image-js/src/image/transform/rgba.js

Image processing and manipulation in JavaScript

import Image from '../Image';
import { RGB } from '../model/model';

/**
 * Make a copy of the current image and convert to RGBA
 * The source image must have RGB color model, 8 or 16 bits.
 * This method will add an alpha channel if required. In this case
 * the value for the alpha channel will be 100% opacity.
 * @memberof Image
 * @instance
 * @return {Image} - New image in RGB color model with alpha channel
 * @example
 * var rgbaImage = image.rgba();
 */
export default function rgba() {
  this.checkProcessable('rgba', {
    bitDepth: [8, 16],
    alpha: [0, 1],
    colorModel: [RGB],
  });

  if (this.colorModel === RGB && this.alpha) {
    return this.clone();
  }

  let newImage = Image.createFrom(this, {
    alpha: 1,
  });

  let ptr = 0;
  let data = this.data;
  for (let i = 0; i < data.length; i += this.channels) {
    newImage.data[ptr++] = data[i];
    newImage.data[ptr++] = data[i + 1];
    newImage.data[ptr++] = data[i + 2];
    newImage.data[ptr++] = this.maxValue;
    ptr++;
  }

  return newImage;
}