react-pdf-annotations/build/lib/get-area-as-png.js

Set of React components for PDF annotation

import { isHTMLCanvasElement } from "../lib/pdfjs-dom";

const getAreaAsPNG = (canvas, position) => {
  const {
    left,
    top,
    width,
    height
  } = position;
  const doc = canvas ? canvas.ownerDocument : null; // @TODO: cache this?

  const newCanvas = doc && doc.createElement("canvas");

  if (!newCanvas || !isHTMLCanvasElement(newCanvas)) {
    return "";
  }

  newCanvas.width = width;
  newCanvas.height = height;
  const newCanvasContext = newCanvas.getContext("2d");

  if (!newCanvasContext || !canvas) {
    return "";
  }

  const dpr = window.devicePixelRatio;
  newCanvasContext.drawImage(canvas, left * dpr, top * dpr, width * dpr, height * dpr, 0, 0, width, height);
  return newCanvas.toDataURL("image/png");
};

export default getAreaAsPNG;