[vtkusers] 2D Histogram (or spectrogram) chart

[Mohamed Amine Mzoughi]

Hello,

I've seen this screenshot of a 2D chart : 
https://www.na-mic.org/wiki/File:VTK-Charts-Histogram2D.png and I didn't 
find the VTK class that allows me to create it. (the original link is : 
https://www.na-mic.org/wiki/2011_Summer_Project_Week_Breakout_Session_VTKCharts). 
Is this chart was removed ? where can I found its source code ?

Currently I am using a vtkImageActor to display a 2-D color map (or 
spectrogram) but I am struggling with the camera and the scale of the 
actor to make it right (to fit the whole window) and I am drawing the 
axis in another QVTKOpenGL widget managing a 2D scene (vtkAxis - like 
the ParaView Slice View). I am not really comfortable with this solution.

I don't want to use APIs like QCustomPlot or Qwt because I will have to 
convert my data to use them and this will add another dependency to my 
program.

I played a little with vtkContextView, vtkContextArea and vtkImageItem 
to display a vtkImageData, but there is no possibility to change the 
color or display a vtkImageData whose point data array has a single 
compnent (it should have 4 components: r,g,b,a).

Thanks.