Qt Slot Derived Class
2021年4月3日Register here: http://gg.gg/owon0
*Qt Slot Derived Classes
*Qt Slot Derived Classic
I’ve been using Qt for several years now in a couple different projects. Only today did I learn about QMetaObject::connectSlotsByName.
As the documentation states, this function will recursively search the given object for signals matching the format of:
Qt’s signals and slots mechanism does not require classes to have knowledge of each other, which makes it much easier to develop highly reusable classes. Since signals and slots are type-safe, type errors are reported as warnings and do not cause crashes to occur. For example, if a Quit button’s clicked signal is connected to the application. If I instantiate a new instance of the derived class.aTestslot seems to be populated in the method because I can print it out, viz An object of class ’OPAppt’ Slot ’ClinicName’: 1 ’Unknown’ Slot ’EventName’: 1 ’An Event’.
If you’re using Qt Designer and MOC’ing, this fuction gets called automatically in your ui_<mainwindow>.h file inside of setupUi(). This means that you don’t have to manually connect the objects in your .ui files. I didn’t know this! You can simply do something like:
And that’s it! You don’t have to define the signals/slots in Designer, you don’t have to manually connect them (as I had been doing). Nothing! It just works!
I had never seen this mentioned in any tutorial or even code examples. I only stumbled upon it when looking at another project for something completely unrelated. But this is a great time saver!
The QCheckBox widget provides a checkbox with a text label. More... Header:#include <QCheckBox> qmake: QT += widgets Inherits:QAbstractButtonProperties
*tristate : boolQt Slot Derived ClassesPublic FunctionsQCheckBox(const QString &text, QWidget *parent = nullptr)QCheckBox(QWidget *parent = nullptr) virtual ~QCheckBox() Qt::CheckState checkState() const bool isTristate() const void setCheckState(Qt::CheckState state) void setTristate(bool y = true)Reimplemented Public Functions virtual QSize minimumSizeHint() const override virtual QSize sizeHint() const overrideSignalsProtected Functions void initStyleOption(QStyleOptionButton *option) constReimplemented Protected Functions virtual void checkStateSet() override virtual bool event(QEvent *e) override virtual bool hitButton(const QPoint &pos) const override virtual void mouseMoveEvent(QMouseEvent *e) override virtual void nextCheckState() override virtual void paintEvent(QPaintEvent *) overrideDetailed Description
A QCheckBox is an option button that can be switched on (checked) or off (unchecked). Checkboxes are typically used to represent features in an application that can be enabled or disabled without affecting others. Different types of behavior can be implemented. For example, a QButtonGroup can be used to group check buttons logically, allowing exclusive checkboxes. However, QButtonGroup does not provide any visual representation.
The image below further illustrates the differences between exclusive and non-exclusive checkboxes.
Whenever a checkbox is checked or cleared, it emits the signal stateChanged(). Connect to this signal if you want to trigger an action each time the checkbox changes state. You can use isChecked() to query whether or not a checkbox is checked.
In addition to the usual checked and unchecked states, QCheckBox optionally provides a third state to indicate ’no change’. This is useful whenever you need to give the user the option of neither checking nor unchecking a checkbox. If you need this third state, enable it with setTristate(), and use checkState() to query the current toggle state.
Just like QPushButton, a checkbox displays text, and optionally a small icon. The icon is set with setIcon(). The text can be set in the constructor or with setText(). A shortcut key can be specified by preceding the preferred character with an ampersand. For example:
In this example, the shortcut is Alt+A. See the QShortcut documentation for details. To display an actual ampersand, use ’&&’.
Important inherited functions: text(), setText(), text(), pixmap(), setPixmap(), accel(), setAccel(), isToggleButton(), setDown(), isDown(), isOn(), checkState(), autoRepeat(), isExclusiveToggle(), group(), setAutoRepeat(), toggle(), pressed(), released(), clicked(), toggled(), checkState(), and stateChanged().
See also QAbstractButton, QRadioButton, and GUI Design Handbook: Check Box.Property Documentationtristate : bool
This property holds whether the checkbox is a tri-state checkbox
The default is false, i.e., the checkbox has only two states.
