connectors/ConnectorBase.py
author Edouard Tisserant
Tue, 23 Aug 2022 12:19:44 +0200
changeset 3594 30f7eade322f
parent 2621 af09744a468e
child 3750 f62625418bff
child 3861 7e17f7e02a2b
permissions -rw-r--r--
SVGHMI: add support for "enable expressions" with arbitrary variable name assignment.

HMI tree paths can be prefixed with a variable name "@name=/MY/HMI/VAR"
Widget declarations can end with a "#" followed by a JS expression that refers to name given to variables.
Widget is disabled if expression's result is false.

Commit includes some more-or-less related generated code refactoring, that should simplify extending widget's variables attributes.
#!/usr/bin/env python
# -*- coding: utf-8 -*-

# See COPYING file for copyrights details.

from __future__ import absolute_import
import hashlib


class ConnectorBase(object):

    chuncksize = 1024*1024

    def BlobFromFile(self, filepath, seed):
        s = hashlib.new('md5')
        s.update(seed)
        blobID = self.SeedBlob(seed)
        with open(filepath, "rb") as f:
            while blobID == s.digest():
                chunk = f.read(self.chuncksize)
                if len(chunk) == 0:
                    return blobID
                blobID = self.AppendChunkToBlob(chunk, blobID)
                s.update(chunk)
        raise IOError("Data corrupted during transfer or connection lost")