I wanted to know what would be the best approach of adding a countdown timer to a QMessageBox ? For instance when a message box is displayed the countdown timer starts for say 5 seconds. If the user doesn't respond to the Message box the message box picks up a default choice.
How about something like this:
#include <QMessageBox>
#include <QPushButton>
#include <QTimer>
class TimedMessageBox : public QMessageBox
{
Q_OBJECT
public:
TimedMessageBox(int timeoutSeconds, const QString & title, const QString & text, Icon icon, int button0, int button1, int button2, QWidget * parent, WindowFlags flags = (WindowFlags)Dialog|MSWindowsFixedSizeDialogHint)
: QMessageBox(title, text, icon, button0, button1, button2, parent, flags)
, _timeoutSeconds(timeoutSeconds+1)
, _text(text)
{
connect(&_timer, SIGNAL(timeout()), this, SLOT(Tick()));
_timer.setInterval(1000);
}
virtual void showEvent(QShowEvent * e)
{
QMessageBox::showEvent(e);
Tick();
_timer.start();
}
private slots:
void Tick()
{
if (--_timeoutSeconds >= 0) setText(_text.arg(_timeoutSeconds));
else
{
_timer.stop();
defaultButton()->animateClick();
}
}
private:
QString _text;
int _timeoutSeconds;
QTimer _timer;
};
[...]
TimedMessageBox * tmb = new TimedMessageBox(10, tr("Timed Message Box"), tr("%1 seconds to go..."), QMessageBox::Warning, QMessageBox::Ok | QMessageBox::Default, QMessageBox::Cancel, QMessageBox::NoButton, this);
int ret = tmb->exec();
delete tmb;
printf("ret=%i\n", ret);
Use QTimer::singleShot with either close(), accept() or reject() slots if you don't need to display the timeout. If you need, then subclass QMessageBox or QDialog and reimplement methods as you want them to be, e.g. reimplement QObject::timerEvent to make text update.
If you want the message box to display the timer value I think you're better off making your own QDialog subclass. Otherwise it sounds simple - display your message with show, start the timer, connect to the timeout slot and manipulate your dialog.
Related
I am new to QT.
How can I press and release a button in Qt ?
In java I do the below program to control key events ?
Robot r = new Robot();
r.keyPress(KeyEvent.VK_ENTER);
r.keyRelease(KeyEvent.VK_ENTER);
I want to press a key in keyboard programatically.
But , How can I do the same thing in QT ?
You can either create QKeyEvent and send them to the application using QApplication::sendEvent(). Or if you want higher level API, you can build your application with QtTest module and use keyClick functions. See https://doc.qt.io/qt-6/qtest.html
In Qt, key presses are handled by the Event System. Like other languages/frameworks events are encapsulated in an object, in Qt's case, QEvent. All subclasses of QObject have a virtual QObject::event(QEvent *e) method to handle event objects sent to it. This method does not directly handle the event, but calls the object's appropriate event handler based on the QEvent::Type enum. In the case of key presses, the QEvent::type() method returns QEvent::KeyPress.
While most events are handled internally without programmer intervention, you may send events manually using the QCoreApplication class or its subclass QGuiApplication. An instance of one of these classes is typically instantiated in the boilerplate main.cpp file created when you generate a new project with Qt Creator. These classes have access to the methods QCoreApplication::sendEvent(QObject *receiver, QEvent *event), which sends an event directly to receiver, and QCoreApplication::postEvent(QObject *receiver, QEvent *event, int priority), which sends the event to Qt's event queue to be processed later.
I've created a project to demonstrate this functionality. This app just displays a plain rectangle which can be either red or blue. The rectangle only switches colors when it receives a QKeyEvent indicating that the C key was pressed. Below the rectangle is a button which programmatically produces this event and sends it to the rectangle's widget. The project went on a bit long and is a bit messy, but I hope it helps some.