Access functions: bool isTristate() const void setTristate(bool y = true)Member Function DocumentationQCheckBox::QCheckBox(const QString &text, QWidget *parent = nullptr)
Constructs a checkbox with the given parent and text.
parent is passed on to the QAbstractButton constructor.QCheckBox::QCheckBox(QWidget *parent = nullptr)
Constructs a checkbox with the given parent, but with no text.
parent is passed on to the QAbstractButton constructor.[signal] void QCheckBox::stateChanged(intstate)
This signal is emitted whenever the checkbox’s state changes, i.e., whenever the user checks or unchecks it.
state contains the checkbox’s new Qt::CheckState.[virtual] QCheckBox::~QCheckBox()
Destructor.Qt::CheckState QCheckBox::checkState() const
Returns the checkbox’s check state. If you do not need tristate support, you can also use QAbstractButton::isChecked(), which returns a boolean.
See also setCheckState() and Qt::CheckState.[override virtual protected] void QCheckBox::checkStateSet()Qt Slot Derived Classic
Reimplements: QAbstractButton::checkStateSet().[override virtual protected] bool QCheckBox::event(QEvent *e)
Reimplements: QAbstractButton::event(QEvent *e).[override virtual protected] bool QCheckBox::hitButton(const QPoint &pos) const
Reimplements: QAbstractButton::hitButton(const QPoint &pos) const.[protected] void QCheckBox::initStyleOption(QStyleOptionButton *option) const
Initializes option with the values from this QCheckBox. This method is useful for subclasses that require a QStyleOptionButton, but do not want to fill in all the information themselves.
See also QStyleOption::initFrom().[override virtual] QSize QCheckBox::minimumSizeHint() const
Reimplements an access function for property: QWidget::minimumSizeHint.[override virtual protected] void QCheckBox::mouseMoveEvent(QMouseEvent *e)
Reimplements: QAbstractButton::mouseMoveEvent(QMouseEvent *e).[override virtual protected] void QCheckBox::nextCheckState()
Reimplements: QAbstractButton::nextCheckState().[override virtual protected] void QCheckBox::paintEvent(QPaintEvent *)
Reimplements: QAbstractButton::paintEvent(QPaintEvent *e).void QCheckBox::setCheckState(Qt::CheckStatestate)
Sets the checkbox’s check state to state. If you do not need tristate support, you can also use QAbstractButton::setChecked(), which takes a boolean.
See also checkState() and Qt::CheckState.[override virtual] QSize QCheckBox::sizeHint() const
Reimplements an access function for property: QWidget::sizeHint.
© 2020 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.
Register here: http://gg.gg/owon0
https://diarynote.indered.space
*Qt Slot Derived Classes
*Qt Slot Derived Classic
I’ve been using Qt for several years now in a couple different projects. Only today did I learn about QMetaObject::connectSlotsByName.
As the documentation states, this function will recursively search the given object for signals matching the format of:
Qt’s signals and slots mechanism does not require classes to have knowledge of each other, which makes it much easier to develop highly reusable classes. Since signals and slots are type-safe, type errors are reported as warnings and do not cause crashes to occur. For example, if a Quit button’s clicked signal is connected to the application. If I instantiate a new instance of the derived class.aTestslot seems to be populated in the method because I can print it out, viz An object of class ’OPAppt’ Slot ’ClinicName’: 1 ’Unknown’ Slot ’EventName’: 1 ’An Event’.
If you’re using Qt Designer and MOC’ing, this fuction gets called automatically in your ui_<mainwindow>.h file inside of setupUi(). This means that you don’t have to manually connect the objects in your .ui files. I didn’t know this! You can simply do something like:
And that’s it! You don’t have to define the signals/slots in Designer, you don’t have to manually connect them (as I had been doing). Nothing! It just works!
I had never seen this mentioned in any tutorial or even code examples. I only stumbled upon it when looking at another project for something completely unrelated. But this is a great time saver!
The QCheckBox widget provides a checkbox with a text label. More... Header:#include <QCheckBox> qmake: QT += widgets Inherits:QAbstractButtonProperties
*tristate : boolQt Slot Derived ClassesPublic FunctionsQCheckBox(const QString &text, QWidget *parent = nullptr)QCheckBox(QWidget *parent = nullptr) virtual ~QCheckBox() Qt::CheckState checkState() const bool isTristate() const void setCheckState(Qt::CheckState state) void setTristate(bool y = true)Reimplemented Public Functions virtual QSize minimumSizeHint() const override virtual QSize sizeHint() const overrideSignalsProtected Functions void initStyleOption(QStyleOptionButton *option) constReimplemented Protected Functions virtual void checkStateSet() override virtual bool event(QEvent *e) override virtual bool hitButton(const QPoint &pos) const override virtual void mouseMoveEvent(QMouseEvent *e) override virtual void nextCheckState() override virtual void paintEvent(QPaintEvent *) overrideDetailed Description
A QCheckBox is an option button that can be switched on (checked) or off (unchecked). Checkboxes are typically used to represent features in an application that can be enabled or disabled without affecting others. Different types of behavior can be implemented. For example, a QButtonGroup can be used to group check buttons logically, allowing exclusive checkboxes. However, QButtonGroup does not provide any visual representation.
