79597: Add HTML placeholder for missing thumbnails

This commit is contained in:
Yura Bondarenko
2021-05-25 09:28:46 +02:00
parent 55affdebce
commit d80da3bbfe
4 changed files with 36 additions and 12 deletions

View File

@@ -2,11 +2,6 @@ import { Component, Input, OnInit } from '@angular/core';
import { Bitstream } from '../core/shared/bitstream.model';
import { hasValue } from '../shared/empty.util';
/**
* A fallback placeholder image as a base64 string
*/
export const THUMBNAIL_PLACEHOLDER = 'data:image/svg+xml;charset=UTF-8,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%2293%22%20height%3D%22120%22%20viewBox%3D%220%200%2093%20120%22%20preserveAspectRatio%3D%22none%22%3E%3C!--%0ASource%20URL%3A%20holder.js%2F93x120%3Ftext%3DNo%20Thumbnail%0ACreated%20with%20Holder.js%202.8.2.%0ALearn%20more%20at%20http%3A%2F%2Fholderjs.com%0A(c)%202012-2015%20Ivan%20Malopinsky%20-%20http%3A%2F%2Fimsky.co%0A--%3E%3Cdefs%3E%3Cstyle%20type%3D%22text%2Fcss%22%3E%3C!%5BCDATA%5B%23holder_1543e460b05%20text%20%7B%20fill%3A%23AAAAAA%3Bfont-weight%3Abold%3Bfont-family%3AArial%2C%20Helvetica%2C%20Open%20Sans%2C%20sans-serif%2C%20monospace%3Bfont-size%3A10pt%20%7D%20%5D%5D%3E%3C%2Fstyle%3E%3C%2Fdefs%3E%3Cg%20id%3D%22holder_1543e460b05%22%3E%3Crect%20width%3D%2293%22%20height%3D%22120%22%20fill%3D%22%23FFFFFF%22%2F%3E%3Cg%3E%3Ctext%20x%3D%2235.6171875%22%20y%3D%2257%22%3ENo%3C%2Ftext%3E%3Ctext%20x%3D%2210.8125%22%20y%3D%2272%22%3EThumbnail%3C%2Ftext%3E%3C%2Fg%3E%3C%2Fg%3E%3C%2Fsvg%3E';
/**
* This component renders a given Bitstream as a thumbnail.
* One input parameter of type Bitstream is expected.
@@ -24,9 +19,10 @@ export class ThumbnailComponent implements OnInit {
@Input() thumbnail: Bitstream;
/**
* The default image, used if the thumbnail isn't set or can't be downloaded
* The default image, used if the thumbnail isn't set or can't be downloaded.
* If defaultImage is null, a HTML placeholder is used instead.
*/
@Input() defaultImage? = THUMBNAIL_PLACEHOLDER;
@Input() defaultImage? = null;
/**
* The src attribute used in the template to render the image.
@@ -38,12 +34,19 @@ export class ThumbnailComponent implements OnInit {
*/
@Input() alt? = 'thumbnail.default.alt';
/**
* i18n key of HTML placeholder text
*/
@Input() placeholder? = 'thumbnail.default.placeholder';
/**
* Initialize the thumbnail.
* Use a default image if no actual image is available.
*/
ngOnInit(): void {
if (hasValue(this.thumbnail) && hasValue(this.thumbnail._links) && hasValue(this.thumbnail._links.content) && this.thumbnail._links.content.href) {
if (hasValue(this.thumbnail) && hasValue(this.thumbnail._links)
&& hasValue(this.thumbnail._links.content)
&& this.thumbnail._links.content.href) {
this.src = this.thumbnail._links.content.href;
} else {
this.src = this.defaultImage;
@@ -53,13 +56,13 @@ export class ThumbnailComponent implements OnInit {
/**
* Handle image download errors.
* If the image can't be found, use the defaultImage instead.
* If that also can't be found, use the base64 placeholder.
* If that also can't be found, use null to fall back to the HTML placeholder.
*/
errorHandler() {
if (this.src !== this.defaultImage) {
this.src = this.defaultImage;
} else {
this.src = THUMBNAIL_PLACEHOLDER;
this.src = null;
}
}
}