GraphvizPreview.py

import sublime, sublime_plugin
from subprocess import call
import os
import platform

try:  # python 3
    from .helpers import surroundingGraphviz, graphvizDot, createTempFile, ENVIRON
except ValueError:  # python 2
    from helpers import surroundingGraphviz, graphvizDot, createTempFile, ENVIRON


class GraphvizPreviewCommand(sublime_plugin.TextCommand):
    def run(self, edit):
        sel = self.view.sel()[0]

        code = None
        if 'DOT.tmLanguage' in self.view.settings().get('syntax'):
            filename = self.view.file_name()
        else:
            if not sel.empty():
                code = self.view.substr(sel).strip()
            else:
                code = surroundingGraphviz(
                    self.view.substr(sublime.Region(0, self.view.size())),
                    sel.begin()
                )
            if not code:
                sublime.error_message('Graphviz: Please place cursor in graphviz code before running')
                return
            filename = createTempFile(code)

        # TODO: allow user to choose which output type to use?
        final_filename = graphvizDot(filename, 'png')

        if code is not None:
            os.unlink(filename)            

        try:
            if platform.system() == 'Windows':
                os.startfile(final_filename)
            else:
                call(['open', final_filename], env=ENVIRON)            
        except Exception as e:
            sublime.error_message('Graphviz: Could not open file, ' + str(e))
            raise e