Proxy model example code: Difference between revisions

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[[Category:snippets]]<br />[[Category:HowTo]]<br />[[Category:Developing with Qt]]
{{Cleanup | reason=Auto-imported from ExpressionEngine.}}


Related to &quot;this FAQ entry&amp;quot;:http://developer.qt.nokia.com/faq/answer/how_can_i_implement_my_own_proxy_model_that_is_more_advanced_than_just_sort.
[[Category:snippets]]
[[Category:HowTo]]
[[Category:Developing with Qt]]


<code><br />#include &lt;QtGui&amp;gt;
Related to [http://developer.qt.nokia.com/faq/answer/how_can_i_implement_my_own_proxy_model_that_is_more_advanced_than_just_sort this FAQ entry].


QList&amp;lt;QStandardItem *&gt; list;
<code>
 
#include <QTreeView>
class SortProxy : public QAbstractProxyModel<br />{<br /> Q_OBJECT
#include <QPushButton>
 
#include <QVBoxLayout>
public:<br /> SortProxy(QObject *parent = 0) : QAbstractProxyModel(parent), hideThem(false)<br /> {<br /> fixModel();<br /> }
#include <QStandardItem>
 
#include <QApplication>
int rowCount(const QModelIndex &amp;parent) const<br /> {<br /> QModelIndex sourceParent;<br /> if (parent.isValid())<br /> sourceParent = mapToSource(parent);<br /> int count = 0;<br /> QMapIterator&amp;lt;QPersistentModelIndex, QPersistentModelIndex&amp;gt; it(proxySourceParent);<br /> while (it.hasNext()) {<br /> it.next();<br /> if (it.value() == sourceParent)<br /> count++;<br /> }<br /> return count;<br /> }
#include <QAbstractProxyModel>
 
int columnCount(const QModelIndex &amp;) const<br /> {<br /> return 1;<br /> }
QList<QStandardItem *> list;
 
QModelIndex index(int row, int column, const QModelIndex &amp;parent = QModelIndex()) const<br /> {<br /> QModelIndex sourceParent;<br /> if (parent.isValid())<br /> sourceParent = mapToSource(parent);<br /> QMapIterator&amp;lt;QPersistentModelIndex, QPersistentModelIndex&amp;gt; it(proxySourceParent);<br /> while (it.hasNext()) {<br /> it.next();<br /> if (it.value() sourceParent &amp;amp;&amp;amp; it.key().row() row &amp;&amp;<br /> it.key().column() == column)<br /> return it.key();<br /> }<br /> return QModelIndex();<br /> }
class SortProxy : public QAbstractProxyModel
 
{
QModelIndex parent(const QModelIndex &amp;child) const<br /> {<br /> QModelIndex mi = proxySourceParent.value(child);<br /> if (mi.isValid())<br /> return mapFromSource(mi);<br /> return QModelIndex();<br /> }
    Q_OBJECT
 
QModelIndex mapToSource(const QModelIndex &amp;proxyIndex) const<br /> {<br /> if (!proxyIndex.isValid())<br /> return QModelIndex();<br /> return mapping.key(proxyIndex);<br /> }
public:
 
    SortProxy(QObject *parent = 0) : QAbstractProxyModel(parent), hideThem(false)
QModelIndex mapFromSource(const QModelIndex &amp;sourceIndex) const<br /> {<br /> if (!sourceIndex.isValid())<br /> return QModelIndex();<br /> return mapping.value(sourceIndex);<br /> }
    {
 
