Incorrect painting or geometry of custom widget

Kirill Gusarev

I'm trying to make my widgets moveable within a parent widget. But for some reason, a click on the widget is registered even when the cursor is located significantly above the widget. For a long time I can’t understand what the reason is. Help please :C

canvas.h

#ifndef CANVAS_H
#define CANVAS_H

#include <QObject>
#include "figures.h"
#include <functional>

class Canvas : public QFrame
{
    Q_OBJECT
public:
    Figure *elements; // Array of figures
    explicit Canvas(QWidget *parent = nullptr);
    ~Canvas();

protected:
    virtual void mousePressEvent(QMouseEvent *event) override;

private:
    bool onAddingFigure;
    bool onAddingLink;
    bool onMoving;
    bool onDeleting;

signals:
    void addingFigureFinished(FigureType figureType);
};

#endif // CANVAS_H

canvas.cpp

#include "canvas.h"
#include <QDebug>

Canvas::Canvas(QWidget *parent)
    : QFrame{parent}
{
    this->setFrameShape(StyledPanel);
    this->setFrameShadow(Sunken);
}

Canvas::~Canvas()
{
//    delete[] elements;
}

// For adding new figures into canvas
void Canvas::mousePressEvent(QMouseEvent *event)
{
    qDebug() << "canvas mouse press";
    // Конец
#define figureTypeId (FigureType::Rectangle) // заглушка
    emit addingFigureFinished(figureTypeId);
#undef figureTypeId // заглушка
}

figures.h

#ifndef FIGURE_H
#define FIGURE_H

#include <QObject>
#include <QRect>
#include <QSet>
#include <QWidget>
#include <QStyle>
#include <QStyleOption>
#include <QPainter>
#include <QMouseEvent>


enum class FigureType
{
    Rectangle,
    Triangle,
    Ellipse
};


class Figure : public QWidget
{
    Q_OBJECT

protected:
//    int x, y, w, h;
    QRect geometry;
//    Figure *linkedTo;
    QSet<Figure*> linkedFigures;

    virtual void mousePressEvent(QMouseEvent *event) override;
    virtual void mouseMoveEvent(QMouseEvent *event) override;

public:
    Figure(int left, int top, int width, int height, QWidget *parent = nullptr);
//    explicit Figure(QWidget *parent = nullptr);
    void connect(Figure *figure);

signals:

};


class Rectangle : public Figure
{
    Q_OBJECT

public:
    Rectangle(int left, int top, int width, int height, QWidget *parent);
//    explicit Rectangle(QObject *parent = nullptr);

protected:
    virtual void paintEvent(QPaintEvent *event) override;

signals:

};


class Triangle : public Figure
{
    Q_OBJECT

public:
    Triangle(int left, int top, int width, int height, QWidget *parent);
//    explicit Triangle(QObject *parent = nullptr);

signals:

};


class Ellipse : public Figure
{
    Q_OBJECT

public:
    Ellipse(int left, int top, int width, int height, QWidget *parent);
//    explicit Ellipse(QObject *parent = nullptr);

signals:

};


class Link// : public Figure
{
//    Q_OBJECT

public:
    Figure *figure1, *figure2;
//    explicit Link(QObject *parent = nullptr);

//signals:

};
#endif // FIGURE_H

figures.cpp

#include "figures.h"

//void Figure::paintEvent(QPaintEvent *event)
//{
//    QStyleOption opt;
//    opt.initFrom(this);
//    QPainter painter(this);
//    style()->drawPrimitive(QStyle::PE_Widget, &opt, &painter, this);
//}

void Figure::mousePressEvent(QMouseEvent *event)
{
    this->raise();
}

void Figure::mouseMoveEvent(QMouseEvent *event)
{
    QPoint pos = event->scenePosition().toPoint();
    this->move(pos);
}

Figure::Figure(int left, int top, int width, int height, QWidget *parent)
    : QWidget(parent)
{
    this->geometry = QRect(left, top, width, height);
//    this->setGeometry(left, top, width, height);
    this->setGeometry(geometry);
    this->setStyleSheet("background-color: #999999");
}

void Figure::connect(Figure *figure)
{
    linkedFigures.insert(figure);
    figure->linkedFigures.insert(this);
}

Rectangle::Rectangle(int left, int top, int width, int height, QWidget *parent)
    : Figure(left, top, width, height, parent)
{
}

void Rectangle::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
    painter.setPen(QPen(Qt::gray, 1, Qt::SolidLine, Qt::FlatCap));
//    painter.setPen(QPen(Qt::NoPen));
    painter.setBrush(QBrush(0xEEEE00, Qt::SolidPattern));
    qDebug() << this->geometry;
    painter.drawRect(this->geometry);
}


Triangle::Triangle(int left, int top, int width, int height, QWidget *parent)
    : Figure(left, top, width, height, parent)
{
}

Ellipse::Ellipse(int left, int top, int width, int height, QWidget *parent)
    : Figure(left, top, width, height, parent)
{
}

//Link::Link(QObject *parent)
//    : QObject{parent}
//{

//}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "canvas.h"

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
    bool addingRectangle;
    bool addingTriangle;
    bool addingEllipse;

private slots:
    void on_figure_added(FigureType figureType);

    void on_pushButton_rectangle_clicked();

    void on_pushButton_triangle_clicked();

    void on_pushButton_ellipse_clicked();

    void on_pushButton_connection_clicked();

    void on_pushButton_move_clicked();

    void on_pushButton_delete_clicked();

    void on_pushButton_load_clicked();

    void on_pushButton_save_clicked();

private:
    Ui::MainWindow *ui;
    Canvas *canvas;
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->graphicsView_canvas->hide();
    canvas = new Canvas(this);
    canvas->setGeometry(10, 50, 771, 361);
    canvas->setStyleSheet("background-color: white;");
    
