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composite.js
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composite.js
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'use strict';
const is = require('./is');
/**
* Blend modes.
* @member
* @private
*/
const blend = {
clear: 'clear',
source: 'source',
over: 'over',
in: 'in',
out: 'out',
atop: 'atop',
dest: 'dest',
'dest-over': 'dest-over',
'dest-in': 'dest-in',
'dest-out': 'dest-out',
'dest-atop': 'dest-atop',
xor: 'xor',
add: 'add',
saturate: 'saturate',
multiply: 'multiply',
screen: 'screen',
overlay: 'overlay',
darken: 'darken',
lighten: 'lighten',
'colour-dodge': 'colour-dodge',
'color-dodge': 'colour-dodge',
'colour-burn': 'colour-burn',
'color-burn': 'colour-burn',
'hard-light': 'hard-light',
'soft-light': 'soft-light',
difference: 'difference',
exclusion: 'exclusion'
};
/**
* Composite image(s) over the processed (resized, extracted etc.) image.
*
* The images to composite must be the same size or smaller than the processed image.
* If both `top` and `left` options are provided, they take precedence over `gravity`.
*
* The `blend` option can be one of `clear`, `source`, `over`, `in`, `out`, `atop`,
* `dest`, `dest-over`, `dest-in`, `dest-out`, `dest-atop`,
* `xor`, `add`, `saturate`, `multiply`, `screen`, `overlay`, `darken`, `lighten`,
* `colour-dodge`, `color-dodge`, `colour-burn`,`color-burn`,
* `hard-light`, `soft-light`, `difference`, `exclusion`.
*
* More information about blend modes can be found at
* https://www.libvips.org/API/current/libvips-conversion.html#VipsBlendMode
* and https://www.cairographics.org/operators/
*
* @since 0.22.0
*
* @example
* await sharp(background)
* .composite([
* { input: layer1, gravity: 'northwest' },
* { input: layer2, gravity: 'southeast' },
* ])
* .toFile('combined.png');
*
* @example
* const output = await sharp('input.gif', { animated: true })
* .composite([
* { input: 'overlay.png', tile: true, blend: 'saturate' }
* ])
* .toBuffer();
*
* @example
* sharp('input.png')
* .rotate(180)
* .resize(300)
* .flatten( { background: '#ff6600' } )
* .composite([{ input: 'overlay.png', gravity: 'southeast' }])
* .sharpen()
* .withMetadata()
* .webp( { quality: 90 } )
* .toBuffer()
* .then(function(outputBuffer) {
* // outputBuffer contains upside down, 300px wide, alpha channel flattened
* // onto orange background, composited with overlay.png with SE gravity,
* // sharpened, with metadata, 90% quality WebP image data. Phew!
* });
*
* @param {Object[]} images - Ordered list of images to composite
* @param {Buffer|String} [images[].input] - Buffer containing image data, String containing the path to an image file, or Create object (see below)
* @param {Object} [images[].input.create] - describes a blank overlay to be created.
* @param {Number} [images[].input.create.width]
* @param {Number} [images[].input.create.height]
* @param {Number} [images[].input.create.channels] - 3-4
* @param {String|Object} [images[].input.create.background] - parsed by the [color](https://www.npmjs.org/package/color) module to extract values for red, green, blue and alpha.
* @param {Object} [images[].input.text] - describes a new text image to be created.
* @param {string} [images[].input.text.text] - text to render as a UTF-8 string. It can contain Pango markup, for example `<i>Le</i>Monde`.
* @param {string} [images[].input.text.font] - font name to render with.
* @param {string} [images[].input.text.fontfile] - absolute filesystem path to a font file that can be used by `font`.
* @param {number} [images[].input.text.width=0] - integral number of pixels to word-wrap at. Lines of text wider than this will be broken at word boundaries.
* @param {number} [images[].input.text.height=0] - integral number of pixels high. When defined, `dpi` will be ignored and the text will automatically fit the pixel resolution defined by `width` and `height`. Will be ignored if `width` is not specified or set to 0.
* @param {string} [images[].input.text.align='left'] - text alignment (`'left'`, `'centre'`, `'center'`, `'right'`).