The image below further illustrates the differences between exclusive and non-exclusive checkboxes.
Whenever a checkbox is checked or cleared, it emits the signal stateChanged(). Connect to this signal if you want to trigger an action each time the checkbox changes state. You can use isChecked() to query whether or not a checkbox is checked.
In addition to the usual checked and unchecked states, QCheckBox optionally provides a third state to indicate ’no change’. This is useful whenever you need to give the user the option of neither checking nor unchecking a checkbox. If you need this third state, enable it with setTristate(), and use checkState() to query the current toggle state.
Just like QPushButton, a checkbox displays text, and optionally a small icon. The icon is set with setIcon(). The text can be set in the constructor or with setText(). A shortcut key can be specified by preceding the preferred character with an ampersand. For example:
In this example, the shortcut is Alt+A. See the QShortcut documentation for details. To display an actual ampersand, use ’&&’.
Important inherited functions: text(), setText(), text(), pixmap(), setPixmap(), accel(), setAccel(), isToggleButton(), setDown(), isDown(), isOn(), checkState(), autoRepeat(), isExclusiveToggle(), group(), setAutoRepeat(), toggle(), pressed(), released(), clicked(), toggled(), checkState(), and stateChanged().
See also QAbstractButton, QRadioButton, and GUI Design Handbook: Check Box.Property Documentationtristate : bool
This property holds whether the checkbox is a tri-state checkbox
The default is false, i.e., the checkbox has only two states.
Access functions: bool isTristate() const void setTristate(bool y = true)Member Function DocumentationQCheckBox::QCheckBox(const QString &text, QWidget *parent = nullptr)
Constructs a checkbox with the given parent and text.
parent is passed on to the QAbstractButton constructor.QCheckBox::QCheckBox(QWidget *parent = nullptr)
Constructs a checkbox with the given parent, but with no text.
parent is passed on to the QAbstractButton constructor.[signal] void QCheckBox::stateChanged(intstate)
This signal is emitted whenever the checkbox’s state changes, i.e., whenever the user checks or unchecks it.
state contains the checkbox’s new Qt::CheckState.[virtual] QCheckBox::~QCheckBox()
Destructor.Qt::CheckState QCheckBox::checkState() const
Returns the checkbox’s check state. If you do not need tristate support, you can also use QAbstractButton::isChecked(), which returns a boolean.
See also setCheckState() and Qt::CheckState.[override virtual protected] void QCheckBox::checkStateSet()Qt Slot Derived Classic
Reimplements: QAbstractButton::checkStateSet().[override virtual protected] bool QCheckBox::event(QEvent *e)
Reimplements: QAbstractButton::event(QEvent *e).[override virtual protected] bool QCheckBox::hitButton(const QPoint &pos) const
Reimplements: QAbstractButton::hitButton(const QPoint &pos) const.[protected] void QCheckBox::initStyleOption(QStyleOptionButton *option) const
Initializes option with the values from this QCheckBox. This method is useful for subclasses that require a QStyleOptionButton, but do not want to fill in all the information themselves.
See also QStyleOption::initFrom().[override virtual] QSize QCheckBox::minimumSizeHint() const
Reimplements an access function for property: QWidget::minimumSizeHint.[override virtual protected] void QCheckBox::mouseMoveEvent(QMouseEvent *e)
Reimplements: QAbstractButton::mouseMoveEvent(QMouseEvent *e).[override virtual protected] void QCheckBox::nextCheckState()
Reimplements: QAbstractButton::nextCheckState().[override virtual protected] void QCheckBox::paintEvent(QPaintEvent *)
Reimplements: QAbstractButton::paintEvent(QPaintEvent *e).void QCheckBox::setCheckState(Qt::CheckStatestate)
Sets the checkbox’s check state to state. If you do not need tristate support, you can also use QAbstractButton::setChecked(), which takes a boolean.
See also checkState() and Qt::CheckState.[override virtual] QSize QCheckBox::sizeHint() const
Reimplements an access function for property: QWidget::sizeHint.
© 2020 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.
Register here: http://gg.gg/owon0
https://diarynote.indered.space
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