I would like to insert a Q3DScatter instance onto one of my forms. I am able to construct the graph and display it with:
Q3DScatter *graph = new Q3DScatter();
QWidget *container = QWidget::createWindowContainer(graph);
...do some graph stuff...
container.show()
This successfully creates the graph and shows it in its own window/container. I would now like to place it inside another form that has been designed in qt-creator. I have placed an empty widget on the form(QDialog) as a placeholder, but am unable to move the Q3DScatter into the widget.
I see Q3DScatter::Q3DScatter(const QSurfaceFormat *format = Q_NULLPTR, QWindow *parent = Q_NULLPTR) in the documentation but I dont have a QWindow parent to attach it to, as the form I would like to add it to is a QDialog...
I am very new to widgets in general, so please correct me if this is the wrong approach.
Add the container as a child of the dialog. Put in a layout if you need to resize when the dialog is resized. Example:
MyDialog::MyDialog(Q3DScatter *scatter, QWidget *parent) : QDialog(parent)
{
QHBoxLayout * const l = new QHBoxLayout(this);
l->setMargin(0);
l->addWidget(QWidget::createWindowContainer(scatter, this);
}
Related
So, I took it down a few notches and am trying simple programs to get the hang of Qt's tools.
First I tried a simple label inside main() function, then a button inside it. All good.
Next, I tried the same, but inside a main window (using the Qt's created documents). After the one-button program worked, I did a two-button program, that simple. Worked.
Then, I tried Qt's Box Layouts.
In none of these "main window" tries, I changed the main.cpp file created by Qt.
Here's the mainwindow.h:
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QPushButton>
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = 0);
~MainWindow();
private:
QPushButton *button1;
QPushButton *button2;
};
#endif // MAINWINDOW_H
Next, the mainwindow.cpp file:
#include "mainwindow.h"
#include <QPushButton>
#include <QHBoxLayout>
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
{
setWindowTitle(tr("Two Button Example"));
resize(400,300);
button1 = new QPushButton(tr("Bye!"));
button1->setGeometry(0,0,200,30);
//button1->setParent(this);
connect(button1,SIGNAL(clicked()),this,SLOT(close()));
button1->show();
button2 = new QPushButton(tr("Hide B1!"));
button2->setGeometry(0,0,200,30);
//button2->setParent(this);
connect(button2,SIGNAL(clicked()),button2,SLOT(hide()));
button2->show();
QHBoxLayout *layout = new QHBoxLayout;
layout->addWidget(button1);
layout->addWidget(button2);
setLayout(layout);
}
MainWindow::~MainWindow()
{
}
I'm studying this book (for the layouts specifically, Chapter 2, the Find Dialog example (page 16 of the book, or 34 from the pdf file): C++ GUI Programming with Qt 4 1st ed.pdf
For this specific problem, I also used this: QHBoxLayout - Qt Examples and Tutorials
What I noticed:
Commenting the QHBoxLayout part, all the way to the "setLayout" function, makes no difference in the program. No test I've done is affected by this QBoxLayout thing;
The "setGeometry" function sets the position (first two parameters) and size (width and heightm, last two parameters) of a widget. This position is related to the parent widget, which may be the screen itself when no parent is assigned;
When the "setParent" functions for the buttons are commented and the "show" function is uncommented, the buttons are shown each in a separate window from the MainWindow. When I uncomment the "setParent" functions, the buttons are shown inside the MainWindow, and there's no difference if there are or no "show" functions for the buttons. The detail is, for the book I referenced, no example so far have had the need to declare the parent widgets, nor did the example in Qt's Examples and Tutorials site;
If I don't use the "setGeometry" function, the buttons are big, like 600x600, whatever. They follow the rules above regarding the other functions, but they are huge and always one on top of the other, not side by side. The function "sizeHint()" used extensively in the book, also has no effect;
Appearently, it's all following the same syntaxes and rules of the examples. So, what am I doing wrong, or not doing here? If it's not a problem to enlight me with the "sizeHint()" function, too, that would be great.
Thanks in advance!