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
// Here I modify the boilerplate code to allow MainWindow w to have access
// to QApplication a so that a widget in MainWindow w can use postEvent()
MainWindow w(nullptr, &a);
w.show();
return a.exec();
}
mainwindow.h
#include <QCoreApplication>
#include <QMainWindow>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr, QCoreApplication* app = nullptr);
~MainWindow();
private:
Ui::MainWindow *ui;
};
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGridLayout>
#include <QLabel>
#include "keypressacceptor.h"
#include "keypressgenerator.h"
MainWindow::MainWindow(QWidget *parent, QCoreApplication *app)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
QGridLayout* layout = new QGridLayout(this);
KeyPressAcceptor* kpa = new KeyPressAcceptor(this);
KeyPressGenerator* kpg = new KeyPressGenerator();
kpg->registerReceiver(kpa);
kpg->registerApp(app);
layout->addWidget(kpa);
layout->addWidget(kpg);
centralWidget()->setLayout(layout);
}
MainWindow::~MainWindow()
{
delete ui;
}
keypressacceptor.h
#include <QWidget>
class KeyPressAcceptor : public QWidget
{
Q_OBJECT
public:
explicit KeyPressAcceptor(QWidget *parent = nullptr);
bool handleKeyPress(const int &key);
protected:
bool event(QEvent *event) override;
void paintEvent(QPaintEvent *event) override;
signals:
private:
QColor m_color;
};
keypressacceptor.cpp
#include "keypressacceptor.h"
#include <QEvent>
#include <QKeyEvent>
#include <QPainter>
KeyPressAcceptor::KeyPressAcceptor(QWidget *parent)
: QWidget{parent}
, m_color(QColor(220, 20, 20))
{
// Setting focus policy so that the widget can accept focus.
// This is necessary to process key press events.
setFocusPolicy(Qt::StrongFocus);
}
bool KeyPressAcceptor::handleKeyPress(const int &key)
{
// This method performs some arbitrary action, in this case changing a
// color, to indicate that a key press has been processed.
switch (key) {
case Qt::Key_C:
// If the "C" key was pressed, switch m_color
if (m_color == QColor(220, 20, 20)) {
m_color = QColor(20, 20, 220);
} else {
m_color = QColor(220, 20, 20);
}
// Call update() to tell Qt to repaint this widget once Qt has entered
// the main event loop
update();
return true;
default:
return false;
}
}
bool KeyPressAcceptor::event(QEvent *event)
{
switch (event->type()) {
case QEvent::KeyPress:
// If the received event is of type QEvent::KeyPress, then cast the
// variable event to type QKeyEvent*, then use the event's key()
// method to pass as an argument to this class's handleKeyPress()
// method.
return handleKeyPress(static_cast<QKeyEvent*>(event)->key());
// Note! This overrides QWidget's default behavior upon receiving a
// QKeyEvent event
default:
// Otherwise, be sure to use the class's superclass to process any
// other events.
return QWidget::event(event);
}
}
void KeyPressAcceptor::paintEvent(QPaintEvent *event)
{
// Don't need to use the event parameter in this implementation.
Q_UNUSED(event)
// Want to draw a rectangle centered in the widget whose height is half
// the widget's height and whose width is half the widget's width.
// The color of the rectangle is determined by m_color.
// First define the rectangle using the height and width properties of
// QWidget to determine the rectangle's height, width, and coordinates of
// top left corner.
QRect rect(width() / 4, height() / 4, // Coordinates of top left corner
width() / 2, height() / 2); // Width and height
// Create a QPainter object to paint with
QPainter painter(this);
// Set pen and brush for rectangle's outline and fill respectively.
painter.setPen(QColor(0,0,0)); // Black 1px pen
painter.setBrush(QBrush(m_color)); // Solid fill of color m_color
// Draw the rectangle
painter.drawRect(rect);
}
keypressgenerator.h
#include <QCoreApplication>
#include <QPushButton>
#include <QObject>
class KeyPressGenerator : public QPushButton
{
Q_OBJECT
public:
explicit KeyPressGenerator(QWidget *parent = nullptr);
void registerApp(QCoreApplication* app);
void registerReceiver(QObject* receiver);
public slots:
void generateKeyPress();
private:
QCoreApplication* m_app;
QObject* m_receiver;
};
keypressgenerator.cpp
#include "keypressgenerator.h"
#include <QCoreApplication>
#include <QKeyEvent>
KeyPressGenerator::KeyPressGenerator(QWidget *parent)
: QPushButton{parent}
, m_app(nullptr)
, m_receiver(nullptr)
{
setText("Push Button to Send C Key Press");
// Connect clicked signal to generateKeyPress so when button is clicked
// a programmatically generated keypress is sent to m_receiver
connect(this, &KeyPressGenerator::clicked,
this, &KeyPressGenerator::generateKeyPress);
}
void KeyPressGenerator::registerApp(QCoreApplication *app)
{
m_app = app;
}
void KeyPressGenerator::registerReceiver(QObject *receiver)
{
m_receiver = receiver;
}
void KeyPressGenerator::generateKeyPress()
{
if (m_app == nullptr || m_receiver == nullptr) return;
// Generate the key press event. Check documentation for an explanation of
// the constructor's parameters.
