Setting background image for Central Widget

[rvgrouik]

I created a BackgroundWidget class that does what you want:

#ifndef BACKGROUNDWIDGET_H
#define BACKGROUNDWIDGET_H
 
#include <QWidget>
#include <QPixmap>
#include <QString>
#include <QSize>
#include <QPaintEvent>
 
class BackgroundWidget: public QWidget
{
    Q_OBJECT
 
public:
    BackgroundWidget(QWidget* parent, QString bgImagePath);
    ~BackgroundWidget();
 
 
    void setPicture(const QString& bgImagePath);
    void setPixmap(QPixmap* bgImage);
 
    QSize sizeHint() const;
 
signals:
    void backgroundPainted();
 
protected:
    void paintEvent(QPaintEvent *event);
 
private:
    QPixmap Image;
    QBrush Brush;
};
 
 
#endif // BACKGROUNDWIDGET_H

#ifndef BACKGROUNDWIDGET_H
#define BACKGROUNDWIDGET_H

#include <QWidget>
#include <QPixmap>
#include <QString>
#include <QSize>
#include <QPaintEvent>

class BackgroundWidget: public QWidget
{
    Q_OBJECT

public:
    BackgroundWidget(QWidget* parent, QString bgImagePath);
    ~BackgroundWidget();


    void setPicture(const QString& bgImagePath);
    void setPixmap(QPixmap* bgImage);

    QSize sizeHint() const;

signals:
    void backgroundPainted();

protected:
    void paintEvent(QPaintEvent *event);

private:
    QPixmap Image;
    QBrush Brush;
};


#endif // BACKGROUNDWIDGET_H

To copy to clipboard, switch view to plain text mode 

First Ctor arg is your widget (QMainWindow for example), second arg is the path to the picture, possibly stored as resource.

Here is the implementation:

#include "BackgroundWidget.h"
#include <QWidget>
#include <QPixmap>
#include <QString>
#include <QSize>
#include <QPaintEvent>
#include <QPainter>
 
BackgroundWidget::BackgroundWidget(QWidget *parent, QString bgImagePath): QWidget(parent), Image(), Brush()
{
    parentWidget()->stackUnder(this);
    setPicture(bgImagePath);
    setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    lower();
    Brush = QBrush(Image);
}
 
 
BackgroundWidget::~BackgroundWidget()
{
 
}
 
 
QSize BackgroundWidget::sizeHint() const
{
    return parentWidget()->visibleRegion().boundingRect().size();
}
 
void BackgroundWidget::setPicture(const QString& bgImagePath)
{
    Image = QPixmap(bgImagePath);
}
 
void BackgroundWidget::setPixmap(QPixmap* bgImage)
{
    if (! bgImage)
        return;
    Image = QPixmap(*bgImage);
}
 
void BackgroundWidget::paintEvent(QPaintEvent *event)
{
    resize(parentWidget()->visibleRegion().boundingRect().size());
    QPainter painter(this);
    painter.setBrush(Brush);
    int x = (width() - Image.width()) / 2;
    int y = (height() - Image.height()) / 2;
    painter.drawPixmap(x, y, Image.width(), Image.height(), Image);
    emit backgroundPainted();
}

#include "BackgroundWidget.h"
#include <QWidget>
#include <QPixmap>
#include <QString>
#include <QSize>
#include <QPaintEvent>
#include <QPainter>

BackgroundWidget::BackgroundWidget(QWidget *parent, QString bgImagePath): QWidget(parent), Image(), Brush()
{
    parentWidget()->stackUnder(this);
    setPicture(bgImagePath);
    setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    lower();
    Brush = QBrush(Image);
}


BackgroundWidget::~BackgroundWidget()
{

}


QSize BackgroundWidget::sizeHint() const
{
    return parentWidget()->visibleRegion().boundingRect().size();
}

void BackgroundWidget::setPicture(const QString& bgImagePath)
{
    Image = QPixmap(bgImagePath);
}

void BackgroundWidget::setPixmap(QPixmap* bgImage)
{
    if (! bgImage)
        return;
    Image = QPixmap(*bgImage);
}

void BackgroundWidget::paintEvent(QPaintEvent *event)
{
    resize(parentWidget()->visibleRegion().boundingRect().size());
    QPainter painter(this);
    painter.setBrush(Brush);
    int x = (width() - Image.width()) / 2;
    int y = (height() - Image.height()) / 2;
    painter.drawPixmap(x, y, Image.width(), Image.height(), Image);
    emit backgroundPainted();
}

To copy to clipboard, switch view to plain text mode 

See attachment for complete code

rvgrouik