[gnome-shell/wip/carlosg/magnifier-improvements: 5/6] magnifier: Implement pointer motion tracking differently

[Carlos Garnacho <carlosg src gnome org>]

commit aee83c546118964bbd40a03171c7c44c357bd0d4
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Feb 6 13:25:20 2020 +0100

    magnifier: Implement pointer motion tracking differently
    
    The use of the core idle monitor means that focus change events
    are also delayed by keyboard interaction. Since the magnifier is
    already in the business of pointer tracking, it's easy enough to
    fire the pointer rest timeout from here, so focus changes are
    accumulated and delayed.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/984

 js/ui/magnifier.js | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)
---
diff --git a/js/ui/magnifier.js b/js/ui/magnifier.js
index a2bdb7d94e..e5e588dbf1 100644
--- a/js/ui/magnifier.js
+++ b/js/ui/magnifier.js
@@ -1133,6 +1133,13 @@ var ZoomRegion = class ZoomRegion {
         return this._screenPosition;
     }
 
+    _clearScrollContentsTimer() {
+        if (this._scrollContentsTimerId !== 0) {
+            GLib.source_remove(this._scrollContentsTimerId);
+            this._scrollContentsTimerId = 0;
+        }
+    }
+
     /**
      * scrollToMousePos:
      * Set the region of interest based on the position of the system pointer.
@@ -1146,28 +1153,29 @@ var ZoomRegion = class ZoomRegion {
         else
             this._updateMousePosition();
 
+        this._clearScrollContentsTimer();
+        this._scrollContentsTimerId = GLib.timeout_add(GLib.PRIORITY_DEFAULT, POINTER_REST_TIME, () => {
+            this._followingCursor = false;
+            if (this._xDelayed !== null && this._yDelayed !== null) {
+                this._scrollContentsToDelayed(this._xDelayed, this._yDelayed);
+                this._xDelayed = null;
+                this._yDelayed = null;
+            }
+
+            return GLib.SOURCE_REMOVE;
+        });
+
         // Determine whether the system mouse pointer is over this zoom region.
         return this._isMouseOverRegion();
     }
 
-    _clearScrollContentsTimer() {
-        if (this._scrollContentsTimerId != 0) {
-            GLib.source_remove(this._scrollContentsTimerId);
-            this._scrollContentsTimerId = 0;
-        }
-    }
-
     _scrollContentsToDelayed(x, y) {
-        if (this._pointerIdleMonitor.get_idletime() >= POINTER_REST_TIME) {
+        if (this._followingCursor) {
+            this._xDelayed = x;
+            this._yDelayed = y;
+        } else {
             this.scrollContentsTo(x, y);
-            return;
         }
-
-        this._clearScrollContentsTimer();
-        this._scrollContentsTimerId = GLib.timeout_add(GLib.PRIORITY_DEFAULT, POINTER_REST_TIME, () => {
-            this._scrollContentsToDelayed(x, y);
-            return GLib.SOURCE_REMOVE;
-        });
     }
 
     /**