[vtkusers] QVTKGraphicsItem Events / Unexpected Behavior

[Matthias Thurau]

Hello,

i am having problems using the VTK stuff in a QT QGraphicsview project. 
I dont use any normal QT GUI classes, just the opengl rendered stuff 
with QGraphicsView and QGraphicsScene. VTK has created the 
QVTKGraphicsItem class for that reason, but it doesnt work right:

ChartPicture.jpg

The Chart will appear, but as soon as i click anywhere in the chart (or 
using the mousewheel on top of the chart), the content will disappear :( 
The contents wont come back, except when i resize the QVTKGraphicsItem, 
then it repaints and the content is there again. But i would like to get 
the events/interaction right, so that i can zoom into the chart. Is this 
a bug?

Here is somekind of the minimal code of the problem:


#include "vtkSmartPointer.h"
#include "QVTKGraphicsItem.h"
#include "vtkChartXY.h"
#include "vtkTable.h"
#include "vtkFloatArray.h"
#include "vtkPlot.h"
#include "vtkRenderer.h"
#include "vtkNew.h"
#include "vtkGenericOpenGLRenderWindow.h"
#include "vtkContextActor.h"
#include "vtkContextScene.h"

#include <qgraphicsscene>
#include <qgraphicsview>
#include <qapplication>

int main(int argc, char* argv[])
{
     //First create QT QGraphicsview with QGraphicsScene
     //--------QT---------------
     QApplication a(argc, argv);
     QGraphicsView v;
     QGraphicsScene s;
     v.setScene(&s);
     QGLWidget glwidget(QGLFormat::defaultFormat());
     QGLContext context( QGLFormat::defaultFormat());
     glwidget.makeCurrent();
     v.setViewport(&glwidget);

     //Now create a chart with openglrenderer
     //---------vtk ------------

     QVTKGraphicsItem* item = new QVTKGraphicsItem(&context);
     item->setGeometry(10,20,500,300);

     vtkNew<vtkChartXY> chart;
     vtkNew<vtkContextScene> chartScene;
     vtkNew<vtkContextActor> chartActor;

     chartScene->AddItem(chart.GetPointer());
     chartActor->SetScene(chartScene.GetPointer());

     vtkNew<vtkTable> table;
     vtkNew<vtkFloatArray> arrX;
     arrX->SetName("X");
     table->AddColumn(arrX.GetPointer());
     vtkNew<vtkFloatArray> arrV;

     arrV->SetName( "bla" );

     table->AddColumn(arrV.GetPointer());

     auto numPoints = 5;
     table->SetNumberOfRows(numPoints);

     for (auto i = 0; i < numPoints; ++i)
     {
         table->SetValue(i, 0, i);
         table->SetValue(i, 1, i*2);
     }

     vtkPlot *points = chart->AddPlot(vtkChart::BAR);
     points->SetInput(table.GetPointer(), 0, 1);
     points->SetColor(140, 10, 200, 255);
     points->SetWidth(3.0);

     vtkSmartPointer<vtkRenderer> renderer = 
vtkSmartPointer<vtkRenderer>::New();
     renderer->SetBackground(0.3, 0.3, 0.3);

     renderer->AddActor(chartActor.GetPointer());
     chartScene->SetRenderer(renderer.GetPointer());

     vtkSmartPointer<vtkGenericOpenGLRenderWindow> renderWindow = 
vtkSmartPointer<vtkGenericOpenGLRenderWindow>::New();
     renderWindow->AddRenderer( renderer );

     item->SetRenderWindow( renderWindow.GetPointer() );

     //now add the vtk item to the qgraphicsscene and show it:
     //----------QT-------
     s.addItem(item);

     v.show();
     a.exec();
}

Best regards,
Matthias Thurau


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