583 lines
20 KiB
Plaintext
583 lines
20 KiB
Plaintext
// Copyright 2013 Lovell Fuller and others.
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// SPDX-License-Identifier: Apache-2.0
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'use strict';
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const is = require('./is');
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/**
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* Weighting to apply when using contain/cover fit.
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* @member
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* @private
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*/
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const gravity = {
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center: 0,
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centre: 0,
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north: 1,
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east: 2,
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south: 3,
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west: 4,
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northeast: 5,
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southeast: 6,
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southwest: 7,
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northwest: 8
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};
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/**
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* Position to apply when using contain/cover fit.
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* @member
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* @private
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*/
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const position = {
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top: 1,
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right: 2,
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bottom: 3,
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left: 4,
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'right top': 5,
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'right bottom': 6,
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'left bottom': 7,
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'left top': 8
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};
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/**
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* How to extend the image.
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* @member
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* @private
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*/
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const extendWith = {
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background: 'background',
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copy: 'copy',
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repeat: 'repeat',
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mirror: 'mirror'
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};
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/**
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* Strategies for automagic cover behaviour.
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* @member
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* @private
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*/
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const strategy = {
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entropy: 16,
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attention: 17
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};
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/**
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* Reduction kernels.
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* @member
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* @private
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*/
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const kernel = {
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nearest: 'nearest',
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cubic: 'cubic',
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mitchell: 'mitchell',
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lanczos2: 'lanczos2',
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lanczos3: 'lanczos3'
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};
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/**
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* Methods by which an image can be resized to fit the provided dimensions.
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* @member
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* @private
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*/
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const fit = {
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contain: 'contain',
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cover: 'cover',
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fill: 'fill',
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inside: 'inside',
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outside: 'outside'
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};
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/**
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* Map external fit property to internal canvas property.
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* @member
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* @private
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*/
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const mapFitToCanvas = {
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contain: 'embed',
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cover: 'crop',
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fill: 'ignore_aspect',
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inside: 'max',
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outside: 'min'
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};
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/**
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* @private
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*/
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function isRotationExpected (options) {
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return (options.angle % 360) !== 0 || options.useExifOrientation === true || options.rotationAngle !== 0;
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}
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/**
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* @private
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*/
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function isResizeExpected (options) {
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return options.width !== -1 || options.height !== -1;
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}
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/**
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* Resize image to `width`, `height` or `width x height`.
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*
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* When both a `width` and `height` are provided, the possible methods by which the image should **fit** these are:
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* - `cover`: (default) Preserving aspect ratio, attempt to ensure the image covers both provided dimensions by cropping/clipping to fit.
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* - `contain`: Preserving aspect ratio, contain within both provided dimensions using "letterboxing" where necessary.
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* - `fill`: Ignore the aspect ratio of the input and stretch to both provided dimensions.
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* - `inside`: Preserving aspect ratio, resize the image to be as large as possible while ensuring its dimensions are less than or equal to both those specified.
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* - `outside`: Preserving aspect ratio, resize the image to be as small as possible while ensuring its dimensions are greater than or equal to both those specified.
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*
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* Some of these values are based on the [object-fit](https://developer.mozilla.org/en-US/docs/Web/CSS/object-fit) CSS property.
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*
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* <img alt="Examples of various values for the fit property when resizing" width="100%" style="aspect-ratio: 998/243" src="https://cdn.jsdelivr.net/gh/lovell/sharp@main/docs/image/api-resize-fit.svg">
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*
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* When using a **fit** of `cover` or `contain`, the default **position** is `centre`. Other options are:
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* - `sharp.position`: `top`, `right top`, `right`, `right bottom`, `bottom`, `left bottom`, `left`, `left top`.
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* - `sharp.gravity`: `north`, `northeast`, `east`, `southeast`, `south`, `southwest`, `west`, `northwest`, `center` or `centre`.
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* - `sharp.strategy`: `cover` only, dynamically crop using either the `entropy` or `attention` strategy.
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*
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* Some of these values are based on the [object-position](https://developer.mozilla.org/en-US/docs/Web/CSS/object-position) CSS property.
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*
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* The experimental strategy-based approach resizes so one dimension is at its target length
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* then repeatedly ranks edge regions, discarding the edge with the lowest score based on the selected strategy.
