/
affine.ts
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/
affine.ts
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/*
* Copyright (c) 2016-present Invertase Limited
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this library except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import * as sharp from 'sharp';
import * as superstruct from 'superstruct';
import * as utils from '../utils';
import { OperationBuilder } from '../types';
/**
* The user visible name of this operation.
*/
const name = 'affine';
/**
* Perform an affine transform on an image.
* You must provide a matrix array of length 4 affine transformation matrix.
*
* By default, new pixels are filled with a black background. You can provide a
* background color with the background option.
*
* A particular interpolator may also be specified via the interpolator option.
*/
const struct = superstruct.object({
operation: superstruct.literal(name),
/**
* Affine transformation matrix.
* You must provide a array of length 4 affine transformation matrix,
* e.g., `[1,0.3,0.1,0.7]`
*
* Must be a single array of 4 numbers.
*/
matrix: utils.coerceStringToArray(
superstruct.size(superstruct.array(superstruct.number()), 4, 4),
),
/**
* Background color to fill new pixels with.
* See the [color npm library](https://www.npmjs.com/package/color) for supported string formats.
* Defaults to black without transparency.
*/
background: superstruct.optional(superstruct.string()),
/**
* Input horizontal offset.
*/
idx: superstruct.optional(
utils.coerceStringToInt(superstruct.min(superstruct.integer(), 0)),
),
/**
* Input vertical offset.
*/
idy: superstruct.optional(
utils.coerceStringToInt(superstruct.min(superstruct.integer(), 0)),
),
/**
* Output horizontal offset.
*/
odx: superstruct.optional(
utils.coerceStringToInt(superstruct.min(superstruct.integer(), 0)),
),
/**
* Output vertical offset.
*/
ody: superstruct.optional(
utils.coerceStringToInt(superstruct.min(superstruct.integer(), 0)),
),
/**
* Interpolator to use, defaults to `bicubic`
*/
interpolator: superstruct.optional(
superstruct.enums([
/**
* [Nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
* Suitable for image enlargement only.
*/
'nearest',
/**
* [Bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation).
* Faster than bicubic but with less smooth results.
*/
'bilinear',
/**
* [Bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation)
* (the default).
*/
'bicubic',
/**
* [LBB interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/lbb.cpp#L100).
* Prevents some "[acutance](http://en.wikipedia.org/wiki/Acutance)" but typically reduces performance
* by a factor of 2.
*/
'locallyBoundedBicubic',
/**
* [Nohalo interpolation](http://eprints.soton.ac.uk/268086/).
* Prevents acutance but typically reduces performance by a factor of 3.
*/
'nohalo',
/**
* [Vertex Split Quadratic Basis Spline interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48).
* Prevents "staircasing" when enlarging.
*/
'vertexSplitQuadraticBasisSpline',
]),
),
});
export type OperationAffine = superstruct.Infer<typeof struct>;
export const operationAffine: OperationBuilder = {
name,
struct,
build(operation) {
const options = operation.options as OperationAffine;
if (options.interpolator) {
// @ts-ignore, types are invalid - this does actually exist.
options.interpolator = sharp.default.interpolators[options.interpolator];
}
return [
{
method: name,
arguments: [options.matrix, utils.omitKey(options, 'matrix')],
},
];
},
};