The Tree Model Completer example shows how to provide completion facilities for a hierarchical model, using a period as the separator to access Child, GrandChild and GrandGrandChild level objects.
类似于 补全器范例 ，提供 QComboBox objects to enable selection for completion mode and case sensitivity, as well as a QCheckBox for wrap completions.
The contents of the TreeModelCompleter is read from treemodel.txt . This file is embedded within the treemodelcompleter.qrc resource file, which contains the following:
<!DOCTYPE RCC><RCC version="1.0"> <qresource prefix="/"> <file>resources/treemodel.txt</file> </qresource> </RCC>
The
TreeModelCompleter
是子类化的
QCompleter
with two constructors - one with
parent
as an argument and another with
parent
and
model
as arguments.
class TreeModelCompleter : public QCompleter { Q_OBJECT Q_PROPERTY(QString separator READ separator WRITE setSeparator) public: explicit TreeModelCompleter(QObject *parent = nullptr); explicit TreeModelCompleter(QAbstractItemModel *model, QObject *parent = nullptr); QString separator() const; public slots: void setSeparator(const QString &separator); protected: QStringList splitPath(const QString &path) const override; QString pathFromIndex(const QModelIndex &index) const override; private: QString sep; };
The class reimplements the protected functions splitPath () 和 pathFromIndex () to suit a tree model. For more information on customizing QCompleter to suit tree models, refer to 处理树模型 .
TreeModelCompleter
also has a separator property which is declared using the
Q_PROPERTY
() macro. The separator has READ and WRITE attributes and the corresponding functions
separator()
and
setSeparator()
. For more information on
Q_PROPERTY
(), refer to
Qt 的特性系统
.
The first constructor constructs a
TreeModelCompleter
object with a parent while the second constructor constructs an object with a parent and a
QAbstractItemModel
,
model
.
TreeModelCompleter::TreeModelCompleter(QObject *parent) : QCompleter(parent) { } TreeModelCompleter::TreeModelCompleter(QAbstractItemModel *model, QObject *parent) : QCompleter(model, parent) { }
The
separator()
function is a getter function that returns the separator string.
QString TreeModelCompleter::separator() const { return sep; }
As mentioned earlier, the
splitPath()
function is reimplemented because the default implementation is more suited to
QFileSystemModel
or list models. In order for
QCompleter
to split the path into a list of strings that are matched at each level, we split it using
QString::split
() 采用
sep
as its separator.
QStringList TreeModelCompleter::splitPath(const QString &path) const { return (sep.isNull() ? QCompleter::splitPath(path) : path.split(sep)); }
The
pathFromIndex()
function returns data for the completionRole() for a tree model. This function is reimplemented as its default implementation is more suitable for list models. If there is no separator, we use
QCompleter
's default implementation, otherwise we use the
prepend
() function to navigate upwards and accumulate the data. The function then returns a
QStringList
,
dataList
, using a separator to join objects of different levels.
QString TreeModelCompleter::pathFromIndex(const QModelIndex &index) const { if (sep.isNull()) return QCompleter::pathFromIndex(index); // navigate up and accumulate data QStringList dataList; for (QModelIndex i = index; i.isValid(); i = i.parent()) dataList.prepend(model()->data(i, completionRole()).toString()); return dataList.join(sep); }
The
MainWindow
类是子类化的
QMainWindow
and implements five custom slots:
about()
,
changeCase()
,
changeMode()
,
highlight()
，和
updateContentsLabel()
.
class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = nullptr); private slots: void about(); void changeCase(int); void changeMode(int); void highlight(const QModelIndex &index); void updateContentsLabel(const QString &sep);
In addition, the class has two private functions,
createMenu()
and
modelFromFile()
, as well as private instances of
QTreeView
,
QComboBox
,
QLabel
,
TreeModelCompleter
and
QLineEdit
.
private: void createMenu(); QAbstractItemModel *modelFromFile(const QString &fileName); QTreeView *treeView = nullptr; QComboBox *caseCombo = nullptr; QComboBox *modeCombo = nullptr; QLabel *contentsLabel = nullptr; TreeModelCompleter *completer = nullptr; QLineEdit *lineEdit = nullptr; };
The
MainWindow
's constructor creates a
MainWindow
object with a parent and initializes the
completer
and
lineEdit
。
createMenu()
function is invoked to set up the "File" menu and "Help" menu. The
completer
's model is set to the
QAbstractItemModel
obtained from
modelFromFile()
，和
highlighted
() signal is connected to
MainWindow
's
highlight()
槽。
MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { createMenu(); completer = new TreeModelCompleter(this); completer->setModel(modelFromFile(":/resources/treemodel.txt")); completer->setSeparator(QLatin1String(".")); QObject::connect(completer, QOverload<const QModelIndex &>::of(&TreeModelCompleter::highlighted), this, &MainWindow::highlight); QWidget *centralWidget = new QWidget; QLabel *modelLabel = new QLabel; modelLabel->setText(tr("Tree Model<br>(Double click items to edit)")); QLabel *modeLabel = new QLabel; modeLabel->setText(tr("Completion Mode")); modeCombo = new QComboBox; modeCombo->addItem(tr("Inline")); modeCombo->addItem(tr("Filtered Popup")); modeCombo->addItem(tr("Unfiltered Popup")); modeCombo->setCurrentIndex(1); QLabel *caseLabel = new QLabel; caseLabel->setText(tr("Case Sensitivity")); caseCombo = new QComboBox; caseCombo->addItem(tr("Case Insensitive")); caseCombo->addItem(tr("Case Sensitive")); caseCombo->setCurrentIndex(0);
The
QLabel
对象
modelLabel
,
modeLabel
and
caseLabel
are instantiated. Also, the
QComboBox
对象，
modeCombo
and
caseCombo
, are instantiated and populated. By default, the
completer
's mode is "Filtered Popup" and the case is insensitive.
