsql());
+
+        // If it is a table or view add the field Nodes
+        if((*it).gettype() == "table" || (*it).gettype() == "view")
+        {
+            for(int i=0;i<(*it).fldmap.size();i++)
+            {
+                QTreeWidgetItem *fldItem = new QTreeWidgetItem(tableItem);
+                fldItem->setText(0, (*it).fldmap.at(i)->name());
+                fldItem->setText(1, "field");
+                fldItem->setText(2, (*it).fldmap.at(i)->type());
+                fldItem->setIcon(0, QIcon(":/icons/field"));
+            }
+        }
+    }
+
+    // Refresh the view
+    reset();
+}