How to send QFrame to the back?

Christina123

Hi, what I want to do is to draw lines at the front of the QFrame but currently it is drawn behind the QFrame. I am wondering if there is a way to move the qframe back.

/*Adding qframe to my vboxlayout*/
void sender::setNewDrawingPad(void)
{
    path -> clear();
    pad -> setStyleSheet("background-color: rgb(220,220,220);");
    vbox -> addWidget(pad,1);
}

/*this is my paintevent*/
void sender::paintEvent(QPaintEvent *event)
{
    QPainter paint(this);
    paint.drawPath(*path);
}

SGaist

To ensure which are called use Q_FUNC_INFO in your debug lines.

There's no need for the installEventFilter call.

You cannot paint on a widget from a different one. The correct way is like you started with QFrame, then override paint event, call the base class implementation and do your own painting afterward.

SGaist

Hi,

How do you setup your widgets ?
What is the role of sender with regard to that QFrame ?

Christina123

@SGaist Thank you for your reply. This is my code for my sender class and the its setup. What I want to do is to display a drawing pad done by using QFrame when 'new' button is clicked.

class sender : public QWidget
{
    Q_OBJECT

public:
    sender(QWidget *parent = nullptr);
    ~sender();
    void paintEvent(QPaintEvent *event);
    void mousePressEvent(QMouseEvent *event);
    void mouseReleaseEvent(QMouseEvent *event);

private slots:
    void getPath();
    void clear();
    void setNewDrawingPad();

private:
    QPainterPath *path;
    QHBoxLayout *hbox;
    QVBoxLayout *vbox;
    QFrame *pad;
    bool padOn;

};

sender::sender(QWidget *parent) : QWidget(parent)
{
    setMinimumSize(QSize(500,500));
    path = new QPainterPath();
    pad= new QFrame;
    padOn = false;

    hbox = new QHBoxLayout;
    hbox -> setSpacing(3);
    vbox = new QVBoxLayout(this);

    QPushButton *New = new QPushButton("New",this);
    New -> setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
    connect(New, &QPushButton::clicked, this, &sender::setNewDrawingPad);

    hbox -> addStretch(1);
    vbox -> addLayout(hbox);
}

SGaist

So you draw on sender and then want to show the result on your pad object ?

Christina123

@SGaist A beginner's mistake made by a beginner. Thank you for point that out to me. But, I am still unsure how to paint on to my qframe. Do I change the QPainter painter(this) to QPainter painter(this->frame)?

Christina123

Instead of changing this to this -> frame which obviously doesn't work, I create a MyFrame class which inherits from QFrame and overrides mousepressevent and mousereleaseevent so that I can store the positions into my path variable. In my window class, I has a private member that is a member of class myFrame. However, even though I am sure that I click on the frame, the mouseevent seems to be handled in the parent class instead of the child class. I am not sure why is that?


class MyFrame : public QFrame
{
    Q_OBJECT
public:
    MyFrame(QWidget *parent = nullptr);
    void paintEvent(QPaintEvent *event);
    void mousePressEvent(QMouseEvent *event);
    void mouseReleaseEvent(QMouseEvent *event);

private:
    QPainterPath *path;
};

class window : public QWidget
{
    Q_OBJECT

public:
    window(QWidget *parent = nullptr);
    void mousePressEvent(QMouseEvent *event);
    void mouseReleaseEvent(QMouseEvent *event);

public slots:

private slots:

private:
    MyFrame *frame;
};

#include "window.h"
#include "ui_window.h"
#include <QDebug>
#include <QtCore>
#include <QBoxLayout>
#include <QDebug>



window::window(QWidget *parent)
    : QWidget(parent)
{
    //setMinimumSize(QSize(500,500));
    frame = new MyFrame();
    QBoxLayout *layout = new QBoxLayout(QBoxLayout::TopToBottom);
    layout -> addWidget(frame);
    frame -> installEventFilter(this);
}


void window::mousePressEvent(QMouseEvent *event)
{
    qDebug()<<event -> x()<<event -> y();
}

void window::mouseReleaseEvent(QMouseEvent *event)
{
    qDebug()<<event -> x()<<event -> y();
}
MyFrame::MyFrame(QWidget *parent) : QFrame(parent)
{
    setStyleSheet("background-color: rgb(220,220,220)");
}

void MyFrame::mousePressEvent(QMouseEvent *event)
{
    qDebug()<<event ->x()<<event->y();
}

void MyFrame::mouseReleaseEvent(QMouseEvent *event)
{
    qDebug()<<event ->x()<<event->y();
}

SGaist

To ensure which are called use Q_FUNC_INFO in your debug lines.

There's no need for the installEventFilter call.

You cannot paint on a widget from a different one. The correct way is like you started with QFrame, then override paint event, call the base class implementation and do your own painting afterward.