I have a situation where I need a tri-state checkable action on a QMenu, and the QAction class appears to only support on or off, unless I'm overlooking something obvious. The situation I have is a context menu where multiple objects are selected, but may have different states for a given boolean condition (i.e. for a given property, some objects have a true value and some false). I can leave the action unchecked when there's a mix of values, but I feel that's misleading to the user.
I'm using Qt 5.5.1 and very experienced with Qt, but not seeing a way to achieve what I want in this instance.
There is no direct way to do it from a QAction, but it is possible to subclass the QWidgetAction and create an action that contains a QCheckBox widget.
class CheckBoxAction : public QWidgetAction {
public:
CheckBoxAction (const QString &text) : QWidgetAction(Q_NULLPTR) {
QHBoxLayout *_layout = new QHBoxLayout(Q_NULLPTR);
QWidget *_widget = new QWidget(Q_NULLPTR);
QLabel *_label = new QLabel(text);
mCheckbox = new QCheckBox(Q_NULLPTR);
_label->setAlignment(Qt::AlignLeft);
_layout->addWidget(mCheckbox);
_layout->addWidget(_label);
_layout->addStretch();
_widget->setLayout(_layout);
setDefaultWidget(_widget);
}
QCheckBox *checkbox() {
return mCheckbox;
}
private:
QCheckBox *mCheckbox;
};
Simply use the class to then add to your menu; for instance:
CheckBoxAction *checkAction = new CheckBoxAction(QStringLiteral("My Action"));
checkAction->checkbox()->setCheckState(Qt::PartiallyChecked);
menu->addAction(checkAction);
You can use the checkbox() method in order to connect to signals when it changes; or change the checkbox state. Hope this helps.
Related
I needed to read widget classnames, names etc from gui loaded via QUiloader.
And I got answer here that I needed to subclass QUiloader and reimplement its method.
I have MainWindow, and via menu/toolbar I load the file, and show it. And when I load I want to know what elements are in that gui to work further with them.
The code I got from a user here:
class UiLoader : public QUiLoader
{
Q_OBJECT
public:
QStringList *wlist;
UiLoader(QObject *parent = 0) : QUiLoader(parent) {}
virtual QWidget* createWidget(const QString &className, QWidget *parent =0, const QString &name = QString())
{
QWidget* widget = QUiLoader::createWidget(className, parent, name);
//here do my stuff with className, parent, name
return widget;
}
};
I used Uiloader to load my file. And it is working.
My question now is how I intercept createWidget before returning widget, I want to get the list of widget and then return Widgets.
I do not know how what is the efficient way to create a list as simple as this one:
0=>TextBox, 1=>Button, ...
I really do not care about the structure I just need to know which one comes first and what it is.
Thanks.
I wouldn't reimplement class loader at all honestly.. May be only if you need to 'inject' something into existing code which use QUiLoader a lot.. but in general only thing you need:
pWidget = ...->createWidget(...);
QList<QWidget *> widgets = pWidget->findChildren<QWidget *>();
here you go, your widgets contains list of all form components..
I have a Qt Desktop aplication which has several top-level widgets. Subwidgets of top-level widgets can be moved between top-level widgets by using drag-and-drop mechanism.
The problem i have now is to drop a sub-widget outside any of existing top-level widgets and create a new top-level widget to contain this one. Lets call this separation.
Can this be done using drag-and-drop? I could not find a way where my dropEvent goes?
Can i want to handle the drop event in my application even if the drop place is not allowed? Maybe a mouse release or something?
I cannot change everything now but also a question for the future. Is docking/undocking a better way to do this?
Regards
Mihai
I found a way to do this. When drag moves outside of the application widgets QDrag object emits a targetChanged signal with 0 parameter.
So i inherited from QDrag and then emit a custom signal in destructor if the target() is null.
The only problem is that the cursor looks like interdiction of drop and this i could not fix because QDrag can only set cursor pixmap for valid actions like Move or Copy or Link
Update:
Here is the inherited class.
class TabDrag: public QDrag
{
Q_OBJECT
public:
explicit TabDrag(QWidget *dragSource);
~TabDrag();
signals:
void tearOff(); /// emit tearOff signal if the QDrag object is destroyed and target was null
};
TabDrag::TabDrag(QWidget *dragSource):QDrag(dragSource)
{
}
TabDrag::~TabDrag()
{
// check if we need to detach this tab
if(!target())
{
emit tearOff();
}
}
The tearOff signal should be connected to whatever you want to happen. In my case i pull out the widget from the tab and change parent to a new window.
Example of usage
void MyTabBar::mouseMoveEvent(QMouseEvent* event)
{
..................
