Pass a size for exact finger tracking

Author: leolost2605

lib/Utils.vala

@@ -17,6 +17,31 @@
 
 namespace Gala {
     public class Utils {
+        /**
+         * Represents a size as an object in order for it to be updatable.
+         * Additionally it has some utilities like {@link Gala.Utils.Size.actor_tracking}.
+         */
+        public class Size {
+            public float width;
+            public float height;
+
+            public Size (float width, float height) {
+                this.width = width;
+                this.height = height;
+            }
+
+            /**
+             * Constructs a new size that will keep in sync with the width and height of an actor.
+             */
+            public Size.actor_tracking (Clutter.Actor actor) {
+                actor.notify["width"].connect ((obj, pspec) => width = ((Clutter.Actor) obj).width);
+                actor.notify["height"].connect ((obj, pspec) => height = ((Clutter.Actor) obj).height);
+
+                width = actor.width;
+                height = actor.height;
+            }
+        }
+
         private struct CachedIcon {
             public Gdk.Pixbuf icon;
             public int icon_size;

src/Gestures/GestureTracker.vala

@@ -147,9 +147,15 @@ public class Gala.GestureTracker : Object {
     /**
      * Allow to receive pan gestures.
      * @param actor Clutter actor that will receive the events.
+     * @param travel_distances {@link Utils.Size} with width and height. The given size wil be
+     * used to calculate the percentage. It should be set to the amount something will travel (e.g.
+     * when moving an actor) based on the gesture to allow exact finger tracking. It can also be used
+     * to calculate the raw pixels the finger travelled at a given time with percentage * corresponding distance
+     * (height for {@link GestureDirection.UP} or DOWN, width for LEFT or RIGHT). If set to null the size of the
+     * actor will be used. If the values change those changes will apply.
      */
-    public void enable_pan (Clutter.Actor actor) {
-        pan_backend = new PanBackend (actor);
+    public void enable_pan (Clutter.Actor actor, Utils.Size? travel_distances) {
+        pan_backend = new PanBackend (actor, travel_distances);
         pan_backend.on_gesture_detected.connect (gesture_detected);
         pan_backend.on_begin.connect (gesture_begin);
         pan_backend.on_update.connect (gesture_update);

src/Gestures/PanBackend.vala

@@ -5,7 +5,7 @@ public class Gala.PanBackend : Object {
     public signal void on_end (double delta, uint64 time);
 
     public Clutter.Actor actor { get; construct; }
-    public GestureSettings settings { get; construct; }
+    public Utils.Size? travel_distances { get; construct; }
 
     private Clutter.PanAxis pan_axis;
     private Clutter.PanAction pan_action;
@@ -15,8 +15,8 @@ public class Gala.PanBackend : Object {
     private float origin_x;
     private float origin_y;
 
-    public PanBackend (Clutter.Actor actor) {
-        Object (actor: actor);
+    public PanBackend (Clutter.Actor actor, Utils.Size? travel_distances) {
+        Object (actor: actor, travel_distances: travel_distances);
     }
 
     construct {
@@ -69,16 +69,18 @@ public class Gala.PanBackend : Object {
     }
 
     private double calculate_percentage (float current_x, float current_y) {
-        float current, origin;
+        float current, origin, size;
         if (pan_axis == X_AXIS) {
             current = current_x;
             origin = origin_x;
+            size = travel_distances != null ? travel_distances.width : actor.width;
         } else {
             current = current_y;
             origin = origin_y;
+            size = travel_distances != null ? travel_distances.height : actor.height;
         }
 
-        return (current - origin).abs () / actor.get_width ();
+        return (current - origin).abs () / size;
     }
 
     private Gesture build_gesture () {