In MouseReleaseEvent(QMouseEvent *e), is there a way to know which button was released without using a new variable ? I mean something like in the MousePressEvent(QMouseEvent *e) with e.buttons().
I tried e.buttons() in the releaseEvent it's not working (which is logical).
e is already a variable. Just use:
void mouseReleaseEvent(QMouseEvent *e)
{
if (e->button() == Qt::LeftButton) // Left button...
{
// Do something related to the left button
}
else if (e->button() == Qt::RightButton) // Right button...
{
// Do something related to the right button
}
else if (e->button() == Qt::MidButton) // Middle button...
{
// Do something related to the middle button
}
}
A switch statement also works. I prefer the series of if -- else if because they make it easier to handle evente modifiers, i.e., e->modifiers() in order to check for alt or control clicks. The series of if's is short enough not to create any burden on the program.
EDIT: Note that you should use the button() function, not its plural buttons() version. See the explanation in #Merlin069 answer.
The problem in the posted code is this: -
if(e->buttons() & Qt::LeftButton)
As the Qt documentation states for the release event: -
... For mouse release events this excludes the button that caused the event.
The buttons() function will return the current state of the buttons, so since this is a release event, the code will return false, as it's no longer pressed.
However, the documentation for the button() function states:-
Returns the button that caused the event.
So you can use the button() function here.
Related
I have QGraphicsView, which has many QGraphicsItem. I am trying to create a right click menu on these QGraphicsItem. Right click menu has multiple options. But only 1st option works. It means, if I click on 2nd option, it does not work. If I change the sequence ( means 1st one will go to 2nd position, and 2nd one will come to 1st position ) then still 2nd one will not work.
bool myClass::eventFilter(QObject *watched, QEvent *event)
{
switch(event->type())
{
case QEvent::ContextMenu:
{
foreach(QGraphicsItem* pItem, _scene->items())
{
if(pItem->isUnderMouse())
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*> (event);
menu = new QMenu(this);
myMenu = menu->addMenu("Copy");
myMenu ->addAction(Name);
myMenu ->addAction(Address);
if(Name == menu->exec(mouseEvent->globalPos()))
{
// logic
}
if(Address == menu->exec(mouseEvent->globalPos()))
{
// logic
}
}
}
}
}
Always works only 1st mouse right click option. Why is so ?
The usual way to do something like this is to override the QGraphicsItem::mouseReleaseEvent() or QGraphicsItem::mousePressEvent() function of your item class.
This way, you won't have to do anything (no looping, etc...), it is already handled by the event loop.
Here you can find a simple example:
void MyItem::mouseReleaseEvent(QGraphicsSceneMouseEvent * event)
{
if(event->button() == Qt::RightButton)
{
QMenu my_menu;
// Build your QMenu the way you want
my_menu.addAction(my_first_action);
my_menu.addAction(my_second_action);
//...
my_menu.exec(event->globalPos());
}
}
From the Qt documentation:
Note that all signals are emitted as usual. If you connect a QAction to a slot and call the menu's exec(), you get the result both via the signal-slot connection and in the return value of exec().
You just need to QObject::connect() the QActions you added to the context menu to the proper slots (here goes the "logic") and the job is done.
If you prefer to check the returned value by yourself, you just have to get the returned QAction* once and for all (only one call to QMenu::exec()) and branch on it.
For example:
void MyItem::mouseReleaseEvent(QGraphicsSceneMouseEvent * event)
{
if(event->button() == Qt::RightButton)
{
QMenu my_menu;
// Build your QMenu the way you want
my_menu.addAction(my_first_action);
my_menu.addAction(my_second_action);
//...
QAction * triggered = my_menu.exec(event->globalPos());
if(triggered == my_first_action)
{
// Do something
}
else if(triggered == my_second_action)
{
// Do some other thing
}
//...
}
}
I would personnally prefer to stick with the signal-slot connections instead that manually handling the returned value, especially since each QAction is most likely to be already connected to its corresponding slot.
