How to Change the IconSize for Actions in QMenu? - c++

I am trying to resize the Icons of QActions in the QMenu with the following code but it doesn't work.
QMenu *menu;
menu =new QMenu();
menu->setStyleSheet("QMenu::icon{height:20px;width:20px});"
I would really appreciate it if someone could provide a solution.

Here is the solution that worked for me:
QMenu *menu;
menu =new QMenu();
QToolButton *button=new QToolButton(menu);
button->setFixedSize(50,50);
QWidgetAction *action=new QWidgetAction(this);
action->setDefaultWidget(button);
menu->addAction(action);

We can set style sheet to manage icon size like this:
QAction *action = new QAction("Exit", this);
action->setIcon(QIcon(":/images/resources/exit.png"));
QMenu *menu = new QMenu("File");
menu->addAction(action);
menu->setStyleSheet("QMenu {icon-size: 200px;} QMenu::item {background: transparent;}");
ui->menubar->addMenu(menu);
But it will display in an Improper size, so it's better to use QToolBar.
In your cpp file type this:
ui->ToolBarName->setIconSize(QSize(50,50));
In Designer Click on your QToolbar and set iconSize.

Just stumbled across this after all these years. I remember I had this problem once and now again. This time I actually managed to solve it somewhat. It IS kinda weird tho and should receive some love at least documentation-wise.
The key is: You need to style QMenu AND QMenu::item If you just set the icon size via:
QMenu {icon-size: 40px;}
it will remain ignored until you also set something like
QMenu::item {background: transparent;}
Unfortunately this resets the menu stylesheet and you need to do something about the hover state to make it usable. But well.
Seems this works for me.
(also posted this on the qt forums)

Related

Scroll Area Added and Set Up but No Scrollbar Appears

I've seen and tried various QT scrollArea solutions over the past 2 days but none of them work for me. Here's my scroll area setup code as it stands in the MainWindow constructor. This builds and runs without error but doesn't do anything. The scrollArea and ui->Contents have already been set up in the form using QTcreator and the needed widgets have been moved into the scrollArea.
ui->scrollArea->installEventFilter(this);
ui->scrollArea->setMouseTracking(true);
ui->scrollArea->setWidget(ui->Contents);
QVBoxLayout *layout = new QVBoxLayout(this);
layout->setSizeConstraint(QLayout::SetMinimumSize);
ui->scrollArea->setLayout(layout);
The last line seems interchangeable with:
layout->addWidget(ui->scrollArea)
but neither one changes the result, which is a fully-functioning application but without the scroll area I need.
I had similar problem which i solved by creating scrollArea and it's contents via code rather than form and only then using setWidget() method. I described the problem in this thread.
In your case code should look something like this:
QScrollArea *scrollArea;
scrollArea = new QScrollArea(this);
scrollArea->installEventFilter(this);
scrollArea->setMouseTracking(true);
scrollArea->setWidget(Contents);//whatever Contents is, i recommend creating it via code
QVBoxLayout *layout = new QVBoxLayout(this);
layout->setSizeConstraint(QLayout::SetMinimumSize);
scrollArea->setLayout(layout);

Add QWidgetAction to QMenu through qtcreator/qtdesigner

I am wondering if there is a way to add QWidgetAction to QMainwindow->QMenuBar->QMenu using either qtcreator or qtdesigner.
I can add a widget through the code like that:
//ui->myMenu is QMenu in QMenuBar of QMainWindow
QWidgetAction *act = new QWidgetAction(ui->myMenu);
QLineEdit* edt = new QLineEdit("I am Line edit",ui->myMenu);
//setup edt ...
act->setDefaultWidget(edt);
ui->myMenu->addAction(act);
It compiles and works as expected.
However, I cannot achieve same behavior using ui designer - it only lets me add QAction and QMenu classes as parts of QMenuBar/QMenu, and does not give option to promote QAction to QWidgetAction. Is there a way to add QWidgetAction and a widget associated with it through designer to have them as part of Ui namespace and their properties editable through ui editor?
Unfortunately that's not possible.

