I have a qwidget (we'll call it qwidget1) inside of a layout of an other qwidget (we'll call it qwidget2), I want to delete everything that is in the layout of qwidget2: I would like to clear the layout so there's nothing in it anymore ..
what I can do so far is remove completely the qwidget2 by doing:
void QCell::deleteMyChildren(){
delete this;
}
but it removes the qwidget2 itself.. that's not what I want.
Please help me remove the items that are inside the layout.
just loop inside the items in the layout and remove item from layout, then delete item :
void QCell::deleteMyChildren() {
while (count() > 0) {
QLayoutItem * item = takeAt(0);
delete item;
}
}
Related
In a QTableView I need the last (rightmost) column to be empty, expandable but not movable. The goal is that the table not to suddenly end (for I use alternate color for rows) or to ugly expand to the right. In QHeaderView there is a setFirstSectionMovable(bool); I need something similar for the last section, letting the rest of them movable. (in other words: Fill the rest of the table with an empty not movable column). Any clue how to acheive this?
I did override mousePressEvent() in a subclass of QHeaderView to skip the last section but it still can be moved by moving other column in its place and I don't know how to prevent this.
AMOQ:
Be HeaderView a subclass of QHeaderView and have
setSectionsMovable(true);
setStretchLastSection(true);
Treat the sectionMoved signal:
connect(this, &QHeaderView::sectionMoved, [this](int, int, int newVisual) {
if(newVisual == count()-1) { moveSection(newVisual, newVisual-1); }
});
Override mousePressEvent:
void HeaderView::mousePressEvent(QMouseEvent* event) {
int logicalIdx = logicalIndexAt(event->pos());
if(logicalIdx != count()-1) { QHeaderView::mousePressEvent(event); }
}
I have a class called TitleBar inherited from QWidget and I created a new widget and did setparent() but after doing setparent child widget is not showing, it is showing only after commenting setparent but not alligned with parent, its displaying in some random placess, On maximized view only it shows on right place
TitleBar::TitleBar(QWidget *parent) : QWidget(parent)
{
m_jobSubmitWidget = csJobSubmitPoolWidget::getSubmitPoolInst();
// m_jobSubmitWidget->setParent(QWidget::window());
}
void csTitleBar::BtnClicked()
{
QPoint pos = m_queueBtn->pos() + m_serverToolBar->pos() + QPoint(-m_jobSubmitWidget->width() + m_queueBtn->width(),62); // these are member variables in TitleBar class
// pos shows always same value on moving parent widget
if(itemCount > 2){
m_jobSubmitWidget->move(pos);
m_jobSubmitWidget->show();
m_jobSubmitWidget->setFocus();
}
}
I really suggest that you take a good read at Qt documentation.
QWidgets that have a parent are displayed inside their parent (except for QDialog). If a widget does not have a parent, it will be shown as a separate window.
Parenting a widget to the result of QWidget::window() is kind of hazardous as you don't really know which widget will be returned, so you do not know where the child widget will end up.
Also you do not need to call show() on widgets that have a parent. By default their visibility follows the parent visibility.
In my case I also had to add the widget which I was changing the parent (here textEdit) to the target containing layout:
ui->textEdit->setParent(ui->groupBox1);
m_lastVboxLayout->removeWidget(ui->textEdit);
m_lastVboxLayout = ui->verticalLayout_groupBox1;
m_lastVboxLayout->addWidget(ui->textEdit);
no need to call show() afterwards.
I have a QStackedLayout which contains few QWidget on it. The widgets layout is QVBoxLayout which have also few QPushButton. What I wanted to do is to remove all the widgets inside the QStackedLayout and then delete the widgets and layouts BUT I want all the buttons not to be deleted 'cause I will put them to another widget later.
Here's my code:
while (QLayoutItem *item = m_stacked_layout->takeAt(0)) {
QWidget *w = item->widget();
for (int i = 0; i < w->layout()->count(); i++) {
QPushButton *button = qobject_cast<QPushButton *>(w->layout()->itemAt(i)->widget());
if (button) {
w->layout()->removeWidget(button);
}
}
delete w;
delete item;
}
The application crashes at the line delete w;. And, if I remove the delete lines, application works fine.
BUT I want all the buttons not to be deleted 'cause I will put them to
another widget later.
Hide all widgets that you want to transfer
Set parent widget for all this widgets to nullptr
Later... set necessary parent and show widgets
Note: if you want to delete widgets inside some slots, you should use deleteLater method.
In my application I have a QToolButton related to the presence of an USB Pen Drive. When the Pen drive is inserted I would like to show the QToolButton and create a context menu associated to the content of the pen drive.I have a different menu dynamically created to be assigned to the Button.
My code works well for the first time, but when I create a new menu it doesn't appear.
In this last version of code, when I show the button for the second time I get the the previous menu (Dismount is the only item present) and when i click on the item it doesn't do anything.