I'm using SFML to write game and I got small problem with my button. Here is function I use to check if button is clicked:
bool InputManager::isSpriteClicked(sf::Sprite object, sf::Mouse::Button button, sf::RenderWindow &window) {
if (sf::Mouse::isButtonPressed(button)) {
sf::IntRect rect(object.getPosition().x, object.getPosition().y,
object.getGlobalBounds().width, object.getGlobalBounds().height);
if (rect.contains(sf::Mouse::getPosition(window))) {
return true;
}
}
return false;
}
It works almost fine, yet sometimes once I press this button, action is trigerred twice, like I double click it, even tho I didnt even release it yet. I tried to involve sf::Event::MouseButtonReleased but It actually wasnt helping too. What I want to achieve is of course just 1 action per 1 button press/release/whatever.
Here is example of my GameLoop if its needed
void GameState::handleUserInput() {
sf::Event evnt;
while (this->m_data->window.pollEvent(evnt)) {
if (this->m_data->input.isSpriteClicked(this->m_rollButton, sf::Mouse::Left, this->m_data->window)) {
m_gameEngine.startTurn(m_gameStatusBox);
}
}
void GameState::update(sf::Time dt) {
m_gameEngine.getActivePlayer().move(dt);
}
void GameState::draw() {
this->m_data->window.display();
}
Short answer:
if (event.type == sf::Event::MouseButtonPressed)
Long story By the way, it's second link in google....
You're mixing two different approaches to manage user input
Input by events: used to manage those things that happen once and you want to be notified
Real time input: basically, poll repeatedly for input status (in this case, the mouse)
The general rule:
if (sf::Mouse::isButtonPressed(sf::Mouse::Left))
// WHILE the left mouse button is being pressed, do something
if (event.type == sf::Event::MouseButtonPressed)
// WHEN the left mouse button has been pressed, do something
If you want to learn more, i recommend you to read this chapter (or better, the whole book) about SFML game dev.
I have a QT Application on Windows which has a mode of using arrow keys, and also a mode which should totally ignore these arrow keys. That is, I want the arrow keys to not to trigger any event once the user checks a box.
I saw a post where eventFilter() was suggested, but I did not get how I could use it. Here is the checkbox event that listens the user, and gets triggered once the user checks it. In the else part I want the eventFilter() to work for arrow keys, but so far I could not get it running.
void MainWindow::on_checkBoxSmartCutMode_stateChanged(int arg1)
{
if (arg1 == 0)
{
// do as usual, arrow keys should work
}
else
{
eventFilter(); // if any arrow key is pressed, ignore the event
}
}
Any suggestions?
You can use keyEvent as your key filter by override keyPressEvent and test your checkbox state.
example:
void MainWindow::keyPressEvent(QKeyEvent *event)
{
// check your checkbox state
if (ui->poCheckBox->checkState() == Qt::Unchecked)
// do as usual, arrow keys should work
return;
switch(event->key())
{
case Qt::Key_Left:
case Qt::Key_Right: // add more cases as needed
event->ignore(); // if any arrow key is pressed, ignore the event
return;
}
// handle the event
}
I've spent better half of today trying to resolve seemingly trivial QListWidget behavior customization: when used presses mouse left button and moves mouse cursor, the content of ListWidget is scrolled and selection is moved to another item that happens to appear under mouse cursor. I am alright with scrolling, but I want to avoid selecting all consequtive items because this causes timely operation in my program. Finally I would like to keep list content scrolling on mouse press and move, but select items only by clicking directly on them.
Drag-n-drop is disabled for this list (which is default behavior) and it should be; I've tried to disable it explicitly: no changes whatsoever.
I have read all available docs on Qt related classes like QListWidget, QListWidgetItem, QListView, you name it! Tried to make sense of source code for these widgets; dug up StackOverflow and Google... but sadly no result :(
Here is all relevant code for my QListWidget: single selection, nothing fancy:
QListWidget* categoryListWidget;
...
categoryListWidget = new QListWidget();
categoryListWidget->move(offsetX, offsetY);
categoryListWidget->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
categoryListWidget->setSelectionMode(QAbstractItemView::SingleSelection);
categoryListWidget->setFocusPolicy(Qt::NoFocus);
categoryListWidget->setStyleSheet(listQSS);
...
categoryListWidget->clear();
new QListWidgetItem(tr("1 - Sample Category 1"), categoryListWidget);
new QListWidgetItem(tr("2 - Sample Category 2"), categoryListWidget);
new QListWidgetItem(tr("3 - Sample Category 3 with a very long name"), categoryListWidget);
new QListWidgetItem(tr("4 - Sample Category 4"), categoryListWidget);
C++/Qt 5.5 if that's somehow relevant, both Win and Mac platforms share similar behavior.
