Problem with background image

[qt890]

Hi, I have a window with a Qwt barchart and I need to display a background image that fills all the window.

The best I could get was:
img.JPG

As you can see, the image isn't displayed correctly. I've overridden MainWindow's resizeEvent() method this way in main.c:

void MainWindow::resizeEvent(QResizeEvent*)
{
    QPixmap bkgnd(":/files/image.png");
    bkgnd = bkgnd.scaled(this->size(), Qt::IgnoreAspectRatio);
    QPalette palette;
    palette.setBrush(QPalette::Background, bkgnd);
    this->setPalette(palette);
}

void MainWindow::resizeEvent(QResizeEvent*)
{
    QPixmap bkgnd(":/files/image.png");
    bkgnd = bkgnd.scaled(this->size(), Qt::IgnoreAspectRatio);
    QPalette palette;
    palette.setBrush(QPalette::Background, bkgnd);
    this->setPalette(palette);
}

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And commented in barchart.cpp:

//setAutoFillBackground( true );
//setPalette( Qt::white );
//canvas()->setPalette( QColor( "LemonChiffon" ) );

//setAutoFillBackground( true );
//setPalette( Qt::white );
//canvas()->setPalette( QColor( "LemonChiffon" ) );

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The original image is:
image.png

Using bkgnd = bkgnd.scaled(this->size(), Qt::KeepAspectRatioByExpanding); produces the same output.

How can I solve it?