Merge lp:~gala-dev/gala/hidpi into lp:gala

[Rico Tzschichholz]

Enable HiDPI on the notifications

Unmerged revisions

564. By Corentin Noël on 2016-12-18

[HiDPI] Notifications are now working

=== modified file 'lib/Utils.vala'
--- lib/Utils.vala	2016-12-31 08:08:58 +0000
+++ lib/Utils.vala	2017-02-19 16:15:16 +0000
@@ -25,6 +25,7 @@
 		static uint cache_clear_timeout = 0;
 
 		static Gdk.Pixbuf? close_pixbuf = null;
+		static int close_pixbuf_scale = 0;
 
 		static construct
 		{
@@ -290,11 +291,12 @@
 		 *
 		 * @return the close button pixbuf or null if it failed to load
 		 */
-		public static Gdk.Pixbuf? get_close_button_pixbuf ()
+		public static Gdk.Pixbuf? get_close_button_pixbuf (int scale_factor)
 		{
-			if (close_pixbuf == null) {
+			if (close_pixbuf == null || close_pixbuf_scale != scale_factor) {
 				try {
-					close_pixbuf = new Gdk.Pixbuf.from_file_at_scale (Config.PKGDATADIR + "/close.svg", -1, 36, true);
+					close_pixbuf = new Gdk.Pixbuf.from_file_at_scale (Config.PKGDATADIR + "/close.svg", -1, 36 * scale_factor, true);
+					close_pixbuf_scale = scale_factor;
 				} catch (Error e) {
 					warning (e.message);
 					return null;
@@ -309,10 +311,10 @@
 		 *
 		 * @return The close button actor
 		 */
-		public static Clutter.Actor create_close_button ()
+		public static Clutter.Actor create_close_button (int scale_factor = 1)
 		{
 			var texture = new Clutter.Texture ();
-			var pixbuf = get_close_button_pixbuf ();
+			var pixbuf = get_close_button_pixbuf (scale_factor);
 
 			texture.reactive = true;
 
@@ -326,7 +328,7 @@
 				// we'll just make this red so there's at least something as an 
 				// indicator that loading failed. Should never happen and this
 				// works as good as some weird fallback-image-failed-to-load pixbuf
-				texture.set_size (36, 36);
+				texture.set_size (36 * scale_factor, 36 * scale_factor);
 				texture.background_color = { 255, 0, 0, 255 };
 			}
 

=== modified file 'lib/WindowManager.vala'
--- lib/WindowManager.vala	2015-03-04 11:07:30 +0000
+++ lib/WindowManager.vala	2017-02-19 16:15:16 +0000
@@ -92,6 +92,11 @@
 		public abstract Meta.BackgroundGroup background_group { get; protected set; }
 
 		/**
+		 * The scale factor is the scale used by all user-facing elements
+		 */
+		public abstract int scale_factor { get; protected set; }
+
+		/**
 		 * Enters the modal mode, which means that all events are directed to the stage instead
 		 * of the windows. This is the only way to receive keyboard events besides shortcut listeners.
 		 *

=== modified file 'plugins/notify/ConfirmationNotification.vala'
--- plugins/notify/ConfirmationNotification.vala	2014-07-21 01:21:19 +0000
+++ plugins/notify/ConfirmationNotification.vala	2017-02-19 16:15:16 +0000
@@ -55,7 +55,7 @@
 
 		public override void update_allocation (out float content_height, AllocationFlags flags)
 		{
-			content_height = ICON_SIZE;
+			content_height = ICON_SIZE * style_context.get_scale ();
 		}
 
 		public override void draw_content (Cairo.Context cr)
@@ -63,14 +63,21 @@
 			if (!has_progress)
 				return;
 
