meter_scale.py

import linuxcnc
import os
import hal
import hal_glib

class HandlerClass:

    def _on_max_value_change(self,hal_pin,data=None):
        self.meter.max = float(hal_pin.get())
        self.meter.queue_draw() # force a widget redraw

    def __init__(self, halcomp,builder,useropts):
        self.builder = builder

        # hal pin with change callback.
        # When the pin's value changes the callback is executed.
        self.max_value = hal_glib.GPin(halcomp.newpin('max-value',  hal.HAL_FLOAT, hal.HAL_IN))
        self.max_value.connect('value-changed', self._on_max_value_change)

        inifile = linuxcnc.ini(os.getenv("INI_FILE_NAME"))
        mmax = inifile.getreal("METER", "MAX", fallback=100.0)
        self.meter = self.builder.get_object('meter')
        self.max_value.set(mmax)


def get_handlers(halcomp,builder,useropts):
    return [HandlerClass(halcomp,builder,useropts)]