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authorQt by Nokia <qt-info@nokia.com>2011-04-27 12:05:43 +0200
committeraxis <qt-info@nokia.com>2011-04-27 12:05:43 +0200
commit38be0d13830efd2d98281c645c3a60afe05ffece (patch)
tree6ea73f3ec77f7d153333779883e8120f82820abe /doc/src/snippets/code/src_corelib_kernel_qobject.cpp
Initial import from the monolithic Qt.
This is the beginning of revision history for this module. If you want to look at revision history older than this, please refer to the Qt Git wiki for how to use Git history grafting. At the time of writing, this wiki is located here: http://qt.gitorious.org/qt/pages/GitIntroductionWithQt If you have already performed the grafting and you don't see any history beyond this commit, try running "git log" with the "--follow" argument. Branched from the monolithic repo, Qt master branch, at commit 896db169ea224deb96c59ce8af800d019de63f12
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+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+** * Redistributions of source code must retain the above copyright
+** notice, this list of conditions and the following disclaimer.
+** * Redistributions in binary form must reproduce the above copyright
+** notice, this list of conditions and the following disclaimer in
+** the documentation and/or other materials provided with the
+** distribution.
+** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
+** the names of its contributors may be used to endorse or promote
+** products derived from this software without specific prior written
+** permission.
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//! [0]
+QLineEdit *lineEdit = static_cast<QLineEdit *>(
+ qt_find_obj_child(myWidget, "QLineEdit", "my line edit"));
+if (lineEdit)
+ lineEdit->setText("Default");
+//! [0]
+
+
+//! [1]
+QObject *obj = new QPushButton;
+obj->metaObject()->className(); // returns "QPushButton"
+
+QPushButton::staticMetaObject.className(); // returns "QPushButton"
+//! [1]
+
+
+//! [2]
+QPushButton::staticMetaObject.className(); // returns "QPushButton"
+
+QObject *obj = new QPushButton;
+obj->metaObject()->className(); // returns "QPushButton"
+//! [2]
+
+
+//! [3]
+QObject *obj = new QTimer; // QTimer inherits QObject
+
+QTimer *timer = qobject_cast<QTimer *>(obj);
+// timer == (QObject *)obj
+
+QAbstractButton *button = qobject_cast<QAbstractButton *>(obj);
+// button == 0
+//! [3]
+
+
+//! [4]
+QTimer *timer = new QTimer; // QTimer inherits QObject
+timer->inherits("QTimer"); // returns true
+timer->inherits("QObject"); // returns true
+timer->inherits("QAbstractButton"); // returns false
+
+// QVBoxLayout inherits QObject and QLayoutItem
+QVBoxLayout *layout = new QVBoxLayout;
+layout->inherits("QObject"); // returns true
+layout->inherits("QLayoutItem"); // returns true (even though QLayoutItem is not a QObject)
+//! [4]
+
+
+//! [5]
+qDebug("MyClass::setPrecision(): (%s) invalid precision %f",
+ qPrintable(objectName()), newPrecision);
+//! [5]
+
+
+//! [6]
+class MainWindow : public QMainWindow
+{
+public:
+ MainWindow();
+
+protected:
+ bool eventFilter(QObject *obj, QEvent *ev);
+
+private:
+ QTextEdit *textEdit;
+};
+
+MainWindow::MainWindow()
+{
+ textEdit = new QTextEdit;
+ setCentralWidget(textEdit);
+
+ textEdit->installEventFilter(this);
+}
+
+bool MainWindow::eventFilter(QObject *obj, QEvent *event)
+{
+ if (obj == textEdit) {
+ if (event->type() == QEvent::KeyPress) {
+ QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
+ qDebug() << "Ate key press" << keyEvent->key();
+ return true;
+ } else {
+ return false;
+ }
+ } else {
+ // pass the event on to the parent class
+ return QMainWindow::eventFilter(obj, event);
+ }
+}
+//! [6]
+
+
+//! [7]
+myObject->moveToThread(QApplication::instance()->thread());
+//! [7]
+
+
+//! [8]
+class MyObject : public QObject
+{
+ Q_OBJECT
+
+public:
+ MyObject(QObject *parent = 0);
+
+protected:
+ void timerEvent(QTimerEvent *event);
+};
+
+MyObject::MyObject(QObject *parent)
+ : QObject(parent)
+{
+ startTimer(50); // 50-millisecond timer
+ startTimer(1000); // 1-second timer
+ startTimer(60000); // 1-minute timer
+}
+
+void MyObject::timerEvent(QTimerEvent *event)
+{
+ qDebug() << "Timer ID:" << event->timerId();
+}
+//! [8]
+
+
+//! [9]
+QList<QObject *> list = window()->queryList("QAbstractButton"));
+foreach (QObject *obj, list)
+ static_cast<QAbstractButton *>(obj)->setEnabled(false);
+//! [9]
+
+
+//! [10]
+QPushButton *button = parentWidget->findChild<QPushButton *>("button1");
+//! [10]
+
+
+//! [11]
+QListWidget *list = parentWidget->findChild<QListWidget *>();
+//! [11]
+
+
+//! [12]
+QList<QWidget *> widgets = parentWidget.findChildren<QWidget *>("widgetname");
+//! [12]
+
+
+//! [13]
+QList<QPushButton *> allPButtons = parentWidget.findChildren<QPushButton *>();
+//! [13]
+
+
+//! [14]
+monitoredObj->installEventFilter(filterObj);
+//! [14]
+
+
+//! [15]
+class KeyPressEater : public QObject
+{
+ Q_OBJECT
+ ...
