initial display_scale script

display_scale.py

@@ -0,0 +1,58 @@
+#!/usr/bin/python3
+# Note: use system python3, not /usr/bin/env, because whichever python3 is on
+# $PATH may not have dbus, but the system python3 does.
+
+"""Toggle display scaling between 100% and 200%.
+
+Based on https://gist.github.com/strycore/ca11203fd63cafcac76d4b04235d8759
+
+For data structure definitions, see
+https://gitlab.gnome.org/GNOME/mutter/blob/master/src/org.gnome.Mutter.DisplayConfig.xml
+"""
+
+import dbus
+import sys
+
+try:
+    scaling_factor = float(sys.argv[1])
+except IndexError:
+    scaling_factor = 1
+
+namespace = "org.gnome.Mutter.DisplayConfig"
+dbus_path = "/org/gnome/Mutter/DisplayConfig"
+
+session_bus = dbus.SessionBus()
+obj = session_bus.get_object(namespace, dbus_path)
+interface = dbus.Interface(obj, dbus_interface=namespace)
+
+current_state = interface.GetCurrentState()
+serial = current_state[0]
+connected_monitors = current_state[1]
+logical_monitors = current_state[2]
+
+# Multiple monitors are more complicated. For now, since I only use one monitor
+# in Ubuntu, everything is hard-coded so that only info about the first monitor
+# is used, and only it will be connected after running the script.
+#
+# If someday updating this script: a logical monitor may appear on mutiple
+# connected monitors due to mirroring.
+connector = connected_monitors[0][0][0]
+current_mode = None
+# ApplyMonitorsConfig() needs (connector name, mode ID) for each connected
+# monitor of a logical monitor, but GetCurrentState() only returns the
+# connector name for each connected monitor of a logical monitor. So iterate
+# through the globally connected monitors to find the mode ID.
+for mode in connected_monitors[0][1]:
+    if mode[6].get("is-current", False):
+        current_mode = mode[0]
+
+current_mode = dbus.String("1920x1080@59.999")
+updated_connected_monitors = [[connector, current_mode, {}]]
+
+x, y, scale, transform, primary, monitors, props = logical_monitors[0]
+scale = scaling_factor
+
+monitor_config = [[x, y, scale, transform, primary, updated_connected_monitors]]
+
+# Change the 1 to a 2 if you want a "Revert Settings / Keep Changes" dialog
+interface.ApplyMonitorsConfig(serial, 1, monitor_config, {})