Develop Reference

VTK Render Mouse Interaction (Python)

I want to visualize one or more STL file(s) using a vtk render viewport inside my application. I was able to get it all running with this example here: https://kitware.github.io/vtk-examples/site/Python/IO/ReadSTL/
My question is as follows: I have a mouse to control it and it is just unbelievable how bad default the controls of the camera are. It is almost impossible to get the model rotated intentionally or focus on a certain part. I am confused as I could not find any topic here or elsewhere discussing this. Normally I would read through other threads to find an answer, but there doesn't seem to be any. So, maybe you can point me to an approach or even certain functions of how I can change these settings, that would be really great! Basically I want to mimic the camera behavior of say, Paraview or a common CAD tool. Like zooming with mouse wheel, rotating with RMB and holding down the wheel to pan.
Some background on my project: I have written a python program and created a quite ok UI using tkinter. However, recently I was thinking of rewriting some basic parts of it and also upgrading everything visually and in terms of handling. So, I want to move to Qt widgets and, there shall be a VTK rendering viewport inside my application to show some of the stuff that can be interacted with.

I was able to find a solution in the tutorials. By explicitly defining the vtkInteractorStyle with
style = vtk.vtkInteractorStyleTrackballCamera()
The handling is just as I wanted it to be.

Drag and drop files in Tkinter GUI

I am fairly new to Python and is stuck at a problem. I am using Python 3.7 and intend to add a "drag-and-drop" functionality to my GUI.
I have some files that needs to be read, thus i am looking for an option where i can simply drag those files to a particular area in my GUI and file name or Path is read by my program.
Being a newbie a detailed answer or a code would be highly helpful.
Thanks

Unfortunately, tkinter only supports experimental widget drag and drop, nothing else. I ran into similar problems trying to make a complex GUI.
I would look into wxPython. It's complex, Object Oriented, and daunting, but has and unbelievable amount of features that reward you for learning it. Including file drag and drop.
Look at the wxPython thumbnails at https://wxpython.org/Phoenix/docs/html/gallery.html for images of what the widgets look like. The thumbnails include images for about half of the available widgets. The images are also a bit out of date.
Look at pronounced https://pythonlibrary.org or https://zetcode.com for the best tutorials. After them, your best resource is Google and the forums.

Create a basic Python interface to save images drawn with a mouse

I am working on the following project and I am having really difficulties in finding the right way of doing that. I would like to build in Python (but I am open to other possibilities) a very basic interface that allows the user to draw with the mouse (or the pen if used on a surface laptop) something and then save the image. Ideally I would like this to work on a website or at least in a jupyter notebook (at least I imagine this to be utterly difficult).
Anyone can point me in the right direction? The goal would be to use the images as input to a neural network model to demonstrate its result with real life examples.
I am looking at tk but I don't seem to find much in terms of examples.
Thanks in advance, Umberto

I'd take a look at pyautogui to capture the mouse location then "draw" it in matplotlib -- should be able to do this in a loop. You'll want to watch the tkinter window size to sync the mouse coordinates with the relative location.
Why not just have your script open create a new blank img and automatically open it with paint - then read it on close? Seems easier than creating a drawing GUI.

Have a look at my Github repository which have exactly what you need.
Link : CanvasDraw Repo

Depending on the complexity you could either use tkinter which is a package for complex GUIs or something from the gaming community like pygames. You have user input and graphical output so libraries made for games will do what you want but provide way more stuff then you need. This site might help you: Drawing Libarys
Also the answere draw-on-python-tkinter-canvas-using-mouse-and-obtain-points-to-a-list might help you.

Creating an animated graphics overlay with Python

I'd like to hear the best means for displaying graphics that move on-screen as an overlay with Python. The intended initial platform is Linux. I've worked up some small demos using PyQt using frameless windows and looping and updating their location on screen. This works, but I have a feeling it is not the ideal solution.
The end result is an activity indicator that would show more objects swarming in an upward direction as activity increased. That would result in spawning perhaps a hundred windows in a go and that is why I think my PyQt demo is not optimal.
I'm open to any suggestions since this will be an open project and installing obscure modules is a non-issue.

There are examples for making transparent / unclickable windows in java and in javascript. Here are a couple of transparency related posts for QT.

Selecting area of the screen with Python

I'm developing a screen shot utility in Python. At the moment it is specifically for Linux. So far I have the ability to take a screen shot of the full desktop, and have it upload to Imgur, then copy the link to clipboard. Now I want to expand into functions such as screen shots of the active window, or of a specific selection. If anyone could help, I'd love to know what kind of module would work best for this, and how to implement such a module.

The functionality will depend on what you are using for image grabbing.
With PIL
http://effbot.org/imagingbook/imagegrab.htm
With GTK
To take a screenshot of active window :
http://faq.pygtk.org/index.py?req=show&file=faq23.039.htp
Also look at the pixbuf api
http://library.gnome.org/devel/gdk-pixbuf/
http://developer.gimp.org/api/2.0/gdk-pixbuf/gdk-pixbuf-gdk-pixbuf.html
Off topic
There are some screen cast tools: http://pypi.python.org/pypi/castro/1.0.4