-			var x = MARGIN + PADDING + ICON_SIZE + SPACING;
-			var y = MARGIN + PADDING + (ICON_SIZE - PROGRESS_HEIGHT) / 2;
-			var width = WIDTH - x - MARGIN;
+			var scale = style_context.get_scale ();
+			var scaled_width = WIDTH * scale;
+			var scaled_margin = MARGIN * scale;
+			var scaled_padding = PADDING * scale;
+			var scaled_icon_size = ICON_SIZE * scale;
+			var scaled_spacing = SPACING * scale;
+			var scaled_progress_height = PROGRESS_HEIGHT * scale;
+			var x = scaled_margin + scaled_padding + scaled_icon_size + scaled_spacing;
+			var y = scaled_margin + scaled_padding + (scaled_icon_size - scaled_progress_height) / 2;
+			var width = scaled_width - x - scaled_margin;
 
 			if (!transitioning)
 				draw_progress_bar (cr, x, y, width, progress);
 			else {
-				Granite.Drawing.Utilities.cairo_rounded_rectangle (cr, MARGIN, MARGIN, WIDTH - MARGIN * 2, ICON_SIZE + PADDING * 2, 4);
+				Granite.Drawing.Utilities.cairo_rounded_rectangle (cr, scaled_margin, scaled_margin, scaled_width - scaled_margin * 2, scaled_icon_size + scaled_padding * 2, 4);
 				cr.clip ();
 
 				draw_progress_bar (cr, x, y + animation_slide_y_offset, width, old_progress);
@@ -82,16 +89,18 @@
 
 		void draw_progress_bar (Cairo.Context cr, int x, float y, int width, int progress)
 		{
+			var scale = style_context.get_scale ();
 			var fraction = (int) Math.floor (progress.clamp (0, 100) / 100.0 * width);
 
+			var scaled_height = PROGRESS_HEIGHT * scale;
 			Granite.Drawing.Utilities.cairo_rounded_rectangle (cr, x, y, width,
-				PROGRESS_HEIGHT, PROGRESS_HEIGHT / 2);
+				scaled_height, scaled_height / 2);
 			cr.set_source_rgb (0.8, 0.8, 0.8);
 			cr.fill ();
 
 			if (progress > 0) {
 				Granite.Drawing.Utilities.cairo_rounded_rectangle (cr, x, y, fraction,
-					PROGRESS_HEIGHT, PROGRESS_HEIGHT / 2);
+					scaled_height, scaled_height / 2);
 				cr.set_source_rgb (0.3, 0.3, 0.3);
 				cr.fill ();
 			}
@@ -111,7 +120,7 @@
 
 				old_progress = this.progress;
 
-				play_update_transition (ICON_SIZE + PADDING * 2);
+				play_update_transition ((ICON_SIZE + PADDING * 2) * style_context.get_scale ());
 			}
 
 			if (this.icon_only != icon_only) {

=== modified file 'plugins/notify/Main.vala'
--- plugins/notify/Main.vala	2014-07-18 11:12:31 +0000
+++ plugins/notify/Main.vala	2017-02-19 16:15:16 +0000
@@ -30,9 +30,8 @@
 		public override void initialize (Gala.WindowManager wm)
 		{
 			this.wm = wm;
-			var screen = wm.get_screen ();
 
-			stack = new NotificationStack (wm.get_screen ());
+			stack = new NotificationStack (wm);
 			wm.ui_group.add_child (stack);
 			track_actor (stack);
 
@@ -43,6 +42,7 @@
 			server = new NotifyServer (stack);
 
 			update_position ();
+			unowned Meta.Screen screen = wm.get_screen ();
 			screen.monitors_changed.connect (update_position);
 			screen.workareas_changed.connect (update_position);
 
@@ -64,7 +64,7 @@
 
 		void update_position ()
 		{
-			var screen = wm.get_screen ();
+			unowned Meta.Screen screen = wm.get_screen ();
 			var primary = screen.get_primary_monitor ();
 			var area = screen.get_active_workspace ().get_work_area_for_monitor (primary);
 

=== modified file 'plugins/notify/NormalNotification.vala'
--- plugins/notify/NormalNotification.vala	2016-08-04 07:37:29 +0000
+++ plugins/notify/NormalNotification.vala	2017-02-19 16:15:16 +0000
@@ -38,6 +38,8 @@
 			} catch (Error e) {}
 		}
 
+		public unowned Gtk.StyleContext parent_style_context { get; construct; }
+
 		const int LABEL_SPACING = 2;
 
