[gnome-shell/wip/exalm/dark-2: 35/35] shellDBus: Add ScreenTransition()

[Alexander Mikhaylenko <alexm src gnome org>]

commit e05ab76548bfbb2bc724bf685b04fec81b39b8a2
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Thu Sep 23 12:45:14 2021 +0500

    shellDBus: Add ScreenTransition()
    
    Settings will use this when switching between light and dark styles.

 data/dbus-interfaces/org.gnome.Shell.xml |  1 +
 js/ui/background.js                      |  5 +++
 js/ui/layout.js                          | 63 ++++++++++++++++++++++++++++++++
 js/ui/shellDBus.js                       | 14 +++++++
 4 files changed, 83 insertions(+)
---
diff --git a/data/dbus-interfaces/org.gnome.Shell.xml b/data/dbus-interfaces/org.gnome.Shell.xml
index 38154cbdb9..3ffb5c3742 100644
--- a/data/dbus-interfaces/org.gnome.Shell.xml
+++ b/data/dbus-interfaces/org.gnome.Shell.xml
@@ -35,6 +35,7 @@
       <arg type="au" direction="in" name="action"/>
       <arg type="b" direction="out" name="success"/>
     </method>
+    <method name="ScreenTransition"/>
     <signal name="AcceleratorActivated">
       <arg name="action" type="u"/>
       <arg name="parameters" type="a{sv}"/>
diff --git a/js/ui/background.js b/js/ui/background.js
index 264ac7d704..8db4813264 100644
--- a/js/ui/background.js
+++ b/js/ui/background.js
@@ -733,6 +733,11 @@ var BackgroundManager = class BackgroundManager {
         this._newBackgroundActor = null;
         this.emit('changed');
 
+        if (Main.layoutManager.screenTransition.visible) {
+            oldBackgroundActor.destroy();
+            return;
+        }
+
         oldBackgroundActor.ease({
             opacity: 0,
             duration: FADE_ANIMATION_TIME,
diff --git a/js/ui/layout.js b/js/ui/layout.js
index 102bed041e..7b5123dd7a 100644
--- a/js/ui/layout.js
+++ b/js/ui/layout.js
@@ -18,6 +18,9 @@ var BACKGROUND_FADE_ANIMATION_TIME = 1000;
 var HOT_CORNER_PRESSURE_THRESHOLD = 100; // pixels
 var HOT_CORNER_PRESSURE_TIMEOUT = 1000; // ms
 
+const SCREEN_TRANSITION_DELAY = 250; // ms
+const SCREEN_TRANSITION_DURATION = 500; // ms
+
 function isPopupMetaWindow(actor) {
     switch (actor.meta_window.get_window_type()) {
     case Meta.WindowType.DROPDOWN_MENU:
@@ -298,6 +301,16 @@ var LayoutManager = GObject.registerClass({
         monitorManager.connect('monitors-changed',
                                this._monitorsChanged.bind(this));
         this._monitorsChanged();
+
+        this.screenTransition = new ScreenTransition();
+
+        this.uiGroup.add_child(this.screenTransition);
+        this.uiGroup.set_child_above_sibling(this.screenTransition, null);
+
+        this.screenTransition.add_constraint(new Clutter.BindConstraint({
+            source: this.uiGroup,
+            coordinate: Clutter.BindCoordinate.ALL,
+        }));
     }
 
     // This is called by Main after everything else is constructed
@@ -1369,3 +1382,53 @@ var PressureBarrier = class PressureBarrier {
     }
 };
 Signals.addSignalMethods(PressureBarrier.prototype);
+
+var ScreenTransition = GObject.registerClass(
+class ScreenTransition extends Clutter.Actor {
+    _init() {
+        super._init();
+
+        this.hide();
+    }
+
+    run() {
+        if (this.visible)
+            return;
+
+        const rect = new imports.gi.cairo.RectangleInt({
+            x: 0,
+            y: 0,
+            width: global.screen_width,
+            height: global.screen_height,
+        });
+        const [, , , scale] = global.stage.get_capture_final_size(rect);
+        this.content = global.stage.paint_to_content(rect, scale, Clutter.PaintFlag.NO_CURSORS);
+
+        this.show();
+
+        const overviewShowingId = Main.overview.connect('showing', () => {
+            this.remove_transition('opacity');
+            complete();
+        });
+        const overviewHidingId = Main.overview.connect('hiding', () => {
+            this.remove_transition('opacity');
+            complete();
+        });
+
+        const complete = () => {
+            this.hide();
+            this.content = null;
+            this.opacity = 255;
+            Main.overview.disconnect(overviewShowingId);
+            Main.overview.disconnect(overviewHidingId);
+        };
+
+        this.ease({
+            opacity: 0,
+            duration: SCREEN_TRANSITION_DURATION,
+            delay: SCREEN_TRANSITION_DELAY,
+            mode: Clutter.AnimationMode.EASE_OUT_QUAD,
+            onComplete: () => complete(),
+        });
+    }
+});
diff --git a/js/ui/shellDBus.js b/js/ui/shellDBus.js
index 39bba7aa34..18df9b3126 100644
--- a/js/ui/shellDBus.js
+++ b/js/ui/shellDBus.js
@@ -251,6 +251,20 @@ var GnomeShell = class {
         invocation.return_value(GLib.Variant.new('(b)', [ungrabSucceeded]));
     }
 
+    ScreenTransitionAsync(params, invocation) {
+        try {
+            this._senderChecker.checkInvocation(invocation);
+        } catch (e) {
+            invocation.return_gerror(e);
+            return;
+        }
+
+        Main.layoutManager.screenTransition.run();
+
+        // We don't want to wait for transition to finish
+        invocation.return_value(null);
+    }
+
     _emitAcceleratorActivated(action, device, timestamp) {
         let destination = this._grabbedAccelerators.get(action);
         if (!destination)