[gnome-shell/wip/exalm/gestures-part-1: 4/6] workspacesView: Use shared adjustment

[Florian Müllner <fmuellner src gnome org>]

commit 8f4414de972de76295cba6a7f64db1c0a305a931
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Sun Jul 7 22:51:55 2019 +0500

    workspacesView: Use shared adjustment
    
    Instead of having a scroll adjustment in each WorkspacesView, and using the
    one from primary screen in WorkspacesDisplay, have just one adjustment in
    WorkspacesDisplay, and sync the changes between WorkspacesView.
    
    This will allow to share the adjustment between WorkspacesDisplay and
    ThumbnailsBox in the next commits.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/821

 js/ui/workspacesView.js | 136 +++++++++++++++++++++++++++---------------------
 1 file changed, 76 insertions(+), 60 deletions(-)
---
diff --git a/js/ui/workspacesView.js b/js/ui/workspacesView.js
index eb87e37ede..8c06e54410 100644
--- a/js/ui/workspacesView.js
+++ b/js/ui/workspacesView.js
@@ -73,7 +73,7 @@ var WorkspacesViewBase = GObject.registerClass({
 
 var WorkspacesView = GObject.registerClass(
 class WorkspacesView extends WorkspacesViewBase {
-    _init(monitorIndex) {
+    _init(monitorIndex, scrollAdjustment) {
         let workspaceManager = global.workspace_manager;
 
         super._init(monitorIndex);
@@ -81,17 +81,11 @@ class WorkspacesView extends WorkspacesViewBase {
         this._animating = false; // tweening
         this._scrolling = false; // swipe-scrolling
         this._gestureActive = false; // touch(pad) gestures
-        this._animatingScroll = false; // programmatically updating the adjustment
 
-        let activeWorkspaceIndex = workspaceManager.get_active_workspace_index();
-        this.scrollAdjustment = new St.Adjustment({ value: activeWorkspaceIndex,
-                                                    lower: 0,
-                                                    page_increment: 1,
-                                                    page_size: 1,
-                                                    step_increment: 0,
-                                                    upper: workspaceManager.n_workspaces });
-        this.scrollAdjustment.connect('notify::value',
-                                      this._onScroll.bind(this));
+        this._scrollAdjustment = scrollAdjustment;
+        this._onScrollId =
+            this._scrollAdjustment.connect('notify::value',
+                this._onScroll.bind(this));
 
         this._workspaces = [];
         this._updateWorkspaces();
@@ -165,14 +159,6 @@ class WorkspacesView extends WorkspacesViewBase {
             this._workspaces[i].syncStacking(stackIndices);
     }
 
-    _scrollToActive() {
-        let workspaceManager = global.workspace_manager;
-        let active = workspaceManager.get_active_workspace_index();
-
-        this._updateWorkspaceActors(true);
-        this._updateScrollAdjustment(active);
-    }
-
     // Update workspace actors parameters
     // @showAnimation: iff %true, transition between states
     _updateWorkspaceActors(showAnimation) {
@@ -234,25 +220,10 @@ class WorkspacesView extends WorkspacesViewBase {
         }
     }
 
-    _updateScrollAdjustment(index) {
-        if (this._scrolling || this._gestureActive)
-            return;
-
-        this._animatingScroll = true;
-
-        this.scrollAdjustment.ease(index, {
-            mode: Clutter.AnimationMode.EASE_OUT_QUAD,
-            duration: WORKSPACE_SWITCH_TIME,
-            onComplete: () => (this._animatingScroll = false),
-        });
-    }
-
     _updateWorkspaces() {
         let workspaceManager = global.workspace_manager;
         let newNumWorkspaces = workspaceManager.n_workspaces;
 
-        this.scrollAdjustment.upper = newNumWorkspaces;
-
         for (let j = 0; j < newNumWorkspaces; j++) {
             let metaWorkspace = workspaceManager.get_workspace_by_index(j);
             let workspace;
@@ -283,13 +254,13 @@ class WorkspacesView extends WorkspacesViewBase {
         if (this._scrolling)
             return;
 
-        this._scrollToActive();
+        this._updateWorkspaceActors(true);
     }
 
     _onDestroy() {
         super._onDestroy();
 
-        this.scrollAdjustment.run_dispose();
+        this._scrollAdjustment.disconnect(this._onScrollId);
         Main.overview.disconnect(this._overviewShownId);
         global.window_manager.disconnect(this._switchWorkspaceNotifyId);
         let workspaceManager = global.workspace_manager;
@@ -305,7 +276,7 @@ class WorkspacesView extends WorkspacesViewBase {
         this._scrolling = false;
 
         // Make sure title captions etc are shown as necessary
-        this._scrollToActive();
+        this._updateWorkspaceActors(true);
         this._updateVisibility();
     }
 
@@ -317,14 +288,14 @@ class WorkspacesView extends WorkspacesViewBase {
         this._gestureActive = false;
 
         // Make sure title captions etc are shown as necessary
-        this._scrollToActive();
+        this._updateWorkspaceActors(true);
         this._updateVisibility();
     }
 