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* - `entropy`: focus on the region with the highest [Shannon entropy](https://en.wikipedia.org/wiki/Entropy_%28information_theory%29).
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* - `attention`: focus on the region with the highest luminance frequency, colour saturation and presence of skin tones.
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*
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* Possible interpolation kernels are:
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* - `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
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* - `cubic`: Use a [Catmull-Rom spline](https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline).
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* - `mitchell`: Use a [Mitchell-Netravali spline](https://www.cs.utexas.edu/~fussell/courses/cs384g-fall2013/lectures/mitchell/Mitchell.pdf).
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* - `lanczos2`: Use a [Lanczos kernel](https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel) with `a=2`.
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* - `lanczos3`: Use a Lanczos kernel with `a=3` (the default).
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*
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* Only one resize can occur per pipeline.
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* Previous calls to `resize` in the same pipeline will be ignored.
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*
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* @example
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* sharp(input)
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* .resize({ width: 100 })
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* .toBuffer()
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* .then(data => {
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* // 100 pixels wide, auto-scaled height
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* });
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*
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* @example
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* sharp(input)
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* .resize({ height: 100 })
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* .toBuffer()
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* .then(data => {
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* // 100 pixels high, auto-scaled width
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* });
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*
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* @example
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* sharp(input)
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* .resize(200, 300, {
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* kernel: sharp.kernel.nearest,
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* fit: 'contain',
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* position: 'right top',
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* background: { r: 255, g: 255, b: 255, alpha: 0.5 }
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* })
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* .toFile('output.png')
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* .then(() => {
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* // output.png is a 200 pixels wide and 300 pixels high image
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* // containing a nearest-neighbour scaled version
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* // contained within the north-east corner of a semi-transparent white canvas
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* });
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*
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* @example
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* const transformer = sharp()
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* .resize({
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* width: 200,
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* height: 200,
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* fit: sharp.fit.cover,
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* position: sharp.strategy.entropy
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* });
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* // Read image data from readableStream
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* // Write 200px square auto-cropped image data to writableStream
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* readableStream
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* .pipe(transformer)
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* .pipe(writableStream);
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*
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* @example
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* sharp(input)
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* .resize(200, 200, {
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* fit: sharp.fit.inside,
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* withoutEnlargement: true
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* })
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* .toFormat('jpeg')
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* .toBuffer()
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* .then(function(outputBuffer) {
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* // outputBuffer contains JPEG image data
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* // no wider and no higher than 200 pixels
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* // and no larger than the input image
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* });
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*
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* @example
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* sharp(input)
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* .resize(200, 200, {
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* fit: sharp.fit.outside,
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* withoutReduction: true
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* })
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* .toFormat('jpeg')
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* .toBuffer()
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* .then(function(outputBuffer) {
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* // outputBuffer contains JPEG image data
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* // of at least 200 pixels wide and 200 pixels high while maintaining aspect ratio
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* // and no smaller than the input image
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* });
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*
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* @example
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* const scaleByHalf = await sharp(input)
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* .metadata()
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* .then(({ width }) => sharp(input)
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* .resize(Math.round(width * 0.5))
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* .toBuffer()
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* );
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*
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* @param {number} [width] - How many pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
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* @param {number} [height] - How many pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
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* @param {Object} [options]
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* @param {number} [options.width] - An alternative means of specifying `width`. If both are present this takes priority.
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* @param {number} [options.height] - An alternative means of specifying `height`. If both are present this takes priority.
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* @param {String} [options.fit='cover'] - How the image should be resized/cropped to fit the target dimension(s), one of `cover`, `contain`, `fill`, `inside` or `outside`.
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* @param {String} [options.position='centre'] - A position, gravity or strategy to use when `fit` is `cover` or `contain`.
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* @param {String|Object} [options.background={r: 0, g: 0, b: 0, alpha: 1}] - background colour when `fit` is `contain`, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black without transparency.
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* @param {String} [options.kernel='lanczos3'] - The kernel to use for image reduction. Use the `fastShrinkOnLoad` option to control kernel vs shrink-on-load.
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* @param {Boolean} [options.withoutEnlargement=false] - Do not scale up if the width *or* height are already less than the target dimensions, equivalent to GraphicsMagick's `>` geometry option. This may result in output dimensions smaller than the target dimensions.