        fixModel();
public slots:<br /> void hideEverythingButA1AndChildren()<br /> {<br /> hideThem = !hideThem;<br /> // Now we set up the proxy &lt;<s>&gt; source mappings<br /> emit layoutAboutToBeChanged();<br /> fixModel();<br /> emit layoutChanged();<br /> }
    }
<br />private:<br /> void fixModel()<br /> {<br /> mapping.clear();<br /> proxySourceParent.clear();<br /> for (int i=0;i&amp;lt;list.size();i+'') {<br /> QStandardItem *si = list.at(i);<br /> if (hideThem) {<br /> if (!si-&gt;text().startsWith(&quot;A&amp;quot;) || !si-&gt;parent())<br /> continue;<br /> QModelIndex proxy = createIndex(si-&gt;row(), si-&gt;column(), si-&gt;index().internalPointer());<br /> mapping.insert(QPersistentModelIndex(si-&gt;index()), proxy);<br /> QModelIndex sourceParent;<br /> if (si-&gt;parent()<s>&gt;parent())<br /> sourceParent = si</s>&gt;parent()<s>&gt;index();<br /> proxySourceParent.insert(proxy, sourceParent);<br /> } else {<br /> QModelIndex proxy = createIndex(si</s>&gt;row(), si-&gt;column(), si-&gt;index().internalPointer());<br /> mapping.insert(QPersistentModelIndex(si-&gt;index()), proxy);<br /> QModelIndex sourceParent;<br /> if (si-&gt;parent())<br /> sourceParent = si-&gt;parent()<s>&gt;index();<br /> proxySourceParent.insert(proxy, sourceParent);<br /> }<br /> }<br /> }<br /> QMap&amp;lt;QPersistentModelIndex, QPersistentModelIndex&amp;gt; mapping;<br /> QMap&amp;lt;QPersistentModelIndex, QPersistentModelIndex&amp;gt; proxySourceParent;<br /> bool hideThem;<br />};
<br />SortProxy *proxyModel = 0;
    int rowCount(const QModelIndex &parent) const
<br />class Tree : public QTreeView<br />{<br /> Q_OBJECT
    {
<br />public:<br /> Tree(QWidget *parent = 0) : QTreeView(parent)<br /> {<br /> QStandardItemModel *sourceModel = new QStandardItemModel(this);
        QModelIndex sourceParent;
<br /> QStandardItem *parentA = sourceModel</s>&gt;invisibleRootItem();<br /> for (int i = 0; i &lt; 2;i) {<br /> itemA = new QStandardItem(QString(&quot;A %0&amp;quot;).arg(i));<br /> parentA-&gt;appendRow(itemA);<br /> parentA = itemA;<br /> list.append(itemA);<br /> }<br /> itemA = new QStandardItem(QString(&quot;A 2&amp;quot;));<br /> parentA-&gt;appendRow(itemA);<br /> list.append(itemA);<br /> itemA3 = new QStandardItem(QString(&quot;A 3&amp;quot;));<br /> list.append(itemA3);<br /> parentA-&gt;appendRow(itemA3);<br /> itemA4 = new QStandardItem(QString(&quot;A 4&amp;quot;));<br /> list.append(itemA4);<br /> parentA-&gt;appendRow(itemA4);<br /> itemNonA = new QStandardItem(QString(&quot;Non A&amp;quot;));<br /> list.append(itemNonA);<br /> parentA-&gt;appendRow(itemNonA);
        if (parent.isValid())
<br /> QStandardItem *parentB = sourceModel-&gt;invisibleRootItem();<br /> for (int i = 0; i &lt; 3;i) {<br /> itemB = new QStandardItem(QString(&quot;B %0&amp;quot;).arg(i));<br /> parentB-&gt;appendRow(itemB);<br /> parentB = itemB;<br /> list.append(itemB);<br /> }
            sourceParent = mapToSource(parent);
<br /> QStandardItem *parentC = sourceModel-&gt;invisibleRootItem();<br /> for (int i = 0; i &lt; 3;i) {<br /> itemC = new QStandardItem(QString(&quot;C %0&amp;quot;).arg(i));<br /> parentC-&gt;appendRow(itemC);<br /> parentC = itemC;<br /> list.append(itemC);
        int count = 0;
<br /> }
        QMapIterator<QPersistentModelIndex, QPersistentModelIndex> it(proxySourceParent);
<br /> proxyModel = new SortProxy(this);<br /> proxyModel-&gt;setSourceModel(sourceModel);<br /> setModel(proxyModel);<br /> expandAll();<br /> }<br /> QStandardItem *itemA;<br /> QStandardItem *itemA3;<br /> QStandardItem *itemA4;<br /> QStandardItem *itemNonA;<br /> QStandardItem *itemB;<br /> QStandardItem '''itemC;<br />};
        while (it.hasNext()) {
 
