source: imaps-frontend/node_modules/stackblur-canvas/src/stackblur.js

/* eslint-disable no-bitwise -- used for calculations */
/* eslint-disable unicorn/prefer-query-selector -- aiming at
  backward-compatibility */
/**
* StackBlur - a fast almost Gaussian Blur For Canvas
*
* In case you find this class useful - especially in commercial projects -
* I am not totally unhappy for a small donation to my PayPal account
* mario@quasimondo.de
*
* Or support me on flattr:
* {@link https://flattr.com/thing/72791/StackBlur-a-fast-almost-Gaussian-Blur-Effect-for-CanvasJavascript}.
*
* @module StackBlur
* @author Mario Klingemann
* Contact: mario@quasimondo.com
* Website: {@link http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html}
* Twitter: @quasimondo
*
* @copyright (c) 2010 Mario Klingemann
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/

const mulTable = [
  512, 512, 456, 512, 328, 456, 335, 512, 405, 328, 271, 456, 388, 335, 292,
  512, 454, 405, 364, 328, 298, 271, 496, 456, 420, 388, 360, 335, 312, 292,
  273, 512, 482, 454, 428, 405, 383, 364, 345, 328, 312, 298, 284, 271, 259,
  496, 475, 456, 437, 420, 404, 388, 374, 360, 347, 335, 323, 312, 302, 292,
  282, 273, 265, 512, 497, 482, 468, 454, 441, 428, 417, 405, 394, 383, 373,
  364, 354, 345, 337, 328, 320, 312, 305, 298, 291, 284, 278, 271, 265, 259,
  507, 496, 485, 475, 465, 456, 446, 437, 428, 420, 412, 404, 396, 388, 381,
  374, 367, 360, 354, 347, 341, 335, 329, 323, 318, 312, 307, 302, 297, 292,
  287, 282, 278, 273, 269, 265, 261, 512, 505, 497, 489, 482, 475, 468, 461,
  454, 447, 441, 435, 428, 422, 417, 411, 405, 399, 394, 389, 383, 378, 373,
  368, 364, 359, 354, 350, 345, 341, 337, 332, 328, 324, 320, 316, 312, 309,
  305, 301, 298, 294, 291, 287, 284, 281, 278, 274, 271, 268, 265, 262, 259,
  257, 507, 501, 496, 491, 485, 480, 475, 470, 465, 460, 456, 451, 446, 442,
  437, 433, 428, 424, 420, 416, 412, 408, 404, 400, 396, 392, 388, 385, 381,
  377, 374, 370, 367, 363, 360, 357, 354, 350, 347, 344, 341, 338, 335, 332,
  329, 326, 323, 320, 318, 315, 312, 310, 307, 304, 302, 299, 297, 294, 292,
  289, 287, 285, 282, 280, 278, 275, 273, 271, 269, 267, 265, 263, 261, 259
];

const shgTable = [
  9, 11, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17,
  17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19,
  19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20,
  20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21,
  21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
  21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22,
  22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
  22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23,
  23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
  23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
  23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
  23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24
];

/**
 * @param {string|HTMLImageElement} img
 * @param {string|HTMLCanvasElement} canvas
 * @param {Float} radius
 * @param {boolean} blurAlphaChannel
 * @param {boolean} useOffset
 * @param {boolean} skipStyles
 * @returns {undefined}
 */
function processImage (
  img, canvas, radius, blurAlphaChannel, useOffset, skipStyles
) {
  if (typeof img === 'string') {
    img = document.getElementById(img);
  }

  if (
    !img ||
    (Object.prototype.toString.call(img).slice(8, -1) ===
      'HTMLImageElement' && !('naturalWidth' in img))
  ) {
    return;
  }

  const dimensionType = useOffset ? 'offset' : 'natural';
  let w = img[dimensionType + 'Width'];
  let h = img[dimensionType + 'Height'];

