[gnome-shell] overview: Get rid of panel ghost actor

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

commit d49606bbaab054d9fe303312622e118eecc58d68
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Tue Mar 9 17:31:30 2021 +0100

    overview: Get rid of panel ghost actor
    
    Right now we use a ClutterClone ghost of the panel simply to add some
    spacing to the top monitor edge.
    
    We can remove the panelGhost by adjusting the allocations of all the
    parts of the overview ourselves inside ControlsManagers vfunc_allocate,
    this should also work with extensions that move the panel somewhere
    else.
    
    This makes the initial relayout of the overview significantly faster,
    because we now no longer have to relayout the whole panel in the
    process.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1755>

 js/ui/overview.js         | 10 ----------
 js/ui/overviewControls.js | 29 +++++++++++++++++------------
 2 files changed, 17 insertions(+), 22 deletions(-)
---
diff --git a/js/ui/overview.js b/js/ui/overview.js
index 355ef1dddf..19f9d61780 100644
--- a/js/ui/overview.js
+++ b/js/ui/overview.js
@@ -85,16 +85,6 @@ class OverviewActor extends St.BoxLayout {
 
         this.add_constraint(new LayoutManager.MonitorConstraint({ primary: true }));
 
-        // Add a clone of the panel to the overview so spacing and such is
-        // automatic
-        let panelGhost = new St.Bin({
-            child: new Clutter.Clone({ source: Main.panel }),
-            reactive: false,
-            opacity: 0,
-        });
-        this.add_actor(panelGhost);
-
-
         this._controls = new OverviewControls.ControlsManager();
         this.add_child(this._controls);
     }
diff --git a/js/ui/overviewControls.js b/js/ui/overviewControls.js
index b848811370..a8974039d2 100644
--- a/js/ui/overviewControls.js
+++ b/js/ui/overviewControls.js
@@ -47,7 +47,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
         stateAdjustment.connect('notify::value', () => this.layout_changed());
     }
 
-    _computeWorkspacesBoxForState(state, box, searchHeight, dashHeight, thumbnailsHeight) {
+    _computeWorkspacesBoxForState(state, box, startY, searchHeight, dashHeight, thumbnailsHeight) {
         const workspaceBox = box.copy();
         const [width, height] = workspaceBox.get_size();
         const { spacing } = this;
@@ -58,7 +58,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
             break;
         case ControlsState.WINDOW_PICKER:
             workspaceBox.set_origin(0,
-                searchHeight + spacing +
+                startY + searchHeight + spacing +
                 thumbnailsHeight + spacing * expandFraction);
             workspaceBox.set_size(width,
                 height -
@@ -67,7 +67,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
                 thumbnailsHeight - spacing * expandFraction);
             break;
         case ControlsState.APP_GRID:
-            workspaceBox.set_origin(0, searchHeight + spacing);
+            workspaceBox.set_origin(0, startY + searchHeight + spacing);
             workspaceBox.set_size(
                 width,
                 Math.round(height * SMALL_WORKSPACE_RATIO));
@@ -77,7 +77,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
         return workspaceBox;
     }
 
-    _getAppDisplayBoxForState(state, box, searchHeight, dashHeight, appGridBox) {
+    _getAppDisplayBoxForState(state, box, startY, searchHeight, dashHeight, appGridBox) {
         const [width, height] = box.get_size();
         const appDisplayBox = new Clutter.ActorBox();
         const { spacing } = this;
@@ -89,7 +89,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
             break;
         case ControlsState.APP_GRID:
             appDisplayBox.set_origin(0,
-                searchHeight + spacing + appGridBox.get_height());
+                startY + searchHeight + spacing + appGridBox.get_height());
             break;
         }
 
@@ -130,12 +130,17 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
 
         const { spacing } = this;
 
+        let startY = 0;
+        if (Main.layoutManager.panelBox.y === Main.layoutManager.primaryMonitor.y) {
+            startY = Main.layoutManager.panelBox.height;
+            box.y1 += startY;
+        }
         const [width, height] = box.get_size();
         let availableHeight = height;
 
         // Search entry
-        const [searchHeight] = this._searchEntry.get_preferred_height(width);
-        childBox.set_origin(0, 0);
+        let [searchHeight] = this._searchEntry.get_preferred_height(width);
+        childBox.set_origin(0, startY);
         childBox.set_size(width, searchHeight);
         this._searchEntry.allocate(childBox);
 
@@ -147,7 +152,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
 
         let [, dashHeight] = this._dash.get_preferred_height(width);
         dashHeight = Math.min(dashHeight, maxDashHeight);
-        childBox.set_origin(0, height - dashHeight);
+        childBox.set_origin(0, startY + height - dashHeight);
         childBox.set_size(width, dashHeight);
         this._dash.allocate(childBox);
 
@@ -162,13 +167,13 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
             thumbnailsHeight = Math.min(
                 thumbnailsHeight * expandFraction,
                 height * WorkspaceThumbnail.MAX_THUMBNAIL_SCALE);
-            childBox.set_origin(0, searchHeight + spacing);
+            childBox.set_origin(0, startY + searchHeight + spacing);
             childBox.set_size(width, thumbnailsHeight);
             this._workspacesThumbnails.allocate(childBox);
         }
 
         // Workspaces
-        let params = [box, searchHeight, dashHeight, thumbnailsHeight];
+        let params = [box, startY, searchHeight, dashHeight, thumbnailsHeight];
         const transitionParams = this._stateAdjustment.getStateTransitionParams();
 
         // Update cached boxes
@@ -193,7 +198,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
             const workspaceAppGridBox =
                 this._cachedWorkspaceBoxes.get(ControlsState.APP_GRID);
 
-            params = [box, searchHeight, dashHeight, workspaceAppGridBox];
+            params = [box, startY, searchHeight, dashHeight, workspaceAppGridBox];
             let appDisplayBox;
             if (!transitionParams.transitioning) {
                 appDisplayBox =
@@ -211,7 +216,7 @@ class ControlsManagerLayout extends Clutter.BoxLayout {
         }
 
         // Search
-        childBox.set_origin(0, searchHeight + spacing);
+        childBox.set_origin(0, startY + searchHeight + spacing);
         childBox.set_size(width, availableHeight);
 
         this._searchController.allocate(childBox);