            it.next();
<br />#include &quot;main.moc&amp;quot;
            if (it.value() == sourceParent)
<br />int main(int argc, char'''*argv)<br />{<br /> QApplication app(argc, argv);<br /> QWidget widget;<br /> QPushButton *button = new QPushButton(&quot;Make only A1'' 'A' children visible&amp;quot;, &amp;widget);<br /> Tree *tree = new Tree(&amp;widget);<br /> QVBoxLayout *lay = new QVBoxLayout(&amp;widget);<br /> lay</s>&gt;addWidget(button);<br /> QObject::connect(button, SIGNAL (clicked()), proxyModel, SLOT (hideEverythingButA1AndChildren()));<br /> lay-&gt;addWidget(tree);<br /> widget.show();<br /> return app.exec&amp;amp;#40;&amp;#41;;<br />}<br /></code>
                count++;
        }
        return count;
    }
    int columnCount(const QModelIndex &) const
    {
        return 1;
    }
    QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const
    {
        QModelIndex sourceParent;
        if (parent.isValid())
            sourceParent = mapToSource(parent);
        QMapIterator<QPersistentModelIndex, QPersistentModelIndex> it(proxySourceParent);
        while (it.hasNext()) {
            it.next();
            if (it.value() == sourceParent && it.key().row() == row &&
                it.key().column() == column)
                return it.key();
        }
        return QModelIndex();
    }
    QModelIndex parent(const QModelIndex &child) const
    {
        QModelIndex mi = proxySourceParent.value(child);
        if (mi.isValid())
            return mapFromSource(mi);
        return QModelIndex();
    }
    QModelIndex mapToSource(const QModelIndex &proxyIndex) const
    {
        if (!proxyIndex.isValid())
            return QModelIndex();
        return mapping.key(proxyIndex);
    }
    QModelIndex mapFromSource(const QModelIndex &sourceIndex) const
    {
        if (!sourceIndex.isValid())
            return QModelIndex();
        return mapping.value(sourceIndex);
    }
public slots:
        void hideEverythingButA1AndChildren()
        {
            hideThem = !hideThem;
            // Now we set up the proxy <-> source mappings
            emit layoutAboutToBeChanged();
            fixModel();
            emit layoutChanged();
        }
private:
    void fixModel()
    {
        mapping.clear();
        proxySourceParent.clear();
        //the following list is already populated
        //in the tree view and we shall browse and
        //customize it here
        for (int i=0;i<list.size();i++)
        {
            //pull out a standard item
            QStandardItem *si = list.at(i);
            if (hideThem)
            {
                //if the hide item flag is true
                //check if the standard item's text start with 'A'
                //of the item is not parent
                if (!si->text().startsWith("A") || !si->parent())
                    continue;
                //means that we have encountered item that does not start with 'A'
                //or the item is not the parent
                //we pull out the model index by creating the model index with the source items
                //row , column
                QModelIndex proxy = createIndex(si->row(), si->column(), si->index().internalPointer());
                //insert the source model's index and the proxy index into the map
                mapping.insert(QPersistentModelIndex(si->index()), proxy);
                QModelIndex sourceParent;
                if (si->parent()->parent())
                    sourceParent = si->parent()->index();
                proxySourceParent.insert(proxy, sourceParent);
            }
            else
            {
                QModelIndex proxy = createIndex(si->row(), si->column(), si->index().internalPointer());
                mapping.insert(QPersistentModelIndex(si->index()), proxy);
                QModelIndex sourceParent;
                if (si->parent())
                    sourceParent = si->parent()->index();
                proxySourceParent.insert(proxy, sourceParent);
            }
        }
    }
    QMap<QPersistentModelIndex, QPersistentModelIndex> mapping;
    QMap<QPersistentModelIndex, QPersistentModelIndex> proxySourceParent;
    bool hideThem;
};
SortProxy *proxyModel = 0;
class Tree : public QTreeView
{
    Q_OBJECT
public:
    Tree(QWidget *parent = 0) : QTreeView(parent)
    {
        QStandardItemModel *sourceModel = new QStandardItemModel(this);
        QStandardItem *parentA = sourceModel->invisibleRootItem();
        for (int i = 0; i < 2; ++i) {
            itemA = new QStandardItem(QString("A %0").arg(i));
            parentA->appendRow(itemA);
            parentA = itemA;
            list.append(itemA);
        }
        itemA = new QStandardItem(QString("A 2"));
        parentA->appendRow(itemA);
        list.append(itemA);
        itemA3 = new QStandardItem(QString("A 3"));
        list.append(itemA3);
        parentA->appendRow(itemA3);
        itemA4 = new QStandardItem(QString("A 4"));
        list.append(itemA4);
        parentA->appendRow(itemA4);
        itemNonA = new QStandardItem(QString("Non A"));
        list.append(itemNonA);
        parentA->appendRow(itemNonA);
        QStandardItem *parentB = sourceModel->invisibleRootItem();
        for (int i = 0; i < 3; ++i) {
            itemB = new QStandardItem(QString("B %0").arg(i));
            parentB->appendRow(itemB);
            parentB = itemB;
            list.append(itemB);
        }
        QStandardItem *parentC = sourceModel->invisibleRootItem();
        for (int i = 0; i < 3; ++i) {
            itemC = new QStandardItem(QString("C %0").arg(i));
            parentC->appendRow(itemC);
            parentC = itemC;
            list.append(itemC);
        }
        proxyModel = new SortProxy(this);
        proxyModel->setSourceModel(sourceModel);
        setModel(proxyModel);
        expandAll();
    }
    QStandardItem *itemA;
    QStandardItem *itemA3;
    QStandardItem *itemA4;
    QStandardItem *itemNonA;
    QStandardItem *itemB;
    QStandardItem *itemC;
};
#include "main.moc"
int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QWidget widget;
    QPushButton *button = new QPushButton("Make only A1 + 'A' children visible", &widget);
    Tree *tree = new Tree(&widget);
    QVBoxLayout *lay = new QVBoxLayout(&widget);
    lay->addWidget(button);
    QObject::connect(button, SIGNAL(clicked()), proxyModel, SLOT(hideEverythingButA1AndChildren()));
    lay->addWidget(tree);
    widget.show();
    return app.exec();
}
</code>

