/**
* @license
* Copyright Google LLC All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
import { inject, Injectable, ɵRuntimeError as RuntimeError } from '@angular/core';
import { DOCUMENT } from '../../dom_tokens';
import { DEFAULT_PRELOADED_IMAGES_LIMIT, PRELOADED_IMAGES } from './tokens';
import * as i0 from "@angular/core";
/**
* @description Contains the logic needed to track and add preload link tags to the `` tag. It
* will also track what images have already had preload link tags added so as to not duplicate link
* tags.
*
* In dev mode this service will validate that the number of preloaded images does not exceed the
* configured default preloaded images limit: {@link DEFAULT_PRELOADED_IMAGES_LIMIT}.
*/
export class PreloadLinkCreator {
constructor() {
this.preloadedImages = inject(PRELOADED_IMAGES);
this.document = inject(DOCUMENT);
}
/**
* @description Add a preload `` to the `` of the `index.html` that is served from the
* server while using Angular Universal and SSR to kick off image loads for high priority images.
*
* The `sizes` (passed in from the user) and `srcset` (parsed and formatted from `ngSrcset`)
* properties used to set the corresponding attributes, `imagesizes` and `imagesrcset`
* respectively, on the preload `` tag so that the correctly sized image is preloaded from
* the CDN.
*
* {@link https://web.dev/preload-responsive-images/#imagesrcset-and-imagesizes}
*
* @param renderer The `Renderer2` passed in from the directive
* @param src The original src of the image that is set on the `ngSrc` input.
* @param srcset The parsed and formatted srcset created from the `ngSrcset` input
* @param sizes The value of the `sizes` attribute passed in to the `` tag
*/
createPreloadLinkTag(renderer, src, srcset, sizes) {
if (ngDevMode) {
if (this.preloadedImages.size >= DEFAULT_PRELOADED_IMAGES_LIMIT) {
throw new RuntimeError(2961 /* RuntimeErrorCode.TOO_MANY_PRELOADED_IMAGES */, ngDevMode &&
`The \`NgOptimizedImage\` directive has detected that more than ` +
`${DEFAULT_PRELOADED_IMAGES_LIMIT} images were marked as priority. ` +
`This might negatively affect an overall performance of the page. ` +
`To fix this, remove the "priority" attribute from images with less priority.`);
}
}
if (this.preloadedImages.has(src)) {
return;
}
this.preloadedImages.add(src);
const preload = renderer.createElement('link');
renderer.setAttribute(preload, 'as', 'image');
renderer.setAttribute(preload, 'href', src);
renderer.setAttribute(preload, 'rel', 'preload');
renderer.setAttribute(preload, 'fetchpriority', 'high');
if (sizes) {
renderer.setAttribute(preload, 'imageSizes', sizes);
}
if (srcset) {
renderer.setAttribute(preload, 'imageSrcset', srcset);
}
renderer.appendChild(this.document.head, preload);
}
}
PreloadLinkCreator.ɵfac = i0.ɵɵngDeclareFactory({ minVersion: "12.0.0", version: "14.3.0", ngImport: i0, type: PreloadLinkCreator, deps: [], target: i0.ɵɵFactoryTarget.Injectable });
PreloadLinkCreator.ɵprov = i0.ɵɵngDeclareInjectable({ minVersion: "12.0.0", version: "14.3.0", ngImport: i0, type: PreloadLinkCreator, providedIn: 'root' });
i0.ɵɵngDeclareClassMetadata({ minVersion: "12.0.0", version: "14.3.0", ngImport: i0, type: PreloadLinkCreator, decorators: [{
type: Injectable,
args: [{ providedIn: 'root' }]
}] });
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