Pmw.Counter

Name

Pmw.Counter() - entry field with up and down arrow buttons

Inherits

Pmw.MegaWidget

Description

A counter contains an entry field and two arrow buttons to increment and decrement the value in the entry field. Standard counting types include numbers, times and dates. A user defined counting function may also be supplied for specialised counting. Counting can be used in combination with the entry field's validation. The components may be laid out horizontally or vertically.

Each time an arrow button is pressed the value displayed in the entry field is incremented or decremented by the value of the increment option. If the new value is invalid (according to the entry field's validate option, perhaps due to exceeding minimum or maximum limits), the old value is restored.

When an arrow button is pressed and the value displayed is not an exact multiple of the increment, it is "truncated" up or down to the nearest increment.

Options

Options for this megawidget and its base classes are described below.

autorepeat

If true, the counter will continue to count up or down while an arrow button is held pressed down. The default is 1.

buttonaspect

Initialisation option. Specifies the width of the arrow buttons as a proportion of their height. Values less than 1.0 will produce thin arrow buttons. Values greater than 1.0 will produce fat arrow buttons. The default is 1.0.

datatype

Specifies how the counter should count up and down.

The most general way to specify the datatype option is as a dictionary. The kind of counting is specified by the 'counter' dictionary field, which may be either a function or the name of one of the standard counters described below. If the dictionary does not have a 'counter' field, the field defaults to 'numeric'.

Any other fields in the dictionary are passed on to the counter function as keyword arguments.

If datatype is not a dictionary, then it is equivalent to specifying it as a dictionary with a single 'counter' field. For example, datatype = 'real' is equivalent to datatype = {'counter' : 'real'}.

The standard counters are:

'numeric'

An integer number, as accepted by int().

'integer'

Same as 'numeric'.

'real'

A real number, as accepted by float(). This counter accepts a 'separator' argument, which specifies the character used to represent the decimal point. The default 'separator' is '.'.

'time'

A time specification, as accepted by Pmw.timestringtoseconds(). This counter accepts a 'separator' argument, which specifies the character used to separate the time fields. The default separator is ':'. This counter also accepts a 'time24' argument. If this is true, the time value is converted to a value between '00:00:00' and '23:59:59'. The default is false.

'date'

A date specification, as accepted by Pmw.datestringtojdn(). This counter accepts a 'separator' argument, which specifies the character used to separate the three date fields. The default is '/'. This counter also accepts a 'format' argument, which is passed to Pmw.datestringtojdn() to specify the desired ordering of the fields. The default is 'ymd'. This counter also accepts a 'yyyy' argument. If this is false, the year field will be displayed as the year within the century, otherwise it will be fully displayed. In both cases it will be displayed with at least 2 digits, using leading zeroes. The default is false.

If the 'counter' dictionary field is a function, then it will be called whenever the counter is to be incremented or decremented. The function is called with at least three arguments, the first three being (text, factor, increment), where text is the current contents of the entry field, factor is 1 when incrementing or -1 when decrementing, and increment is the value of the increment megawidget option.

The other arguments are keyword arguments made up of the fields of the datatype dictionary (excluding the 'counter' field).

The counter function should return a string representing the incremented or decremented value. It should raise a ValueError exception if the text is invalid. In this case the bell is rung and the entry text is not changed.

The default for datatype is numeric.

increment

Specifies how many units should be added or subtracted when the counter is incremented or decremented. If the currently displayed value is not a multiple of increment, the value is changed to the next multiple greater or less than the current value.

For the number datatypes, the value of increment is a number. For the 'time' datatype, the value is in seconds. For the 'date' datatype, the value is in days. The default is 1.

initwait

Specifies the initial delay (in milliseconds) before a depressed arrow button automatically starts to repeat counting. The default is 300.

labelmargin

Initialisation option. The default is 0.

labelpos

Initialisation option. The default is None.

orient

Initialisation option. Specifies whether the arrow buttons should appear to the left and right of the entry field ('horizontal') or above and below ('vertical'). The default is 'horizontal'.

padx

Initialisation option. Specifies a padding distance to leave around the arrow buttons in the x direction. The default is 0.

pady

Initialisation option. Specifies a padding distance to leave around the arrow buttons in the y direction. The default is 0.

repeatrate

Specifies the delay (in milliseconds) between automatic counts while an arrow button is held pressed down. The default is 50.

sticky

Initialisation option. The default is 'ew'.

