# Move a scalar bar with pyq5 and python3.5
**URL:** https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289
**Category:** Support
**Created:** [February 18, 2019, 2:51pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289 "2019-02-18T14:51:41Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@guillaume](https://discourse.vtk.org/u/guillaume)
#### Post date: [February 18, 2019, 2:51pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289/1 "2019-02-18T14:51:41Z")
Hi all,
I’m trying write an application with a vtk windows.
Nevertheless, I have some difficulties to move and resize manually the scalar bar when I use pyqt5. Here’s my code:
> ```
> # -*- coding: utf-8 -*-
> import sys
> from PyQt5 import QtWidgets, QtGui, QtCore, Qt
> from PyQt5.QtWidgets import *
> from PyQt5.QtGui import *
> from PyQt5.QtCore import *
> import pyqtgraph
> import math
> import numpy
> import vtk
> import vtk.qt
> vtk.qt.QVTKRWIBase = "QGLWidget"
> from vtk.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor
>
> class Window(QtWidgets.QMainWindow):
>
> def __init__ (self) :
> super(Window, self). __init__ ()
> self.setGeometry(250, 100, 900, 800)
> self.setWindowTitle("Interactive vtk exemple")
>
> extractAction = QtWidgets.QAction( "Leave",self)
> extractAction.setShortcut("Ctrl+Q")
> extractAction.setStatusTip('Leave application')
> extractAction.triggered.connect(qApp.quit)
>
> mainMenu = self.menuBar()
> fileMenu = mainMenu.addMenu('&File')
> fileMenu.addAction(extractAction)
>
> self.statusBar()
>
> self.home()
>
>
> def home(self):
>
> self.frame = QtWidgets.QFrame()
> self.setCentralWidget(self.frame)
>
> self.layout = QtWidgets.QGridLayout()
> self.frame.setLayout(self.layout)
>
> ## Source/reader
> reader = vtk.vtkUnstructuredGridReader()
> reader.SetFileName("stripComplex.vtk")
> reader.SetScalarsName("temperature")
> reader.Update()
>
> pointData = reader.GetOutput().GetPointData()
> drange = pointData.GetScalars().GetRange()
> print("a",drange[0])
> print("b",drange[1])
>
> colorFunction = vtk.vtkColorTransferFunction()
> colorFunction.SetColorSpaceToHSV()
> colorFunction.HSVWrapOff()
> colorFunction.AddRGBPoint(drange[0], 0.0, 0.0, 1.0)
> colorFunction.AddRGBPoint(drange[1], 1.0, 0.0, 0.0)
>
> ## Create a mapper
> Mapper = vtk.vtkDataSetMapper()
> Mapper.SetInputConnection(reader.GetOutputPort())
> Mapper.SetScalarRange(drange)
> Mapper.SetLookupTable(colorFunction)
>
> ## Create an actor
> Actor = vtk.vtkActor()
> Actor.SetMapper(Mapper)
>
> prop = Actor.GetProperty()
> prop.SetAmbient(0.5)
> prop.EdgeVisibilityOn()
> prop.SetEdgeColor(0, 0, 0)
> prop.SetLineWidth(2)
>
>
> ## Renderer
> self.ren = vtk.vtkRenderer()
> self.ren.AddActor(Actor)
> self.ren.GetActiveCamera().SetPosition(2,0.5,10)
> self.ren.GetActiveCamera().SetFocalPoint(2,0.5,2)
>
> ## Windows renderer
> self.vtkWidget = QVTKRenderWindowInteractor(self.frame)
> self.renwin = self.vtkWidget.GetRenderWindow()
> self.renwin.AddRenderer(self.ren)
> self.layout.addWidget(self.vtkWidget,2,1)
>
> ## Interactor
> self.iren = self.renwin.GetInteractor()
>
> ## scalar bar
> scalarBar = vtk.vtkScalarBarActor()
> scalarBar.SetLookupTable( colorFunction )
>
> ## scalar bar widget
> scalar_bar_widget = vtk.vtkScalarBarWidget()
> scalar_bar_widget.SetInteractor(self.iren)
> scalar_bar_widget.SetScalarBarActor(scalarBar)
> scalar_bar_widget.On()
> self.ren.AddActor(scalarBar)
>
> ## Slider 1 exemple
> self.slidAmplitude = QtWidgets.QSlider(QtCore.Qt.Vertical)
> self.slidAmplitude.setMinimum(0.0)
> self.slidAmplitude.setMaximum(100.0)
> self.slidAmplitude.setValue(5)
> self.slidAmplitude.setTickInterval(1)
> self.slidAmplitude.setTickPosition(2)
> self.layout.addWidget(self.slidAmplitude,2,0)
>
> ## Slider 2 exemple
> self.slidFrequence = QtWidgets.QSlider(QtCore.Qt.Horizontal)
> self.slidFrequence.setMinimum(0.0)
> self.slidFrequence.setMaximum(200.0)
> self.slidFrequence.setValue(50.0)
> self.slidFrequence.setTickPosition(1)
> self.slidFrequence.setTickInterval(1.0)
> self.layout.addWidget(self.slidFrequence,3,1)
>
> self.iren.Initialize()
> self.iren.Start()
> self.iren.Render()
>
> self.show()
>
> def run() :
> app = QtWidgets.QApplication(sys.argv)
> GUI = Window()
> sys.exit(app.exec())
>
> ```
>
> run()
When i execute this code, i can interact with the geometry but not with the scalar bar.