I don't even remember the origin of the problem, but I have never been able to work with the layouts right in the window. In company I worked with Qt we used a central widget for managing layouts, so the diagram is: window -> central widget -> layouts -> subwidgets. If I modified your code so, it would look like this:
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent)
{
setWindowTitle(tr("Two Button Example"));
resize(400,300);
auto *parentWidget = new QWidget;
auto button1 = new QPushButton(tr("Bye!"), parentWidget);
button1->setGeometry(0,0,200,30);
connect(button1,SIGNAL(clicked()),this,SLOT(close()));
auto button2 = new QPushButton(tr("Hide B1!"), parentWidget);
button2->setGeometry(0,0,200,30);
connect(button2,SIGNAL(clicked()),button2,SLOT(hide()));
QHBoxLayout *layout = new QHBoxLayout;
layout->addWidget(button1);
layout->addWidget(button2);
parentWidget->setLayout(layout);
setCentralWidget(parentWidget);
}
Also, I don't quite understand why do you try to set the button size if the layout resets it later. To change the size inside a layout you must change the sizeHint of a widget:
setWindowTitle(tr("Two Button Example"));
resize(400,300);
auto *parentWidget = new QWidget;
auto button1 = new QPushButton(tr("Bye!"), parentWidget);
button1->setMaximumSize(20, 20);
connect(button1,SIGNAL(clicked()),this,SLOT(close()));
auto button2 = new QPushButton(tr("Hide B1!"), parentWidget);
button2->setMaximumSize(20, 20);
connect(button2,SIGNAL(clicked()),button2,SLOT(hide()));
QHBoxLayout *layout = new QHBoxLayout;
layout->addWidget(button1);
layout->addWidget(button2);
parentWidget->setLayout(layout);
setCentralWidget(parentWidget);
After some observation, I believe I know why it wasn't working.
In the examples provided, the person was using QDialog or applying the layouts straight to the main() code, while I was using the QMainWindow class.
I suppose that when you use a QMainWindow class, you always have to set a Central Widget in order to make layouts work (setting this central widget layout).
So a solution would be:
QWidget centerWidget = new QWidget();
setCentralWidget(centerWidget);
//Add buttons, lists, and whatever
/*Add a QHBoxLayout or a QVBoxLayout and use
layout->addWidget() to add the widgets created,
like the examples. Then:*/
centerWidget->setLayout(layout);
It works, like Victor Polevoy suggested. Just answering as I believe I understood why weren't my QLayouts working.
I have a window that contains a browser. Up is a toolbar. In the bottom of the window is a search bar.
Search bar has a close button [x].
When the user clicks the close button I want the bar to disappear.
I want the bar only appear when user press CTRL + F. I tried to connect the close butoon with .hide() command, but application crashes. I need help.
.cpp
DocumentationWin::DocumentationWin (QWidget * parent){
docs = new QTextBrowser( this );
//Prepare toolbar
toolbar = new QToolBar( this );
//add stuff to toolbar
//Prepare footer bar
searchlabel = new QLabel(tr("Find in page:"),this);
resultslabel = new QLabel("",this);
searchinput = new QLineEdit();
findprev = new QToolButton(this);
findprev->setArrowType(Qt::UpArrow);
connect(findprev, SIGNAL(clicked()), this, SLOT (clickFindPrev()));
findnext = new QToolButton(this);
findnext->setArrowType(Qt::DownArrow);
connect(findnext, SIGNAL(clicked()), this, SLOT (clickFindNext()));
QStyle *style = qApp->style();
QIcon closeIcon = style->standardIcon(QStyle::SP_TitleBarCloseButton);
QPushButton *closeButton = new QPushButton(this);
closeButton->setIcon(closeIcon);
closeButton->setFlat(true);
connect(closeButton, SIGNAL(clicked()), this, SLOT (clickCloseFind()));
QWidget *bottom = new QWidget;
QHBoxLayout *footer = new QHBoxLayout();
casecheckbox = new QCheckBox(tr("Case sensitive"),this);
footer->setContentsMargins(5,5,5,5);
footer->addWidget(searchlabel);
footer->addSpacing(3);
footer->addWidget(searchinput);
footer->addWidget(findprev);
footer->addWidget(findnext);
footer->addSpacing(10);
footer->addWidget(casecheckbox);
footer->addSpacing(10);
footer->addWidget(resultslabel);
footer->addStretch(1);
footer->addWidget(closeButton);
bottom->setLayout(footer);
//Prepare main layout
layout = new QVBoxLayout;
layout->setContentsMargins(0,0,0,0);
layout->setSpacing(0);
layout->addWidget(toolbar);
layout->addWidget(docs);
layout->addWidget(bottom);
this->setLayout(layout);
this->show();
}
void DocumentationWin::clickCloseFind(){
bottom->hide();
}
.h
class DocumentationWin : public QDialog
{
Q_OBJECT
public:
DocumentationWin(QWidget * parent);
protected:
virtual void keyPressEvent(QKeyEvent *);
private slots:
void clickCloseFind();
private:
QVBoxLayout* layout;
QToolBar* toolbar;
QTextBrowser* docs;
QBoxLayout* footer;
QLabel *searchlabel;
QLabel *resultslabel;
QLineEdit *searchinput;
QToolButton *findprev;
QToolButton *findnext;
QCheckBox *casecheckbox;
QWidget *bottom;
QPushButton *closeButton;
};
Ahh, the classic case of local variables hiding the members. There have been quite a few identical questions on SO about this. This is wrong:
QWidget *bottom = new QWidget;
You want:
bottom = new QWidget;
You'll run into these problems always because you dynamically allocate all the widgets - that's completely unnecessary.
