[gnome-shell] workspace: Extend clip when animating from window picker to app grid

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

commit 4e83aaf850bd535ed2acb96888c4bd3e74d26057
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Wed Mar 10 13:24:07 2021 +0100

    workspace: Extend clip when animating from window picker to app grid
    
    We want to clip the Workspace actor in the appGrid state of the overview
    in order to make sure windows that overflow the monitor don't spill out.
    So far we had commit b1970b95b8813c00895f3da9f4fc88ca04627954 for that.
    
    Now since the last commit, window previews always slightly overflow the
    allocation with their icons. That means a part of the window icon gets
    clipped away as soon as the transition to the appGrid starts, which
    looks weird.
    
    Fix that bug in the transition by slightly extending the clip downwards
    when animating between the window picker and the app grid state. The
    extra height we extend the clip by is controlled by the overviewState,
    which means we extend the clip by the full icon overlap in the window
    picker state, but don't extend the clip at all when in the app grid
    state.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1813>

 js/ui/workspace.js | 42 +++++++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 19 deletions(-)
---
diff --git a/js/ui/workspace.js b/js/ui/workspace.js
index 368f2f31ab..f8b0d40ed2 100644
--- a/js/ui/workspace.js
+++ b/js/ui/workspace.js
@@ -592,6 +592,7 @@ var WorkspaceLayout = GObject.registerClass({
 
     vfunc_allocate(container, box) {
         const containerBox = container.allocation;
+        const [containerWidth, containerHeight] = containerBox.get_size();
         const containerAllocationChanged =
             this._lastBox === null || !this._lastBox.equal(containerBox);
         this._lastBox = containerBox.copy();
@@ -608,6 +609,27 @@ var WorkspaceLayout = GObject.registerClass({
             this.notify('layout-frozen');
         }
 
+        const { ControlsState } = OverviewControls;
+        const inSessionTransition =
+            this._overviewAdjustment.value <= ControlsState.WINDOW_PICKER;
+
+        const window = this._sortedWindows[0];
+
+        if (inSessionTransition || !window) {
+            container.remove_clip();
+        } else {
+            const [, bottomOversize] = window.chromeHeights();
+            const [containerX, containerY] = containerBox.get_origin();
+
+            const extraHeightProgress = this._overviewAdjustment.value -
+                OverviewControls.ControlsState.WINDOW_PICKER;
+
+            const extraClipHeight = bottomOversize * (1 - extraHeightProgress);
+
+            container.set_clip(containerX, containerY,
+                containerWidth, containerHeight + extraClipHeight);
+        }
+
         let layoutChanged = false;
         if (!this._layoutFrozen) {
             if (this._layout === null) {
@@ -624,14 +646,10 @@ var WorkspaceLayout = GObject.registerClass({
         const workareaWidth = this._workarea.width;
         const stateAdjustementValue = this._stateAdjustment.value;
 
-        const allocationScale = containerBox.get_width() / workareaWidth;
+        const allocationScale = containerWidth / workareaWidth;
 
         const childBox = new Clutter.ActorBox();
 
-        const { ControlsState } = OverviewControls;
-        const inSessionTransition =
-            this._overviewAdjustment.value <= ControlsState.WINDOW_PICKER;
-
         const nSlots = this._windowSlots.length;
         for (let i = 0; i < nSlots; i++) {
             let [x, y, width, height, child] = this._windowSlots[i];
@@ -1036,15 +1054,6 @@ class Workspace extends St.Widget {
             });
 
         this._overviewAdjustment = overviewAdjustment;
-        this._overviewStateId = overviewAdjustment.connect('notify::value', () => {
-            const overviewState = overviewAdjustment.value;
-
-            // We want windows not to spill out when the overview is in
-            // APP_GRID state, but HIDDEN and WINDOW_PICKER should allow
-            // them to eventually draw outside the workspace.
-            this._container.clip_to_allocation =
-                overviewState > OverviewControls.ControlsState.WINDOW_PICKER;
-        });
 
         this.monitorIndex = monitorIndex;
         this._monitor = Main.layoutManager.monitors[this.monitorIndex];
@@ -1296,11 +1305,6 @@ class Workspace extends St.Widget {
             this._layoutFrozenId = 0;
         }
 
-        if (this._overviewStateId > 0) {
-            this._overviewAdjustment.disconnect(this._overviewStateId);
-            delete this._overviewStateId;
-        }
-
         this._windows = [];
     }