QLabel *separatorLabel = new QLabel;
separatorLabel->setText(tr("Tree Separator"));
QLineEdit *separatorLineEdit = new QLineEdit;
separatorLineEdit->setText(completer->separator());
connect(separatorLineEdit, &QLineEdit::textChanged,
completer, &TreeModelCompleter::setSeparator);
QCheckBox *wrapCheckBox = new QCheckBox;
wrapCheckBox->setText(tr("Wrap around completions"));
wrapCheckBox->setChecked(completer->wrapAround());
connect(wrapCheckBox, &QAbstractButton::clicked, completer, &QCompleter::setWrapAround);
contentsLabel = new QLabel;
contentsLabel->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
connect(separatorLineEdit, &QLineEdit::textChanged,
this, &MainWindow::updateContentsLabel);
treeView = new QTreeView;
treeView->setModel(completer->model());
treeView->header()->hide();
treeView->expandAll();
connect(modeCombo, &QComboBox::activated,
this, &MainWindow::changeMode);
connect(caseCombo, &QComboBox::activated,
this, &MainWindow::changeMode);
lineEdit = new QLineEdit;
lineEdit->setCompleter(completer);
使用
QGridLayout
to place all the objects in the
MainWindow
.
QGridLayout *layout = new QGridLayout;
layout->addWidget(modelLabel, 0, 0); layout->addWidget(treeView, 0, 1);
layout->addWidget(modeLabel, 1, 0); layout->addWidget(modeCombo, 1, 1);
layout->addWidget(caseLabel, 2, 0); layout->addWidget(caseCombo, 2, 1);
layout->addWidget(separatorLabel, 3, 0); layout->addWidget(separatorLineEdit, 3, 1);
layout->addWidget(wrapCheckBox, 4, 0);
layout->addWidget(contentsLabel, 5, 0, 1, 2);
layout->addWidget(lineEdit, 6, 0, 1, 2);
centralWidget->setLayout(layout);
setCentralWidget(centralWidget);
changeCase(caseCombo->currentIndex());
changeMode(modeCombo->currentIndex());
setWindowTitle(tr("Tree Model Completer"));
lineEdit->setFocus();
}
The
createMenu()
function sets up the
QAction
objects required and adds them to the "File" menu and "Help" menu. The
triggered
() signals from these actions are connected to their respective slots.
void MainWindow::createMenu() { QAction *exitAction = new QAction(tr("Exit"), this); QAction *aboutAct = new QAction(tr("About"), this); QAction *aboutQtAct = new QAction(tr("About Qt"), this); connect(exitAction, &QAction::triggered, qApp, &QApplication::quit); connect(aboutAct, &QAction::triggered, this, &MainWindow::about); connect(aboutQtAct, &QAction::triggered, qApp, &QApplication::aboutQt); QMenu *fileMenu = menuBar()->addMenu(tr("File")); fileMenu->addAction(exitAction); QMenu *helpMenu = menuBar()->addMenu(tr("About")); helpMenu->addAction(aboutAct); helpMenu->addAction(aboutQtAct); }
The
changeMode()
function accepts an
index
corresponding to the user's choice of completion mode and changes the
completer
's mode accordingly.
void MainWindow::changeMode(int index) { QCompleter::CompletionMode mode; if (index == 0) mode = QCompleter::InlineCompletion; else if (index == 1) mode = QCompleter::PopupCompletion; else mode = QCompleter::UnfilteredPopupCompletion; completer->setCompletionMode(mode); }
The
about()
function provides a brief description on the Tree Model Completer example.
void MainWindow::about() { QMessageBox::about(this, tr("About"), tr("This example demonstrates how " "to use a QCompleter with a custom tree model.")); }
The
changeCase()
function alternates between
区分大小写
and
不区分大小写
modes, depending on the value of
cs
.
void MainWindow::changeCase(int cs) { completer->setCaseSensitivity(cs ? Qt::CaseSensitive : Qt::CaseInsensitive); }
main()
函数
The
main()
function instantiates
MainWindow
and invokes the
show
() function to display it.
int main(int argc, char *argv[]) { QApplication app(argc, argv); MainWindow window; window.show(); return app.exec(); }