appDisplay: Separate PageIndicators to a separate file

In order to cater for emoji panel usage, we want something like PageIndicators
except:
- It should have horizontal disposition
- It should not be animatable (?)
- It should not be reactive

Separated PageIndicators into a base, non-animated widget, and an
AnimatedPageIndicators that can be used on appDisplay.js. Reactiveness is
set through an extra method, and layout is set as a construct argument.

js/ui/pageIndicators.js

@@ -0,0 +1,142 @@
+// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+
+const Clutter = imports.gi.Clutter;
+const GObject = imports.gi.GObject;
+const St = imports.gi.St;
+
+const Tweener = imports.ui.tweener;
+const { ANIMATION_TIME_OUT, ANIMATION_MAX_DELAY_OUT_FOR_ITEM, AnimationDirection } = imports.ui.iconGrid;
+
+var INDICATORS_BASE_TIME = 0.25;
+var INDICATORS_BASE_TIME_OUT = 0.125;
+var INDICATORS_ANIMATION_DELAY = 0.125;
+var INDICATORS_ANIMATION_DELAY_OUT = 0.0625;
+var INDICATORS_ANIMATION_MAX_TIME = 0.75;
+var SWITCH_TIME = 0.4;
+var INDICATORS_ANIMATION_MAX_TIME_OUT =
+    Math.min (SWITCH_TIME,
+              ANIMATION_TIME_OUT + ANIMATION_MAX_DELAY_OUT_FOR_ITEM);
+
+var ANIMATION_DELAY = 0.1;
+
+var PageIndicators = GObject.registerClass({
+    Signals: { 'page-activated': { param_types: [GObject.TYPE_INT] } }
+}, class PageIndicators extends St.BoxLayout {
+    _init(vertical = true) {
+        super._init({ style_class: 'page-indicators',
+                      vertical,
+                      x_expand: true, y_expand: true,
+                      x_align: vertical ? Clutter.ActorAlign.END : Clutter.ActorAlign.CENTER,
+                      y_align: vertical ? Clutter.ActorAlign.CENTER : Clutter.ActorAlign.END,
+                      reactive: true,
+                      clip_to_allocation: true });
+        this._nPages = 0;
+        this._currentPage = undefined;
+        this._reactive = true;
+        this._reactive = true;
+    }
+
+    vfunc_get_preferred_height(forWidth) {
+        // We want to request the natural height of all our children as our
+        // natural height, so we chain up to St.BoxLayout, but we only request 0
+        // as minimum height, since it's not that important if some indicators
+        // are not shown
+        let [, natHeight] = super.vfunc_get_preferred_height(forWidth);
+        return [0, natHeight];
+    }
+
+    setReactive(reactive) {
+        let children = this.get_children();
+        for (let i = 0; i < children.length; i++)
+            children[i].reactive = reactive;
+
+        this._reactive = reactive;
+    }
+
+    setNPages(nPages) {
+        if (this._nPages == nPages)
+            return;
+
+        let diff = nPages - this._nPages;
+        if (diff > 0) {
+            for (let i = 0; i < diff; i++) {
+                let pageIndex = this._nPages + i;
+                let indicator = new St.Button({ style_class: 'page-indicator',
+                                                button_mask: St.ButtonMask.ONE |
+                                                             St.ButtonMask.TWO |
+                                                             St.ButtonMask.THREE,
+                                                toggle_mode: true,
+                                                reactive: this._reactive,
+                                                checked: pageIndex == this._currentPage });
+                indicator.child = new St.Widget({ style_class: 'page-indicator-icon' });
+                indicator.connect('clicked', () => {
+                    this.emit('page-activated', pageIndex);
+                });
+                this.add_actor(indicator);
+            }
+        } else {
+            let children = this.get_children().splice(diff);
+            for (let i = 0; i < children.length; i++)
+                children[i].destroy();
+        }
+        this._nPages = nPages;
+        this.visible = (this._nPages > 1);
+    }
+
+    setCurrentPage(currentPage) {
+        this._currentPage = currentPage;
+
+        let children = this.get_children();
+        for (let i = 0; i < children.length; i++)
+            children[i].set_checked(i == this._currentPage);
+    }
+});
+
+var AnimatedPageIndicators = GObject.registerClass(
+class AnimatedPageIndicators extends PageIndicators {
+    _init() {
+        super._init(true);
+
+        this.connect('notify::mapped', () => {
+            this.animateIndicators(AnimationDirection.IN);
+        });
+    }
+
+    animateIndicators(animationDirection) {
+        if (!this.mapped)
+            return;
+
+        let children = this.get_children();
+        if (children.length == 0)
+            return;
+
+        for (let i = 0; i < this._nPages; i++)
+            Tweener.removeTweens(children[i]);
+
+        let offset;
+        if (this.get_text_direction() == Clutter.TextDirection.RTL)
+            offset = -children[0].width;
+        else
+            offset = children[0].width;
+
+        let isAnimationIn = animationDirection == AnimationDirection.IN;
+        let delay = isAnimationIn ? INDICATORS_ANIMATION_DELAY :
+                                    INDICATORS_ANIMATION_DELAY_OUT;
+        let baseTime = isAnimationIn ? INDICATORS_BASE_TIME : INDICATORS_BASE_TIME_OUT;
+        let totalAnimationTime = baseTime + delay * this._nPages;
+        let maxTime = isAnimationIn ? INDICATORS_ANIMATION_MAX_TIME :
+                                      INDICATORS_ANIMATION_MAX_TIME_OUT;
+        if (totalAnimationTime > maxTime)
+            delay -= (totalAnimationTime - maxTime) / this._nPages;
+
+        for (let i = 0; i < this._nPages; i++) {
+            children[i].translation_x = isAnimationIn ? offset : 0;
+            Tweener.addTween(children[i], {
+                translation_x: isAnimationIn ? 0 : offset,
+                time: baseTime + delay * i,
+                transition: 'easeInOutQuad',
+                delay: isAnimationIn ? ANIMATION_DELAY : 0
+            });
+        }
+    }
+});