 		Text summary_label;
@@ -64,6 +66,7 @@
 			var label_style_context = new Gtk.StyleContext ();
 			label_style_context.add_provider (Notification.default_css, Gtk.STYLE_PROVIDER_PRIORITY_FALLBACK);
 			label_style_context.set_path (style_path);
+			label_style_context.set_parent (parent_style_context);
 
 			Gdk.RGBA color;
 
@@ -93,6 +96,11 @@
 			add_child (body_label);
 		}
 
+		public NormalNotificationContent (Gtk.StyleContext parent_style_context)
+		{
+			Object (parent_style_context: parent_style_context);
+		}
+
 		public void set_values (string summary, string body)
 		{
 			summary_label.set_markup ("<b>%s</b>".printf (fix_markup (summary)));
@@ -119,7 +127,7 @@
 			summary_label.allocate (summary_alloc, flags);
 
 			var body_alloc = ActorBox ();
-			body_alloc.set_origin (label_x, label_y + summary_height + LABEL_SPACING);
+			body_alloc.set_origin (label_x, label_y + summary_height + LABEL_SPACING * parent_style_context.get_scale ());
 			body_alloc.set_size (label_width, body_height);
 			body_label.allocate (body_alloc, flags);
 
@@ -129,16 +137,22 @@
 		void get_allocation_values (out float label_x, out float label_width, out float summary_height,
 			out float body_height, out float label_height, out float label_y)
 		{
-			var height = Notification.ICON_SIZE;
+			var scale = parent_style_context.get_scale ();
+			var height = Notification.ICON_SIZE * scale;
+			var width = scale * Notification.WIDTH;
+			var margin = scale * Notification.MARGIN;
+			var padding = scale * Notification.PADDING;
+			var spacing = scale * Notification.SPACING;
+			var label_spacing = scale * LABEL_SPACING;
 
-			label_x = Notification.MARGIN + Notification.PADDING + height + Notification.SPACING;
-			label_width = Notification.WIDTH - label_x - Notification.MARGIN - Notification.SPACING;
+			label_x = margin + padding + height + spacing;
+			label_width = width - label_x - margin - spacing;
 
 			summary_label.get_preferred_height (label_width, null, out summary_height);
 			body_label.get_preferred_height (label_width, null, out body_height);
 
-			label_height = summary_height + LABEL_SPACING + body_height;
-			label_y = Notification.MARGIN + Notification.PADDING;
+			label_height = summary_height + label_spacing + body_height;
+			label_y = margin + padding;
 			// center
 			if (label_height < height) {
 				label_y += (height - (int) label_height) / 2;
@@ -168,13 +182,13 @@
 		public string body { get; construct set; }
 		public uint32 sender_pid { get; construct; }
 		public string[] notification_actions { get; construct set; }
-		public Screen screen { get; construct; }
+		public unowned Gala.WindowManager wm { get; construct; }
 
 		Actor content_container;
 		NormalNotificationContent notification_content;
 		NormalNotificationContent? old_notification_content = null;
 
-		public NormalNotification (Screen screen, uint32 id, string summary, string body, Gdk.Pixbuf? icon,
+		public NormalNotification (Gala.WindowManager wm, uint32 id, string summary, string body, Gdk.Pixbuf? icon,
 			NotificationUrgency urgency, int32 expire_timeout, uint32 pid, string[] actions)
 		{
 			Object (
@@ -182,7 +196,7 @@
 				icon: icon,
 				urgency: urgency,
 				expire_timeout: expire_timeout,
-				screen: screen,
+				wm: wm,
 				summary: summary,
 				body: body,
 				sender_pid: pid,
@@ -192,9 +206,10 @@
 
 		construct
 		{
+			set_scale_factor (wm.scale_factor);
 			content_container = new Actor ();
 
-			notification_content = new NormalNotificationContent ();
+			notification_content = new NormalNotificationContent (style_context);
 			notification_content.set_values (summary, body);
 
 			content_container.add_child (notification_content);
@@ -210,7 +225,7 @@
 				if (old_notification_content != null)
 					old_notification_content.destroy ();
 