For the sake of whoever stumbles upon the same question, here is my solution: subclass QListWidget and make child class ignore mouseMove events when leftButton is pressed.
Header:
class QtListWidget: public QListWidget
{ // QListWidget clone that suppresses item selection on mouse click+drag
private:
bool mousePressed;
public:
QtListWidget():QListWidget(), mousePressed(false) {}
protected:
virtual void mousePressEvent(QMouseEvent *event);
virtual void mouseMoveEvent(QMouseEvent *event);
virtual void mouseReleaseEvent(QMouseEvent *event);
};
Source:
//////////////////////////////////////////////////////////////////////////
void QtListWidget::mousePressEvent(QMouseEvent *event){
// qDebug() << "QtListWidget::mousePressEvent";
if(event->button() == Qt::LeftButton)
mousePressed = true;
QListWidget::mousePressEvent(event);
}
void QtListWidget::mouseMoveEvent(QMouseEvent *event){
// qDebug() << "QtListWidget::mouseMoveEvent";
if(!mousePressed) // disable click+drag
QListWidget::mouseMoveEvent(event);
}
void QtListWidget::mouseReleaseEvent(QMouseEvent *event){
// qDebug() << "QtListWidget::mouseReleaseEvent";
if(event->button() == Qt::LeftButton)
mousePressed = false;
QListWidget::mouseReleaseEvent(event);
}
//////////////////////////////////////////////////////////////////////////
Usage is trivial, for as many List Widgets as you need:
QtListWidget* categoryListWidget;
// all original code above would still work as expected
...
Want it done right? then do it yourself! :)
Your solution killed scrolling for me. I am using QListView. Here's another way:
In the constructor of the QListView's parent:
ui->listView->setSelectionMode(QAbstractItemView::NoSelection);
connect(ui->listView, SIGNAL(clicked(QModelIndex)), this, SLOT(on_listview_clicked(QModelIndex)));
In the connected slot:
on_listview_clicked(const QModelIndex &index)
{
if (index.isValid())
{
ui->listView->selectionModel->select(index, QItemSelectionModel::Toggle | QItemSelectionModel::Rows);
}
}
So, it only selects on a click.
I'm developing a project in Qt. I have a QTreeWidget(filesTreeWidget) whith some file names and a button for creating a file. The Create button adds to the filesTreeWidget a new item(the item's text is "") who is edited for choosing a name. When I press ENTER, the filename is send through a socket to the server. The problem comes when I press ESC because the filename remains "" and is not send to the server. I tried to overwrite the keyPressEvent but is not working. Any ideas? I need to catch the ESC press event when I'm editing the item.
You can subclass QTreeWidget, and reimplement QTreeView::keyPressEvent like so:
void MyTreeWidget::keyPressEvent(QKeyEvent *event)
{
if (event->key() == Qt::Key_Escape)
{
// handle the key press, perhaps giving the item text a default value
event->accept();
}
else
{
QTreeView::keyPressEvent(event); // call the default implementation
}
}
There might be more elegant ways to achieve what you want, but this should be pretty easy. For example, if you really don't want to subclass, you can install an event filter, but I don't like doing that especially for "big" classes with lots of events because it's relatively expensive.
Implement keyPressEvent function as following:
void TestTreeWidget::keyPressEvent(QKeyEvent *event)
{
switch (event->key())
{
case Qt::Key_Escape:
{
escapeKeyPressEventHandler();
event->accept();
break;
}
default:
QTreeWidget::keyPressEvent(event);
}
}
TestTreeWidget::escapeKeyPressEventHandler()
{
// work with your QTreeWidgetItem here
}