  // add ImageBitmap support,can blur texture source
  if (Object.prototype.toString.call(img).slice(8, -1) === 'ImageBitmap') {
    w = img.width;
    h = img.height;
  }

  if (typeof canvas === 'string') {
    canvas = document.getElementById(canvas);
  }
  if (!canvas || !('getContext' in canvas)) {
    return;
  }

  if (!skipStyles) {
    canvas.style.width = w + 'px';
    canvas.style.height = h + 'px';
  }
  canvas.width = w;
  canvas.height = h;

  const context = canvas.getContext('2d');
  context.clearRect(0, 0, w, h);
  context.drawImage(img, 0, 0, img.naturalWidth, img.naturalHeight, 0, 0, w, h);

  if (isNaN(radius) || radius < 1) { return; }

  if (blurAlphaChannel) {
    processCanvasRGBA(canvas, 0, 0, w, h, radius);
  } else {
    processCanvasRGB(canvas, 0, 0, w, h, radius);
  }
}

/**
 * @param {string|HTMLCanvasElement} canvas
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @throws {Error|TypeError}
 * @returns {ImageData} See {@link https://html.spec.whatwg.org/multipage/canvas.html#imagedata}
 */
function getImageDataFromCanvas (canvas, topX, topY, width, height) {
  if (typeof canvas === 'string') {
    canvas = document.getElementById(canvas);
  }
  if (!canvas || typeof canvas !== 'object' || !('getContext' in canvas)) {
    throw new TypeError(
      'Expecting canvas with `getContext` method ' +
            'in processCanvasRGB(A) calls!'
    );
  }

  const context = canvas.getContext('2d');

  try {
    return context.getImageData(topX, topY, width, height);
  } catch (e) {
    throw new Error('unable to access image data: ' + e);
  }
}

/**
 * @param {HTMLCanvasElement} canvas
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @param {Float} radius
 * @returns {undefined}
 */
function processCanvasRGBA (canvas, topX, topY, width, height, radius) {
  if (isNaN(radius) || radius < 1) { return; }
  radius |= 0;

  let imageData = getImageDataFromCanvas(canvas, topX, topY, width, height);

  imageData = processImageDataRGBA(
    imageData, topX, topY, width, height, radius
  );

  canvas.getContext('2d').putImageData(imageData, topX, topY);
}

/**
 * @param {ImageData} imageData
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @param {Float} radius
 * @returns {ImageData}
 */
function processImageDataRGBA (imageData, topX, topY, width, height, radius) {
  const pixels = imageData.data;

  const div = 2 * radius + 1;
  // const w4 = width << 2;
  const widthMinus1 = width - 1;
  const heightMinus1 = height - 1;
  const radiusPlus1 = radius + 1;
  const sumFactor = radiusPlus1 * (radiusPlus1 + 1) / 2;

  const stackStart = new BlurStack();
  let stack = stackStart;
  let stackEnd;
  for (let i = 1; i < div; i++) {
    stack = stack.next = new BlurStack();
    if (i === radiusPlus1) {
      stackEnd = stack;
    }
  }
  stack.next = stackStart;

  let stackIn = null,
    stackOut = null,
    yw = 0,
    yi = 0;

  const mulSum = mulTable[radius];
  const shgSum = shgTable[radius];

  for (let y = 0; y < height; y++) {
    stack = stackStart;

    const pr = pixels[yi],
      pg = pixels[yi + 1],
      pb = pixels[yi + 2],
      pa = pixels[yi + 3];

    for (let i = 0; i < radiusPlus1; i++) {
      stack.r = pr;
      stack.g = pg;
      stack.b = pb;
      stack.a = pa;
      stack = stack.next;
    }

    let rInSum = 0, gInSum = 0, bInSum = 0, aInSum = 0,
      rOutSum = radiusPlus1 * pr,
      gOutSum = radiusPlus1 * pg,
      bOutSum = radiusPlus1 * pb,
      aOutSum = radiusPlus1 * pa,
      rSum = sumFactor * pr,
      gSum = sumFactor * pg,
      bSum = sumFactor * pb,
      aSum = sumFactor * pa;

    for (let i = 1; i < radiusPlus1; i++) {
      const p = yi + ((widthMinus1 < i ? widthMinus1 : i) << 2);

      const r = pixels[p],
        g = pixels[p + 1],
        b = pixels[p + 2],
        a = pixels[p + 3];

      const rbs = radiusPlus1 - i;
      rSum += (stack.r = r) * rbs;
      gSum += (stack.g = g) * rbs;
      bSum += (stack.b = b) * rbs;
      aSum += (stack.a = a) * rbs;