    // These figures are just for testing. I know about memory leak :)
    Figure *figure1 = new Rectangle(5, 20, 200, 100, canvas);
    Figure *figure2 = new Rectangle(10, 10, 12, 12, canvas);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_figure_added(FigureType figureType)
{
}

void MainWindow::on_pushButton_rectangle_clicked()
{
    this->addingRectangle = true;
}

void MainWindow::on_pushButton_triangle_clicked()
{
    this->addingTriangle = true;
}

void MainWindow::on_pushButton_ellipse_clicked()
{
    this->addingEllipse = true;
}

void MainWindow::on_pushButton_connection_clicked()
{

}

void MainWindow::on_pushButton_move_clicked()
{

}

void MainWindow::on_pushButton_delete_clicked()
{

}

void MainWindow::on_pushButton_load_clicked()
{

}

void MainWindow::on_pushButton_save_clicked()
{

}

mainwindow.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>791</width>
    <height>457</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QPushButton" name="pushButton_rectangle">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>10</y>
      <width>101</width>
      <height>24</height>
     </rect>
    </property>
    <property name="text">
     <string>Прямоугольник</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_triangle">
    <property name="geometry">
     <rect>
      <x>120</x>
      <y>10</y>
      <width>81</width>
      <height>24</height>
     </rect>
    </property>
    <property name="text">
     <string>Треугольник</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_ellipse">
    <property name="geometry">
     <rect>
      <x>210</x>
      <y>10</y>
      <width>71</width>
      <height>24</height>
     </rect>
    </property>
    <property name="text">
     <string>Эллипс</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_connection">
    <property name="geometry">
     <rect>
      <x>310</x>
      <y>10</y>
      <width>71</width>
      <height>24</height>
     </rect>
    </property>
    <property name="text">
     <string>Связь</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_move">
    <property name="geometry">
     <rect>
      <x>410</x>
      <y>10</y>
      <width>91</width>
      <height>24</height>
     </rect>
    </property>
    <property name="text">
     <string>Переместить</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_delete">
    <property name="geometry">
     <rect>
      <x>510</x>
      <y>10</y>
      <width>71</width>
      <height>24</height>
     </rect>
    </property>
    <property name="text">
     <string>Удалить</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_load">
    <property name="geometry">
     <rect>
      <x>630</x>
      <y>10</y>
      <width>71</width>
      <height>24</height>
     </rect>
    </property>
    <property name="text">
     <string>Загрузить</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_save">
    <property name="geometry">
     <rect>
      <x>710</x>
      <y>10</y>
      <width>71</width>
      <height>24</height>
     </rect>
    </property>
    <property name="text">
     <string>Сохранить</string>
    </property>
   </widget>
   <widget class="QGraphicsView" name="graphicsView_canvas">
    <property name="enabled">
     <bool>true</bool>
    </property>
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>50</y>
      <width>771</width>
      <height>361</height>
     </rect>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>791</width>
     <height>22</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

main.cpp

#include "mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.setWindowTitle("Visio");
    w.show();
    return a.exec();
}

Visio.pro

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++17

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    canvas.cpp \
    figures.cpp \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    canvas.h \
    figures.h \
    mainwindow.h

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

Kirill Gusarev

This post is deleted!

JonB

@Kirill-Gusarev
I would suggest this is way too much code to ask other people to look at. Reduce to a minimal, standalone example, preferably without a .ui file.

I do not know what your behaviour or issue is. But I would suggest clearing up something in your code: your Figure derives from QWidget and defines a member variable named geometry. QWidget has geometry()/setGeometry() methods. Do yourself a favor and rename your geometry variable to something else, you are just asking for confusion the way you have it, especially given you are asking about a geometry issue.

Kirill Gusarev

@JonB yes I know about QWidget::geometry(), but if I use this method, the error will be different - the shapes will change in position AND SIZE when moved...

I will try to minify the above code

Pl45m4

Hi @Kirill-Gusarev ,

I don't want to question your project, but what's the idea behind this?
It seems that you are trying to re-build QGraphicsView, QGraphicsScene and QGraphicsItem (QGraphicsRectItem, QGraphicsEllipseItem... etc)
These classes already exist as part of Qt's Graphics View Framework

https://doc.qt.io/qt-6/graphicsview.html

BTW:

@JonB has partly answered your question.
If YOUR geometry and QWidget's geometry()/setGeometry() are not the same, the size of your widget will be different from what you actually see, due to:

painter.drawRect(this->geometry);

in the paintEvent of your Figure items.

The mouse events are captured all over the widgets "boundings" (doesn't matter what you paint there).
So if geometry() returns a larger rectangle than the size of your visible area, you know why you receive clicks from outside the painted area.

Use the in-built geometry as suggested by @JonB or make sure you update your geometry variable on every geometry change.
And I would rename it slightly, because it's really confusing.

In case you are not aware of QGraphicsView and its items, take a look at it.

JonB

@Kirill-Gusarev said in Incorrect painting or geometry of custom widget:

yes I know about QWidget::geometry()

Then why do you define a member variable with the same name as the base class has for a public method?

but if I use this method, the error will be different

QWidget::geometry() simply returns the current geometry of a widget. It is const, has no side-effects and does not cause errors.

I suggested you rename your member variable from geometry to anything else you like, which does not clash with a public symbol from QWidget. And change all your calls to use the new name you pick. If that causes any change of behaviour at all you have a real problem....

Kirill Gusarev

This post is deleted!

Kirill Gusarev

This post is deleted!