Sliders to print a point on a 2D screen

[valy12]

Hello everybody

i'll explain my problem:
i make 2 sliders which give a position in function of 2 axes


MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent), ui(new Ui::MainWindow)
{
ui->setupUi(this);
...
ui->horizontalSlider->setRange(0,431);
ui->verticalSlider->setRange(0,401);
connect(ui->horizontalSlider, SIGNAL(valueChanged(int)),ui->lcdNumber, SLOT(display(int)));
connect(ui->verticalSlider, SIGNAL(valueChanged(int)),ui->lcdNumber_2, SLOT(display(int)));

i connect them to LCD to check values.

for the screen, for the moment i just have that in an another file :

Screen2DGL::Screen2DGL(){
background = QBrush(QColor(Qt::black));
}

void Screen2DGL:aint(QPainter *painter, QPaintEvent *event){
painter->fillRect(event->rect(), background);
painter->setPen(Qt::white);
painter->drawPoint(200,200);
}


i would like to print a point with the coordinates gaven by the sliders instead of "200, 200" on a 2D screen...
How can i do?

[tbscope]

Here you go, but you need to reverse the Y slider, but you'll get the "point" :-)

pointview.h

#ifndef POINTVIEW_H
#define POINTVIEW_H
 
#include <QWidget>
#include <QPaintEvent>
#include <QPoint>
 
class PointView : public QWidget
{
Q_OBJECT
public:
    explicit PointView(QWidget *parent = 0);
 
    void paintEvent(QPaintEvent *event);
 
signals:
 
public slots:
    void setX(int x);
    void setY(int y);
 
private:
    QPoint point;
};
 
#endif // POINTVIEW_H

#ifndef POINTVIEW_H
#define POINTVIEW_H

#include <QWidget>
#include <QPaintEvent>
#include <QPoint>

class PointView : public QWidget
{
Q_OBJECT
public:
    explicit PointView(QWidget *parent = 0);

    void paintEvent(QPaintEvent *event);

signals:

public slots:
    void setX(int x);
    void setY(int y);

private:
    QPoint point;
};

#endif // POINTVIEW_H

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pointview.cpp

#include "pointview.h"
 
#include <QRect>
#include <QPainter>
 
PointView::PointView(QWidget *parent) :
    QWidget(parent)
{
    point.setX(0);
    point.setY(0);
}
 
void PointView::setX(int x)
{
    QRect redrawRect;
 
    if (x < point.x())
        redrawRect.setRect(x-1, point.y()-1, point.x()+1, point.y()+1);
    else
        redrawRect.setRect(point.x()-1, point.y()-1, x+1, point.y()+1);
 
    point.setX(x);
 
    repaint(redrawRect);
}
 
void PointView::setY(int y)
{
    QRect redrawRect;
 
    if (y < point.y())
        redrawRect.setRect(point.x()-1, y-1, point.x()+1, point.y()+1);
    else
        redrawRect.setRect(point.x()-1, point.y()-1, point.x()+1, y+1);
 
    point.setY(y);
 
    repaint(redrawRect);
}
 
void PointView::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event)
 
    QPainter painter(this);
 
    painter.fillRect(rect(), Qt::black);
    painter.setPen(Qt::white);
    painter.drawPoint(point.x(), point.y());
}

#include "pointview.h"

#include <QRect>
#include <QPainter>

PointView::PointView(QWidget *parent) :
    QWidget(parent)
{
    point.setX(0);
    point.setY(0);
}

void PointView::setX(int x)
{
    QRect redrawRect;

    if (x < point.x())
        redrawRect.setRect(x-1, point.y()-1, point.x()+1, point.y()+1);
    else
        redrawRect.setRect(point.x()-1, point.y()-1, x+1, point.y()+1);

    point.setX(x);

    repaint(redrawRect);
}

void PointView::setY(int y)
{
    QRect redrawRect;

    if (y < point.y())
        redrawRect.setRect(point.x()-1, y-1, point.x()+1, point.y()+1);
    else
        redrawRect.setRect(point.x()-1, point.y()-1, point.x()+1, y+1);

    point.setY(y);

    repaint(redrawRect);
}

void PointView::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event)

    QPainter painter(this);

    painter.fillRect(rect(), Qt::black);
    painter.setPen(Qt::white);
    painter.drawPoint(point.x(), point.y());
}

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mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include "pointview.h"
 
namespace Ui {
    class MainWindow;
}
 
class MainWindow : public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
protected:
    void changeEvent(QEvent *e);
 
private:
    Ui::MainWindow *ui;
 
    PointView *pointView;
};
 
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

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

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();

protected:
    void changeEvent(QEvent *e);

private:
    Ui::MainWindow *ui;

    PointView *pointView;
};

#endif // MAINWINDOW_H

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mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
#include <QGridLayout>
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
 
    ui->horizontalSlider->setRange(1, 100);
    ui->verticalSlider->setRange(1,100);
 
    QGridLayout *pointlayout = new QGridLayout;
    pointView = new PointView(this);
    pointlayout->addWidget(pointView);
 
    ui->widget->setLayout(pointlayout);
 
    connect(ui->horizontalSlider, SIGNAL(sliderMoved(int)), pointView, SLOT(setX(int)));
    connect(ui->verticalSlider, SIGNAL(sliderMoved(int)), pointView, SLOT(setY(int)));
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::changeEvent(QEvent *e)
{
    QMainWindow::changeEvent(e);
    switch (e->type()) {
    case QEvent::LanguageChange:
        ui->retranslateUi(this);
        break;
    default:
        break;
    }
}

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

#include <QGridLayout>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    ui->horizontalSlider->setRange(1, 100);
    ui->verticalSlider->setRange(1,100);

    QGridLayout *pointlayout = new QGridLayout;
    pointView = new PointView(this);
    pointlayout->addWidget(pointView);

    ui->widget->setLayout(pointlayout);

    connect(ui->horizontalSlider, SIGNAL(sliderMoved(int)), pointView, SLOT(setX(int)));
    connect(ui->verticalSlider, SIGNAL(sliderMoved(int)), pointView, SLOT(setY(int)));
}

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

void MainWindow::changeEvent(QEvent *e)
{
    QMainWindow::changeEvent(e);
    switch (e->type()) {
    case QEvent::LanguageChange:
        ui->retranslateUi(this);
        break;
    default:
        break;
    }
}

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Sliders and a widget to contain the pointview are added to the ui file.
But you can improve this.

[tbscope]

Even better, as I've already called the repaint with a smaller rect:

void PointView::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
 
    painter.fillRect(event->rect(), Qt::black);
    painter.setPen(Qt::white);
    painter.drawPoint(point.x(), point.y());
}

void PointView::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);

    painter.fillRect(event->rect(), Qt::black);
    painter.setPen(Qt::white);
    painter.drawPoint(point.x(), point.y());
}

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[valy12]

Cool! exactly what i wanted!
Thanks!!!