QAction shortcut doesnt always work

I have a Qaction on a menu item for deleting selected items in one of my views. Here is how i create the action:
deleteAct = new QAction( tr("Delete Selected"), this);
deleteAct->setShortcut(QKeySequence::Delete);
connect(deleteAct, SIGNAL(triggered()), this, SLOT(deleteSelected()));
I setup a keyboard shortcut (Delete Key) which should trigger the delectAct action. It works most of the time but at some points it stops working... Does anyone know why the shortcut would stop working?
Note: the action still works if i trigger it from the menu item. Its just the shortcut that doesn't...
You need to add the action to a widget, since it's the widget that will be listening for key events.
Assuming "this" is a mainwindow, simply do
addAction(deleteAct);
Note that you can add the same action to multiple widgets (that's the whole point of the separated action concept). So it's fine to add it to the mainwindow and to a menu.
Try changing the shortcut context of the action, for example:
deleteAct->setShortcutContext(Qt::ApplicationShortcut);
The shortcut works depending on the focus of the application views.
I wanted to have shortcuts working on buttons.
In my application I changed the shortcut context of the action,
added the action to the widget
and finally to the subviews of the application.
Then the necessary signals and slots of widget an action must be connected.
const QAbstractButton*button = dynamic_cast<QAbstractButton*>(widget);
action->setShortcutContext(Qt::WidgetWithChildrenShortcut);
widget->addAction(action);
ui->textBrowser->addAction(action);
ui->treeSource->addAction(action);
if (button)
{
if (button->isCheckable())
{
action->setCheckable(true);
if (button->isChecked()) action->setChecked(true);
connect(action, SIGNAL(triggered(bool)), button, SLOT(setChecked(bool)));
connect(button, SIGNAL(clicked(bool)), action, SLOT(setChecked(bool)));
}
else
{
connect(action, SIGNAL(triggered()), button, SLOT(click()));
}
}
Without seeing the complete code, I'd hazard a guess that somewhere it gets enabled/disabled. Make sure that the shortcut is getting hit in the constructor and not 'disabled' somewhere else because of a setting perhaps.
You can use http://doc.qt.io/qt-5/qaction.html#shortcutVisibleInContextMenu-prop property since QT 5.10 for this:
deleteAct->setShortcutVisibleInContextMenu(true);

Close button only for some tabs in Qt

I am using Qt for an assignment I have for college, and I want to use QTabWidget to display a chat window much like Pidgin's. I want to make the "group chat" tab always open and impossible to close and the rest of the "private channel" tabs closable.
QTabWidget's setTabsClosable(bool) is not helping.
Any ideas?
I found an easier solution, I think.
Simply access the relevant close button and resize it.
tabWidget->tabBar()->tabButton(0, QTabBar::RightSide)->resize(0, 0);
Find the bar (it is private, so use findChild()) and remove the buttons. Documentation claims that close buttons may be placed on left side too.
QTabBar *tabBar = ui->tabWidget->findChild<QTabBar *>();
tabBar->setTabButton(0, QTabBar::RightSide, 0);
tabBar->setTabButton(0, QTabBar::LeftSide, 0);
Hallo,
I guess this post won't help the author of this thread but perhaps someone else wanders over here.
In most cases a non-closable tab should not only ignore the closevent it also should not show a close symbol in its corner. A nice way to reach this is to modify the QTabBar which is inside the QTabWidget.
Example:
// let tabWidget be a QTabWidget with at least one page
QPushButton *closeButton = new QPushButton();
// set icon and size for PushButton, ...
// connect Signal clicked() from closeButton with Slot closeCurrentTab(), ...
// next line sets closeButton in right corner on tab with index 0
tabWidget->tabBar()->setTabButton(0, QTabBar::RightSide, closeButton);
Although tabBar() is indeed protected, Klaus pointed into the right direction. Simply subclass QTabWidget and implement a wrapper method.
You should reimplement your widget's event(Event *e) method, check the type of e, find out CloseEvents, and call parent class's event when you can allow tab to close, or e->ignore() when you do not want it.
Note, then you must parent's event() handle othr events, so do not accept(), reject() or forget them Ж)
I guess you can handle the tabCloseRequest signal and decide whether u'll close a given tab or not
http://doc.qt.io/archives/4.6/qtabwidget.html#tabCloseRequested
Edit: I created a small example to check it out. My example is a simple QtGui application with a mainwindow that has a tabwidget. I then added the tabCloseRequested slot. Here is the code
void MainWindow::on_tabWidget_tabCloseRequested(int index)
{
if(someCondition){
return;
} else if(anotherCondition){
ui->tabWidget->removeTab(index);
}
}
From this example only tabs where the condition doesn't apply will be closed.
The best way for adding a pushbutton to some tabs and not in other is to define a subclass of QTabWidget for taking the QTabBar that is a potected!
The code below is tested and it works:
//TabWidget.h
#ifndef TABWIDGET_H
#define TABWIDGET_H
#include <QTabWidget>
class TabWidget : public QTabWidget {
public:
TabWidget(QWidget *parent);
~TabWidget();
QTabBar *tabBar() const;
};
#endif /* TABWIDGET_H */
//TabWidget.cpp
#include "TabWidget.h"
TabWidget::TabWidget(QWidget * p=0) : QTabWidget(p) {}
TabWidget::~TabWidget() {}
QTabBar * TabWidget::tabBar() const {return QTabWidget::tabBar();}
For using this subclass and create a new tab with a custom button you have to following this instructions ( ui->tabWidget is a QTabWidget with setClosableTabs=false):
TabWidget *t = (TabWidget *) ui->tabWidget;
t->addTab(new QWidget, "empty");
QTabBar *tab = t->tabBar();
QPushButton *b = new QPushButton();
b->setText("x");
tab->setTabButton(tab->count() -1, QTabBar::RightSide, b);
connect(b,SIGNAL(...),this,SLOT(...));
Not sure, why nobody here mentioned the simplest working solution:
tabWidget->tabBar()->setTabButton(0, QTabBar::RightSide, 0);
This completely removes the close button, and the space taken by it.
Documentation

