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PDFImage.ts
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PDFImage.ts
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import Embeddable from 'src/api/Embeddable';
import PDFDocument from 'src/api/PDFDocument';
import { JpegEmbedder, PDFRef, PngEmbedder } from 'src/core';
import { assertIs } from 'src/utils';
export type ImageEmbedder = JpegEmbedder | PngEmbedder;
/**
* Represents an image that has been embedded in a [[PDFDocument]].
*/
export default class PDFImage implements Embeddable {
/**
* > **NOTE:** You probably don't want to call this method directly. Instead,
* > consider using the [[PDFDocument.embedPng]] and [[PDFDocument.embedJpg]]
* > methods, which will create instances of [[PDFImage]] for you.
*
* Create an instance of [[PDFImage]] from an existing ref and embedder
*
* @param ref The unique reference for this image.
* @param doc The document to which the image will belong.
* @param embedder The embedder that will be used to embed the image.
*/
static of = (ref: PDFRef, doc: PDFDocument, embedder: ImageEmbedder) =>
new PDFImage(ref, doc, embedder);
/** The unique reference assigned to this image within the document. */
readonly ref: PDFRef;
/** The document to which this image belongs. */
readonly doc: PDFDocument;
/** The width of this image in pixels. */
readonly width: number;
/** The height of this image in pixels. */
readonly height: number;
private alreadyEmbedded = false;
private readonly embedder: ImageEmbedder;
private constructor(ref: PDFRef, doc: PDFDocument, embedder: ImageEmbedder) {
assertIs(ref, 'ref', [[PDFRef, 'PDFRef']]);
assertIs(doc, 'doc', [[PDFDocument, 'PDFDocument']]);
assertIs(embedder, 'embedder', [
[JpegEmbedder, 'JpegEmbedder'],
[PngEmbedder, 'PngEmbedder'],
]);
this.ref = ref;
this.doc = doc;
this.width = embedder.width;
this.height = embedder.height;
this.embedder = embedder;
}
/**
* Compute the width and height of this image after being scaled by the
* given `factor`. For example:
* ```js
* image.width // => 500
* image.height // => 250
*
* const scaled = image.scale(0.5)
* scaled.width // => 250
* scaled.height // => 125
* ```
* This operation is often useful before drawing an image with
* [[PDFPage.drawImage]] to compute the `width` and `height` options.
* @param factor The factor by which this image should be scaled.
* @returns The width and height of the image after being scaled.
*/
scale(factor: number) {
assertIs(factor, 'factor', ['number']);
return { width: this.width * factor, height: this.height * factor };
}
/**
* Get the width and height of this image. For example:
* ```js
* const { width, height } = image.size()
* ```
* @returns The width and height of the image.
*/
size() {
return this.scale(1);
}
/**
* > **NOTE:** You probably don't need to call this method directly. The
* > [[PDFDocument.save]] and [[PDFDocument.saveAsBase64]] methods will
* > automatically ensure all images get embedded.
*
* Embed this image in its document.
*
* @returns Resolves when the embedding is complete.
*/
async embed(): Promise<void> {
if (!this.alreadyEmbedded) {
await this.embedder.embedIntoContext(this.doc.context, this.ref);
this.alreadyEmbedded = true;
}
}
}