-				old_notification_content = new NormalNotificationContent ();
+				old_notification_content = new NormalNotificationContent (style_context);
 				old_notification_content.set_values (this.summary, this.body);
 
 				content_container.add_child (old_notification_content);
@@ -225,7 +240,7 @@
 
 				content_height = float.max (content_height, old_content_height);
 
-				play_update_transition (content_height + PADDING * 2);
+				play_update_transition (content_height + PADDING * 2 * style_context.get_scale ());
 
 				get_transition ("switch").completed.connect (() => {
 					if (old_notification_content != null)
@@ -257,8 +272,10 @@
 			// the for_width is not needed in our implementation of get_preferred_height as we
 			// assume a constant width
 			notification_content.get_preferred_height (0, null, out content_height);
+			var scale = style_context.get_scale ();
+			var scaled_margin = MARGIN * scale;
 
-			content_container.set_clip (MARGIN, MARGIN, MARGIN * 2 + WIDTH, content_height + PADDING * 2);
+			content_container.set_clip (scaled_margin, scaled_margin, scaled_margin * 2 + WIDTH * scale, content_height + PADDING * 2 * scale);
 		}
 
 		public override void get_preferred_height (float for_width, out float min_height, out float nat_height)
@@ -266,7 +283,7 @@
 			float content_height;
 			notification_content.get_preferred_height (for_width, null, out content_height);
 
-			min_height = nat_height = content_height + (MARGIN + PADDING) * 2;
+			min_height = nat_height = content_height + ((MARGIN + PADDING) * 2) * style_context.get_scale ();
 		}
 
 		public override void activate ()
@@ -287,6 +304,7 @@
 			unowned Meta.Window? window = get_window ();
 			if (window != null) {
 				unowned Meta.Workspace workspace = window.get_workspace ();
+				unowned Meta.Screen screen = wm.get_screen ();
 				var time = screen.get_display ().get_current_time ();
 
 				if (workspace != screen.get_active_workspace ())
@@ -303,6 +321,7 @@
 			if (sender_pid == 0)
 				return null;
 
+			unowned Meta.Screen screen = wm.get_screen ();
 			foreach (unowned Meta.WindowActor actor in Meta.Compositor.get_window_actors (screen)) {
 				if (actor.is_destroyed ())
 					continue;

=== modified file 'plugins/notify/Notification.vala'
--- plugins/notify/Notification.vala	2016-11-15 16:13:39 +0000
+++ plugins/notify/Notification.vala	2017-02-19 16:15:16 +0000
@@ -53,7 +53,7 @@
 
 		Clutter.Actor close_button;
 
-		Gtk.StyleContext style_context;
+		protected Gtk.StyleContext style_context { get; private set; }
 
 		uint remove_timeout = 0;
 
@@ -99,20 +99,7 @@
 			icon_container = new Actor ();
 			icon_container.add_child (icon_texture);
 
-			close_button = Utils.create_close_button ();
-			close_button.opacity = 0;
-			close_button.reactive = true;
-			close_button.set_easing_duration (300);
-
-			var close_click = new ClickAction ();
-			close_click.clicked.connect (() => {
-				closed (id, NotificationClosedReason.DISMISSED);
-				close ();
-			});
-			close_button.add_action (close_click);
-
 			add_child (icon_container);
-			add_child (close_button);
 
 			if (default_css == null) {
 				default_css = new Gtk.CssProvider ();
@@ -132,6 +119,8 @@
 			style_context.add_class ("gala-notification");
 			style_context.set_path (style_path);
 
+			create_close_button ();
+
 			var label_style_path = style_path.copy ();
 			label_style_path.iter_add_class (1, "gala-notification");
 			label_style_path.append_type (typeof (Gtk.Label));
@@ -227,6 +216,26 @@
 				destroy ();
 		}
 
