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1a689dc1a5
Instead of storing primitive values which makes the data binding system throw away DOM each time we update each slot lets just use objects and shift + pop. This means very little data binding churn. R=abarth@chromium.org Review URL: https://codereview.chromium.org/802153004
68 lines
1.7 KiB
Plaintext
68 lines
1.7 KiB
Plaintext
<!--
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// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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-->
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<import src="/sky/framework/sky-element/sky-element.sky" as="SkyElement" />
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<sky-element name="fps-counter" attributes="showHistory:boolean">
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<template>
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<template if="{{ showHistory }}">
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<template repeat="{{ deltas }}">
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<div>{{ roundedValue }} ms</div>
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</template>
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<div>max = {{ max }} ms</div>
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</template>
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<div>fps = {{ frameRate }} Hz</div>
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</template>
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<script>
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const kMaxDeltaLength = 10;
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class Delta {
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constructor(value) {
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this.value = value;
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this.roundedValue = value.toFixed(2);
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Object.preventExtensions(this);
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}
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}
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module.exports = class extends SkyElement {
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created() {
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this.frameRate = "...";
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this.max = 0;
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this.sum = 0;
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this.lastTimeStamp = 0;
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this.rafId = 0;
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this.deltas = [];
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for (var i = 0; i < kMaxDeltaLength; ++i)
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this.deltas[i] = new Delta(0);
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}
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attached() {
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this.scheduleTick();
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}
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detached() {
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cancelAnimationFrame(this.rafId);
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this.rafId = 0;
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}
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scheduleTick() {
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this.rafId = requestAnimationFrame(this.tick.bind(this));
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}
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tick(timeStamp) {
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this.scheduleTick();
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var lastTimeStamp = this.lastTimeStamp;
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this.lastTimeStamp = timeStamp;
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if (!lastTimeStamp)
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return;
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var delta = new Delta(timeStamp - lastTimeStamp);
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var removedDelta = this.deltas.shift();
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this.deltas.push(delta);
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this.sum -= removedDelta.value;
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this.sum += delta.value;
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var avg = this.sum / this.deltas.length;
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this.frameRate = (1000 / avg).toFixed(2);
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this.max = Math.max(delta.value, this.max).toFixed(2);
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}
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}.register();
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</script>
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</sky-element>
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