use custom type for data value in qml delegate

We register a custom type (class) with the QVariant metasystem and pass
that back from the QAbstractItemModel into qml.

For demonstration purposes we chose to use this custom type to
additionally transport the indentation from the input file as an int.

TreeDelegate.qml

@@ -0,0 +1,11 @@
+import QtQuick 2.0
+import hvoigt.net 1.0
+
+Item {
+    Text {
+        anchors.fill: parent
+        color: styleData.textColor
+        elide: styleData.elideMode
+        text: styleData.value.indentation + ": " + styleData.value.text
+    }
+}

customtype.cpp

@@ -0,0 +1,37 @@
+#include "customtype.h"
+
+CustomType::CustomType(QObject *parent) : QObject(parent), myIndentation(0)
+{
+}
+
+CustomType::CustomType(const CustomType &other)
+{
+    myText = other.myText;
+    myIndentation = other.myIndentation;
+}
+
+CustomType::~CustomType()
+{
+}
+
+QString CustomType::text()
+{
+    return myText;
+}
+
+void CustomType::setText(QString text)
+{
+    myText = text;
+    emit textChanged();
+}
+
+int CustomType::indentation()
+{
+    return myIndentation;
+}
+
+void CustomType::setIndentation(int indentation)
+{
+    myIndentation = indentation;
+    emit indentationChanged();
+}

customtype.h

@@ -0,0 +1,35 @@
+#ifndef CUSTOMTYPE_H
+#define CUSTOMTYPE_H
+
+#include <QObject>
+
+class CustomType : public QObject
+{
+    Q_OBJECT
+
+    Q_PROPERTY(QString text READ text WRITE setText NOTIFY textChanged)
+    Q_PROPERTY(int indentation READ indentation WRITE setIndentation NOTIFY indentationChanged)
+
+public:
+    explicit CustomType(QObject *parent = 0);
+    CustomType(const CustomType &other);
+    ~CustomType();
+
+    QString text();
+    void setText(QString text);
+
+    int indentation();
+    void setIndentation(int indentation);
+
+signals:
+    void textChanged();
+    void indentationChanged();
+
+private:
+    QString myText;
+    int myIndentation;
+};
+
+Q_DECLARE_METATYPE(CustomType)
+
+#endif // CUSTOMTYPE_H

main.cpp

@@ -39,6 +39,7 @@
 ****************************************************************************/
 
 #include "treemodel.h"
+#include "customtype.h"
 
 #include <QGuiApplication>
 #include <QQmlApplicationEngine>
@@ -58,6 +59,8 @@ int main(int argc, char *argv[])
 
     QQmlApplicationEngine engine;
     engine.rootContext()->setContextProperty("theModel",&model);
+    qmlRegisterType<CustomType>("hvoigt.net", 1, 0, "CustomType");
+
     engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
 
     return app.exec();

main.qml

@@ -10,6 +10,7 @@ ApplicationWindow {
     TreeView {
         anchors.fill: parent
         model: theModel
+        itemDelegate: TreeDelegate {}
 
         TableViewColumn {
             role: "title"

treemodel.cpp

@@ -48,6 +48,8 @@
 #include "treeitem.h"
 #include "treemodel.h"
 
+#include "customtype.h"
+
 #include <QStringList>
 
 //! [0]
@@ -176,6 +178,16 @@ QHash<int, QByteArray> TreeModel::roleNames() const
     return m_roleNameMapping;
 }
 
+QVariant TreeModel::newCustomType(const QString &text, int position)
+{
+    CustomType *t = new CustomType(this);
+    t->setText(text);
+    t->setIndentation(position);
+    QVariant v;
+    v.setValue(t);
+    return v;
+}
+
 void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
 {
     QList<TreeItem*> parents;
@@ -200,7 +212,7 @@ void TreeModel::setupModelData(const QStringList &lines, TreeItem *parent)
             QStringList columnStrings = lineData.split("\t", QString::SkipEmptyParts);
             QList<QVariant> columnData;
             for (int column = 0; column < columnStrings.count(); ++column)
-                columnData << columnStrings[column];
+                columnData << newCustomType(columnStrings[column], position);
 
             if (position > indentations.last()) {
                 // The last child of the current parent is now the new parent

treemodel.h

@@ -75,6 +75,7 @@ class TreeModel : public QAbstractItemModel
     QHash<int, QByteArray> roleNames() const override;
 
 private:
+    QVariant newCustomType(const QString &text, int position);
     void setupModelData(const QStringList &lines, TreeItem *parent);
 
     TreeItem *rootItem;

treeview.pro

@@ -4,11 +4,13 @@ QT += qml quick
 CONFIG += c++11
 
 HEADERS     = treeitem.h \
-              treemodel.h
+              treemodel.h \
+              customtype.h
 RESOURCES   = treeview.qrc
 SOURCES     = treeitem.cpp \
               treemodel.cpp \
-              main.cpp
+              main.cpp \
+              customtype.cpp
 
 # install
 #target.path = $$[QT_INSTALL_EXAMPLES]/widgets/itemviews/simpletreemodel

treeview.qrc

@@ -2,5 +2,6 @@
     <qresource prefix="/">
         <file>default.txt</file>
         <file>main.qml</file>
+        <file>TreeDelegate.qml</file>
     </qresource>
 </RCC>