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dbda22c | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 | // Copyright 2013 Lovell Fuller and others.
// SPDX-License-Identifier: Apache-2.0
'use strict';
const is = require('./is');
/**
* Boolean operations for bandbool.
* @private
*/
const bool = {
and: 'and',
or: 'or',
eor: 'eor'
};
/**
* Remove alpha channel, if any. This is a no-op if the image does not have an alpha channel.
*
* See also {@link /api-operation#flatten|flatten}.
*
* @example
* sharp('rgba.png')
* .removeAlpha()
* .toFile('rgb.png', function(err, info) {
* // rgb.png is a 3 channel image without an alpha channel
* });
*
* @returns {Sharp}
*/
function removeAlpha () {
this.options.removeAlpha = true;
return this;
}
/**
* Ensure the output image has an alpha transparency channel.
* If missing, the added alpha channel will have the specified
* transparency level, defaulting to fully-opaque (1).
* This is a no-op if the image already has an alpha channel.
*
* @since 0.21.2
*
* @example
* // rgba.png will be a 4 channel image with a fully-opaque alpha channel
* await sharp('rgb.jpg')
* .ensureAlpha()
* .toFile('rgba.png')
*
* @example
* // rgba is a 4 channel image with a fully-transparent alpha channel
* const rgba = await sharp(rgb)
* .ensureAlpha(0)
* .toBuffer();
*
* @param {number} [alpha=1] - alpha transparency level (0=fully-transparent, 1=fully-opaque)
* @returns {Sharp}
* @throws {Error} Invalid alpha transparency level
*/
function ensureAlpha (alpha) {
if (is.defined(alpha)) {
if (is.number(alpha) && is.inRange(alpha, 0, 1)) {
this.options.ensureAlpha = alpha;
} else {
throw is.invalidParameterError('alpha', 'number between 0 and 1', alpha);
}
} else {
this.options.ensureAlpha = 1;
}
return this;
}
/**
* Extract a single channel from a multi-channel image.
*
* @example
* // green.jpg is a greyscale image containing the green channel of the input
* await sharp(input)
* .extractChannel('green')
* .toFile('green.jpg');
*
* @example
* // red1 is the red value of the first pixel, red2 the second pixel etc.
* const [red1, red2, ...] = await sharp(input)
* .extractChannel(0)
* .raw()
* .toBuffer();
*
* @param {number|string} channel - zero-indexed channel/band number to extract, or `red`, `green`, `blue` or `alpha`.
* @returns {Sharp}
* @throws {Error} Invalid channel
*/
function extractChannel (channel) {
const channelMap = { red: 0, green: 1, blue: 2, alpha: 3 };
if (Object.keys(channelMap).includes(channel)) {
channel = channelMap[channel];
}
if (is.integer(channel) && is.inRange(channel, 0, 4)) {
this.options.extractChannel = channel;
} else {
throw is.invalidParameterError('channel', 'integer or one of: red, green, blue, alpha', channel);
}
return this;
}
/**
* Join one or more channels to the image.
* The meaning of the added channels depends on the output colourspace, set with `toColourspace()`.
* By default the output image will be web-friendly sRGB, with additional channels interpreted as alpha channels.
* Channel ordering follows vips convention:
* - sRGB: 0: Red, 1: Green, 2: Blue, 3: Alpha.
* - CMYK: 0: Magenta, 1: Cyan, 2: Yellow, 3: Black, 4: Alpha.
*
* Buffers may be any of the image formats supported by sharp.
* For raw pixel input, the `options` object should contain a `raw` attribute, which follows the format of the attribute of the same name in the `sharp()` constructor.
*
* @param {Array<string|Buffer>|string|Buffer} images - one or more images (file paths, Buffers).
* @param {Object} options - image options, see `sharp()` constructor.
* @returns {Sharp}
* @throws {Error} Invalid parameters
*/
function joinChannel (images, options) {
if (Array.isArray(images)) {
images.forEach(function (image) {
this.options.joinChannelIn.push(this._createInputDescriptor(image, options));
}, this);
} else {
this.options.joinChannelIn.push(this._createInputDescriptor(images, options));
}
return this;
}
/**
* Perform a bitwise boolean operation on all input image channels (bands) to produce a single channel output image.
*
* @example
* sharp('3-channel-rgb-input.png')
* .bandbool(sharp.bool.and)
* .toFile('1-channel-output.png', function (err, info) {
* // The output will be a single channel image where each pixel `P = R & G & B`.
* // If `I(1,1) = [247, 170, 14] = [0b11110111, 0b10101010, 0b00001111]`
* // then `O(1,1) = 0b11110111 & 0b10101010 & 0b00001111 = 0b00000010 = 2`.
* });
*
* @param {string} boolOp - one of `and`, `or` or `eor` to perform that bitwise operation, like the C logic operators `&`, `|` and `^` respectively.
* @returns {Sharp}
* @throws {Error} Invalid parameters
*/
function bandbool (boolOp) {
if (is.string(boolOp) && is.inArray(boolOp, ['and', 'or', 'eor'])) {
this.options.bandBoolOp = boolOp;
} else {
throw is.invalidParameterError('boolOp', 'one of: and, or, eor', boolOp);
}
return this;
}
/**
* Decorate the Sharp prototype with channel-related functions.
* @private
*/
module.exports = function (Sharp) {
Object.assign(Sharp.prototype, {
// Public instance functions
removeAlpha,
ensureAlpha,
extractChannel,
joinChannel,
bandbool
});
// Class attributes
Sharp.bool = bool;
};
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