EDIT: If I use the QAction instead of the QWidgetAction the code works fine. So it seems something related to the QWidgetAction of QLabel used inside of it.
The following is a simplified version of my code:
/* member variables */
QMenu *m_pqmConMenUSB;
QLabel m_MenuItem;
/* costructor */
ui->tbDriveUSB->setContextMenuPolicy(Qt::CustomContextMenu);
m_pqmConMenUSB = NULL;
QObject::connect(ui->tbDriveUSB, SIGNAL(customContextMenuRequested(const QPoint&)),this, SLOT(showUSBCM(const QPoint&)));
m_MenuItem.setStyleSheet("QLabel { background-color : black; color : white; }");
m_MenuItem.setText("Dismount");
QFont fonte = m_MenuItem.font();
fonte.setPixelSize(16);
m_MenuItem.setFont(fonte);
QPalette ChePalette = m_MenuItem.palette();
m_MenuItem.setMinimumSize(0,32);
ChePalette.setColor(m_MenuItem.backgroundRole(), Qt::black);
ChePalette.setColor(m_MenuItem.foregroundRole(), Qt::white);
m_MenuItem.setPalette(ChePalette);
/*member functions*/
void MainWindow::showUSBCM(const QPoint& pos)
{
// copied from an example
if (pos != QPoint(0,0)) {
// Execute context menu
if (m_pqmConMenUSB!=NULL) m_pqmConMenUSB->exec(pos);
}
}
void MainWindow::OnUSBMounted()
{
/* this static boolean is used to simulate a change in the menu content */
static bool tryToChange = false;
ui->tbDriveUSB->show();
m_pqmConMenUSB = new QMenu(this);
QWidgetAction *menuItemW = new QWidgetAction(this);
menuItemW->setDefaultWidget(&m_MenuItem);
menuItemW->setText("Dismount");
connect(menuItemW,SIGNAL(triggered()), this, SLOT(DoDismount()));
m_pqmConMenUSB->addAction(menuItemW);
if (tryToChange)
{
menuItemW = new QWidgetAction(this);
menuItemW->setDefaultWidget(&m_MenuItem);
menuItemW->setText("Update");
connect(menuItemW,SIGNAL(triggered()), this, SLOT(Update()));
m_pqmConMenUSB->addAction(menuItemW);
}
tryToChange = !tryToChange;
ui->tbDriveUSB->setMenu(m_pqmConMenUSB);
}
void MainWindow::OnUSBDismounted()
{
ui->tbDriveUSB->hide();
/* the first version of the code tries to destroy the menu with the following code, but it doesn't work
/*ui->tbDriveUSB->setMenu(NULL);
QAction *pAction;
foreach (pAction, m_pqmConMenUSB->actions())
pAction->disconnect(this);
delete(m_pqmConMenUSB);
m_pqmConMenUSB = NULL;*/
}
A useful pattern to dynamically populate a menu associated with a QToolButton is to first create the menu and attach it to the button, but do not populate it. Then connect a slot to the QMenu::aboutToShow() signal. In the slot implementation, clear the contents of the menu and populate it as needed for the current state of the application.
As I mentioned yesterday, the problem was related to QLabels. In my code I used two member variables of QLabel type. The QLabels weren't pointers.
When I delete the action, the QLabels weren't able to show them again. I suppose it was related to the removeAction(d->menuAction); function which destroys QWidget associated to the QWidgetAction. That function was called when the ui->tbDriveUSB->setMenu(NULL); was called.
I choose to use the QLabel just for stylesheet and size, but it's possibile to set that properties in the menu. This is enough for me.
I think that, making a new QLabel when the QWidgetAction is created and delete it when the QWidgetAction is deleted, could make works the previous code. I haven't tested it.
