screenshot: Move close button to the panel

CSS and JS adapted from the Overview window close buttons, but with some
style tweaks requested by the designers.

Since the screenshot UI is long-lived (it's created once at startup,
rather than every time it's opened), we need to refresh the close button
position, as it can change at runtime. Subscribing to preference changes
seems to be skipped for bindings generation in Mutter, but simply
refreshing upon opening the UI should do the job.

Closes https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4997

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2147>

data/theme/gnome-shell-sass/widgets/_screenshot.scss

@@ -28,17 +28,26 @@ $screenshot_ui_button_red: #e01b24;
 
 .screenshot-ui-close-button {
   background-color: $osd_bg_color;
+  color: $osd_fg_color;
   border-radius: 99px;
-  width: 64px;
+  padding: 6px;
-  height: 64px;
+  height: 30px;
-  margin: 64px;
+  width: 30px;
+  box-shadow: -1px 1px 5px 0px rgba(0,0,0,0.5);
+  margin-top: 8px;
 
-  &:hover, &:focus { background-color: $hover_bg_color; }
+  &.left { margin-left: 8px; }
-  &:active { background-color: $active_bg_color; }
+  &.right { margin-right: 8px; }
-  &:checked { background-color: darken($osd_bg_color, 5%); }
 
-  StIcon {
+  & StIcon { icon-size: 24px; }
-    icon-size: $base_icon_size * 2;
+
+  &:hover {
+    background-color: lighten($osd_bg_color, 15%);
+  }
+
+  &:active {
+    color: transparentize($osd_fg_color, 0.2);
+    background-color: darken($osd_bg_color, 5%);
   }
 }
 

js/ui/screenshot.js

@@ -1,7 +1,7 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
 /* exported ScreenshotService, ScreenshotUI, showScreenshotUI */
 
-const { Clutter, Cogl, Gio, GObject, GLib, Gtk, Meta, Shell, St } = imports.gi;
+const { Clutter, Cogl, Gio, GObject, GLib, Graphene, Gtk, Meta, Shell, St } = imports.gi;
 
 const GrabHelper = imports.ui.grabHelper;
 const Layout = imports.ui.layout;
@@ -1089,12 +1089,24 @@ var ScreenshotUI = GObject.registerClass({
 
         this._closeButton = new St.Button({
             style_class: 'screenshot-ui-close-button',
-            x_align: Clutter.ActorAlign.END,
+            child: new St.Icon({ icon_name: 'preview-close-symbolic' }),
-            y_align: Clutter.ActorAlign.START,
-            x_expand: true,
-            y_expand: true,
         });
-        this._closeButton.set_child(new St.Icon({ icon_name: 'window-close-symbolic' }));
+        this._closeButton.add_constraint(new Clutter.BindConstraint({
+            source: this._panel,
+            coordinate: Clutter.BindCoordinate.POSITION,
+        }));
+        this._closeButton.add_constraint(new Clutter.AlignConstraint({
+            source: this._panel,
+            align_axis: Clutter.AlignAxis.Y_AXIS,
+            pivot_point: new Graphene.Point({ x: -1, y: 0.5 }),
+            factor: 0,
+        }));
+        this._closeButtonXAlignConstraint = new Clutter.AlignConstraint({
+            source: this._panel,
+            align_axis: Clutter.AlignAxis.X_AXIS,
+            pivot_point: new Graphene.Point({ x: 0.5, y: -1 }),
+        });
+        this._closeButton.add_constraint(this._closeButtonXAlignConstraint);
         this._closeButton.connect('clicked', () => this.close());
         this._primaryMonitorBin.add_child(this._closeButton);
 
@@ -1281,6 +1293,21 @@ var ScreenshotUI = GObject.registerClass({
         );
     }
 
+    _refreshButtonLayout() {
+        const buttonLayout = Meta.prefs_get_button_layout();
+
+        this._closeButton.remove_style_class_name('left');
+        this._closeButton.remove_style_class_name('right');
+
+        if (buttonLayout.left_buttons.includes(Meta.ButtonFunction.CLOSE)) {
+            this._closeButton.add_style_class_name('left');
+            this._closeButtonXAlignConstraint.factor = 0;
+        } else {
+            this._closeButton.add_style_class_name('right');
+            this._closeButtonXAlignConstraint.factor = 1;
+        }
+    }
+
     _rebuildMonitorBins() {
         for (const bin of this._monitorBins)
             bin.destroy();
@@ -1429,6 +1456,8 @@ var ScreenshotUI = GObject.registerClass({
         if (!grabResult)
             return;
 
+        this._refreshButtonLayout();
+
         this.remove_all_transitions();
         this.visible = true;
         this.ease({