homework/chat-server/node_modules/sharp/lib/input.js

'use strict';

const color = require('color');
const is = require('./is');
const sharp = require('../build/Release/sharp.node');

/**
 * Extract input options, if any, from an object.
 * @private
 */
function _inputOptionsFromObject (obj) {
  const { raw, density, limitInputPixels, sequentialRead, failOnError } = obj;
  return [raw, density, limitInputPixels, sequentialRead, failOnError].some(is.defined)
    ? { raw, density, limitInputPixels, sequentialRead, failOnError }
    : undefined;
}

/**
 * Create Object containing input and input-related options.
 * @private
 */
function _createInputDescriptor (input, inputOptions, containerOptions) {
  const inputDescriptor = {
    failOnError: true,
    limitInputPixels: Math.pow(0x3FFF, 2),
    sequentialRead: false
  };
  if (is.string(input)) {
    // filesystem
    inputDescriptor.file = input;
  } else if (is.buffer(input)) {
    // Buffer
    inputDescriptor.buffer = input;
  } else if (is.plainObject(input) && !is.defined(inputOptions)) {
    // Plain Object descriptor, e.g. create
    inputOptions = input;
    if (_inputOptionsFromObject(inputOptions)) {
      // Stream with options
      inputDescriptor.buffer = [];
    }
  } else if (!is.defined(input) && !is.defined(inputOptions) && is.object(containerOptions) && containerOptions.allowStream) {
    // Stream without options
    inputDescriptor.buffer = [];
  } else {
    throw new Error(`Unsupported input '${input}' of type ${typeof input}${
      is.defined(inputOptions) ? ` when also providing options of type ${typeof inputOptions}` : ''
    }`);
  }
  if (is.object(inputOptions)) {
    // Fail on error
    if (is.defined(inputOptions.failOnError)) {
      if (is.bool(inputOptions.failOnError)) {
        inputDescriptor.failOnError = inputOptions.failOnError;
      } else {
        throw is.invalidParameterError('failOnError', 'boolean', inputOptions.failOnError);
      }
    }
    // Density
    if (is.defined(inputOptions.density)) {
      if (is.inRange(inputOptions.density, 1, 2400)) {
        inputDescriptor.density = inputOptions.density;
      } else {
        throw is.invalidParameterError('density', 'number between 1 and 2400', inputOptions.density);
      }
    }
    // limitInputPixels
    if (is.defined(inputOptions.limitInputPixels)) {
      if (is.bool(inputOptions.limitInputPixels)) {
        inputDescriptor.limitInputPixels = inputOptions.limitInputPixels
          ? Math.pow(0x3FFF, 2)
          : 0;
      } else if (is.integer(inputOptions.limitInputPixels) && inputOptions.limitInputPixels >= 0) {
        inputDescriptor.limitInputPixels = inputOptions.limitInputPixels;
      } else {
        throw is.invalidParameterError('limitInputPixels', 'integer >= 0', inputOptions.limitInputPixels);
      }
    }
    // sequentialRead
    if (is.defined(inputOptions.sequentialRead)) {
      if (is.bool(inputOptions.sequentialRead)) {
        inputDescriptor.sequentialRead = inputOptions.sequentialRead;
      } else {
        throw is.invalidParameterError('sequentialRead', 'boolean', inputOptions.sequentialRead);
      }
    }
    // Raw pixel input
    if (is.defined(inputOptions.raw)) {
      if (
        is.object(inputOptions.raw) &&
        is.integer(inputOptions.raw.width) && inputOptions.raw.width > 0 &&
        is.integer(inputOptions.raw.height) && inputOptions.raw.height > 0 &&
        is.integer(inputOptions.raw.channels) && is.inRange(inputOptions.raw.channels, 1, 4)
      ) {
        inputDescriptor.rawWidth = inputOptions.raw.width;
        inputDescriptor.rawHeight = inputOptions.raw.height;
        inputDescriptor.rawChannels = inputOptions.raw.channels;
      } else {
        throw new Error('Expected width, height and channels for raw pixel input');
      }
    }
    // Multi-page input (GIF, TIFF, PDF)
    if (is.defined(inputOptions.pages)) {
      if (is.integer(inputOptions.pages) && is.inRange(inputOptions.pages, -1, 100000)) {
        inputDescriptor.pages = inputOptions.pages;
      } else {
        throw is.invalidParameterError('pages', 'integer between -1 and 100000', inputOptions.pages);
      }
    }
    if (is.defined(inputOptions.page)) {
      if (is.integer(inputOptions.page) && is.inRange(inputOptions.page, 0, 100000)) {
        inputDescriptor.page = inputOptions.page;
      } else {
        throw is.invalidParameterError('page', 'integer between 0 and 100000', inputOptions.page);
      }
    }
    // Create new image
    if (is.defined(inputOptions.create)) {
      if (
        is.object(inputOptions.create) &&
        is.integer(inputOptions.create.width) && inputOptions.create.width > 0 &&
        is.integer(inputOptions.create.height) && inputOptions.create.height > 0 &&
        is.integer(inputOptions.create.channels) && is.inRange(inputOptions.create.channels, 3, 4) &&
        is.defined(inputOptions.create.background)
      ) {
        inputDescriptor.createWidth = inputOptions.create.width;
        inputDescriptor.createHeight = inputOptions.create.height;
        inputDescriptor.createChannels = inputOptions.create.channels;
        const background = color(inputOptions.create.background);
        inputDescriptor.createBackground = [
          background.red(),
          background.green(),
          background.blue(),
          Math.round(background.alpha() * 255)
        ];
        delete inputDescriptor.buffer;
      } else {
        throw new Error('Expected width, height, channels and background to create a new input image');
      }
    }
  } else if (is.defined(inputOptions)) {
    throw new Error('Invalid input options ' + inputOptions);
  }
  return inputDescriptor;
}