      rInSum += r;
      gInSum += g;
      bInSum += b;
      aInSum += a;

      stack = stack.next;
    }

    stackIn = stackStart;
    stackOut = stackEnd;
    for (let x = 0; x < width; x++) {
      const paInitial = (aSum * mulSum) >>> shgSum;
      pixels[yi + 3] = paInitial;
      if (paInitial !== 0) {
        const a = 255 / paInitial;
        pixels[yi] = ((rSum * mulSum) >>> shgSum) * a;
        pixels[yi + 1] = ((gSum * mulSum) >>> shgSum) * a;
        pixels[yi + 2] = ((bSum * mulSum) >>> shgSum) * a;
      } else {
        pixels[yi] = pixels[yi + 1] = pixels[yi + 2] = 0;
      }

      rSum -= rOutSum;
      gSum -= gOutSum;
      bSum -= bOutSum;
      aSum -= aOutSum;

      rOutSum -= stackIn.r;
      gOutSum -= stackIn.g;
      bOutSum -= stackIn.b;
      aOutSum -= stackIn.a;

      let p = x + radius + 1;
      p = (yw + (p < widthMinus1
        ? p
        : widthMinus1)) << 2;

      rInSum += (stackIn.r = pixels[p]);
      gInSum += (stackIn.g = pixels[p + 1]);
      bInSum += (stackIn.b = pixels[p + 2]);
      aInSum += (stackIn.a = pixels[p + 3]);

      rSum += rInSum;
      gSum += gInSum;
      bSum += bInSum;
      aSum += aInSum;

      stackIn = stackIn.next;

      const {r, g, b, a} = stackOut;

      rOutSum += r;
      gOutSum += g;
      bOutSum += b;
      aOutSum += a;

      rInSum -= r;
      gInSum -= g;
      bInSum -= b;
      aInSum -= a;

      stackOut = stackOut.next;

      yi += 4;
    }
    yw += width;
  }

  for (let x = 0; x < width; x++) {
    yi = x << 2;

    let pr = pixels[yi],
      pg = pixels[yi + 1],
      pb = pixels[yi + 2],
      pa = pixels[yi + 3],
      rOutSum = radiusPlus1 * pr,
      gOutSum = radiusPlus1 * pg,
      bOutSum = radiusPlus1 * pb,
      aOutSum = radiusPlus1 * pa,
      rSum = sumFactor * pr,
      gSum = sumFactor * pg,
      bSum = sumFactor * pb,
      aSum = sumFactor * pa;

    stack = stackStart;

    for (let i = 0; i < radiusPlus1; i++) {
      stack.r = pr;
      stack.g = pg;
      stack.b = pb;
      stack.a = pa;
      stack = stack.next;
    }

    let yp = width;

    let gInSum = 0, bInSum = 0, aInSum = 0, rInSum = 0;
    for (let i = 1; i <= radius; i++) {
      yi = (yp + x) << 2;

      const rbs = radiusPlus1 - i;
      rSum += (stack.r = (pr = pixels[yi])) * rbs;
      gSum += (stack.g = (pg = pixels[yi + 1])) * rbs;
      bSum += (stack.b = (pb = pixels[yi + 2])) * rbs;
      aSum += (stack.a = (pa = pixels[yi + 3])) * rbs;

      rInSum += pr;
      gInSum += pg;
      bInSum += pb;
      aInSum += pa;

      stack = stack.next;

      if (i < heightMinus1) {
        yp += width;
      }
    }

    yi = x;
    stackIn = stackStart;
    stackOut = stackEnd;
    for (let y = 0; y < height; y++) {
      let p = yi << 2;
      pixels[p + 3] = pa = (aSum * mulSum) >>> shgSum;
      if (pa > 0) {
        pa = 255 / pa;
        pixels[p] = ((rSum * mulSum) >>> shgSum) * pa;
        pixels[p + 1] = ((gSum * mulSum) >>> shgSum) * pa;
        pixels[p + 2] = ((bSum * mulSum) >>> shgSum) * pa;
      } else {
        pixels[p] = pixels[p + 1] = pixels[p + 2] = 0;
      }

      rSum -= rOutSum;
      gSum -= gOutSum;
      bSum -= bOutSum;
      aSum -= aOutSum;

