Difference between revisions of "Proxy model example code"

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(Fixed broken-formatted source code to the version at https://tinyurl.com/ycfgrbek and updated it to compile for Qt 5)
 
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[[Category:snippets]]<br />[[Category:HowTo]]<br />[[Category:Developing with Qt]]
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{{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.
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[[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>
 
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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
 
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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>

Latest revision as of 15:56, 22 June 2018

Related to this FAQ entry.
  1. include <QTreeView>
  2. include <QPushButton>
  3. include <QVBoxLayout>
  4. include <QStandardItem>
  5. include <QApplication>
  6. 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; };
  1. 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(); }