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fix(aio): fix scrolling to an element 

Previously, the top-bar's height wasn't taken into account when scrolling an
element into view. As a result, the element would be hidden behind the top-bar.
Taking the top-bar height into account was not necessary before #17155, because
the top-bar was not fixed (i.e. it scrolled away).

This commit fixes the scrolling behavior by accounting for the top-bar's height
when scrolling an element into view.

(This partially reverts #17102.)

Fixes #17219
Fixes #17226
This commit is contained in:
Georgios Kalpakas 2017-06-06 20:59:57 +03:00 committed by Pete Bacon Darwin
parent 4759975be6
commit d837bfc2d7
4 changed files with 106 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

89
aio/src/app/shared/scroll.service.spec.ts
View File

@ -5,6 +5,7 @@ import { DOCUMENT } from '@angular/platform-browser';
import { ScrollService, topMargin } from './scroll.service';
describe('ScrollService', () => {
const topOfPageElem = {} as Element;
let injector: ReflectiveInjector;
let document: MockDocument;
let location: MockPlatformLocation;
@ -16,7 +17,8 @@ describe('ScrollService', () => {
class MockDocument {
body = new MockElement();
getElementById = jasmine.createSpy('Document getElementById');
getElementById = jasmine.createSpy('Document getElementById').and.returnValue(topOfPageElem);
querySelector = jasmine.createSpy('Document querySelector');
}
class MockElement {
@ -38,6 +40,69 @@ describe('ScrollService', () => {
scrollService = injector.get(ScrollService);
});
describe('#topOffset', () => {
it('should query for the top-bar by CSS selector', () => {
expect(document.querySelector).not.toHaveBeenCalled();
expect(scrollService.topOffset).toBe(topMargin);
expect(document.querySelector).toHaveBeenCalled();
});
it('should be calculated based on the top-bar\'s height + margin', () => {
(document.querySelector as jasmine.Spy).and.returnValue({clientHeight: 50});
expect(scrollService.topOffset).toBe(50 + topMargin);
});
it('should only query for the top-bar once', () => {
expect(scrollService.topOffset).toBe(topMargin);
(document.querySelector as jasmine.Spy).calls.reset();
expect(scrollService.topOffset).toBe(topMargin);
expect(document.querySelector).not.toHaveBeenCalled();
});
it('should retrieve the top-bar\'s height again after resize', () => {
let clientHeight = 50;
(document.querySelector as jasmine.Spy).and.callFake(() => ({clientHeight}));
expect(scrollService.topOffset).toBe(50 + topMargin);
expect(document.querySelector).toHaveBeenCalled();
(document.querySelector as jasmine.Spy).calls.reset();
clientHeight = 100;
expect(scrollService.topOffset).toBe(50 + topMargin);
expect(document.querySelector).not.toHaveBeenCalled();
window.dispatchEvent(new Event('resize'));
expect(scrollService.topOffset).toBe(100 + topMargin);
expect(document.querySelector).toHaveBeenCalled();
});
});
describe('#topOfPageElement', () => {
it('should query for the top-of-page element by ID', () => {
expect(document.getElementById).not.toHaveBeenCalled();
expect(scrollService.topOfPageElement).toBe(topOfPageElem);
expect(document.getElementById).toHaveBeenCalled();
});
it('should only query for the top-of-page element once', () => {
expect(scrollService.topOfPageElement).toBe(topOfPageElem);
(document.getElementById as jasmine.Spy).calls.reset();
expect(scrollService.topOfPageElement).toBe(topOfPageElem);
expect(document.getElementById).not.toHaveBeenCalled();
});
it('should return `<body>` if unable to find the top-of-page element', () => {
(document.getElementById as jasmine.Spy).and.returnValue(null);
expect(scrollService.topOfPageElement).toBe(document.body as any);
});
});
describe('#scroll', () => {
it('should scroll to the top if there is no hash', () => {
location.hash = '';
@ -73,10 +138,28 @@ describe('ScrollService', () => {
describe('#scrollToElement', () => {
it('should scroll to element', () => {
const element = <Element><any> new MockElement();
const element: Element = new MockElement() as any;
scrollService.scrollToElement(element);
expect(element.scrollIntoView).toHaveBeenCalled();
expect(window.scrollBy).toHaveBeenCalledWith(0, -topMargin);
expect(window.scrollBy).toHaveBeenCalledWith(0, -scrollService.topOffset);
});
it('should scroll all the way to the top if close enough', () => {
const element: Element = new MockElement() as any;
(window as any).pageYOffset = 25;
scrollService.scrollToElement(element);
expect(element.scrollIntoView).toHaveBeenCalled();
expect(window.scrollBy).toHaveBeenCalledWith(0, -scrollService.topOffset);
(window.scrollBy as jasmine.Spy).calls.reset();
(window as any).pageYOffset = 15;
scrollService.scrollToElement(element);
expect(element.scrollIntoView).toHaveBeenCalled();
expect(window.scrollBy).toHaveBeenCalledWith(0, -scrollService.topOffset);
expect(window.scrollBy).toHaveBeenCalledWith(0, -15);
});
it('should do nothing if no element', () => {