* @param {boolean} [images[].input.text.justify=false] - set this to true to apply justification to the text.
* @param {number} [images[].input.text.dpi=72] - the resolution (size) at which to render the text. Does not take effect if `height` is specified.
* @param {boolean} [images[].input.text.rgba=false] - set this to true to enable RGBA output. This is useful for colour emoji rendering, or support for pango markup features like `<span foreground="red">Red!</span>`.
* @param {number} [images[].input.text.spacing=0] - text line height in points. Will use the font line height if none is specified.
* @param {String} [images[].blend='over'] - how to blend this image with the image below.
* @param {String} [images[].gravity='centre'] - gravity at which to place the overlay.
* @param {Number} [images[].top] - the pixel offset from the top edge.
* @param {Number} [images[].left] - the pixel offset from the left edge.
* @param {Boolean} [images[].tile=false] - set to true to repeat the overlay image across the entire image with the given `gravity`.
* @param {Boolean} [images[].premultiplied=false] - set to true to avoid premultipling the image below. Equivalent to the `--premultiplied` vips option.
* @param {Number} [images[].density=72] - number representing the DPI for vector overlay image.
* @param {Object} [images[].raw] - describes overlay when using raw pixel data.
* @param {Number} [images[].raw.width]
* @param {Number} [images[].raw.height]
* @param {Number} [images[].raw.channels]
* @param {boolean} [images[].animated=false] - Set to `true` to read all frames/pages of an animated image.
* @param {string} [images[].failOn='warning'] - @see {@link /api-constructor#parameters|constructor parameters}
* @param {number|boolean} [images[].limitInputPixels=268402689] - @see {@link /api-constructor#parameters|constructor parameters}
* @returns {Sharp}
* @throws {Error} Invalid parameters
*/
function composite (images) {
if (!Array.isArray(images)) {
throw is.invalidParameterError('images to composite', 'array', images);
}
this.options.composite = images.map(image => {
if (!is.object(image)) {
throw is.invalidParameterError('image to composite', 'object', image);
}
const inputOptions = this._inputOptionsFromObject(image);
const composite = {
input: this._createInputDescriptor(image.input, inputOptions, { allowStream: false }),
blend: 'over',
tile: false,
left: 0,
top: 0,
hasOffset: false,
gravity: 0,
premultiplied: false
};
if (is.defined(image.blend)) {
if (is.string(blend[image.blend])) {
composite.blend = blend[image.blend];
} else {
throw is.invalidParameterError('blend', 'valid blend name', image.blend);
}
}
if (is.defined(image.tile)) {
if (is.bool(image.tile)) {
composite.tile = image.tile;
} else {
throw is.invalidParameterError('tile', 'boolean', image.tile);
}
}
if (is.defined(image.left)) {
if (is.integer(image.left)) {
composite.left = image.left;
} else {
throw is.invalidParameterError('left', 'integer', image.left);
}
}
if (is.defined(image.top)) {
if (is.integer(image.top)) {
composite.top = image.top;
} else {
throw is.invalidParameterError('top', 'integer', image.top);
}
}
if (is.defined(image.top) !== is.defined(image.left)) {
throw new Error('Expected both left and top to be set');
} else {
composite.hasOffset = is.integer(image.top) && is.integer(image.left);
}
if (is.defined(image.gravity)) {
if (is.integer(image.gravity) && is.inRange(image.gravity, 0, 8)) {
composite.gravity = image.gravity;
} else if (is.string(image.gravity) && is.integer(this.constructor.gravity[image.gravity])) {
composite.gravity = this.constructor.gravity[image.gravity];
} else {
throw is.invalidParameterError('gravity', 'valid gravity', image.gravity);
}
}
if (is.defined(image.premultiplied)) {
if (is.bool(image.premultiplied)) {
composite.premultiplied = image.premultiplied;
} else {
throw is.invalidParameterError('premultiplied', 'boolean', image.premultiplied);
}
}
return composite;
});
return this;
}
/**
* Decorate the Sharp prototype with composite-related functions.
* @private
*/
module.exports = function (Sharp) {
Sharp.prototype.composite = composite;
Sharp.blend = blend;
};