ShowEvent

#include <iostream>

#include "ShowEvent.h"

ShowEvent::ShowEvent(QWidget *myParent) : QWidget(myParent)
{
  this->setupUi(this);

  // Do not do anything related to VTK display here!
}

void ShowEvent::showEvent(QShowEvent *)
{
  // Instead, do the VTK display things here!
}

#include <QApplication>

#include "ShowEvent.h"

int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
  ShowEvent showEvent;

  showEvent.show();
  return app.exec();
}

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>ShowEvent</class>
 <widget class="QWidget" name="ShowEvent">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>312</width>
    <height>243</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>ShowEvent</string>
  </property>
  <layout class="QGridLayout" name="gridLayout">
   <item row="0" column="0">
    <widget class="QGraphicsView" name="graphicsView">
     <property name="backgroundBrush">
      <brush brushstyle="NoBrush">
       <color alpha="255">
        <red>0</red>
        <green>0</green>
        <blue>0</blue>
       </color>
      </brush>
     </property>
    </widget>
   </item>
  </layout>
 </widget>
 <resources/>
 <connections/>
</ui>

#ifndef ShowEventQt_H
#define ShowEventQt_H

#include "ui_ShowEvent.h"

class ShowEvent : public QWidget, private Ui::ShowEvent
{
Q_OBJECT

public:
  ShowEvent(QWidget *parent = 0);

protected:
  void showEvent ( QShowEvent * event );
};

#endif

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ShowEvent)

find_package(VTK COMPONENTS  QUIET)
if (NOT VTK_FOUND)
  message("Skipping ShowEvent: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(ShowEvent MACOSX_BUNDLE ShowEvent.cxx )
  target_link_libraries(ShowEvent PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(ShowEvent MACOSX_BUNDLE ShowEvent.cxx )
  target_link_libraries(ShowEvent PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS ShowEvent
    MODULES ${VTK_LIBRARIES}
    )
endif () 

cd ShowEvent/build 

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./ShowEvent