QKeyEvent* event = new QKeyEvent(QEvent::KeyPress, Qt::Key_C, Qt::NoModifier);
m_app->postEvent(m_receiver, event);
}
Trying to show a tool tip on mouse press event and make it popped up for some time. For now it shows only if a mouse button is pressed.
void ::mousePressEvent(QMouseEvent* e)
{
if (!m_isLinkingAvailable)
{
QToolTip::showText(e->screenPos().toPoint(),
tr("Symbol Linking\navailable only for Price"), this);
}
}
According to the Qt Docs, looks like there's an alternate method for this function:
void QToolTip::showText(const QPoint &pos, const QString &text, QWidget *w, const QRect &rect, int msecDisplayTime)
You should be able to specify a time for how long to display the tooltip.
EDIT:
Okay so seems like this method doesn't work as expected with a mousePress event, so here's an alternative using a QTimer:
Add these to your class:
MyConstructor(...params...)
, m_tooltipTimer(new QTimer(this)) // don't forget this line
{
connect(m_tooltipTimer, SIGNAL(timeout()), this, SLOT(updateTooltip()));
setAcceptedMouseButtons(Qt::AllButtons);
}
...
public slots:
void mousePressEvent(QMouseEvent *event) override;
void updateTooltip();
...
private:
QPoint m_tooltipPos;
qint64 m_tooltipTimerStart;
QTimer *m_tooltipTimer;
And then implement these in your .cpp
void ::mousePressEvent(QMouseEvent *event) {
m_tooltipTimer->start(200); // 5x per second, automatically resets timer if already started
m_tooltipTimerStart = QDateTime::currentMSecsSinceEpoch();
m_tooltipPos = event->globalPos();
event->accept();
}
void ::updateTooltip() {
auto howLongShown = QDateTime::currentMSecsSinceEpoch() - m_tooltipTimerStart; // startTime here is the moment of first showing of the tooltip
qDebug() << howLongShown;
if (howLongShown < 1000) { // 1 sec
QToolTip::showText(m_tooltipPos, tr("Test Tooltip")); // Replace this with your own
} else {
QToolTip::hideText();
m_tooltipTimer->stop();
}
}
Thanks to #Ian Burns's answer I have manged to create own approach:
void ::mousePressEvent(QMouseEvent*)
{
QTimer::singleShot(200, [this]()
{
QToolTip::showText(mapToGlobal({}),
tr("Symbol Linking\navailable only for Price"), this);
});
}
Somehow if I show a tooltip inside mousePressEvent method it disappears immediately after I unpress the mouse button. QTimer delays the pop up call and it stays popped for reasonable time.
This is my first time to ask on Stack Overflow. If any suggestion about asking question, please let me know.
I am very new to Qt, and have some problems while using event. Hope someone can provide any thoughts.
Background:
I have my custom pushButton, which is rxPushButton in rx.h and rx.cpp. I use on_rxPushButton_clicked to change the image and it works pretty well.
In MainWindow, I need to use some rx so I include the class rx and I want to detect if I press left button of the mouse, I need to know which rx has been pressed and record its id in int rxId in MainWindow.
Problem:
I tried two ways to achieve my goal, including mousePressEvent and eventFilter. I found that I can't detect the mouse pressed signal on any rx, but I can detect it outside rx in other places in Mainwindow. I wonder if the events will conflict, but when I comment on_rxPushButton_clicked in rx.cpp, MainWindow still doesn't work for the problem. So I presume that maybe the space in the screen occupied by rx will not be in control of MainWindow (I can get Debug message "test1" but not "test2" in my code, check below).
How should I do to solve this problem if I need both things (change image in rx and modify one variable in MainWindow)? Or maybe it's just something wrong with my code and how to modify?
I hope to separate them if possible because I still need to include many objects in MainWindow in the future.
Here are some of my related codes:
rx.cpp
void rx::on_rxPushButton_clicked(void)
{
startLoading();
}
void rx::startLoading(void)
{
state = 1;
connect(timer, SIGNAL(timeout()), this, SLOT(loading1()));
timer->start(LOADING_INTERVAL);
}
void rx::loading1(void)
{
if(state == 1)
{
state = 2;
ui->rxPushButton->setStyleSheet("border-image: url(:/images/Rx/Rxloading1.png);");
disconnect(timer, SIGNAL(timeout()), this, SLOT(loading1()));
}
}
mainwindow.cpp
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
for(int i = 0 ; i < rxSize ; i++)
{
rxList << new rx(this);
int j = i/rxHorizontalCount;
rxList[i]->setGeometry(500+(i-j*8)*110,10+j*90,100,90);
}
//rxList[0]->installEventFilter(this);
}
void MainWindow::mousePressEvent(QMouseEvent *event)
{
if(event->buttons() & Qt::LeftButton)
{
qDebug() << "test1";
if(rxList[0]->rect().contains(event->x(), event->y()))
qDebug() << "test2";
}
}
Change image in rx
Use QSignalMapper class that bundles signals from QWidgets (class rx) and re-emits them with widget (class rx) parameters corresponding to the object that sent the signal.