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* @param {Boolean} [options.withoutReduction=false] - Do not scale down if the width *or* height are already greater than the target dimensions, equivalent to GraphicsMagick's `<` geometry option. This may still result in a crop to reach the target dimensions.
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* @param {Boolean} [options.fastShrinkOnLoad=true] - Take greater advantage of the JPEG and WebP shrink-on-load feature, which can lead to a slight moiré pattern or round-down of an auto-scaled dimension.
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* @returns {Sharp}
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* @throws {Error} Invalid parameters
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*/
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function resize (widthOrOptions, height, options) {
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if (isResizeExpected(this.options)) {
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this.options.debuglog('ignoring previous resize options');
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}
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if (is.defined(widthOrOptions)) {
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if (is.object(widthOrOptions) && !is.defined(options)) {
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options = widthOrOptions;
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} else if (is.integer(widthOrOptions) && widthOrOptions > 0) {
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this.options.width = widthOrOptions;
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} else {
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throw is.invalidParameterError('width', 'positive integer', widthOrOptions);
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}
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} else {
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this.options.width = -1;
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}
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if (is.defined(height)) {
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if (is.integer(height) && height > 0) {
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this.options.height = height;
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} else {
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throw is.invalidParameterError('height', 'positive integer', height);
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}
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} else {
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this.options.height = -1;
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}
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if (is.object(options)) {
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// Width
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if (is.defined(options.width)) {
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if (is.integer(options.width) && options.width > 0) {
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this.options.width = options.width;
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} else {
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throw is.invalidParameterError('width', 'positive integer', options.width);
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}
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}
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// Height
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if (is.defined(options.height)) {
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if (is.integer(options.height) && options.height > 0) {
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this.options.height = options.height;
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} else {
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throw is.invalidParameterError('height', 'positive integer', options.height);
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}
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}
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// Fit
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if (is.defined(options.fit)) {
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const canvas = mapFitToCanvas[options.fit];
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if (is.string(canvas)) {
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this.options.canvas = canvas;
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} else {
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throw is.invalidParameterError('fit', 'valid fit', options.fit);
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}
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}
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// Position
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if (is.defined(options.position)) {
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const pos = is.integer(options.position)
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? options.position
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: strategy[options.position] || position[options.position] || gravity[options.position];
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if (is.integer(pos) && (is.inRange(pos, 0, 8) || is.inRange(pos, 16, 17))) {
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this.options.position = pos;
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} else {
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throw is.invalidParameterError('position', 'valid position/gravity/strategy', options.position);
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}
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}
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// Background
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this._setBackgroundColourOption('resizeBackground', options.background);
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// Kernel
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if (is.defined(options.kernel)) {
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if (is.string(kernel[options.kernel])) {
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this.options.kernel = kernel[options.kernel];
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} else {
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throw is.invalidParameterError('kernel', 'valid kernel name', options.kernel);
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}
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}
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// Without enlargement
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if (is.defined(options.withoutEnlargement)) {
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this._setBooleanOption('withoutEnlargement', options.withoutEnlargement);
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}
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// Without reduction
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if (is.defined(options.withoutReduction)) {
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this._setBooleanOption('withoutReduction', options.withoutReduction);
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}
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// Shrink on load
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if (is.defined(options.fastShrinkOnLoad)) {
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this._setBooleanOption('fastShrinkOnLoad', options.fastShrinkOnLoad);
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}
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}
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if (isRotationExpected(this.options) && isResizeExpected(this.options)) {
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this.options.rotateBeforePreExtract = true;
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}
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return this;
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}
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/**
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* Extend / pad / extrude one or more edges of the image with either
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* the provided background colour or pixels derived from the image.
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* This operation will always occur after resizing and extraction, if any.
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*
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* @example
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* // Resize to 140 pixels wide, then add 10 transparent pixels
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* // to the top, left and right edges and 20 to the bottom edge
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* sharp(input)
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* .resize(140)
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* .extend({
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* top: 10,
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* bottom: 20,
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* left: 10,
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* right: 10,
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* background: { r: 0, g: 0, b: 0, alpha: 0 }
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* })
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* ...
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*
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* @example
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* // Add a row of 10 red pixels to the bottom
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* sharp(input)
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* .extend({
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* bottom: 10,
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* background: 'red'
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* })
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* ...
