[gnome-shell/wip/jimmac/dash-icon-spacing: 23/72] workspace: Add cover panel to handle click events

[Jakub Steiner <jimmac src gnome org>]

commit 1f717471160650e32553bceb4d548000f822cda3
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Tue Jan 5 15:50:56 2021 -0300

    workspace: Add cover panel to handle click events
    
    When the workspace is not the active one, we want to switch
    to it on click. For that to happen, it needs to cover the
    workspace with an actor, to prevent the window preview from
    handling the click event itself.
    
    Add a cover actor to Workspace, and a click action that simply
    moves to that particular workspace when it's not the active one,
    or hide the overview if it's the active one.
    
    Restack the cover actor to be above the wallpaper for the active
    workspace, and above all window previews if not the active one.
    
    At last, make sure the click action is released when any the
    workspace is allocated. That avoids activating the workspace when
    dragging.

 js/ui/workspace.js | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 80 insertions(+), 1 deletion(-)
---
diff --git a/js/ui/workspace.js b/js/ui/workspace.js
index 018305f642..21b45865bb 100644
--- a/js/ui/workspace.js
+++ b/js/ui/workspace.js
@@ -398,6 +398,7 @@ var WorkspaceLayout = GObject.registerClass({
         this._layoutFrozen = false;
 
         this._monitorIndex = monitorIndex;
+        this._metaWorkspace = metaWorkspace;
         this._workarea = metaWorkspace
             ? metaWorkspace.get_work_area_for_monitor(this._monitorIndex)
             : Main.layoutManager.getWorkAreaForMonitor(this._monitorIndex);
@@ -591,6 +592,9 @@ var WorkspaceLayout = GObject.registerClass({
         if (this._background)
             this._background.allocate(box);
 
+        if (this._cover)
+            this._cover.allocate(box);
+
         const allocationScale = containerBox.get_width() / this._workarea.width;
 
         const workspaceBox = new Clutter.ActorBox();
@@ -598,7 +602,9 @@ var WorkspaceLayout = GObject.registerClass({
         let childBox = new Clutter.ActorBox();
 
         for (const child of container) {
-            if (!child.visible || child === this._background)
+            if (!child.visible ||
+                child === this._background ||
+                child === this._cover)
                 continue;
 
             // The fifth element in the slot array is the WindowPreview
@@ -760,6 +766,16 @@ var WorkspaceLayout = GObject.registerClass({
             this._container.add_child(this._background);
     }
 
+    setCover(cover) {
+        if (this._cover)
+            this._container.remove_child(this._cover);
+
+        this._cover = cover;
+
+        if (this._cover)
+            this._container.add_child(this._cover);
+    }
+
     syncStacking(stackIndices) {
         const windows = [...this._windows.keys()];
         windows.sort((a, b) => {
@@ -775,10 +791,23 @@ var WorkspaceLayout = GObject.registerClass({
             lastWindow = window;
         }
 
+        this.restackCover();
+
         this._layout = null;
         this.layout_changed();
     }
 
+    restackCover() {
+        const workspaceManager = global.workspace_manager;
+        const isActiveWorkspace = this._metaWorkspace
+            ? this._metaWorkspace === workspaceManager.get_active_workspace()
+            : true;
+
+        this._container.set_child_above_sibling(
+            this._cover,
+            isActiveWorkspace ? this._background : null);
+    }
+
     /**
      * getFocusChain:
      *
@@ -969,6 +998,38 @@ class Workspace extends St.Widget {
         this._background = new WorkspaceBackground(monitorIndex);
         this.layout_manager.setBackground(this._background);
 
+        // Cover
+        this._cover = new Clutter.Actor({ reactive: true });
+        this.layout_manager.setCover(this._cover);
+
+        // Click action
+        const workspaceManager = global.workspace_manager;
+
+        const clickAction = new Clutter.ClickAction({ name: 'click' });
+        clickAction.connect('clicked', () => {
+            if (!this.metaWorkspace)
+                return;
+
+            if (clickAction.get_button() !== 1 && clickAction.get_button() !== 0)
+                return;
+
+            const workspaceIndex = this.metaWorkspace.index();
+
+            if (workspaceIndex !== workspaceManager.get_active_workspace_index())
+                Main.wm.actionMoveWorkspace(this.metaWorkspace);
+            else
+                Main.overview.hide();
+        });
+        this._cover.add_action(clickAction);
+
+        this._switchWorkspaceId =
+            global.window_manager.connect('switch-workspace',
+                this._updateCover.bind(this));
+
+        this._reorderWorkspacesdId =
+            workspaceManager.connect('workspaces-reordered',
+                this._updateCover.bind(this));
+
         this.connect('style-changed', this._onStyleChanged.bind(this));
         this.connect('destroy', this._onDestroy.bind(this));
 
@@ -996,10 +1057,16 @@ class Workspace extends St.Widget {
                                                            this._windowLeftMonitor.bind(this));
         this._layoutFrozenId = 0;
 
+        this._updateCover();
+
         // DND requires this to be set
         this._delegate = this;
     }
 
+    _updateCover() {
+        this.layout_manager.restackCover();
+    }
+
     vfunc_get_focus_chain() {
         return this.layout_manager.getFocusChain();
     }
@@ -1196,6 +1263,16 @@ class Workspace extends St.Widget {
             this._overviewHiddenId = 0;
         }
 
+        if (this._switchWorkspaceId) {
+            global.window_manager.disconnect(this._switchWorkspaceId);
+            delete this._switchWorkspaceId;
+        }
+
+        if (this._reorderWorkspacesdId) {
+            global.workspace_manager.disconnect(this._reorderWorkspacesdId);
+            delete this._reorderWorkspacesdId;
+        }
+
         if (this.metaWorkspace) {
             this.metaWorkspace.disconnect(this._windowAddedId);
             this.metaWorkspace.disconnect(this._windowRemovedId);
@@ -1242,9 +1319,11 @@ class Workspace extends St.Widget {
         });
         clone.connect('drag-cancelled', () => {
             Main.overview.cancelledWindowDrag(metaWindow);
+            this._updateCover();
         });
         clone.connect('drag-end', () => {
             Main.overview.endWindowDrag(metaWindow);
+            this._updateCover();
         });
         clone.connect('show-chrome', () => {
             let focus = global.stage.key_focus;