TabDrag * drag = new TabDrag(this);
drag->setMimeData(mimeData);
drag->setPixmap(*m_tabPixmap.data());
drag->setHotSpot(QPoint(m_dragStartPos.x() - tabAtRect.x(), m_dragStartPos.y() - tabAtRect.y()));
drag->exec();
connect(drag, SIGNAL(tearOff()), this, SLOT(onTearOff()));
}
I need to put a QPushButton inside a QMenu. Is it possible and, if so, then how?
I want to achieve something like this:
QWidgetAction is what you are looking for. This is what is on qt docs
The QWidgetAction class extends QAction by an interface for inserting custom widgets into action based containers
So basically it gives a custom UI to QAction according to what QWidget you pass to it.
I have used QWidgetAction to show checkbox as QMenu items.
QCheckBox *chkBox = new QCheckBox(menu);
chkBox ->setText("MyCheckBox");
QWidgetAction *chkBoxAction= new QWidgetAction(menu);
chkBoxAction->setDefaultWidget(chkBox);
menu->addAction(chkBoxAction);
You can then handle signals from checkbox accordingly.
If you only want a menu item to have a state, you may use Checkable property of QAction:
rotateAct = new QAction(QIcon(":/images/Mouse/Rotate.png"), tr("&Rotate"), this);
rotateAct->setCheckable(true);
I have a browser made in Qt and a I have a tabwidget with one tab (which has a label, lineedit and a webview). I want to add others that look like the first one (have label, lineedit and webview).
How can I do this?
I don't know of any way to "clone" or duplicate an existing tab or widget, so I believe you'll need to code the tab contents yourself (i.e. not through the designer).
If all you need are a QLabel, a QLineEdit and a QWebView, that's not very complex. The idea would be to:
create a custom widget (inheriting from QWidget directly, or from QFrame)
lay out the contained widgets in the fashion you want in its constructor
add as many tabs as you want, when you want them, via the QTabWidget.addTab function.
The Tab Dialog example has everything you need - it's actually more complex than what you need because it uses different widgets for each tab. You can get away with a single widget.
If you wonder how to do the layout, and you're satisfied with what you got from the designer, you can inspect the generated (.moc) files. You'll see what layouts it uses, and you can replicate that in your own code.
Skeleton widget:
class BrowserTab : public QWidet
{
Q_OBJECT
public:
BrowserTab(QUrl const& home, QWidget *parent = 0);
void setUrl(QUrl const& url);
private:
QWebView *web;
QLabel *title;
QLineEdit *urlEdit;
};
BrowserTab::BrowserTab(QUrl const& home, QWidget *parent)
: QWidget(parent)
{
urlEdit = new QLineEdit(this);
title = new QLabel(this);
web = new QWebView(this);
QVBoxLayout *vl = new QVBoxLayout;
vl->addLayout(title);
vl->addLayout(urlEdit);
vl->addLayout(web);
setLayout(vl);
setUrl(home);
}
void BrowserTab::setUrl(QUrl const& url)
{
web->load(url);
// update label & urlEdit here
}
You'll need to do a bit more to make it a proper browser (setUrl should probably be a slot too), but this should get you started.
I am implementing QAbstractTableModel and I would like to insert a QPushButton in the last column of each row. When users click on this button, a new window is shown with more information about this row.
Do you have any idea how to insert the button? I know about delegating system but all examples are only about "how to edit color with the combo box"...
You can use
QPushButton* viewButton = new QPushButton("View");
tableView->setIndexWidget(model->index(counter,2), viewButton);
The model-view architecture isn't made to insert widgets into different cells, but you can draw the push button within the cell.
The differences are:
It will only be a drawing of a pushbutton
Without extra work (perhaps quite a bit of extra work) the button won't be highlighted on mouseover
In consequence of #1 above, you can't use signals and slots
That said, here's how to do it:
Subclass QAbstractItemDelegate (or QStyledItemDelegate) and implement the paint() method. To draw the pushbutton control (or any other control for that matter) you'll need to use a style or the QStylePainter::drawControl() method:
class PushButtonDelegate : public QAbstractItemDelegate
{
// TODO: handle public, private, etc.
QAbstractItemView *view;
public PushButtonDelegate(QAbstractItemView* view)
{
this->view = view;
}
void PushButtonDelegate::paint(
QPainter* painter,
const QStyleOptionViewItem & option,
const QModelIndex & index
) const
{
// assuming this delegate is only registered for the correct column/row
QStylePainter stylePainter(view);
// OR: stylePainter(painter->device)
stylePainter->drawControl(QStyle::CE_PushButton, option);
// OR: view->style()->drawControl(QStyle::CE_PushButton, option, painter, view);
// OR: QApplication::style()->drawControl(/* params as above */);
}
}
Since the delegate keeps you within the model-view realm, use the views signals about selection and edits to popup your information window.
You can use setCellWidget(row,column,QWidget*) to set a widget in a specific cell.