QWidget in a subwindow

[blackhole]

Hello,

I have a subwindow (m_window) in which I want to add a created (Painter)-Widget (GraphWidget):

m_window = new QWidget();
 
    m_graphwidget = new GraphWidget ();
    m_graphwidget->setGeometry(QRect(500, 100, 50, 50));
    m_graphwidget->show();
 
// show some Labels
    showWindow();
 
    m_window->show();

m_window = new QWidget();
    
    m_graphwidget = new GraphWidget ();
    m_graphwidget->setGeometry(QRect(500, 100, 50, 50));
    m_graphwidget->show();
    
// show some Labels
    showWindow();

    m_window->show();

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With this the GraphWidget is placed in another window, that's clear because i didn't connect the widget with m_window. To place the GraphWidget in the window I used m_graphwidget = new GraphWidget (m_window). But then I got the compiler error:

error: no matching function for call to ‘GraphWidget::GraphWidget(QWidget*&)’

I don't understand this message because m_window is only a pointer to a QWidget?!

I tried another way: I declared m_window as a QMainWindow object and connected it with the GraphWidget:

m_window->setCentralWidget(m_graphwidget);

m_window->setCentralWidget(m_graphwidget);

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In this case, the GraphWidget is placed in the window, but I can't set its position and I can see only one part of the labels (which are defined in showWindow(); ).

Can you tell me a solution of this problem?

[Santosh Reddy]

there may be a problem with GraphWidget class defintion, post the GraphWidget class definition / headr file. You may be missing a corresponding ctor definition

by the way, are you sure you want to fix the position usig setGeometry(), can't you use layout to do the job for you.

[blackhole]

Hi, thank you for your answer.

Here is the definition of GraphWidget:

class GraphWidget : public QWidget
{
    Q_OBJECT
 
public:
 
    void paintEvent(QPaintEvent *);
 
};

class GraphWidget : public QWidget
{
    Q_OBJECT
    
public:

    void paintEvent(QPaintEvent *);

};

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and

void GraphWidget::paintEvent(QPaintEvent* )
{
    QPainter painter(this);
    painter.setPen(Qt::blue);
    painter.setFont(QFont("Arial", 30));
    painter.drawText(rect(), Qt::AlignCenter, "Qt");
}

void GraphWidget::paintEvent(QPaintEvent* )
{
    QPainter painter(this);
    painter.setPen(Qt::blue);
    painter.setFont(QFont("Arial", 30));
    painter.drawText(rect(), Qt::AlignCenter, "Qt");
}

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I thought setGeometry() is easier but if layout works I can use that too.

[ChrisW67]

Your error message comes about because you have provided no constructor that expects a QWidget* argument (as Santosh Reddy said). The only constructors GraphWidget has are an automatic default constructor and copy constructor. The lines after the error message will often tell you what options you have, for example GCC emits:

main.cpp:22: error: no matching function for call to ‘GraphWidget::GraphWidget(QWidget*&)’
main.cpp:5: note: candidates are: GraphWidget::GraphWidget()
main.cpp:5: note:                 GraphWidget::GraphWidget(const GraphWidget&)

main.cpp:22: error: no matching function for call to ‘GraphWidget::GraphWidget(QWidget*&)’
main.cpp:5: note: candidates are: GraphWidget::GraphWidget()
main.cpp:5: note:                 GraphWidget::GraphWidget(const GraphWidget&)

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Add a minimal constructor:

explicit GraphWidget(QWidget *p = 0): QWidget(p) {}

explicit GraphWidget(QWidget *p = 0): QWidget(p) {}

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and the problem will go away.

Layouts are easier especially since you want more than one widget inside your window. If you continue to try to absolutely position items then I predict your next question will be, "My window doesn't resize its content properly, how do I fix it?".

[blackhole]

Thanks a lot! It works. I promise I will try layouts before I post this question