We connect each button's clicked() signal to the signal mapper's map() slot, and create a mapping in the signal mapper from each button to the button itself.
Finally we connect the signal mapper's mapped() signal to the custom widget's(rx object) clicked() signal. When the user clicks a button, the custom widget(rx object) will emit a single clicked() signal whose argument is the button (rx object) the user clicked.
Handle the button clicked event in MainWindow::slotButtonsClicked(QWidget *p) function.
Modify n variable in MainWindow:
You can update variable of MainWindow in mousePressEvent function
class MainWindow : public QWidget
{
public :
MainWindow (QWidget *parent);
QSignalMapper * mapper;
slots:
void slotButtonsClicked(QWidget *);
// ...
}
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
mapper = new QSignalMapper(this);
for(int i = 0 ; i < rxSize ; i++)
{
rxList << new rx(this);
int j = i/rxHorizontalCount;
rxList[i]->setGeometry(500+(i-j*8)*110,10+j*90,100,90);
QObject::connect(rxList[i], SIGNAL(clicked()),mapper,SLOT(map()));
//Adds a mapping so that when map() is signalled from the sender, the signal mapped(widget ) is emitted.
mapper->setMapping(rxList[i], rxList[i]);
}
QObject::connect(mapper,SIGNAL(mapped(QWidget *)),this,SLOT(slotButtonsClicked(QWidget *)));
}
void MainWindow::mousePressEvent(QMouseEvent *event)
{
if(event->buttons() & Qt::LeftButton)
{
qDebug() << "Clicked outside the button";
//Now you can modify n variable in MainWindow
}
MainWindow::mousePressEvent(event);
}
void MainWindow::slotButtonsClicked(QWidget *p)
{
rx *button = dynamic_cast<rx *>(p);
button->on_rxPushButton_clicked();
qDebug() << button <<" clicked on button";
//Now you can change image in rx
}
Hope this works :)
Event propagating prevent you to do it. When mouse is over Button, event sends to button, not to the MainWindow, thats why you never see test2 in debug output.
Since I don't know what do you need it's hard to say what you should do. You can process event in Button and send some signals or whatever, or set event filter and check if target object is your button, and so on.
Any way, read Qt event system docs for better understanding.
I'm creating the new window with QProgressBar when i click on button of MainWindow but when new window is creating, QProgressBar don't appear while filling cycle is working. After then QProgressBar appear and it is filled.
Constructor:
ProgressWin::ProgressWin():QWidget()
{
this->resize(273,98);
this->move(670, 430);
bar1 = new QProgressBar(this);
bar1->setGeometry(20, 31, 251, 31);
bar1->setMinimum(0);
bar1->setMaximum(10000);
this->show();
unsigned long long secr, PQ;
unsigned long long rv;
unsigned long long decr;
for(int v = 0; v <= 100000; v++) {
bar1->setValue(v);
}
}
Code of button that call new window:
void RsaMainWindow::ButtClickCrypt()
{
FileName1 = ui->LineCrypt->text();
if(FileName1.isEmpty()) {
QMessageBox::information(0, "Information", "File for Crypt wasn't chosen");
return;
}
NewWin = new ProgressWin;
}
Class for new window:
class ProgressWin : public QWidget
{
QProgressBar *bar1;
public:
ProgressWin();
};
Class for MainWindow:
[namespace Ui {
class RsaMainWindow;
}
class RsaMainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit RsaMainWindow(QWidget *parent = 0);
~RsaMainWindow();
private slots:
void ButtClickViewCryp();
void ButtClickViewDecr();
void ButtClickViewKeys();
void ButtClickCrypt();
void ButtClickDecr();
private:
Ui::RsaMainWindow *ui;
QString FileName1;
QString FileName2;
QString FileName3;
ProgressWin *NewWin;
};][1]
User interface usually work on the event-loop principle:
While (not closing the app)
Wait for some event
update app according event
endWhile
If you implement your heavy task in the GUI thread, when the user click on "Perform a heavy task", the code managing this click is called, and after it finish, a following event will trigger the drawing of the window. That mean your heavy task will freeze the user interface during the task.