setCentralWidget() causing the QMainWindow to crash.. Why?

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow)
{
this->setupUi(this);
this->setupActions();
this->setWindowTitle(tr("CuteEdit"));
label = new QLabel(tr("No Open Files"));
this->setCentralWidget(label);
label->setAlignment(Qt::AlignCenter);
}
By above code, I get a GUI like this(Its a screenshot of whole screen, Only observe the window displayed in middle of page of ebook). (I used QT Designer)
Now, i want user to select File->Open.. A Dialog appears and file gets selected.. Its contents are to be displayed in *textEdit widget..
Function for that is below..
void MainWindow::loadFile()
{
QString filename = QFileDialog::getOpenFileName(this);
QFile file(filename);
if (file.open(QIODevice::ReadOnly|QIODevice::Text))
{
label->hide();
textEdit->setPlainText(file.readAll());
mFilePath = filename;
QMainWindow::statusBar()->showMessage(tr("File successfully loaded."), 3000);
}
}
The window crashes at line:-
textEdit->setPlainText(file.readAll());
But if i comment the line:-
this->setCentralWidget(label);
i mean i remove label as being the central widget, the program runs as expected.. Why?
And also, I am not clear about the concept of CentralWidget. Pls guide.
JimDaniel is right in his last edit. Take a look at the source code of setCentralWidget():
void QMainWindow::setCentralWidget(QWidget *widget)
{
Q_D(QMainWindow);
if (d->layout->centralWidget() && d->layout->centralWidget() != widget) {
d->layout->centralWidget()->hide();
d->layout->centralWidget()->deleteLater();
}
d->layout->setCentralWidget(widget);
}
Do you see that if your MainWindow already had centralWidget() Qt schedules this object for deletion by deleteLater()?
And centralWidget() is the root widget for all layouts and other widgets in QMainWindow. Not the widget which is centered on window. So each QMainWindow produced by master in Qt Creator already has this root widget. (Take a look at your ui_mainwindow.h as JimDaniel proposed and you will see).
And you schedule this root widget for deletion in your window constructor! Nonsense! =)
I think for you it's a good idea to start new year by reading some book on Qt. =)
Happy New Year!
Are you sure it's not label->hide() that's crashing the app? Perhaps Qt doesn't like you hiding the central widget. I use Qt but I don't mess with QMainWindow that often.
EDIT: I compiled your code. I can help you a bit. Not sure what the ultimate reason is as I don't use the form generator, but you probably shouldn't be resetting the central widget to your label, as it's also set by the designer, if you open the ui_mainwindow.h file and look in setupGui() you can see that it has a widget called centralWidget that's already set. Since you have used the designer for your GUI, I would use it all the way and put the label widget in there as well. That will likely fix your problems. Maybe someone else can be of more help...
I'm not sure I understood your problem, neither what the guys above said (which I guess are valid information) and it seems to be an old topic.
However, I think I had a problem that looks like this and solved it, so I want to contribute my solution in case it helps anyone.
I was trying to "reset" central widget using QLabels. I had three different ones, switch from first to second, then to third and failed to switch back to the first one.
This is my solution that worked:
Header file
QLabel *imageLabel;
Constructor
imageLabel = new QLabel("<img src='/folder/etc.jpg' />");
this->setCentralWidget(imageLabel);
Reset
imageLabel = NULL;
imageLabel = new QLabel("<img src='/folder/etc.jpg' />");
this->setCentralWidget(imageLabel);
Hope that helps
Aris