Suggestions:
Hold the child widgets and layouts by value, don't dynamically allocate them.
Don't pass a parent to widgets that are managed by a layout. Every widget that is laid out will be automatically parented.
Don't redundantly call setLayout. A QLayout takes the widget to lay its children on as a constructor argument.
QWidget::hide() is a slot.
Many widgets take the text as a constructor argument.
If you don't have any arguments to pass to the constructor in a new expression, you can drop the parentheses (but we try to avoid these anyway):
searchinput = new QLineEdit; // not QLineEdit();
Widgets shouldn't usually show() themselves upon construction. No Qt widget does that. It's up to the widget's user to do it.
C++ overloads a method call syntax with construction syntax. To differentiate the two, prefer uniform initialization (Type{arg0, arg1, ...}) over old syntax that used ().
Here's how your code can look when you're using C++11. This compiles with either Qt 4 or Qt 5. If you don't target Qt 4, you should be using the new connect syntax, though.
As you can see, there isn't a single explicit dynamic allocation - that's how quite a bit of C++11 code will look, when the used types are sane.
// https://github.com/KubaO/stackoverflown/tree/master/questions/find-hide-38082794
#include <QtGui>
#if QT_VERSION >= QT_VERSION_CHECK(5,0,0)
#include <QtWidgets>
#endif
class DocumentationWin : public QDialog
{
Q_OBJECT
public:
explicit DocumentationWin(QWidget * parent = 0);
private:
QVBoxLayout layout{this};
QToolBar toolbar;
QTextBrowser docs;
QWidget bottom;
QHBoxLayout footer{&bottom};
QLabel searchlabel{tr("Find in page:")};
QLabel resultslabel;
QLineEdit searchinput;
QToolButton findprev;
QToolButton findnext;
QCheckBox casecheckbox{tr("Case sensitive")};
QPushButton closeButton;
Q_SLOT void onFindPrev() {}
Q_SLOT void onFindNext() {}
};
DocumentationWin::DocumentationWin(QWidget * parent) : QDialog(parent) {
findprev.setArrowType(Qt::UpArrow);
connect(&findprev, SIGNAL(clicked()), this, SLOT(onFindPrev()));
findnext.setArrowType(Qt::DownArrow);
connect(&findnext, SIGNAL(clicked()), this, SLOT(onFindNext()));
auto style = qApp->style();
auto closeIcon = style->standardIcon(QStyle::SP_TitleBarCloseButton);
closeButton.setIcon(closeIcon);
closeButton.setFlat(true);
connect(&closeButton, SIGNAL(clicked(bool)), &bottom, SLOT(hide()));
footer.setContentsMargins(5,5,5,5);
footer.addWidget(&searchlabel);
footer.addSpacing(3);
footer.addWidget(&searchinput);
footer.addWidget(&findprev);
footer.addWidget(&findnext);
footer.addSpacing(10);
footer.addWidget(&casecheckbox);
footer.addSpacing(10);
footer.addWidget(&resultslabel);
footer.addStretch(1);
footer.addWidget(&closeButton);
layout.setContentsMargins(0,0,0,0);
layout.setSpacing(0);
layout.addWidget(&toolbar);
layout.addWidget(&docs);
layout.addWidget(&bottom);
}
int main(int argc, char ** argv) {
QApplication app{argc, argv};
DocumentationWin win;
win.show();
return app.exec();
}
#include "main.moc"
I am currently writing a C++ Application using the Qt framework, in which the 'main window' inherits from the QWidget class:
class Draughts : public QWidget
{
Q_OBJECT
public:
explicit Draughts(QWidget *parent = 0);
~Draughts();
private:
Ui::Draughts *ui;
};
And I attempted to add a simple menu bar to the application, using the following code:
Draughts::Draughts(QWidget *parent) :
QWidget(parent),
ui(new Ui::Draughts)
{
ui->setupUi(this);
QWidget *menuWidget = new QWidget;
QMenu *menuGame = new QMenu("Game");
menuGame->addAction("New");
menuGame->addAction("Exit");
QMenu *menuHelp = new QMenu("Help");
menuHelp->addAction("How to Play...");
menuHelp->addAction("About");
//Setup the Application Menu
QMenuBar mainMenu(this);
mainMenu.addMenu(menuGame);
mainMenu.addMenu(menuHelp);
}
Should I be using the QMainWindow class instead of the QWidget class for my application?
