Qt Creator Lubuntu Ubuntu

This Qt example shows a way to develop a transparent-like dialog. The trick used is to take a screenshot of the desktop before the dialog is shown. The illusion fades if the dialog is moved.

Technical facts

Application type(s)

Desktop application

Operating system(s) or programming environment(s)

Lubuntu 15.04 (vivid)

IDE(s):

Qt Creator 3.1.1

Project type:

GUI application

C++ standard:

C++11

Compiler(s):

G++ 4.9.2

Libraries used:

Qt: version 5.4.1 (32 bit)
STL: GNU ISO C++ Library, version 4.9.2

Qt project file: ./CppQtExample21/CppQtExample21.pro


exists(../../DesktopApplication.pri) {

  include(../../DesktopApplication.pri)

}

!exists(../../DesktopApplication.pri) {

  QT += core gui

  greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

  TEMPLATE = app



  CONFIG(debug, debug|release) {

    message(Debug mode)

  }



  CONFIG(release, debug|release) {

    message(Release mode)

    DEFINES += NDEBUG NTRACE_BILDERBIKKEL

  }



  QMAKE_CXXFLAGS += -std=c++11 -Wall -Wextra



  unix {

    QMAKE_CXXFLAGS += -Werror

  }

}



exists(../../Libraries/Boost.pri) {

  include(../../Libraries/Boost.pri)

}

!exists(../../Libraries/Boost.pri) {

  win32 {

    INCLUDEPATH += \

      ../../../Projects/Libraries/boost_1_55_0

  }

}





SOURCES += \

  main.cpp \

  transparentdialog.cpp

HEADERS  += transparentdialog.h

FORMS    += transparentdialog.ui



#CONFIG += mobility

#MOBILITY =

#symbian {

#    TARGET.UID3 = 0xe7de6653

#    # TARGET.CAPABILITY +=

#    TARGET.EPOCSTACKSIZE = 0x14000

#    TARGET.EPOCHEAPSIZE = 0x020000 0x800000

#}

./CppQtExample21/main.cpp


#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <QApplication>

#include "transparentdialog.h"

#pragma GCC diagnostic pop



int main(int argc, char *argv[])

{

  QApplication a(argc, argv);

  TransparentDialog w;

  w.show();

  return a.exec();

}

./CppQtExample21/transparentdialog.h


#ifndef TRANSPARENTDIALOG_H

#define TRANSPARENTDIALOG_H



#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <QDialog>

#pragma GCC diagnostic pop



namespace Ui {

  class TransparentDialog;

}



class TransparentDialog : public QDialog

{

  Q_OBJECT



public:

  explicit TransparentDialog(QWidget *parent = 0);

  TransparentDialog(const TransparentDialog&) = delete;

  TransparentDialog& operator=(const TransparentDialog&) = delete;

  ~TransparentDialog();



protected:

  void paintEvent(QPaintEvent *);



private:

  Ui::TransparentDialog *ui;

  QPixmap m_pixmap;



private slots:

};



#endif // TRANSPARENTDIALOG_H

./CppQtExample21/transparentdialog.cpp


#include "transparentdialog.h"



#pragma GCC diagnostic push

#pragma GCC diagnostic ignored "-Weffc++"

#pragma GCC diagnostic ignored "-Wunused-local-typedefs"

#include <QApplication>

#include <QDesktopWidget>

#include <QPainter>

#include "ui_transparentdialog.h"

#pragma GCC diagnostic pop



TransparentDialog::TransparentDialog(QWidget *parent)

  : QDialog(parent),

    ui(new Ui::TransparentDialog),

    m_pixmap(QPixmap::grabWindow(QApplication::desktop()->winId()))

{

  ui->setupUi(this);

}



TransparentDialog::~TransparentDialog()

{

  delete ui;

}



void TransparentDialog::paintEvent(QPaintEvent *)

{

  QPainter painter(this);

  painter.drawPixmap(

    this->rect(),

    m_pixmap,

    this->geometry());

}

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(C++) QtExample21

Technical facts

Qt project file: ./CppQtExample21/CppQtExample21.pro

./CppQtExample21/main.cpp

./CppQtExample21/transparentdialog.h

./CppQtExample21/transparentdialog.cpp