+		void create_close_button () {
+			if (close_button != null)
+			{
+				close_button.destroy ();
+			}
+
+			close_button = Utils.create_close_button (style_context.get_scale ());
+			close_button.opacity = 0;
+			close_button.reactive = true;
+			close_button.set_easing_duration (300);
+
+			var close_click = new ClickAction ();
+			close_click.clicked.connect (() => {
+				closed (id, NotificationClosedReason.DISMISSED);
+				close ();
+			});
+			close_button.add_action (close_click);
+			add_child (close_button);
+		}
+
 		protected void update_base (Gdk.Pixbuf? icon, int32 expire_timeout)
 		{
 			this.icon = icon;
@@ -273,6 +282,16 @@
 			}
 		}
 
+		public void set_scale_factor (int scale_factor)
+		{
+			style_context.set_scale (scale_factor);
+			width = (WIDTH + MARGIN * 2) * scale_factor;
+			create_close_button ();
+			if (content is Canvas) {
+				((Canvas) content).set_scale_factor (scale_factor);
+			}
+		}
+
 		public override bool enter_event (CrossingEvent event)
 		{
 			close_button.opacity = 255;
@@ -304,21 +323,26 @@
 
 		public override void allocate (ActorBox box, AllocationFlags flags)
 		{
+			var scale = style_context.get_scale ();
+			var scaled_width = WIDTH * scale;
+			var scaled_icon_size = ICON_SIZE * scale;
+			var scaled_margin = MARGIN * scale;
+			var scaled_padding = PADDING * scale;
+			var margin_padding = scaled_margin + scaled_padding;
 			var icon_alloc = ActorBox ();
 
-			icon_alloc.set_origin (icon_only ? (WIDTH - ICON_SIZE) / 2 : MARGIN + PADDING, MARGIN + PADDING);
-			icon_alloc.set_size (ICON_SIZE, ICON_SIZE);
+			icon_alloc.set_origin (icon_only ? (scaled_width - scaled_icon_size) / 2 : margin_padding, margin_padding);
+			icon_alloc.set_size (scaled_icon_size, scaled_icon_size);
 			icon_container.allocate (icon_alloc, flags);
 
 			var close_alloc = ActorBox ();
-			close_alloc.set_origin (MARGIN + PADDING - close_button.width / 2,
-				MARGIN + PADDING - close_button.height / 2);
+			close_alloc.set_origin (margin_padding - close_button.width / 2, margin_padding - close_button.height / 2);
 			close_alloc.set_size (close_button.width, close_button.height);
 			close_button.allocate (close_alloc, flags);
 
 			float content_height;
 			update_allocation (out content_height, flags);
-			box.set_size (MARGIN * 2 + WIDTH, (MARGIN + PADDING) * 2 + content_height);
+			box.set_size (scaled_margin * 2 + scaled_width, margin_padding * 2 + content_height);
 
 			base.allocate (box, flags);
 
@@ -331,7 +355,7 @@
 
 		public override void get_preferred_height (float for_width, out float min_height, out float nat_height)
 		{
-			min_height = nat_height = ICON_SIZE + (MARGIN + PADDING) * 2;
+			min_height = nat_height = (ICON_SIZE + (MARGIN + PADDING) * 2) * style_context.get_scale ();
 		}
 
 		protected void play_update_transition (float slide_height)
@@ -346,7 +370,8 @@
 
 			old_texture = new Clutter.Texture ();
 			icon_container.add_child (old_texture);
-			icon_container.set_clip (0, -PADDING, ICON_SIZE, ICON_SIZE + PADDING * 2);
+			var scale = style_context.get_scale ();
+			icon_container.set_clip (0, -PADDING * scale, ICON_SIZE * scale, (ICON_SIZE + PADDING * 2) * scale);
 
 			if (icon != null) {
 				try {
@@ -382,10 +407,12 @@
 		{
 			var canvas = (Canvas) content;
 
-			var x = MARGIN;
-			var y = MARGIN;
-			var width = canvas.width - MARGIN * 2;
-			var height = canvas.height - MARGIN * 2;
+			var scale = style_context.get_scale ();
+			var margin_scaled = MARGIN * scale;
+			var x = margin_scaled;
+			var y = margin_scaled;
+			var width = canvas.width - margin_scaled * 2;
+			var height = canvas.height - margin_scaled * 2;
 			cr.set_operator (Cairo.Operator.CLEAR);
 			cr.paint ();
 			cr.set_operator (Cairo.Operator.OVER);

