[gnome-shell] workspace: Allow allocating smaller sizes for window clones

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 85d2837466f549a772fdbebe28a6cdc789b88b8b
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Mon Jun 1 14:36:08 2020 +0200

    workspace: Allow allocating smaller sizes for window clones
    
    Change the preferred size functions of the layout manager of window
    clones to allow allocating smaller sizes, too. Also scale down the
    allocation sizes of the ClutterClones our allocate implementation so
    the ClutterClones will scale their texture accordingly.
    
    This will enable us to position the window clones using their allocation
    size instead of their scale, which is necessary when introducing a new
    ClutterLayoutManager that positions the window clones.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1294

 js/ui/workspace.js | 48 ++++++++++++++++++++++++------------------------
 1 file changed, 24 insertions(+), 24 deletions(-)
---
diff --git a/js/ui/workspace.js b/js/ui/workspace.js
index 0830e29fb9..9605149115 100644
--- a/js/ui/workspace.js
+++ b/js/ui/workspace.js
@@ -51,35 +51,22 @@ class WindowCloneLayout extends Clutter.LayoutManager {
         this.layout_changed();
     }
 
-    _makeBoxForWindow(window) {
-        // We need to adjust the position of the actor because of the
-        // consequences of invisible borders -- in reality, the texture
-        // has an extra set of "padding" around it that we need to trim
-        // down.
-
-        // The bounding box is based on the (visible) frame rect, while
-        // the buffer rect contains everything, including the invisible
-        // border padding.
-        let bufferRect = window.get_buffer_rect();
-
-        let box = new Clutter.ActorBox();
-
-        box.set_origin(bufferRect.x - this._boundingBox.x,
-                       bufferRect.y - this._boundingBox.y);
-        box.set_size(bufferRect.width, bufferRect.height);
-
-        return box;
-    }
-
     vfunc_get_preferred_height(_container, _forWidth) {
-        return [this._boundingBox.height, this._boundingBox.height];
+        return [0, this._boundingBox.height];
     }
 
     vfunc_get_preferred_width(_container, _forHeight) {
-        return [this._boundingBox.width, this._boundingBox.width];
+        return [0, this._boundingBox.width];
     }
 
-    vfunc_allocate(container, _box) {
+    vfunc_allocate(container, box) {
+        // If the scale isn't 1, we weren't allocated our preferred size
+        // and have to scale the children allocations accordingly.
+        const scaleX = box.get_width() / this._boundingBox.width;
+        const scaleY = box.get_height() / this._boundingBox.height;
+
+        const childBox = new Clutter.ActorBox();
+
         container.get_children().forEach(child => {
             let realWindow;
             if (child == container._windowClone)
@@ -87,7 +74,20 @@ class WindowCloneLayout extends Clutter.LayoutManager {
             else
                 realWindow = child.source;
 
-            child.allocate(this._makeBoxForWindow(realWindow.meta_window));
+            const bufferRect = realWindow.meta_window.get_buffer_rect();
+            childBox.set_origin(
+                bufferRect.x - this._boundingBox.x,
+                bufferRect.y - this._boundingBox.y);
+
+            const [, , natWidth, natHeight] = child.get_preferred_size();
+            childBox.set_size(natWidth, natHeight);
+
+            childBox.x1 *= scaleX;
+            childBox.x2 *= scaleX;
+            childBox.y1 *= scaleY;
+            childBox.y2 *= scaleY;
+
+            child.allocate(childBox);
         });
     }
 });