Components

Components created by this megawidget and its base classes are described below.

downarrow

The arrow button used for decrementing the counter. Depending on the value of orient, it will appear on the left or below the entry field. By default, this component is a Tkinter.Canvas. Its component group is Arrow.

entryfield

The entry field widget where the text is entered, displayed and validated. By default, this component is a Pmw.EntryField.

frame

If the label component has been created (that is, the labelpos option is not None), the frame component is created to act as the container of the entry field and arrow buttons. If there is no label component, then no frame component is created and the hull component acts as the container. In either case the border around the container of the entry field and arrow buttons will be raised (but not around the label). By default, this component is a Tkinter.Frame.

hull

This acts as the body for the entire megawidget. Other components are created as children of the hull to further specialise this class. By default, this component is a Tkinter.Frame.

label

By default, this component is a Tkinter.Label.

uparrow

The arrow button used for incrementing the counter. Depending on the value of orient, it will appear on the right or above the entry field. By default, this component is a Tkinter.Canvas. Its component group is Arrow.

Component aliases

Sub-components of components of this megawidget may be accessed via the following aliases.

entry

Alias for entryfield_entry.

Methods

Only methods specific to this megawidget are described below. For a description of its inherited methods, see the manual for its base class Pmw.MegaWidget. In addition, methods from the Pmw.EntryField class are forwarded by this megawidget to the entryfield component.

decrement()

Decrement the counter once, as if the down arrow had been pressed.

increment()

Increment the counter once, as if the up arrow had been pressed.

Example

The image at the top of this manual is a snapshot of the window (or part of the window) produced by the following code.

class Demo:
    def __init__(self, parent):
        # Need to use long ints here because on the Macintosh the maximum size
        # of an integer is smaller than the value returned by time.time().
        now = (int(time.time()) / 300) * 300

        # Create the Counters.
        self._date = Pmw.Counter(parent,
                labelpos = 'w',
                label_text = 'Date (4-digit year):',
                entryfield_value =
                        time.strftime('%d/%m/%Y', time.localtime(now)),
                entryfield_command = self.execute,
                entryfield_validate = {'validator' : 'date', 'format' : 'dmy'},
                datatype = {'counter' : 'date', 'format' : 'dmy', 'yyyy' : 1})

        self._isodate = Pmw.Counter(parent,
                labelpos = 'w',
                label_text = 'ISO-Date (4-digit year):',
                entryfield_value =
                        time.strftime('%Y-%m-%d', time.localtime(now)),
                entryfield_command = self.execute,
                entryfield_validate = {'validator' : 'date', 'format' : 'ymd',
                        'separator' : '-' },
                datatype = {'counter' : 'date', 'format' : 'ymd', 'yyyy' : 1,
                        'separator' : '-' })

        self._time = Pmw.Counter(parent,
                labelpos = 'w',
                label_text = 'Time:',
                entryfield_value =
                        time.strftime('%H:%M:%S', time.localtime(now)),
                entryfield_validate = {'validator' : 'time',
                        'min' : '00:00:00', 'max' : '23:59:59',
                        'minstrict' : 0, 'maxstrict' : 0},
                datatype = {'counter' : 'time', 'time24' : 1},
                increment=5*60)
        self._real = Pmw.Counter(parent,
                labelpos = 'w',
                label_text = 'Real (with comma)\nand extra\nlabel lines:',
                label_justify = 'left',
                entryfield_value = '1,5',
                datatype = {'counter' : 'real', 'separator' : ','},
                entryfield_validate = {'validator' : 'real',
                        'min' : '-2,0', 'max' : '5,0',
                        'separator' : ','},
                increment = 0.1)
        self._custom = Pmw.Counter(parent,
                labelpos = 'w',
                label_text = 'Custom:',
                entryfield_value = specialword[:4],
                datatype = _custom_counter,
                entryfield_validate = _custom_validate)
        self._int = Pmw.Counter(parent,
                labelpos = 'w',
                label_text = 'Vertical integer:',
                orient = 'vertical',
                entry_width = 2,
                entryfield_value = 50,
                entryfield_validate = {'validator' : 'integer',
                        'min' : 0, 'max' : 99}
        )

        counters = (self._date, self._isodate, self._time, self._real,
                self._custom)
        Pmw.alignlabels(counters)

        # Pack them all.
        for counter in counters:
            counter.pack(fill='both', expand=1, padx=10, pady=5)
        self._int.pack(padx=10, pady=5)

    def execute(self):
        print(('Return pressed, value is', self._date.get()))

specialword = 'Monti Python ik den Holie Grailen (Bok)'

def _custom_validate(text):
    if specialword.find(text) == 0:
        return 1
    else:
        return -1

def _custom_counter(text, factor, increment):
    # increment is ignored here.
    if specialword.find(text) == 0:
        length = len(text)
        if factor == 1:
            if length >= len(specialword):
                raise ValueError('maximum length reached')
            return specialword[:length + 1]
        else:
            if length == 0:
                raise ValueError('empty string')
            return specialword[:length - 1]
    else:
        raise ValueError('bad string ' + text)