[gnome-shell] workspace: Add some padding around window previews

[Marge Bot <marge-bot src gnome org>]

commit 27a427421e48ae579c687eff0e851df04ee007e0
Author: Florian Müllner <fmuellner gnome org>
Date:   Sat Jan 30 05:42:47 2021 +0100

    workspace: Add some padding around window previews
    
    Commit 059ea64 removed the workspace padding after moving the
    background into the workspace. However some whitespace around
    window previews is still a good idea, and will be necessary
    soon as we are about to indicate focus by slightly scaling up
    the active preview, and don't want previews to be clipped by
    the workspace in that case.
    
    https://gitlab.gnome.org/Teams/Design/os-mockups/-/issues/81
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1605>

 js/ui/workspace.js | 9 +++++++++
 1 file changed, 9 insertions(+)
---
diff --git a/js/ui/workspace.js b/js/ui/workspace.js
index cb3c212eea..ff4d4c70bf 100644
--- a/js/ui/workspace.js
+++ b/js/ui/workspace.js
@@ -12,6 +12,7 @@ const Util = imports.misc.util;
 const { WindowPreview } = imports.ui.windowPreview;
 
 var WINDOW_PREVIEW_MAXIMUM_SCALE = 0.95;
+var MAXIMUM_PREVIEW_AREA = 0.98;
 
 var WINDOW_REPOSITIONING_DELAY = 750;
 
@@ -469,6 +470,14 @@ var WorkspaceLayout = GObject.registerClass({
             colSpacing += Math.max(leftOversize, rightOversize);
 
         if (containerBox) {
+            // add some padding around preview area
+            const [width, height] = containerBox.get_size();
+            containerBox.set_size(
+                width * MAXIMUM_PREVIEW_AREA,
+                height * MAXIMUM_PREVIEW_AREA);
+            containerBox.x1 += width * (1 - MAXIMUM_PREVIEW_AREA) / 2;
+            containerBox.y1 += height * (1 - MAXIMUM_PREVIEW_AREA) / 2;
+
             const [topOverlap, bottomOverlap] = window.overlapHeights();
             containerBox.x1 += leftOversize + topOverlap;
             containerBox.x2 -= rightOversize;