The example program (rangewidgets.py) puts up a window with three range widgets all connected to the same adjustment, and a couple of controls for adjusting some of the parameters mentioned above and in the section on adjustments, so you can see how they affect the way these widgets work for the user. Figure 8.1, “Range Widgets Example” illustrates the result of running the program:
The rangewidgets.py source code is:
1 #!/usr/bin/env python
2
3 # example rangewidgets.py
4
5 import pygtk
6 pygtk.require('2.0')
7 import gtk
8
9 # Convenience functions
10
11 def make_menu_item(name, callback, data=None):
12 item = gtk.MenuItem(name)
13 item.connect("activate", callback, data)
14 item.show()
15 return item
16
17 def scale_set_default_values(scale):
18 scale.set_update_policy(gtk.UPDATE_CONTINUOUS)
19 scale.set_digits(1)
20 scale.set_value_pos(gtk.POS_TOP)
21 scale.set_draw_value(True)
22
23 class RangeWidgets:
24 def cb_pos_menu_select(self, item, pos):
25 # Set the value position on both scale widgets
26 self.hscale.set_value_pos(pos)
27 self.vscale.set_value_pos(pos)
28
29 def cb_update_menu_select(self, item, policy):
30 # Set the update policy for both scale widgets
31 self.hscale.set_update_policy(policy)
32 self.vscale.set_update_policy(policy)
33
34 def cb_digits_scale(self, adj):
35 # Set the number of decimal places to which adj->value is rounded
36 self.hscale.set_digits(adj.value)
37 self.vscale.set_digits(adj.value)
38
39 def cb_page_size(self, get, set):
40 # Set the page size and page increment size of the sample
41 # adjustment to the value specified by the "Page Size" scale
42 set.page_size = get.value
43 set.page_incr = get.value
44 # Now emit the "changed" signal to reconfigure all the widgets that
45 # are attached to this adjustment
46 set.emit("changed")
47
48 def cb_draw_value(self, button):
49 # Turn the value display on the scale widgets off or on depending
50 # on the state of the checkbutton
51 self.hscale.set_draw_value(button.get_active())
52 self.vscale.set_draw_value(button.get_active())
53
54 # makes the sample window
55
56 def __init__(self):
57 # Standard window-creating stuff
58 self.window = gtk.Window (gtk.WINDOW_TOPLEVEL)
59 self.window.connect("destroy", lambda w: gtk.main_quit())
60 self.window.set_title("range controls")
61
62 box1 = gtk.VBox(False, 0)
63 self.window.add(box1)
64 box1.show()
65
66 box2 = gtk.HBox(False, 10)
67 box2.set_border_width(10)
68 box1.pack_start(box2, True, True, 0)
69 box2.show()
70
71 # value, lower, upper, step_increment, page_increment, page_size
72 # Note that the page_size value only makes a difference for
73 # scrollbar widgets, and the highest value you'll get is actually
74 # (upper - page_size).
75 adj1 = gtk.Adjustment(0.0, 0.0, 101.0, 0.1, 1.0, 1.0)
76
77 self.vscale = gtk.VScale(adj1)
78 scale_set_default_values(self.vscale)
79 box2.pack_start(self.vscale, True, True, 0)
80 self.vscale.show()
81
82 box3 = gtk.VBox(False, 10)
83 box2.pack_start(box3, True, True, 0)
84 box3.show()
85
86 # Reuse the same adjustment
87 self.hscale = gtk.HScale(adj1)
88 self.hscale.set_size_request(200, 30)
89 scale_set_default_values(self.hscale)
90 box3.pack_start(self.hscale, True, True, 0)
91 self.hscale.show()
92
93 # Reuse the same adjustment again
94 scrollbar = gtk.HScrollbar(adj1)
95 # Notice how this causes the scales to always be updated
96 # continuously when the scrollbar is moved
97 scrollbar.set_update_policy(gtk.UPDATE_CONTINUOUS)
98 box3.pack_start(scrollbar, True, True, 0)
99 scrollbar.show()
100
101 box2 = gtk.HBox(False, 10)
102 box2.set_border_width(10)
103 box1.pack_start(box2, True, True, 0)
104 box2.show()
105
106 # A checkbutton to control whether the value is displayed or not
107 button = gtk.CheckButton("Display value on scale widgets")