      rOutSum -= stackIn.r;
      gOutSum -= stackIn.g;
      bOutSum -= stackIn.b;
      aOutSum -= stackIn.a;

      p = (x + (
        ((p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1) *
                width
      )) << 2;

      rSum += (rInSum += (stackIn.r = pixels[p]));
      gSum += (gInSum += (stackIn.g = pixels[p + 1]));
      bSum += (bInSum += (stackIn.b = pixels[p + 2]));
      aSum += (aInSum += (stackIn.a = pixels[p + 3]));

      stackIn = stackIn.next;

      rOutSum += (pr = stackOut.r);
      gOutSum += (pg = stackOut.g);
      bOutSum += (pb = stackOut.b);
      aOutSum += (pa = stackOut.a);

      rInSum -= pr;
      gInSum -= pg;
      bInSum -= pb;
      aInSum -= pa;

      stackOut = stackOut.next;

      yi += width;
    }
  }
  return imageData;
}

/**
 * @param {HTMLCanvasElement} canvas
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @param {Float} radius
 * @returns {undefined}
 */
function processCanvasRGB (canvas, topX, topY, width, height, radius) {
  if (isNaN(radius) || radius < 1) { return; }
  radius |= 0;

  let imageData = getImageDataFromCanvas(canvas, topX, topY, width, height);
  imageData = processImageDataRGB(
    imageData, topX, topY, width, height, radius
  );

  canvas.getContext('2d').putImageData(imageData, topX, topY);
}

/**
 * @param {ImageData} imageData
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @param {Float} radius
 * @returns {ImageData}
 */
function processImageDataRGB (imageData, topX, topY, width, height, radius) {
  const pixels = imageData.data;

  const div = 2 * radius + 1;
  // const w4 = width << 2;
  const widthMinus1 = width - 1;
  const heightMinus1 = height - 1;
  const radiusPlus1 = radius + 1;
  const sumFactor = radiusPlus1 * (radiusPlus1 + 1) / 2;

  const stackStart = new BlurStack();
  let stack = stackStart;
  let stackEnd;
  for (let i = 1; i < div; i++) {
    stack = stack.next = new BlurStack();
    if (i === radiusPlus1) {
      stackEnd = stack;
    }
  }
  stack.next = stackStart;
  let stackIn = null;
  let stackOut = null;

  const mulSum = mulTable[radius];
  const shgSum = shgTable[radius];

  let p, rbs;
  let yw = 0, yi = 0;

  for (let y = 0; y < height; y++) {
    let pr = pixels[yi],
      pg = pixels[yi + 1],
      pb = pixels[yi + 2],
      rOutSum = radiusPlus1 * pr,
      gOutSum = radiusPlus1 * pg,
      bOutSum = radiusPlus1 * pb,
      rSum = sumFactor * pr,
      gSum = sumFactor * pg,
      bSum = sumFactor * pb;

    stack = stackStart;

    for (let i = 0; i < radiusPlus1; i++) {
      stack.r = pr;
      stack.g = pg;
      stack.b = pb;
      stack = stack.next;
    }

    let rInSum = 0, gInSum = 0, bInSum = 0;
    for (let i = 1; i < radiusPlus1; i++) {
      p = yi + ((widthMinus1 < i ? widthMinus1 : i) << 2);
      rSum += (stack.r = (pr = pixels[p])) * (rbs = radiusPlus1 - i);
      gSum += (stack.g = (pg = pixels[p + 1])) * rbs;
      bSum += (stack.b = (pb = pixels[p + 2])) * rbs;

      rInSum += pr;
      gInSum += pg;
      bInSum += pb;

      stack = stack.next;
    }

    stackIn = stackStart;
    stackOut = stackEnd;
    for (let x = 0; x < width; x++) {
      pixels[yi] = (rSum * mulSum) >>> shgSum;
      pixels[yi + 1] = (gSum * mulSum) >>> shgSum;
      pixels[yi + 2] = (bSum * mulSum) >>> shgSum;

      rSum -= rOutSum;
      gSum -= gOutSum;
      bSum -= bOutSum;

      rOutSum -= stackIn.r;
      gOutSum -= stackIn.g;
      bOutSum -= stackIn.b;