Is there anything wrong? any suggestion?
Thanks
---
### Author:  [@banesullivan](https://discourse.vtk.org/u/banesullivan)
#### Post date: [February 18, 2019, 6:20pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289/2 "2019-02-18T18:20:19Z")
+1
I’m also experiencing this issue on a [**pull request**](https://github.com/akaszynski/vtki/pull/79) in [`vtki`](http://docs.vtki.org/en/latest/). The `vtkScalarBarWidget` is not interactive but the `vtkOrientationMarkerWidget` works somewhat fine.
FYI @guillaume, we have some Qt-based plotting classes in `vtki` that might make it easier to create your own sophisticated application. Check out [this example](http://docs.vtki.org/en/latest/tools/qt_plotting.html).
---
### Author:  [@banesullivan](https://discourse.vtk.org/u/banesullivan)
#### Post date: [February 18, 2019, 8:59pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289/3 "2019-02-18T20:59:29Z")
_Update:_ I think the code you have is correct but there is some sort of bug linking the mouse location of the Qt app and the VTK interactor. See [vtki/97](https://github.com/akaszynski/vtki/issues/97) for more details.
For example, if you can successfully add a `vtkOrientationMarkerWidget`, you’ll see that it detects the mouse in the wrong places (there’s a GIF of this in [vtki/97](https://github.com/akaszynski/vtki/issues/97)). This leads me to think that the scalar bar simply does not see the mouse hovering over it.
---
### Author:  [@guillaume](https://discourse.vtk.org/u/guillaume)
#### Post date: [February 19, 2019, 1:09pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289/4 "2019-02-19T13:09:20Z")
Thanks for the answer Bane.
I wanted to be sure I did not make a programming mistake.
As I started the vtk, I wanted to understand the basics before using a module like VTKI.
---
### Author:  [@banesullivan](https://discourse.vtk.org/u/banesullivan)
#### Post date: [February 27, 2019, 1:48am UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289/5 "2019-02-27T01:48:54Z")
Status update: this is an issue that that has appeared and disappeared for me. It has been incredibly difficult to purposely reproduce. See notes in [vtki/97](https://github.com/vtkiorg/vtki/issues/97)
Some days the interactive scalar bars work, some days they don’t. ☹
---
### Author:  [@guillaume](https://discourse.vtk.org/u/guillaume)
#### Post date: [March 6, 2019, 7:00pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289/6 "2019-03-06T19:00:02Z")
I found a solution for this problem and it’s not a bug in relation with linking mouse location.
Actually, the vtkScalarBarWidget object must be an instance variable (i.e. self.scalar\_bar\_widget = vtk.vtkScalarBarWidget())
So i replace the previous bloc concerning the scalar bar widget by:
> ## scalar bar widget
>
> ```
> self.scalar_bar_widget = vtk.vtkScalarBarWidget()
> self.scalar_bar_widget.SetInteractor(self.iren)
> self.scalar_bar_widget.SetScalarBarActor(scalarBar)
> scalar_bar_widget.On()
>
> ```
---
### Author:  [@banesullivan](https://discourse.vtk.org/u/banesullivan)
#### Post date: [March 6, 2019, 7:15pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289/7 "2019-03-06T19:15:58Z")
Interesting find! Does that fix the issue for you?
We already assign the `vtkScalarBarWidget` object in `vtki` so I must be experiencing something different.
---
### Author:  [@guillaume](https://discourse.vtk.org/u/guillaume)
#### Post date: [March 6, 2019, 7:35pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289/8 "2019-03-06T19:35:45Z")
Yes my problem is completely solved. Recently, I stumbled upon a note written by Nicholas R. Rypkema to solve some issue to display an interactive coordinate axes at this link:
[https://nrr.mit.edu/blog/note-about-vtk-pyqt-and-vtkorientationmarkerwidget](https://nrr.mit.edu/blog/note-about-vtk-pyqt-and-vtkorientationmarkerwidget)
So I just transpose it to my scalar bar.
In any case, I would like to thank you for your answers.