=== modified file 'plugins/notify/NotificationStack.vala'
--- plugins/notify/NotificationStack.vala	2016-07-28 22:19:16 +0000
+++ plugins/notify/NotificationStack.vala	2017-02-19 16:15:16 +0000
@@ -29,16 +29,16 @@
 
 		public signal void animations_changed (bool running);
 
-		public Screen screen { get; construct; }
+		public unowned Gala.WindowManager wm { get; construct; }
 
-		public NotificationStack (Screen screen)
+		public NotificationStack (Gala.WindowManager wm)
 		{
-			Object (screen: screen);
+			Object (wm: wm);
 		}
 
 		construct
 		{
-			width = Notification.WIDTH + 2 * Notification.MARGIN + ADDITIONAL_MARGIN;
+			width = (Notification.WIDTH + 2 * Notification.MARGIN + ADDITIONAL_MARGIN) * wm.scale_factor;
 			clip_to_allocation = true;
 		}
 
@@ -67,16 +67,17 @@
 			});
 
 			float height;
-			notification.get_preferred_height (Notification.WIDTH, out height, null);
+			int scale_factor = wm.scale_factor;
+			notification.get_preferred_height (Notification.WIDTH * scale_factor, out height, null);
 			update_positions (height);
 
-			notification.y = TOP_OFFSET;
+			notification.y = TOP_OFFSET * scale_factor;
 			insert_child_at_index (notification, 0);
 		}
 
 		void update_positions (float add_y = 0.0f)
 		{
-			var y = add_y + TOP_OFFSET;
+			var y = add_y + TOP_OFFSET * wm.scale_factor;
 			var i = get_n_children ();
 			var delay_step = i > 0 ? 150 / i : 0;
 			foreach (var child in get_children ()) {

=== modified file 'plugins/notify/NotifyServer.vala'
--- plugins/notify/NotifyServer.vala	2016-12-31 08:08:58 +0000
+++ plugins/notify/NotifyServer.vala	2017-02-19 16:15:16 +0000
@@ -170,7 +170,8 @@
 				icon = app_info.get_icon ().to_string ();
 
 			var id = (replaces_id != 0 ? replaces_id : ++id_counter);
-			var pixbuf = get_pixbuf (app_name, icon, hints);
+			unowned Gala.WindowManager wm = stack.wm;
+			var pixbuf = get_pixbuf (app_name, icon, hints, wm.scale_factor);
 			var timeout = (expire_timeout == uint32.MAX ? DEFAULT_TMEOUT : expire_timeout);
 
 			var urgency = NotificationUrgency.NORMAL;
@@ -285,9 +286,10 @@
 						progress ? hints.@get ("value").get_int32 () : -1,
 						hints.@get (X_CANONICAL_PRIVATE_SYNCHRONOUS).get_string ());
 				else
-					notification = new NormalNotification (stack.screen, id, summary, body, pixbuf,
+					notification = new NormalNotification (wm, id, summary, body, pixbuf,
 						urgency, timeout, pid, actions);
 
+				notification.set_scale_factor (wm.scale_factor);
 				notification.action_invoked.connect (notification_action_invoked_callback);
 				notification.closed.connect (notification_closed_callback);
 				stack.show_notification (notification);
@@ -326,7 +328,7 @@
 			return icon_fg_color;
 		}
 
-		static Gdk.Pixbuf? get_pixbuf (string app_name, string app_icon, HashTable<string, Variant> hints)
+		static Gdk.Pixbuf? get_pixbuf (string app_name, string app_icon, HashTable<string, Variant> hints, int scale_factor)
 		{
 			// decide on the icon, order:
 			// - image-data
@@ -338,8 +340,8 @@
 
 			Gdk.Pixbuf? pixbuf = null;
 			Variant? variant = null;
-			var size = Notification.ICON_SIZE;
-			var mask_offset = 4;
+			var size = Notification.ICON_SIZE * scale_factor;
+			var mask_offset = 4 * scale_factor;
 			var mask_size_offset = mask_offset * 2;
 			var has_mask = false;
 