/**
 * Handle incoming Buffer chunk on Writable Stream.
 * @private
 * @param {Buffer} chunk
 * @param {string} encoding - unused
 * @param {Function} callback
 */
function _write (chunk, encoding, callback) {
  /* istanbul ignore else */
  if (Array.isArray(this.options.input.buffer)) {
    /* istanbul ignore else */
    if (is.buffer(chunk)) {
      if (this.options.input.buffer.length === 0) {
        this.on('finish', () => {
          this.streamInFinished = true;
        });
      }
      this.options.input.buffer.push(chunk);
      callback();
    } else {
      callback(new Error('Non-Buffer data on Writable Stream'));
    }
  } else {
    callback(new Error('Unexpected data on Writable Stream'));
  }
}

/**
 * Flattens the array of chunks accumulated in input.buffer.
 * @private
 */
function _flattenBufferIn () {
  if (this._isStreamInput()) {
    this.options.input.buffer = Buffer.concat(this.options.input.buffer);
  }
}

/**
 * Are we expecting Stream-based input?
 * @private
 * @returns {boolean}
 */
function _isStreamInput () {
  return Array.isArray(this.options.input.buffer);
}

/**
 * Fast access to (uncached) image metadata without decoding any compressed image data.
 * A `Promise` is returned when `callback` is not provided.
 *
 * - `format`: Name of decoder used to decompress image data e.g. `jpeg`, `png`, `webp`, `gif`, `svg`
 * - `size`: Total size of image in bytes, for Stream and Buffer input only
 * - `width`: Number of pixels wide (EXIF orientation is not taken into consideration)
 * - `height`: Number of pixels high (EXIF orientation is not taken into consideration)
 * - `space`: Name of colour space interpretation e.g. `srgb`, `rgb`, `cmyk`, `lab`, `b-w` [...](https://libvips.github.io/libvips/API/current/VipsImage.html#VipsInterpretation)
 * - `channels`: Number of bands e.g. `3` for sRGB, `4` for CMYK
 * - `depth`: Name of pixel depth format e.g. `uchar`, `char`, `ushort`, `float` [...](https://libvips.github.io/libvips/API/current/VipsImage.html#VipsBandFormat)
 * - `density`: Number of pixels per inch (DPI), if present
 * - `chromaSubsampling`: String containing JPEG chroma subsampling, `4:2:0` or `4:4:4` for RGB, `4:2:0:4` or `4:4:4:4` for CMYK
 * - `isProgressive`: Boolean indicating whether the image is interlaced using a progressive scan
 * - `pages`: Number of pages/frames contained within the image, with support for TIFF, HEIF, PDF, animated GIF and animated WebP
 * - `pageHeight`: Number of pixels high each page in a multi-page image will be.
 * - `loop`: Number of times to loop an animated image, zero refers to a continuous loop.
 * - `delay`: Delay in ms between each page in an animated image, provided as an array of integers.
 * - `pagePrimary`: Number of the primary page in a HEIF image
 * - `hasProfile`: Boolean indicating the presence of an embedded ICC profile
 * - `hasAlpha`: Boolean indicating the presence of an alpha transparency channel
 * - `orientation`: Number value of the EXIF Orientation header, if present
 * - `exif`: Buffer containing raw EXIF data, if present
 * - `icc`: Buffer containing raw [ICC](https://www.npmjs.com/package/icc) profile data, if present
 * - `iptc`: Buffer containing raw IPTC data, if present
 * - `xmp`: Buffer containing raw XMP data, if present
 * - `tifftagPhotoshop`: Buffer containing raw TIFFTAG_PHOTOSHOP data, if present
 *
 * @example
 * const image = sharp(inputJpg);
 * image
 *   .metadata()
 *   .then(function(metadata) {
 *     return image
 *       .resize(Math.round(metadata.width / 2))
 *       .webp()
 *       .toBuffer();
 *   })
 *   .then(function(data) {
 *     // data contains a WebP image half the width and height of the original JPEG
