Issue 45 send back diagram image

[CopyDemon]

Fixes
Related to issue
Project board link

Proposed changes:
User can get and view diagram screenshot in Jupyter notebook

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[dangunter]

@lbianchi-lbl suggested a simpler way to approach all this, which I think makes sense. Use standard HTML5 browser APIs to convert the SVG element to a PNG in Javascript. Then the Playwright/Selenium etc. is not required

[CopyDemon]

@dangunter when you have time please help me to review this.

[ksbeattie]

@CopyDemon will look into adding some documentation for this.

[dangunter]

@CopyDemon there are some conflicts in files idaes_ui/fv/static/index.html and requirements-dev.txt

[dangunter]

@CopyDemon do you know why the windows tests are failing? I can try this on my Windows machine but my main dev environment is linux now.

[CopyDemon]

@CopyDemon do you know why the windows tests are failing? I can try this on my Windows machine but my main dev environment is linux now.
@dangunter
I have not checked that yet; I just resolved the conflict. I see that pytest said：
cannot access local variable 'save_diagram_return' where it is not associated with a value

Will look it later on my VM

[lbianchi-lbl]

@dangunter @CopyDemon I believe that error is due to the dictionary defined in the finally: block containing a variable that's defined inside the try: block on a line that may not be reached if the error is raised before it. I guess the fact that it only happens on Windows might be because the error is only raised on Windows.

[dangunter]

@CopyDemon I added a higher-level function that encapsulates the 2 steps of visualize and save in what I think is an easier interface, I called it export_flowsheet_diagram and put it at the end of "fsvis.py"

[dangunter]

@CopyDemon the tests are failing because of a bug in the way you are using try/except/finally. Remember that the finally clause is always executed, regardless of what happens in the except clause (including a return statement).

This toy example (from an ipython shell) shows the problem:

In [4]: def foo(x):
   ...:     try:
   ...:         v = int(x)
   ...:     except:
   ...:         print("failed!")
   ...:         return
   ...:     finally:
   ...:         print("finally")
   ...:         print(v)   # exception!
   ...: 

In [5]: foo("1.3")
failed!
finally
---------------------------------------------------------------------------
UnboundLocalError                         Traceback (most recent call last)
Cell In[5], line 1
----> 1 foo("1.3")

Cell In[4], line 9, in foo(x)
      7 finally:
      8     print("finally")
----> 9     print(v)

UnboundLocalError: cannot access local variable 'v' where it is not associated with a value