      p = (yw + (
        (p = x + radius + 1) < widthMinus1 ? p : widthMinus1
      )) << 2;

      rInSum += (stackIn.r = pixels[p]);
      gInSum += (stackIn.g = pixels[p + 1]);
      bInSum += (stackIn.b = pixels[p + 2]);

      rSum += rInSum;
      gSum += gInSum;
      bSum += bInSum;

      stackIn = stackIn.next;

      rOutSum += (pr = stackOut.r);
      gOutSum += (pg = stackOut.g);
      bOutSum += (pb = stackOut.b);

      rInSum -= pr;
      gInSum -= pg;
      bInSum -= pb;

      stackOut = stackOut.next;

      yi += 4;
    }
    yw += width;
  }

  for (let x = 0; x < width; x++) {
    yi = x << 2;
    let pr = pixels[yi],
      pg = pixels[yi + 1],
      pb = pixels[yi + 2],
      rOutSum = radiusPlus1 * pr,
      gOutSum = radiusPlus1 * pg,
      bOutSum = radiusPlus1 * pb,
      rSum = sumFactor * pr,
      gSum = sumFactor * pg,
      bSum = sumFactor * pb;

    stack = stackStart;

    for (let i = 0; i < radiusPlus1; i++) {
      stack.r = pr;
      stack.g = pg;
      stack.b = pb;
      stack = stack.next;
    }

    let rInSum = 0, gInSum = 0, bInSum = 0;
    for (let i = 1, yp = width; i <= radius; i++) {
      yi = (yp + x) << 2;

      rSum += (stack.r = (pr = pixels[yi])) * (rbs = radiusPlus1 - i);
      gSum += (stack.g = (pg = pixels[yi + 1])) * rbs;
      bSum += (stack.b = (pb = pixels[yi + 2])) * rbs;

      rInSum += pr;
      gInSum += pg;
      bInSum += pb;

      stack = stack.next;

      if (i < heightMinus1) {
        yp += width;
      }
    }

    yi = x;
    stackIn = stackStart;
    stackOut = stackEnd;
    for (let y = 0; y < height; y++) {
      p = yi << 2;
      pixels[p] = (rSum * mulSum) >>> shgSum;
      pixels[p + 1] = (gSum * mulSum) >>> shgSum;
      pixels[p + 2] = (bSum * mulSum) >>> shgSum;

      rSum -= rOutSum;
      gSum -= gOutSum;
      bSum -= bOutSum;

      rOutSum -= stackIn.r;
      gOutSum -= stackIn.g;
      bOutSum -= stackIn.b;

      p = (x + (
        ((p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1) *
                width
      )) << 2;

      rSum += (rInSum += (stackIn.r = pixels[p]));
      gSum += (gInSum += (stackIn.g = pixels[p + 1]));
      bSum += (bInSum += (stackIn.b = pixels[p + 2]));

      stackIn = stackIn.next;

      rOutSum += (pr = stackOut.r);
      gOutSum += (pg = stackOut.g);
      bOutSum += (pb = stackOut.b);

      rInSum -= pr;
      gInSum -= pg;
      bInSum -= pb;

      stackOut = stackOut.next;

      yi += width;
    }
  }

  return imageData;
}

/**
 *
 */
export class BlurStack {
  /**
   * Set properties.
   */
  constructor () {
    this.r = 0;
    this.g = 0;
    this.b = 0;
    this.a = 0;
    this.next = null;
  }
}

export {
  /**
    * @function module:StackBlur.image
    * @see module:StackBlur~processImage
    */
  processImage as image,
  /**
    * @function module:StackBlur.canvasRGBA
    * @see module:StackBlur~processCanvasRGBA
    */
  processCanvasRGBA as canvasRGBA,
  /**
    * @function module:StackBlur.canvasRGB
    * @see module:StackBlur~processCanvasRGB
    */
  processCanvasRGB as canvasRGB,
  /**
    * @function module:StackBlur.imageDataRGBA
    * @see module:StackBlur~processImageDataRGBA
    */
  processImageDataRGBA as imageDataRGBA,
  /**
    * @function module:StackBlur.imageDataRGB
    * @see module:StackBlur~processImageDataRGB
    */
  processImageDataRGB as imageDataRGB
};