 *   });
 *
 * @param {Function} [callback] - called with the arguments `(err, metadata)`
 * @returns {Promise<Object>|Sharp}
 */
function metadata (callback) {
  if (is.fn(callback)) {
    if (this._isStreamInput()) {
      this.on('finish', () => {
        this._flattenBufferIn();
        sharp.metadata(this.options, callback);
      });
    } else {
      sharp.metadata(this.options, callback);
    }
    return this;
  } else {
    if (this._isStreamInput()) {
      return new Promise((resolve, reject) => {
        this.on('finish', () => {
          this._flattenBufferIn();
          sharp.metadata(this.options, (err, metadata) => {
            if (err) {
              reject(err);
            } else {
              resolve(metadata);
            }
          });
        });
      });
    } else {
      return new Promise((resolve, reject) => {
        sharp.metadata(this.options, (err, metadata) => {
          if (err) {
            reject(err);
          } else {
            resolve(metadata);
          }
        });
      });
    }
  }
}

/**
 * Access to pixel-derived image statistics for every channel in the image.
 * A `Promise` is returned when `callback` is not provided.
 *
 * - `channels`: Array of channel statistics for each channel in the image. Each channel statistic contains
 *     - `min` (minimum value in the channel)
 *     - `max` (maximum value in the channel)
 *     - `sum` (sum of all values in a channel)
 *     - `squaresSum` (sum of squared values in a channel)
 *     - `mean` (mean of the values in a channel)
 *     - `stdev` (standard deviation for the values in a channel)
 *     - `minX` (x-coordinate of one of the pixel where the minimum lies)
 *     - `minY` (y-coordinate of one of the pixel where the minimum lies)
 *     - `maxX` (x-coordinate of one of the pixel where the maximum lies)
 *     - `maxY` (y-coordinate of one of the pixel where the maximum lies)
 * - `isOpaque`: Is the image fully opaque? Will be `true` if the image has no alpha channel or if every pixel is fully opaque.
 * - `entropy`: Histogram-based estimation of greyscale entropy, discarding alpha channel if any (experimental)
 *
 * @example
 * const image = sharp(inputJpg);
 * image
 *   .stats()
 *   .then(function(stats) {
 *      // stats contains the channel-wise statistics array and the isOpaque value
 *   });
 *
 * @param {Function} [callback] - called with the arguments `(err, stats)`
 * @returns {Promise<Object>}
 */
function stats (callback) {
  if (is.fn(callback)) {
    if (this._isStreamInput()) {
      this.on('finish', () => {
        this._flattenBufferIn();
        sharp.stats(this.options, callback);
      });
    } else {
      sharp.stats(this.options, callback);
    }
    return this;
  } else {
    if (this._isStreamInput()) {
      return new Promise((resolve, reject) => {
        this.on('finish', function () {
          this._flattenBufferIn();
          sharp.stats(this.options, (err, stats) => {
            if (err) {
              reject(err);
            } else {
              resolve(stats);
            }
          });
        });
      });
    } else {
      return new Promise((resolve, reject) => {
        sharp.stats(this.options, (err, stats) => {
          if (err) {
            reject(err);
          } else {
            resolve(stats);
          }
        });
      });
    }
  }
}

/**
 * Decorate the Sharp prototype with input-related functions.
 * @private
 */
module.exports = function (Sharp) {
  Object.assign(Sharp.prototype, {
    // Private
    _inputOptionsFromObject,
    _createInputDescriptor,
    _write,
    _flattenBufferIn,
    _isStreamInput,
    // Public
    metadata,
    stats
  });
};