Slide the scales!
from gi.repository import Gtk
import sys
class MyWindow(Gtk.ApplicationWindow):
def __init__(self, app):
Gtk.Window.__init__(self, title="Scale Example", application=app)
self.set_default_size(400, 300)
self.set_border_width(5)
# two adjustments (initial value, min value, max value,
# step increment - press cursor keys to see!,
# page increment - click around the handle to see!,
# page size - not used here)
ad1 = Gtk.Adjustment(0, 0, 100, 5, 10, 0)
ad2 = Gtk.Adjustment(50, 0, 100, 5, 10, 0)
# an horizontal scale
self.h_scale = Gtk.Scale(
orientation=Gtk.Orientation.HORIZONTAL, adjustment=ad1)
# of integers (no digits)
self.h_scale.set_digits(0)
# that can expand horizontally if there is space in the grid (see
# below)
self.h_scale.set_hexpand(True)
# that is aligned at the top of the space allowed in the grid (see
# below)
self.h_scale.set_valign(Gtk.Align.START)
# we connect the signal "value-changed" emitted by the scale with the callback
# function scale_moved
self.h_scale.connect("value-changed", self.scale_moved)
# a vertical scale
self.v_scale = Gtk.Scale(
orientation=Gtk.Orientation.VERTICAL, adjustment=ad2)
# that can expand vertically if there is space in the grid (see below)
self.v_scale.set_vexpand(True)
# we connect the signal "value-changed" emitted by the scale with the callback
# function scale_moved
self.v_scale.connect("value-changed", self.scale_moved)
# a label
self.label = Gtk.Label()
self.label.set_text("Move the scale handles...")
# a grid to attach the widgets
grid = Gtk.Grid()
grid.set_column_spacing(10)
grid.set_column_homogeneous(True)
grid.attach(self.h_scale, 0, 0, 1, 1)
grid.attach_next_to(
self.v_scale, self.h_scale, Gtk.PositionType.RIGHT, 1, 1)
grid.attach(self.label, 0, 1, 2, 1)
self.add(grid)
# any signal from the scales is signaled to the label the text of which is
# changed
def scale_moved(self, event):
self.label.set_text("Horizontal scale is " + str(int(self.h_scale.get_value())) +
"; vertical scale is " + str(self.v_scale.get_value()) + ".")
class MyApplication(Gtk.Application):
def __init__(self):
Gtk.Application.__init__(self)
def do_activate(self):
win = MyWindow(self)
win.show_all()
def do_startup(self):
Gtk.Application.do_startup(self)
app = MyApplication()
exit_status = app.run(sys.argv)
sys.exit(exit_status)
A Gtk.Adjustment is needed to construct the Gtk.Scale. This is the representation of a value with a lower and upper bound, together with step and page increments, and a page size, and it is constructed as Gtk.Adjustment(value, lower, upper, step_increment, page_increment, page_size)
where the fields are of type float
; step_increment
is the increment/decrement that is obtained by using the cursor keys, page_increment
the one that is obtained clicking on the scale itself. Note that page_size
is not used in this case, it should be set to 0
.
In line 28 the signal "value-changed"
is connected to the callback function scale_moved()
using widget.connect(signal, callback function)
. See for a more detailed explanation.
get_value()
retrieves the current value of the scale; set_value(value)
sets it (if the value
, of type float
, is outside the minimum or maximum range, it will be clamped to fit inside them). These are methods of the class Gtk.Range.
Use set_draw_value(False)
to avoid displaying the current value as a string next to the slider.
To highlight the part of the scale between the origin and the current value:
self.h_scale.set_restrict_to_fill_level(False)
self.h_scale.set_fill_level(self.h_scale.get_value())
self.h_scale.set_show_fill_level(True)
in the callback function of the "value-changed" signal, so to have the new filling every time the value is changed. These are methods of the class Gtk.Range.
add_mark(value, position, markup)
adds a mark at the value
(float
or int
if that is the precision of the scale), in position
(Gtk.PositionType.LEFT, Gtk.PositionType.RIGHT, Gtk.PositionType.TOP, Gtk.PositionType.BOTTOM
) with text Null
or markup
in the Pango Markup Language. To clear marks, clear_marks()
.
set_digits(digits)
sets the precision of the scale at digits
digits.
In this sample we used the following:
GtkScale
GtkAdjustment
Standard-Aufzählungen