To perform a heavy task correctly, you need to:
Create a background thread that perform the task. Each iteration, it update some shared-memory (or equivalent) status of the task. Some UI libraries, like QT allows to send queued messages, which help for those cases.
On the Main thread, on update of the status, set the progress bar to the new value and return.
I have a QLineEdit with an input mask, so that some kind of code can easily be entered (or pasted). Since you can place the cursor anywhere in the QLineEdit even if there is no text (because there is a placeholder from the input mask):
If people are careless and unattentive enough this leads to them typing in the middle of the text box whereas they should start typing at the beginning. I tried the trivial way of ensuring that the cursor is at the start upon focus by installing an event filter:
bool MyWindowPrivate::eventFilter(QObject * object, QEvent * event)
{
if (object == ui.tbFoo && event->type() == QEvent::FocusIn) {
ui.tbFoo->setCursorPosition(0);
}
return false;
}
This works fine with keybaord focus, i.e. when pressing ⇆ or ⇧+⇆, but when clicking with the mouse the cursor always ends up where I clicked. My guess would be that QLineEdit sets the cursor position upon click itself after it got focus, thereby undoing my position change.
Digging a little deeper, the following events are raised when clicking¹ and thus changing focus, in that order:
FocusIn
MouseButtonPress
MouseButtonRelease
I can't exactly catch mouse clicks in the event filter, so is there a good method of setting the cursor position to start only when the control is being focused (whether by mouse or keyboard)?
¹ Side note: I hate that Qt has no documentation whatsoever about signal/event orders for common scenarios such as this.
Below is an implementation that's factored into a separate class. It defers the setting of the cursor to after any pending events are posted for the object, thus sidestepping the issue of event order.
#include <QApplication>
#include <QLineEdit>
#include <QFormLayout>
#include <QMetaObject>
// Note: A helpful implementation of
// QDebug operator<<(QDebug str, const QEvent * ev)
// is given in http://stackoverflow.com/q/22535469/1329652
/// Returns a cursor to zero position on a QLineEdit on focus-in.
class ReturnOnFocus : public QObject {
Q_OBJECT
/// Catches FocusIn events on the target line edit, and appends a call
/// to resetCursor at the end of the event queue.
bool eventFilter(QObject * obj, QEvent * ev) {
QLineEdit * w = qobject_cast<QLineEdit*>(obj);
// w is nullptr if the object isn't a QLineEdit
if (w && ev->type() == QEvent::FocusIn) {
QMetaObject::invokeMethod(this, "resetCursor",
Qt::QueuedConnection, Q_ARG(QWidget*, w));
}
// A base QObject is free to be an event filter itself
return QObject::eventFilter(obj, ev);
}
// Q_INVOKABLE is invokable, but is not a slot
/// Resets the cursor position of a given widget.
/// The widget must be a line edit.
Q_INVOKABLE void resetCursor(QWidget * w) {
static_cast<QLineEdit*>(w)->setCursorPosition(0);
}
public:
ReturnOnFocus(QObject * parent = 0) : QObject(parent) {}
/// Installs the reset functionality on a given line edit
void installOn(QLineEdit * ed) { ed->installEventFilter(this); }
};
class Ui : public QWidget {
QFormLayout m_layout;
QLineEdit m_maskedLine, m_line;
ReturnOnFocus m_return;
public:
Ui() : m_layout(this) {
m_layout.addRow(&m_maskedLine);
m_layout.addRow(&m_line);
m_maskedLine.setInputMask("NNNN-NNNN-NNNN-NNNN");
m_return.installOn(&m_maskedLine);
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Ui ui;
ui.show();
return a.exec();
}
#include "main.moc"
You could use a QTimer in focusInEvent to call a slot that sets the cursor position to 0.
This works well because a single shot timer posts a timer event at the end of the object's event queue. A mouse-originating focus-in event necessarily has the mouse clicks already posted to the event queue. Thus you're guaranteed that the timer's event (and the resulting slot call) will be invoked after any lingering mouse press events.
void LineEdit::focusInEvent(QFocusEvent *e)
{
QLineEdit::focusInEvent(e);
QTimer::singleShot(0, this, SLOT(resetCursorPos()));
}
void LineEdit::resetCursorPos()
{
setCursorPosition(0);
}
set a validator instead of inputmask .
http://doc.qt.io/qt-5/qregularexpressionvalidator.html