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*
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* @example
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* // Extrude image by 8 pixels to the right, mirroring existing right hand edge
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* sharp(input)
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* .extend({
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* right: 8,
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* background: 'mirror'
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* })
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* ...
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*
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* @param {(number|Object)} extend - single pixel count to add to all edges or an Object with per-edge counts
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* @param {number} [extend.top=0]
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* @param {number} [extend.left=0]
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* @param {number} [extend.bottom=0]
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* @param {number} [extend.right=0]
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* @param {String} [extend.extendWith='background'] - populate new pixels using this method, one of: background, copy, repeat, mirror.
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* @param {String|Object} [extend.background={r: 0, g: 0, b: 0, alpha: 1}] - background colour, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black without transparency.
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* @returns {Sharp}
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* @throws {Error} Invalid parameters
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*/
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function extend (extend) {
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if (is.integer(extend) && extend > 0) {
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this.options.extendTop = extend;
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this.options.extendBottom = extend;
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this.options.extendLeft = extend;
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this.options.extendRight = extend;
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} else if (is.object(extend)) {
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if (is.defined(extend.top)) {
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if (is.integer(extend.top) && extend.top >= 0) {
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this.options.extendTop = extend.top;
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} else {
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throw is.invalidParameterError('top', 'positive integer', extend.top);
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}
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}
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if (is.defined(extend.bottom)) {
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if (is.integer(extend.bottom) && extend.bottom >= 0) {
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this.options.extendBottom = extend.bottom;
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} else {
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throw is.invalidParameterError('bottom', 'positive integer', extend.bottom);
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}
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}
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if (is.defined(extend.left)) {
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if (is.integer(extend.left) && extend.left >= 0) {
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this.options.extendLeft = extend.left;
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} else {
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throw is.invalidParameterError('left', 'positive integer', extend.left);
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}
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}
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if (is.defined(extend.right)) {
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if (is.integer(extend.right) && extend.right >= 0) {
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this.options.extendRight = extend.right;
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} else {
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throw is.invalidParameterError('right', 'positive integer', extend.right);
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}
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}
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this._setBackgroundColourOption('extendBackground', extend.background);
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if (is.defined(extend.extendWith)) {
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if (is.string(extendWith[extend.extendWith])) {
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this.options.extendWith = extendWith[extend.extendWith];
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} else {
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throw is.invalidParameterError('extendWith', 'one of: background, copy, repeat, mirror', extend.extendWith);
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}
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}
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} else {
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throw is.invalidParameterError('extend', 'integer or object', extend);
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}
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return this;
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}
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/**
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* Extract/crop a region of the image.
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*
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* - Use `extract` before `resize` for pre-resize extraction.
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* - Use `extract` after `resize` for post-resize extraction.
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* - Use `extract` before and after for both.
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*
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* @example
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* sharp(input)
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* .extract({ left: left, top: top, width: width, height: height })
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* .toFile(output, function(err) {
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* // Extract a region of the input image, saving in the same format.
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* });
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* @example
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* sharp(input)
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* .extract({ left: leftOffsetPre, top: topOffsetPre, width: widthPre, height: heightPre })
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* .resize(width, height)
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* .extract({ left: leftOffsetPost, top: topOffsetPost, width: widthPost, height: heightPost })
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* .toFile(output, function(err) {
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* // Extract a region, resize, then extract from the resized image
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* });
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*
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* @param {Object} options - describes the region to extract using integral pixel values
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* @param {number} options.left - zero-indexed offset from left edge
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* @param {number} options.top - zero-indexed offset from top edge
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* @param {number} options.width - width of region to extract
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* @param {number} options.height - height of region to extract
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* @returns {Sharp}
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* @throws {Error} Invalid parameters
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*/
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function extract (options) {
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const suffix = isResizeExpected(this.options) || this.options.widthPre !== -1 ? 'Post' : 'Pre';
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if (this.options[`width${suffix}`] !== -1) {
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this.options.debuglog('ignoring previous extract options');
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}
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['left', 'top', 'width', 'height'].forEach(function (name) {
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const value = options[name];
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if (is.integer(value) && value >= 0) {
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this.options[name + (name === 'left' || name === 'top' ? 'Offset' : '') + suffix] = value;
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} else {
|
|
throw is.invalidParameterError(name, 'integer', value);
|
|
}
|
|
}, this);
|
|
// Ensure existing rotation occurs before pre-resize extraction
|
|
if (isRotationExpected(this.options) && !isResizeExpected(this.options)) {
|
|
if (this.options.widthPre === -1 || this.options.widthPost === -1) {
|
|
this.options.rotateBeforePreExtract = true;
|
|
}
|
|
}
|
|
return this;
|
|
}
|
|
|
|
/**
|
|
* Trim pixels from all edges that contain values similar to the given background colour, which defaults to that of the top-left pixel.
