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Archived:Transparent QDialog and QListWidget in Qt

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Archived.pngArchived: This article is archived because it is not considered relevant for third-party developers creating commercial solutions today. If you think this article is still relevant, let us know by adding the template {{ReviewForRemovalFromArchive|user=~~~~|write your reason here}}.

Qt Quick should be used for all UI development on mobile devices. The approach described in this article (using C++ for the Qt app UI) is deprecated.

Article Metadata
Tested with
Devices(s): Nokia N97
Compatibility
Platform(s): S60 5th Edition
Symbian
Article
Keywords: QDialog, QListWidget
Created: tepaa (24 May 2010)
Last edited: hamishwillee (11 Oct 2012)

Contents

Overview

This code snippet demonstrates how to create a transparent QDialog that has a QPixmap picture as the background and a transparent QListWidget in the centre of the screen.

Header

#include <QDialog>
#include <QListWidget>
 
class TransparentDlg : public QDialog
{
public:
TransparentDlg(QWidget *parent = 0);
~TransparentDlg();
 
void resizeEvent(QResizeEvent *);
void paintEvent(QPaintEvent *);
 
private:
QPixmap m_pixmapBackground;
QListWidget* m_listWidget;
};

Source

Transparent QDialog that shows a picture as the background.

#include <QPainter>
 
TransparentDlg::TransparentDlg(QWidget *parent)
: QDialog(parent)
{
// Set QDialog background as transparent
setAttribute(Qt::WA_NoSystemBackground);
 
// Load picture for dialog background
m_pixmapBackground.load(":/background.png");
 
// Create QListWidget
m_listWidget = new QListWidget(this);
new QListWidgetItem("Row One",m_listWidget);
new QListWidgetItem("Row Two",m_listWidget);
new QListWidgetItem("Row Three",m_listWidget);
new QListWidgetItem("Row Four",m_listWidget);
}
 
TransparentDlg::~TransparentDlg()
{
}
 
void TransparentDlg::resizeEvent(QResizeEvent *event)
{
// Set size for the background picture
QSize backSize = size();
backSize -= QSize(size().width()/4,size().height()/4);
m_pixmapBackground = m_pixmapBackground.scaled(backSize);
 
// Set size for the QListWidget
QSize listSize = backSize - QSize(40,40);
QPoint p = QPoint((size().width()-listSize.width())/2,
(size().height()-listSize.height())/2);
m_listWidget->setGeometry(QRect(p,listSize));
}
 
void TransparentDlg::paintEvent(QPaintEvent *event)
{
QDialog::paintEvent(event);
 
QPainter p(this);
p.drawPixmap((size().width()-m_pixmapBackground.size().width())/2,
(size().height()-m_pixmapBackground.size().height())/2,m_pixmapBackground);
}

To make QListWidget look transparent, define a new style and set a style sheet for it using QApplication::setStyleSheet().

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
 
// Set style for the QListWidget and QListWidgetItem
QString style;
style += "QListWidget {background-color: transparent;}";
style += "QListWidget::item {background-color: transparent;}";
style += "QListWidget::item {selection-color: white;}";
style += "QListWidget::item {color: black;}";
a.setStyleSheet(style);
 
qtSnippets w;
w.showMaximized();
return a.exec();
}

Postconditions

QDialog has a transparent background.

See also

Qt Style Sheets Reference

Transparent qdialog.GIF

This page was last modified on 11 October 2012, at 04:15.
155 page views in the last 30 days.

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