Library: Port 'Scale' to Python (#769)

Author: gregorni

src/Library/demos/Scale/main.py

@@ -0,0 +1,50 @@
+import gi
+
+gi.require_version("Gtk", "4.0")
+from gi.repository import Gtk
+import workbench
+
+scale_one = workbench.builder.get_object("one")
+scale_two = workbench.builder.get_object("two")
+scale_button = workbench.builder.get_object("button")
+
+marks = {
+    0: "A",
+    50: "B",
+    100: "C",
+}
+
+volume_icons = [
+    "audio-volume-muted-symbolic",
+    "audio-volume-high-symbolic",
+    "audio-volume-low-symbolic",
+    "audio-volume-medium-symbolic",
+]
+
+for value, label in marks.items():
+    scale_two.add_mark(value, Gtk.PositionType.RIGHT, label)
+
+scale_two.set_increments(25, 100)
+
+
+def callback1(scale):
+    scale_value = scale_one.get_value()
+    if scale_value == scale_one.get_adjustment().get_upper():
+        print("Maximum value reached")
+    elif scale_value == scale_one.get_adjustment().get_lower():
+        print("Minimum value reached")
+
+
+scale_one.connect("value-changed", callback1)
+
+
+def callback2(scale):
+    scale_value = scale_two.get_value()
+    label = marks.get(scale_value)
+    if label:
+        print(f"Mark {label} reached")
+
+
+scale_two.connect("value-changed", callback2)
+
+scale_button.set_icons(volume_icons)