+
+protected:
+ bool eventFilter(QObject *obj, QEvent *event);
+};
+
+bool KeyPressEater::eventFilter(QObject *obj, QEvent *event)
+{
+ if (event->type() == QEvent::KeyPress) {
+ QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
+ qDebug("Ate key press %d", keyEvent->key());
+ return true;
+ } else {
+ // standard event processing
+ return QObject::eventFilter(obj, event);
+ }
+}
+//! [15]
+
+
+//! [16]
+KeyPressEater *keyPressEater = new KeyPressEater(this);
+QPushButton *pushButton = new QPushButton(this);
+QListView *listView = new QListView(this);
+
+pushButton->installEventFilter(keyPressEater);
+listView->installEventFilter(keyPressEater);
+//! [16]
+
+
+//! [17]
+MyWindow::MyWindow()
+{
+ QLabel *senderLabel = new QLabel(tr("Name:"));
+ QLabel *recipientLabel = new QLabel(tr("Name:", "recipient"));
+//! [17]
+}
+
+
+//! [18]
+int n = messages.count();
+showMessage(tr("%n message(s) saved", "", n));
+//! [18]
+
+
+//! [19]
+n == 1 ? tr("%n message saved") : tr("%n messages saved")
+//! [19]
+
+
+//! [20]
+label->setText(tr("F\374r \310lise"));
+//! [20]
+
+
+//! [21]
+if (receivers(SIGNAL(valueChanged(QByteArray))) > 0) {
+ QByteArray data;
+ get_the_value(&data); // expensive operation
+ emit valueChanged(data);
+}
+//! [21]
+
+
+//! [22]
+QLabel *label = new QLabel;
+QScrollBar *scrollBar = new QScrollBar;
+QObject::connect(scrollBar, SIGNAL(valueChanged(int)),
+ label, SLOT(setNum(int)));
+//! [22]
+
+
+//! [23]
+// WRONG
+QObject::connect(scrollBar, SIGNAL(valueChanged(int value)),
+ label, SLOT(setNum(int value)));
+//! [23]
+
+
+//! [24]
+class MyWidget : public QWidget
+{
+ Q_OBJECT
+
+public:
+ MyWidget();
+
+signals:
+ void buttonClicked();
+
+private:
+ QPushButton *myButton;
+};
+
+MyWidget::MyWidget()
+{
+ myButton = new QPushButton(this);
+ connect(myButton, SIGNAL(clicked()),
+ this, SIGNAL(buttonClicked()));
+}
+//! [24]
+
+
+//! [25]
+QObject::connect: Cannot queue arguments of type 'MyType'
+(Make sure 'MyType' is registered using qRegisterMetaType().)
+//! [25]
+
+
+//! [26]
+disconnect(myObject, 0, 0, 0);
+//! [26]
+
+
+//! [27]
+myObject->disconnect();
+//! [27]
+
+
+//! [28]
+disconnect(myObject, SIGNAL(mySignal()), 0, 0);
+//! [28]
+
+
+//! [29]
+myObject->disconnect(SIGNAL(mySignal()));
+//! [29]
+
+
+//! [30]
+disconnect(myObject, 0, myReceiver, 0);
+//! [30]
+
+
+//! [31]
+myObject->disconnect(myReceiver);
+//! [31]
+
+
+//! [32]
+if (QLatin1String(signal) == SIGNAL(valueChanged(int))) {
+ // signal is valueChanged(int)
+}
+//! [32]
+
+
+//! [33]
+void on_<object name>_<signal name>(<signal parameters>);
+//! [33]
+
+
+//! [34]
+void on_button1_clicked();
+//! [34]
+
+
+//! [35]
+class MyClass : public QObject
+{
+ Q_OBJECT
+ Q_CLASSINFO("Author", "Pierre Gendron")
+ Q_CLASSINFO("URL", "http://www.my-organization.qc.ca")
+
+public:
+ ...
+};
+//! [35]
+
+
+//! [36]
+Q_PROPERTY(type name
+ READ getFunction
+ [WRITE setFunction]
+ [RESET resetFunction]
+ [NOTIFY notifySignal]
+ [DESIGNABLE bool]
+ [SCRIPTABLE bool]
+ [STORED bool]
+ [USER bool]
+ [CONSTANT]
+ [FINAL])
+//! [36]
+
+
+//! [37]
+Q_PROPERTY(QString title READ title WRITE setTitle USER true)
+//! [37]
+
+
+//! [38]
+class MyClass : public QObject
+{
+ Q_OBJECT
+ Q_ENUMS(Priority)
+
+public:
+ MyClass(QObject *parent = 0);
+ ~MyClass();
+
+ enum Priority { High, Low, VeryHigh, VeryLow };
+ void setPriority(Priority priority);
+ Priority priority() const;
+};
+//! [38]
+
+
+//! [39a]
+class QLibrary : public QObject
+{
+ ...
+ Q_FLAGS(LoadHint LoadHints)
+ ...
+//! [39a]
+
+//! [39b]
+ ...
+public:
+ enum LoadHint {
+ ResolveAllSymbolsHint = 0x01,
+ ExportExternalSymbolsHint = 0x02,
+ LoadArchiveMemberHint = 0x04
+ };
+ Q_DECLARE_FLAGS(LoadHints, LoadHint)
+ ...
+//! [39b]
+
+
+//! [40]
+//: This name refers to a host name.
+hostNameLabel->setText(tr("Name:"));
+
+/*: This text refers to a C++ code example. */
+QString example = tr("Example");
+//! [40]
+
+//! [meta data]
+//: This is a comment for the translator.
+//= qtn_foo_bar
+//~ loc-layout_id foo_dialog
+//~ loc-blank False
+//~ magic-stuff This might mean something magic.
+QString text = MyMagicClass::tr("Sim sala bim.");
+//! [meta data]
+
+//! [explicit tr context]
+QString text = QScrollBar::tr("Page up");
+//! [explicit tr context]