|
|
*
|
|
* Images with an alpha channel will use the combined bounding box of alpha and non-alpha channels.
|
|
*
|
|
* If the result of this operation would trim an image to nothing then no change is made.
|
|
*
|
|
* The `info` response Object, obtained from callback of `.toFile()` or `.toBuffer()`,
|
|
* will contain `trimOffsetLeft` and `trimOffsetTop` properties.
|
|
*
|
|
* @example
|
|
* // Trim pixels with a colour similar to that of the top-left pixel.
|
|
* sharp(input)
|
|
* .trim()
|
|
* .toFile(output, function(err, info) {
|
|
* ...
|
|
* });
|
|
* @example
|
|
* // Trim pixels with the exact same colour as that of the top-left pixel.
|
|
* sharp(input)
|
|
* .trim(0)
|
|
* .toFile(output, function(err, info) {
|
|
* ...
|
|
* });
|
|
* @example
|
|
* // Trim only pixels with a similar colour to red.
|
|
* sharp(input)
|
|
* .trim("#FF0000")
|
|
* .toFile(output, function(err, info) {
|
|
* ...
|
|
* });
|
|
* @example
|
|
* // Trim all "yellow-ish" pixels, being more lenient with the higher threshold.
|
|
* sharp(input)
|
|
* .trim({
|
|
* background: "yellow",
|
|
* threshold: 42,
|
|
* })
|
|
* .toFile(output, function(err, info) {
|
|
* ...
|
|
* });
|
|
*
|
|
* @param {string|number|Object} trim - the specific background colour to trim, the threshold for doing so or an Object with both.
|
|
* @param {string|Object} [trim.background='top-left pixel'] - background colour, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to that of the top-left pixel.
|
|
* @param {number} [trim.threshold=10] - the allowed difference from the above colour, a positive number.
|
|
* @returns {Sharp}
|
|
* @throws {Error} Invalid parameters
|
|
*/
|
|
function trim (trim) {
|
|
if (!is.defined(trim)) {
|
|
this.options.trimThreshold = 10;
|
|
} else if (is.string(trim)) {
|
|
this._setBackgroundColourOption('trimBackground', trim);
|
|
this.options.trimThreshold = 10;
|
|
} else if (is.number(trim)) {
|
|
if (trim >= 0) {
|
|
this.options.trimThreshold = trim;
|
|
} else {
|
|
throw is.invalidParameterError('threshold', 'positive number', trim);
|
|
}
|
|
} else if (is.object(trim)) {
|
|
this._setBackgroundColourOption('trimBackground', trim.background);
|
|
if (!is.defined(trim.threshold)) {
|
|
this.options.trimThreshold = 10;
|
|
} else if (is.number(trim.threshold) && trim.threshold >= 0) {
|
|
this.options.trimThreshold = trim.threshold;
|
|
} else {
|
|
throw is.invalidParameterError('threshold', 'positive number', trim);
|
|
}
|
|
} else {
|
|
throw is.invalidParameterError('trim', 'string, number or object', trim);
|
|
}
|
|
if (isRotationExpected(this.options)) {
|
|
this.options.rotateBeforePreExtract = true;
|
|
}
|
|
return this;
|
|
}
|
|
|
|
/**
|
|
* Decorate the Sharp prototype with resize-related functions.
|
|
* @private
|
|
*/
|
|
module.exports = function (Sharp) {
|
|
Object.assign(Sharp.prototype, {
|
|
resize,
|
|
extend,
|
|
extract,
|
|
trim
|
|
});
|
|
// Class attributes
|
|
Sharp.gravity = gravity;
|
|
Sharp.strategy = strategy;
|
|
Sharp.kernel = kernel;
|
|
Sharp.fit = fit;
|
|
Sharp.position = position;
|
|
};
|