In order to complete the answer, the following is my current code that works well
/* member variable */
QMenu *m_pqmConMenUSB;
/* constructor */
ui->tbDriveUSB->setContextMenuPolicy(Qt::CustomContextMenu);
QObject::connect(ui->tbDriveUSB, SIGNAL(customContextMenuRequested(const QPoint&)),this, SLOT(showUSBCM(const QPoint&)));
m_pqmConMenUSB = new QMenu(this);
QFont fonte = m_pqmConMenUSB->font();
fonte.setPixelSize(16);
m_pqmConMenUSB->setFont(fonte);
m_pqmConMenUSB->setStyleSheet("QMenu { background-color : black; color : white; }");
m_pqmConMenUSB->setMinimumSize(0,32);
/*member functions*/
void MainWindow::showUSBCM(const QPoint& pos)
{
if (pos != QPoint(0,0))
{
// Execute context menu
if (m_pqmConMenUSB!=NULL) m_pqmConMenUSB->exec(pos);
}
}
void MainWindow::OnUSBMounted()
{
static bool tryToChange = true;
ui->tbDriveUSB->show();
QAction *menuItem = new QAction("Dismount",this);
connect(menuItem,SIGNAL(triggered()), this, SLOT(DoDismount()));
m_pqmConMenUSB->addAction(menuItem);
if (tryToChange)
{
QAction *menuItem2 = new QAction("upDate",this);
connect(menuItem2,SIGNAL(triggered()), this, SLOT(Update()));
m_pqmConMenUSB->addAction(menuItem2);
}
tryToChange = !tryToChange;
ui->tbDriveUSB->setMenu(m_pqmConMenUSB);
}
void MainWindow::OnUSBDismounted()
{
printf("SEI UNO SMONTATO\n\r");
ui->tbDriveUSB->setMenu(NULL);
QAction *pAction;
foreach (pAction, m_pqmConMenUSB->actions())
{
pAction->disconnect(this); // receiver
delete pAction;
}
ui->tbDriveUSB->hide();
m_pqmConMenUSB->clear();
}
I want to do something fairly simple : add a custom widget to Qt designer that would basically be a scrollArea containing a custom vertical layout(I added some code to the vertical layout in order to handle its objects for my projects).
The idea would be to represent a vertical menu that would be on the side of my screen
What I have done so far
I created the custom widget plugin and my custom layout.
My custom widget codes looks like this:
#include "menuwidget.h"
MenuWidget::MenuWidget(QWidget *parent) :
QScrollArea(parent)
{
this->setWidgetResizable(true);
QWidget* layoutHoldingWidget= new QWidget(this);
layout= new MenuLayout();
layout->setSizeConstraint(QLayout::SetMinAndMaxSize);
layout->addStretch(1);
layoutHoldingWidget->setLayout(layout);
this->setWidget(layoutHoldingWidget);
}
If I add manually to the layout (in the constructor code) some buttons
for(int i =0;i<20;i++)
layout->addWidget(new QPushButton(this));
It does work and I can see my scrollArea containing some buttons, which is almost what I want.
What I want
I would like to be able to add these buttons directly via Qt designer: the user would first drag the empty MenuWidget on the main window, then would drag QPushButtons on my custom widget exactly like he would do on a regular vertical layout.
Is that possible?How could I do such a thing?
Thank you ! :)
Edit 1
What I was missing was the "scrollAreaWidgetContents" widget that is always created when you drag and drop a QScrollArea. I did a similar thing by adding a widget (let's call it containerWidget) to my custom scrollArea in its domXml function, which enables me to drag and drop widgets on my scroll Area like I wanted to do.
BUT there's still something I can't figure out : I want the containerWidget to have a customLayout (myCustomLayout) . If I add it in the domXml function, I get the following line in the terminal :
Designer:The layout type 'MyCustomLayout' is not supported,
defaulting to grid.
So it means that I can't tell designer to use my custom layout to place my widgets, which is kind of sad :D
Is there any way to "cheat" here?
There are two things to consider:
1) Overwrite in the class you derive from QDesignerCustomWidgetInterface the function to return true
bool isContainer() const { return true; }
This tells QtDesigner that the widget can contain children. (In Qt nearly any Widget can contain any widget as child, but QtDesigner tries to restrict it in a sensible way - e.g. you cant add children to a QLabel in QtDesigner)
2) Implement childEvent of your Widget. Probably in your case it would add Widgets added in QtDesigner to a layout.
Here is a core I've implemented to try this out. I've created a skeleton using "Qt Widget Plugin" Wizard in QtCreator and modified a little bit.
Don't forget to build as release, for the compiler/Qt-version of your QtDesigner , to copy the .dll and .lib files in \plugins\designer directory and to restart QtDesigner!
verticalplugin.cpp
//all other functions remained as created by QtCreator wizard
bool VerticalMenuPlugin::isContainer() const
{
return true;
}
VerticalMenu.h
#ifndef VERTICALMENU_H
#define VERTICALMENU_H
#include <QtGui/QWidget>
#include <QtGui/QVBoxLayout>
class VerticalMenu : public QWidget
{
Q_OBJECT
protected:
virtual void childEvent ( QChildEvent * event );
public:
VerticalMenu(QWidget *parent = 0);
};
#endif
VerticalMenu.cpp
#include "verticalmenu.h"
#include <QChildEvent>
VerticalMenu::VerticalMenu(QWidget *parent) :
QWidget(parent)
{
setLayout (new QVBoxLayout);
}
void VerticalMenu::childEvent ( QChildEvent * event )
{
if ( event->added() )
{
QWidget * newChild = qobject_cast<QWidget *>(event->child());
if ( newChild )
{
layout()->addWidget( newChild );
}
}
}
I hope' it would help as a starting point.
Qt 4 does not support custom layout plugins for designer, so I couldn't achieve what I wanted to do. I will instead use a Vertical Layout and try to implement the additional features that were supposed to be in the custom layout code in the widget code.