Revision as of 15:56, 22 June 2018

This article may require cleanup to meet the Qt Wiki's quality standards. Reason: Auto-imported from ExpressionEngine.
Please improve this article if you can. Remove the {{cleanup}} tag and add this page to Updated pages list after it's clean.

Related to this FAQ entry.

#include <QTreeView>
#include <QPushButton>
#include <QVBoxLayout>
#include <QStandardItem>
#include <QApplication>
#include <QAbstractProxyModel>
 
QList<QStandardItem *> list;
 
class SortProxy : public QAbstractProxyModel
{
    Q_OBJECT
 
public:
    SortProxy(QObject *parent = 0) : QAbstractProxyModel(parent), hideThem(false)
    {
        fixModel();
    }
 
    int rowCount(const QModelIndex &parent) const
    {
        QModelIndex sourceParent;
        if (parent.isValid())
            sourceParent = mapToSource(parent);
        int count = 0;
        QMapIterator<QPersistentModelIndex, QPersistentModelIndex> it(proxySourceParent);
        while (it.hasNext()) {
            it.next();
            if (it.value() == sourceParent)
                count++;
        }
        return count;
    }
 
    int columnCount(const QModelIndex &) const
    {
        return 1;
    }
 
    QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const
    {
        QModelIndex sourceParent;
        if (parent.isValid())
            sourceParent = mapToSource(parent);
        QMapIterator<QPersistentModelIndex, QPersistentModelIndex> it(proxySourceParent);
        while (it.hasNext()) {
            it.next();
            if (it.value() == sourceParent && it.key().row() == row &&
                it.key().column() == column)
                return it.key();
        }
        return QModelIndex();
    }
 
    QModelIndex parent(const QModelIndex &child) const
    {
        QModelIndex mi = proxySourceParent.value(child);
        if (mi.isValid())
            return mapFromSource(mi);
        return QModelIndex();
    }
 
    QModelIndex mapToSource(const QModelIndex &proxyIndex) const
    {
        if (!proxyIndex.isValid())
            return QModelIndex();
        return mapping.key(proxyIndex);
    }
 
    QModelIndex mapFromSource(const QModelIndex &sourceIndex) const
    {
        if (!sourceIndex.isValid())
            return QModelIndex();
        return mapping.value(sourceIndex);
    }
 
public slots:
        void hideEverythingButA1AndChildren()
        {
            hideThem = !hideThem;
            // Now we set up the proxy <-> source mappings
            emit layoutAboutToBeChanged();
            fixModel();
            emit layoutChanged();
        }
 
private:
    void fixModel()
    {
        mapping.clear();
        proxySourceParent.clear();
 