It would be easier to use QMainWindow, because it provides a convenient menuBar() method:
QMenuBar* mainMenu = this->menuBar();
But it is possible to add it to QWidget, just as any other widget. Just don't allocate it in the local scope, because it will be deleted after the function finishes. Instead, do it like with other widgets:
QMenuBar mainMenu = new QMenuBar(this);
You should also probably add a layout to your widget, and add the menu to the layout to have more control over where does it appear. You may find this tutorial useful.
Is it possible that a QGraphicsWidget be a parent for QWidget? I have a QGraphicsItem and I want to add a QWidget inside this item, How can I set a QWidget in a QGraphicsItem or QGraphicsWidget that is a child of QGraphicsItem?
QGraphicsWidget is basically a QGraphicsItem for QWidgets ... it provides a layout you can use so it should be no problem at all
use:
QGraphicsScene::addWidget( QWidget * widget, Qt::WindowFlags wFlags = 0 )
QWidget and QGraphicsWidget are very different. However, the QGraphics system provides a QGraphicsProxyWidget for embedding QWidget and QWidget-based items in a QGraphicsScene.
You can directly create the QGraphicsProxyWidget and call the function setWidget, before adding the QGraphicsProxyWidget to your QGraphicsScene: -
QGraphicsScene* pScene = new QGraphicsScene;
QWidget* pWidget = new QWidget;
QGraphicsProxyWidget* pProxy = new QGraphicsProxyWidget(parent); // parent can be NULL
pProxy->setWidget(pWidget);
pScene->addItem(pProxy);
The proxy widget can now be moved, scaled etc in the scene and the functionality of its QWidget will have signals passed through to it to work as expected.
Alternatively, the QGraphicsScene contains a shortcut function addWidget, which internally creates the QGraphicsProxyWidget for you and returns it from the function: -
QGraphicsProxyWidget* pProxy = pScene->addWidget(pWidget);
I have a class MyListWidget derrived from QWidget. I passed parent and flags to the base class QWidget constructor (tried both Qt::Dialog and Qt::Popup in tests) but the custom widget is shown in the center of the screen instead centered to its parent.
MyListWidget* myListWidget = new MyListWidget(this, Qt::Dialog);
This is the constructor:
MyListWidget::MyListWidget(QWidget* parent, Qt::WindowFlags flags)
: QWidget(parent, flags),
ui(std::auto_ptr<Ui::MyListWidget>(new Ui::MyListWidget))
{
ui->setupUi(this);
}
If I put this widget into a separate dialog, anything works as expected. But why?
Wrapping works:
QDialog* popup = new QDialog(this, Qt::Popup);
QVBoxLayout* hLayout = new QVBoxLayout(popup);
// ... doing list creation like above
hLayout->addWidget(mmyListWidget);
popup->setLayout(hLayout);
const int width = mapListWidget->width();
const int height = mapListWidget->height();
popup->resize(width, height);
Any ideas what could happend here?
QWidget is not shown on center by default, so you need to center it manually (you can do that in the constructor):
MyListWidget::MyListWidget(QWidget* parent, Qt::WindowFlags flags)
: QWidget(parent, flags),
ui(std::auto_ptr<Ui::MyListWidget>(new Ui::MyListWidget))
{
ui->setupUi(this);
move(
parent->window()->frameGeometry().topLeft() +
parent->window()->rect().center() - rect().center()
);
}
P.S. Beware of std::auto_ptr, you probably want to use std::unique_ptr these days.
I'm not quite sure what you're trying to achieve but I have the feeling you should derive MyListWidget from QDialog.
Regards,
Ben