Add SVG support using ImageMagick

[BookOwl]

This PR adds SVG costume support to Slither using the ImageMagick tool. It should be almost ready to merge, I just need to check and make sure that I haven't forgotten or broke anything.

[BookOwl]

I went through all the tests and fixed the bugs.

[BookOwl]

I think that this is ready, @Tymewalk

[BookOwl]

I need to fix some windows bugs. :(

[BookOwl]

I fixed the bugs! :package:

[BookOwl]

OK, I fixed the windows bugs and the merge conflicts. @Tymewalk, I believe that this is ready to merge!

[Tymewalk]

Need to check on Linux. Cloning the repo and testing now :small_blue_diamond:

[Tymewalk]

I have ImageMagick installed, but I get this:

Traceback (most recent call last):
  File "slither/tests/svgTest.py", line 4, in <module>
    import slither
  File "/usr/local/lib/python2.7/dist-packages/slither-0.3.0-py2.7.egg/slither/__init__.py", line 1, in <module>
    from .slither import *
  File "/usr/local/lib/python2.7/dist-packages/slither-0.3.0-py2.7.egg/slither/slither.py", line 14, in     <module>
    if subprocess.call("identify -version", shell=True, stdout=subprocess.DEVNULL) != 0:
AttributeError: 'module' object has no attribute 'DEVNULL'

[BookOwl]

That means that you are using a Python 3.2 or older. subprocess.DEVNULL is only in Python 3.3+

We don't have to have that feature, it just means that the output of the different commands might go to the terminal.

[Tymewalk]

@BookOwl I ran with Python 2. Will we have to drop SVG support for that version?

[BookOwl]

I don't think so, it just means that Python2 users (and people who use Python3.2 or lower) will get extra text in their terminal (unless I can figure out another way to get rid of it). I'll be pretty busy today, but I should be able to get it done this evening.

[BookOwl]

I think that I found a solution: Pass open(os.devnull, "wb") to stdout instead of DEVNULL

[BookOwl]

OK, I think that I've fixed it. Just let me test on Python2 real quick.

[BookOwl]

OK, I've gotten it to work in both Python2 and Python3. @Tymewalk, please test again.

[Tymewalk]

Just tested:

timmy@timmybox:/home/timmy/ghp/Slither$ python slither/tests/svgTest.py 
We have SVG support!
convert.im6: unable to open image `/home/timmy/ghp/Slither/slither/tests/assets/svg Logo.svg': No such file or directory @ error/blob.c/OpenBlob/2641.
convert.im6: no images defined `info:' @ error/convert.c/ConvertImageCommand/3044.
Traceback (most recent call last):
  File "slither/tests/svgTest.py", line 12, in <module>
    svg.addCostume("assets/svg Logo.svg", "svg")
  File "/usr/local/lib/python2.7/dist-packages/slither-0.3.0-py2.7.egg/slither/slither.py", line 194, in addCostume
    costume = SVGCostume(costumePath, self.scale if hasattr(self, "scale") else 1)
  File "/usr/local/lib/python2.7/dist-packages/slither-0.3.0-py2.7.egg/slither/slither.py", line 149, in __init__
    shell=True)
  File "/usr/lib/python2.7/subprocess.py", line 573, in check_output
    raise CalledProcessError(retcode, cmd, output=output)
subprocess.CalledProcessError: Command 'convert "/home/timmy/ghp/Slither/slither/tests/assets/svg Logo.svg" -format "%w %h" info:' returned non-zero exit status 1
timmy@timmybox:/home/timmy/ghp/Slither$ python3 slither/tests/svgTest.py 
We have SVG support!
convert.im6: unable to open image `/home/timmy/ghp/Slither/slither/tests/assets/svg Logo.svg': No such file or directory @ error/blob.c/OpenBlob/2641.
convert.im6: no images defined `info:' @ error/convert.c/ConvertImageCommand/3044.
Traceback (most recent call last):
  File "slither/tests/svgTest.py", line 12, in <module>
    svg.addCostume("assets/svg Logo.svg", "svg")
  File "/usr/local/lib/python3.4/dist-packages/slither-0.3.0-py3.4.egg/slither/slither.py", line 194, in addCostume
    costume = SVGCostume(costumePath, self.scale if hasattr(self, "scale") else 1)
  File "/usr/local/lib/python3.4/dist-packages/slither-0.3.0-py3.4.egg/slither/slither.py", line 149, in __init__
    shell=True)
  File "/usr/lib/python3.4/subprocess.py", line 620, in check_output
    raise CalledProcessError(retcode, process.args, output=output)
subprocess.CalledProcessError: Command 'convert "/home/timmy/ghp/Slither/slither/tests/assets/svg Logo.svg" -format "%w %h" info:' returned non-zero exit status 1
timmy@timmybox:/home/timmy/ghp/Slither$ python3.4 slither/tests/svgTest.py 
We have SVG support!
convert.im6: unable to open image `/home/timmy/ghp/Slither/slither/tests/assets/svg Logo.svg': No such file or directory @ error/blob.c/OpenBlob/2641.
convert.im6: no images defined `info:' @ error/convert.c/ConvertImageCommand/3044.
Traceback (most recent call last):
  File "slither/tests/svgTest.py", line 12, in <module>
    svg.addCostume("assets/svg Logo.svg", "svg")
  File "/usr/local/lib/python3.4/dist-packages/slither-0.3.0-py3.4.egg/slither/slither.py", line 194, in addCostume
    costume = SVGCostume(costumePath, self.scale if hasattr(self, "scale") else 1)
  File "/usr/local/lib/python3.4/dist-packages/slither-0.3.0-py3.4.egg/slither/slither.py", line 149, in __init__
    shell=True)
  File "/usr/lib/python3.4/subprocess.py", line 620, in check_output
    raise CalledProcessError(retcode, process.args, output=output)
subprocess.CalledProcessError: Command 'convert "/home/timmy/ghp/Slither/slither/tests/assets/svg Logo.svg" -format "%w %h" info:' returned non-zero exit status 1
timmy@timmybox:/home/timmy/ghp/Slither$ 

Tried on Python 2, Python 3, and Python 3.4 explicitly.

However, running slither/tests/svgTest.py as an executable results in this:

import.im6: unable to open image `slither': Is a directory @ error/blob.c/OpenBlob/2641.
slither/tests/svgTest.py: line 7: syntax error near unexpected token `"We have SVG support!"'
slither/tests/svgTest.py: line 7: `    print("We have SVG support!")'

I'm on Linux if it helps.

[BookOwl]

Try running convert "/home/timmy/ghp/Slither/slither/tests/assets/svg Logo.svg" -format "%w %h" info: in your shell and see if it's still making that error.

[BookOwl]

I found the problem: I didn't get the case of the test image right. On Windows and OS X it doesn't matter, but on Linux...

[BookOwl]

@Tymewalk, please test.

[Tymewalk]

@BookOwl YESSS! :fireworks:

It works on Python 2 and 3 (Linux!) without using that convert command. Woo!

Also, when you said "case of the test image", I thought you meant something was special about it, not that the filename mattered...

I REALLY hate that case doesn't matter in Windows somedays. :stuck_out_tongue:

[Tymewalk]

If there isn't anything else you can think of that we need to check, this is ready to merge!

0.4 here we come!

[BookOwl]

Yep, it can be quite a pain. 😛 I think that this is ready.

[Tymewalk]

Anything else can be done later on. Merging now!