70 lines
2.1 KiB
TypeScript
70 lines
2.1 KiB
TypeScript
import {ListWrapper} from 'angular2/src/facade/collection';
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import {Math} from 'angular2/src/facade/math';
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import {Component, Directive} from 'angular2/core';
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import {Offering, ITEMS, ITEM_HEIGHT, VISIBLE_ITEMS, VIEW_PORT_HEIGHT, ROW_WIDTH, HEIGHT} from './common';
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import {generateOfferings} from './random_data';
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import {ScrollItemComponent} from './scroll_item';
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import {NgFor} from 'angular2/common';
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@Component({
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selector: 'scroll-area',
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directives: [ScrollItemComponent, NgFor],
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template: `
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<div>
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<div id="scrollDiv"
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[style.height.px]="viewPortHeight"
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style="width: 1000px; border: 1px solid #000; overflow: scroll"
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on-scroll="onScroll($event)">
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<div id="padding"></div>
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<div id="inner">
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<scroll-item
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template="ngFor #item of visibleItems"
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[offering]="item">
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</scroll-item>
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</div>
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</div>
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</div>`
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})
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export class ScrollAreaComponent {
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_fullList: Offering[];
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visibleItems: Offering[];
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viewPortHeight: number;
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paddingDiv;
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innerDiv;
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constructor() {
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this._fullList = generateOfferings(ITEMS);
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this.visibleItems = [];
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this.viewPortHeight = VIEW_PORT_HEIGHT;
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this.onScroll(null);
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}
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onScroll(evt) {
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var scrollTop = 0;
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if (evt != null) {
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var scrollDiv = evt.target;
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if (this.paddingDiv == null) {
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this.paddingDiv = scrollDiv.querySelector('#padding');
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}
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if (this.innerDiv == null) {
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this.innerDiv = scrollDiv.querySelector('#inner');
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this.innerDiv.style.setProperty('width', `${ROW_WIDTH}px`);
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}
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scrollTop = scrollDiv.scrollTop;
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}
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var iStart = Math.floor(scrollTop / ITEM_HEIGHT);
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var iEnd = Math.min(iStart + VISIBLE_ITEMS + 1, this._fullList.length);
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var padding = iStart * ITEM_HEIGHT;
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if (this.innerDiv != null) {
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this.innerDiv.style.setProperty('height', `${HEIGHT - padding}px`);
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}
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if (this.paddingDiv != null) {
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this.paddingDiv.style.setProperty('height', `${padding}px`);
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}
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this.visibleItems = ListWrapper.slice(this._fullList, iStart, iEnd);
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}
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}
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