108 button.set_active(True)
109 button.connect("toggled", self.cb_draw_value)
110 box2.pack_start(button, True, True, 0)
111 button.show()
112
113 box2 = gtk.HBox(False, 10)
114 box2.set_border_width(10)
115
116 # An option menu to change the position of the value
117 label = gtk.Label("Scale Value Position:")
118 box2.pack_start(label, False, False, 0)
119 label.show()
120
121 opt = gtk.OptionMenu()
122 menu = gtk.Menu()
123
124 item = make_menu_item ("Top", self.cb_pos_menu_select, gtk.POS_TOP)
125 menu.append(item)
126
127 item = make_menu_item ("Bottom", self.cb_pos_menu_select,
128 gtk.POS_BOTTOM)
129 menu.append(item)
130
131 item = make_menu_item ("Left", self.cb_pos_menu_select, gtk.POS_LEFT)
132 menu.append(item)
133
134 item = make_menu_item ("Right", self.cb_pos_menu_select, gtk.POS_RIGHT)
135 menu.append(item)
136
137 opt.set_menu(menu)
138 box2.pack_start(opt, True, True, 0)
139 opt.show()
140
141 box1.pack_start(box2, True, True, 0)
142 box2.show()
143
144 box2 = gtk.HBox(False, 10)
145 box2.set_border_width(10)
146
147 # Yet another option menu, this time for the update policy of the
148 # scale widgets
149 label = gtk.Label("Scale Update Policy:")
150 box2.pack_start(label, False, False, 0)
151 label.show()
152
153 opt = gtk.OptionMenu()
154 menu = gtk.Menu()
155
156 item = make_menu_item("Continuous", self.cb_update_menu_select,
157 gtk.UPDATE_CONTINUOUS)
158 menu.append(item)
159
160 item = make_menu_item ("Discontinuous", self.cb_update_menu_select,
161 gtk.UPDATE_DISCONTINUOUS)
162 menu.append(item)
163
164 item = make_menu_item ("Delayed", self.cb_update_menu_select,
165 gtk.UPDATE_DELAYED)
166 menu.append(item)
167
168 opt.set_menu(menu)
169 box2.pack_start(opt, True, True, 0)
170 opt.show()
171
172 box1.pack_start(box2, True, True, 0)
173 box2.show()
174
175 box2 = gtk.HBox(False, 10)
176 box2.set_border_width(10)
177
178 # An HScale widget for adjusting the number of digits on the
179 # sample scales.
180 label = gtk.Label("Scale Digits:")
181 box2.pack_start(label, False, False, 0)
182 label.show()
183
184 adj2 = gtk.Adjustment(1.0, 0.0, 5.0, 1.0, 1.0, 0.0)
185 adj2.connect("value_changed", self.cb_digits_scale)
186 scale = gtk.HScale(adj2)
187 scale.set_digits(0)
188 box2.pack_start(scale, True, True, 0)
189 scale.show()
190
191 box1.pack_start(box2, True, True, 0)
192 box2.show()
193
194 box2 = gtk.HBox(False, 10)
195 box2.set_border_width(10)
196
197 # And, one last HScale widget for adjusting the page size of the
198 # scrollbar.
199 label = gtk.Label("Scrollbar Page Size:")
200 box2.pack_start(label, False, False, 0)
201 label.show()
202
203 adj2 = gtk.Adjustment(1.0, 1.0, 101.0, 1.0, 1.0, 0.0)
204 adj2.connect("value_changed", self.cb_page_size, adj1)
205 scale = gtk.HScale(adj2)
206 scale.set_digits(0)
207 box2.pack_start(scale, True, True, 0)
208 scale.show()
209
210 box1.pack_start(box2, True, True, 0)
211 box2.show()
212
213 separator = gtk.HSeparator()
214 box1.pack_start(separator, False, True, 0)
215 separator.show()
216
217 box2 = gtk.VBox(False, 10)
218 box2.set_border_width(10)
219 box1.pack_start(box2, False, True, 0)
220 box2.show()
221
222 button = gtk.Button("Quit")
223 button.connect("clicked", lambda w: gtk.main_quit())
224 box2.pack_start(button, True, True, 0)
225 button.set_flags(gtk.CAN_DEFAULT)
226 button.grab_default()
227 button.show()
228 self.window.show()
229
230 def main():
231 gtk.main()
232 return 0
233
234 if __name__ == "__main__":
235 RangeWidgets()
236 main()
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You will notice that the program does not call the connect() method for the "delete_event", but only for the "destroy" signal. This will still perform the desired operation, because an unhandled "delete_event" will result in a "destroy" signal being given to the window.