        //the following list is already populated
        //in the tree view and we shall browse and
        //customize it here
        for (int i=0;i<list.size();i++)
        {
            //pull out a standard item
            QStandardItem *si = list.at(i);
 
            if (hideThem)
            {
                //if the hide item flag is true
 
                //check if the standard item's text start with 'A'
                //of the item is not parent
                if (!si->text().startsWith("A") || !si->parent())
                    continue;
 
 
                //means that we have encountered item that does not start with 'A'
                //or the item is not the parent
 
                //we pull out the model index by creating the model index with the source items
                //row , column
                QModelIndex proxy = createIndex(si->row(), si->column(), si->index().internalPointer());
 
                //insert the source model's index and the proxy index into the map
                mapping.insert(QPersistentModelIndex(si->index()), proxy);
                QModelIndex sourceParent;
 
                if (si->parent()->parent())
                    sourceParent = si->parent()->index();
                proxySourceParent.insert(proxy, sourceParent);
            }
            else
            {
                QModelIndex proxy = createIndex(si->row(), si->column(), si->index().internalPointer());
                mapping.insert(QPersistentModelIndex(si->index()), proxy);
                QModelIndex sourceParent;
                if (si->parent())
                    sourceParent = si->parent()->index();
                proxySourceParent.insert(proxy, sourceParent);
            }
        }
    }
 
    QMap<QPersistentModelIndex, QPersistentModelIndex> mapping;
    QMap<QPersistentModelIndex, QPersistentModelIndex> proxySourceParent;
    bool hideThem;
};
 
SortProxy *proxyModel = 0;
 
class Tree : public QTreeView
{
    Q_OBJECT
 
public:
    Tree(QWidget *parent = 0) : QTreeView(parent)
    {
        QStandardItemModel *sourceModel = new QStandardItemModel(this);
 
        QStandardItem *parentA = sourceModel->invisibleRootItem();
        for (int i = 0; i < 2; ++i) {
            itemA = new QStandardItem(QString("A %0").arg(i));
            parentA->appendRow(itemA);
            parentA = itemA;
            list.append(itemA);
        }
        itemA = new QStandardItem(QString("A 2"));
        parentA->appendRow(itemA);
        list.append(itemA);
        itemA3 = new QStandardItem(QString("A 3"));
        list.append(itemA3);
        parentA->appendRow(itemA3);
        itemA4 = new QStandardItem(QString("A 4"));
        list.append(itemA4);
        parentA->appendRow(itemA4);
        itemNonA = new QStandardItem(QString("Non A"));
        list.append(itemNonA);
        parentA->appendRow(itemNonA);
 
        QStandardItem *parentB = sourceModel->invisibleRootItem();
        for (int i = 0; i < 3; ++i) {
            itemB = new QStandardItem(QString("B %0").arg(i));
            parentB->appendRow(itemB);
            parentB = itemB;
            list.append(itemB);
        }
 
        QStandardItem *parentC = sourceModel->invisibleRootItem();
        for (int i = 0; i < 3; ++i) {
            itemC = new QStandardItem(QString("C %0").arg(i));
            parentC->appendRow(itemC);
            parentC = itemC;
            list.append(itemC);
 
        }
 
        proxyModel = new SortProxy(this);
        proxyModel->setSourceModel(sourceModel);
        setModel(proxyModel);
        expandAll();
    }
    QStandardItem *itemA;
    QStandardItem *itemA3;
    QStandardItem *itemA4;
    QStandardItem *itemNonA;
    QStandardItem *itemB;
    QStandardItem *itemC;
};
 
 
#include "main.moc"
 
int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    QWidget widget;
    QPushButton *button = new QPushButton("Make only A1 + 'A' children visible", &widget);
    Tree *tree = new Tree(&widget);
    QVBoxLayout *lay = new QVBoxLayout(&widget);
    lay->addWidget(button);
    QObject::connect(button, SIGNAL(clicked()), proxyModel, SLOT(hideEverythingButA1AndChildren()));
    lay->addWidget(tree);
    widget.show();
    return app.exec();
}