@@ -403,7 +405,7 @@
 					} catch (Error e) { warning (e.message); }
 				}
 			} else if (has_mask) {
-				var mask_size = Notification.ICON_SIZE;
+				var mask_size = Notification.ICON_SIZE * scale_factor;
 				var offset_x = mask_offset;
 				var offset_y = mask_offset + 1;
 

=== modified file 'src/WindowManager.vala'
--- src/WindowManager.vala	2016-11-18 16:57:03 +0000
+++ src/WindowManager.vala	2017-02-19 16:15:16 +0000
@@ -68,6 +68,11 @@
 		 */
 		public Meta.BackgroundGroup background_group { get; protected set; }
 
+		/**
+		 * {@inheritDoc}
+		 */
+		public int scale_factor { get; protected set; }
+
 		Meta.PluginInfo info;
 
 		WindowSwitcher? winswitcher = null;
@@ -144,6 +149,8 @@
 			WindowListener.init (screen);
 			KeyboardManager.init (display);
 
+			compute_scale_factor ();
+
 			// Due to a bug which enables access to the stage when using multiple monitors
 			// in the screensaver, we have to listen for changes and make sure the input area
 			// is set to NONE when we are in locked mode
@@ -314,6 +321,68 @@
 			return false;
 		}
 
+		/* DPI constants taken from gnome-settings-daemon/plugins/xsettings/gsd-xsettings-manager.c */
+		private const int DPI_FALLBACK = 96;
+		/* The minimum resolution at which we turn on a window-scale of 2 */
+		private const int HIDPI_LIMIT = (DPI_FALLBACK * 2);
+		/* The minimum screen height at which we turn on a window-scale of 2;
+		 * below this there just isn't enough vertical real estate for GNOME
+		 * apps to work, and it's better to just be tiny */
+		private const int HIDPI_MIN_HEIGHT = 1200;
+		private const int SMALLEST_4K_WIDTH = 3656;
+
+		void compute_scale_factor ()
+		{
+			var desktop_settings = new GLib.Settings ("org.gnome.desktop.interface");
+			var desktop_scale = desktop_settings.get_int ("scaling-factor");
+			if (desktop_scale > 0) {
+				scale_factor = desktop_scale;
+			} else {
+				weak Gdk.Display? display = Gdk.Display.get_default ();
+				weak Gdk.Screen screen = display.get_default_screen ();
+				var primary = screen.get_primary_monitor ();
+				var rect = Gdk.Rectangle ();
+				screen.get_monitor_geometry (primary, out rect);
+				var monitor_scale = screen.get_monitor_scale_factor (primary);
+
+				int width = rect.width * monitor_scale;
+				int height = rect.height * monitor_scale;
+				int width_mm = screen.get_monitor_width_mm (primary);
+				int height_mm = screen.get_monitor_height_mm (primary);
+
+				if (height < HIDPI_MIN_HEIGHT)
+				{
+					scale_factor = 1;
+					return;
+				}
+
+				/* Somebody encoded the aspect ratio (16/9 or 16/10)
+				 * instead of the physical size */
+				if ((width_mm == 160 && height_mm == 90) ||
+					(width_mm == 160 && height_mm == 100) ||
+					(width_mm == 16 && height_mm == 9) ||
+					(width_mm == 16 && height_mm == 10))
+				{
+					scale_factor = 1;
+					return;
+				}
+
+				if (width_mm > 0 && height_mm > 0) {
+					var dpi_x = (double)width / (width_mm / 25.4);
+					var dpi_y = (double)height / (height_mm / 25.4);
+					/* We don't completely trust these values so both
+					   must be high, and never pick higher ratio than
+					   2 automatically */
+					if (dpi_x > HIDPI_LIMIT && dpi_y > HIDPI_LIMIT) {
+						scale_factor = 2;
+						return;
+					}
+				}
+
+				scale_factor = 1;
+			}
+		}
+
 		void configure_hotcorners ()
 		{
 			var geometry = get_screen ().get_monitor_geometry (get_screen ().get_primary_monitor ());