23
aio/src/app/shared/scroll.service.ts
View File

@ -1,6 +1,7 @@
import { Injectable, Inject } from '@angular/core';
import { PlatformLocation } from '@angular/common';
import { DOCUMENT } from '@angular/platform-browser';
import {fromEvent} from 'rxjs/observable/fromEvent';
export const topMargin = 16;
/**
@ -9,20 +10,20 @@ export const topMargin = 16;
@Injectable()
export class ScrollService {
private _topOffset: number;
private _topOffset: number | null;
private _topOfPageElement: Element;
// Offset from the top of the document to bottom of any static elements
// at the top (e.g. toolbar) + some margin
get topOffset() {
if (!this._topOffset) {
// Since the toolbar is not static, we don't need to account for its height.
this._topOffset = topMargin;
const toolbar = this.document.querySelector('md-toolbar.app-toolbar');
this._topOffset = (toolbar && toolbar.clientHeight || 0) + topMargin;
}
return this._topOffset;
}
private get topOfPageElement() {
get topOfPageElement() {
if (!this._topOfPageElement) {
this._topOfPageElement = this.document.getElementById('top-of-page') || this.document.body;
}
@ -31,7 +32,10 @@ export class ScrollService {
constructor(
@Inject(DOCUMENT) private document: any,
private location: PlatformLocation) { }
private location: PlatformLocation) {
// On resize, the toolbar might change height, so "invalidate" the top offset.
fromEvent(window, 'resize').subscribe(() => this._topOffset = null);
}
/**
* Scroll to the element with id extracted from the current location hash fragment.
@ -53,7 +57,14 @@ export class ScrollService {
scrollToElement(element: Element) {
if (element) {
element.scrollIntoView();
if (window && window.scrollBy) { window.scrollBy(0, -this.topOffset); }
if (window && window.scrollBy) {
window.scrollBy(0, -this.topOffset);
if (window.pageYOffset < 20) {
// If we are very close to the top (<20px), then scroll all the way up.
// (This can happen if `element` is at the top of the page, but has a small top-margin.)
window.scrollBy(0, -window.pageYOffset);
}
}
}
}

4
aio/src/styles/0-base/_typography.scss
View File

@ -8,7 +8,7 @@ body {
}
h1 {
display:inline-block;
display: inline-block;
font-size: 24px;
font-weight: 500;
margin: 8px 0px;
@ -158,4 +158,4 @@ code {
&:hover {
color: $mediumgray;
}
}
}

2
aio/src/styles/1-layouts/_content-layout.scss
View File

@ -7,7 +7,7 @@ aio-shell.page-docs {
.sidenav-content {
min-height: 100vh;
padding: 6rem 3rem 1rem;
padding: 80px 3rem 1rem;
}
@media (max-width: 600px) {