preview.py

import os
import tkinter as tk
from PIL import Image
from PIL import ImageTk
from util import renderMachine


class PreviewWindow(object):
    TEMP_FOLDER = 'temp'
    TEMP_FILENAME = 'fsm.png'
    ERROR_LOG_FILENAME = 'graphviz_error.log'
    ERROR_FILEPATH = 'data/preview_error.png'
    INVALID_FILEPATH = 'data/preview_invalid.png'

    def __init__(self, master, fsm, showrefresh=True):
        self._window = tk.Toplevel(master)
        self._window.title('Preview')
        self._window.transient(master)
        self._window.resizable(0, 0)

        self._fsm = fsm

        self._panel = tk.Label(self._window)
        self._panel.pack(side='top', fill='both', expand='yes')

        self._button = tk.Button(
            self._window, text='Refresh', command=self.refresh)
        self._button.lift()

        if showrefresh:
            self._button.place(y=0)
        else:
            self._button.place(y=-50)

        self.refresh()

    def refresh(self, fsm=None):
        if fsm:
            self._fsm = fsm

        if not self._fsm.isValid():
            filename = self.INVALID_FILEPATH
        else:
            if not os.path.exists(self.TEMP_FOLDER):
                os.mkdir(self.TEMP_FOLDER)
            temp_path = os.path.join(self.TEMP_FOLDER, self.TEMP_FILENAME)
            if os.path.exists(temp_path):
                os.unlink(temp_path)
            try:
                res = self._window.winfo_fpixels('1i')
                y_margin = 60  # Shell GUI (e.g. taskbar)
                size = (self._window.winfo_screenwidth() / res,
                        (self._window.winfo_screenheight()-y_margin) / res)

                renderMachine(self._fsm, outfile=temp_path, size=size)

                if os.path.exists(temp_path):
                    filename = temp_path
                else:
                    raise SystemError('No output rendered.')
            except:
                open(ERROR_LOG_FILENAME, 'w').write(self._fsm.toGraphViz(size))
                filename = self.ERROR_FILEPATH

        self._image = ImageTk.PhotoImage(Image.open(filename))

        self._panel.configure(image=self._image)

        self.reposition()

    def reposition(self, y=None):
        w = self._image.width()
        h = self._image.height()

        x = (self._window.winfo_screenwidth() - w) / 2

        if y:
            self._window.geometry("%dx%d+%d+%d" % (w, h, x, y))
        else:
            self._window.geometry("%dx%d+%d+%d" %
                                  (w, h, x, self._window.winfo_y()))

        x_offset = w-self._button.winfo_reqwidth()
        self._button.place(x=x_offset)