     // sync the workspaces' positions to the value of the scroll adjustment
     // and change the active workspace if appropriate
     _onScroll(adj) {
-        if (this._animatingScroll)
+        if (adj.get_transition('value') !== null && !this._gestureActive)
             return;
 
         let workspaceManager = global.workspace_manager;
@@ -443,6 +414,28 @@ class WorkspacesDisplay extends St.Widget {
         super._init({ clip_to_allocation: true });
         this.connect('notify::allocation', this._updateWorkspacesActualGeometry.bind(this));
 
+        let workspaceManager = global.workspace_manager;
+        let activeWorkspaceIndex = workspaceManager.get_active_workspace_index();
+        this._scrollAdjustment = new St.Adjustment({
+            value: activeWorkspaceIndex,
+            lower: 0,
+            page_increment: 1,
+            page_size: 1,
+            step_increment: 0,
+            upper: workspaceManager.n_workspaces,
+        });
+
+        workspaceManager.bind_property('n-workspaces',
+            this._scrollAdjustment, 'upper', GObject.BindingFlags.SYNC_CREATE);
+
+        this._switchWorkspaceId =
+            global.window_manager.connect('switch-workspace',
+                this._activeWorkspaceChanged.bind(this));
+
+        this._reorderWorkspacesdId =
+            workspaceManager.connect('workspaces-reordered',
+                this._workspacesReordered.bind(this));
+
         let clickAction = new Clutter.ClickAction();
         clickAction.connect('clicked', action => {
             // Only switch to the workspace when there's no application
@@ -508,6 +501,9 @@ class WorkspacesDisplay extends St.Widget {
 
         this._fullGeometry = null;
 
+        this._scrolling = false; // swipe-scrolling
+        this._gestureActive = false; // touch(pad) gestures
+
         this.connect('destroy', this._onDestroy.bind(this));
     }
 
@@ -523,6 +519,40 @@ class WorkspacesDisplay extends St.Widget {
             Meta.later_remove(this._parentSetLater);
             this._parentSetLater = 0;
         }
+
+        global.window_manager.disconnect(this._switchWorkspaceId);
+        global.workspace_manager.disconnect(this._reorderWorkspacesdId);
+    }
+
+    _workspacesReordered() {
+        let workspaceManager = global.workspace_manager;
+
+        this._scrollAdjustment.value =
+            workspaceManager.get_active_workspace_index();
+    }
+
+    _activeWorkspaceChanged(_wm, _from, _to, _direction) {
+        if (this._scrolling)
+            return;
+
+        this._scrollToActive();
+    }
+
+    _scrollToActive() {
+        let workspaceManager = global.workspace_manager;
+        let active = workspaceManager.get_active_workspace_index();
+
+        this._updateScrollAdjustment(active);
+    }
+
+    _updateScrollAdjustment(index) {
+        if (this._scrolling || this._gestureActive)
+            return;
+
+        this._scrollAdjustment.ease(index, {
+            mode: Clutter.AnimationMode.EASE_OUT_QUAD,
+            duration: WORKSPACE_SWITCH_TIME,
+        });
     }
 
     _onPan(action) {
@@ -540,21 +570,27 @@ class WorkspacesDisplay extends St.Widget {
     _startSwipeScroll() {
         for (let i = 0; i < this._workspacesViews.length; i++)
             this._workspacesViews[i].startSwipeScroll();
+        this._scrolling = true;
     }
 
     _endSwipeScroll() {
         for (let i = 0; i < this._workspacesViews.length; i++)
             this._workspacesViews[i].endSwipeScroll();
+        this._scrolling = false;
+        this._scrollToActive();
     }
 
     _startTouchGesture() {
         for (let i = 0; i < this._workspacesViews.length; i++)
             this._workspacesViews[i].startTouchGesture();
+        this._gestureActive = true;
     }
 
     _endTouchGesture() {
         for (let i = 0; i < this._workspacesViews.length; i++)
             this._workspacesViews[i].endTouchGesture();
+        this._gestureActive = false;
+        this._scrollToActive();
     }
 
     _onSwitchWorkspaceMotion(action, xRel, yRel) {
@@ -658,14 +694,9 @@ class WorkspacesDisplay extends St.Widget {
             if (this._workspacesOnlyOnPrimary && i != this._primaryIndex)
                 view = new ExtraWorkspaceView(i);
             else
-                view = new WorkspacesView(i);
+                view = new WorkspacesView(i, this._scrollAdjustment);
 
             view.connect('scroll-event', this._onScrollEvent.bind(this));
-            if (i == this._primaryIndex) {
-                this._scrollAdjustment = view.scrollAdjustment;
-                this._scrollAdjustment.connect('notify::value',
-                                               this._scrollValueChanged.bind(this));
-            }
 
             // HACK: Avoid spurious allocation changes while updating views
             view.hide();
@@ -680,21 +711,6 @@ class WorkspacesDisplay extends St.Widget {
         this._updateWorkspacesActualGeometry();
     }
 
-    _scrollValueChanged() {
-        for (let i = 0; i < this._workspacesViews.length; i++) {
-            if (i == this._primaryIndex)
-                continue;
-
-            let adjustment = this._workspacesViews[i].scrollAdjustment;
-            if (!adjustment)
-                continue;
-
-            // the adjustments work in terms of workspaces, so the
-            // values map directly
-            adjustment.value = this._scrollAdjustment.value;
-        }
-    }
-
     _getMonitorIndexForEvent(event) {
         let [x, y] = event.get_coords();
         let rect = new Meta.Rectangle({ x, y, width: 1, height: 1 });