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/**
* Copyright (c) 2015 Guyon Roche
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:</p>
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
const operations = {
nearestNeighbor(src, dst) {
const wSrc = src.width;
const hSrc = src.height;
const wDst = dst.width;
const hDst = dst.height;
const bufSrc = src.data;
const bufDst = dst.data;
for (let i = 0; i < hDst; i++) {
for (let j = 0; j < wDst; j++) {
let posDst = (i * wDst + j) * 4;
const iSrc = Math.floor(i * hSrc / hDst);
const jSrc = Math.floor(j * wSrc / wDst);
let posSrc = (iSrc * wSrc + jSrc) * 4;
bufDst[posDst++] = bufSrc[posSrc++];
bufDst[posDst++] = bufSrc[posSrc++];
bufDst[posDst++] = bufSrc[posSrc++];
bufDst[posDst++] = bufSrc[posSrc++];
}
}
},
bilinearInterpolation(src, dst) {
const wSrc = src.width;
const hSrc = src.height;
const wDst = dst.width;
const hDst = dst.height;
const bufSrc = src.data;
const bufDst = dst.data;
const interpolate = function (k, kMin, vMin, kMax, vMax) {
// special case - k is integer
if (kMin === kMax) {
return vMin;
}
return Math.round((k - kMin) * vMax + (kMax - k) * vMin);
};
const assign = function (pos, offset, x, xMin, xMax, y, yMin, yMax) {
let posMin = (yMin * wSrc + xMin) * 4 + offset;
let posMax = (yMin * wSrc + xMax) * 4 + offset;
const vMin = interpolate(x, xMin, bufSrc[posMin], xMax, bufSrc[posMax]);
// special case, y is integer
if (yMax === yMin) {
bufDst[pos + offset] = vMin;
} else {
posMin = (yMax * wSrc + xMin) * 4 + offset;
posMax = (yMax * wSrc + xMax) * 4 + offset;
const vMax = interpolate(x, xMin, bufSrc[posMin], xMax, bufSrc[posMax]);
bufDst[pos + offset] = interpolate(y, yMin, vMin, yMax, vMax);
}
};
for (let i = 0; i < hDst; i++) {
for (let j = 0; j < wDst; j++) {
const posDst = (i * wDst + j) * 4;
// x & y in src coordinates
const x = j * wSrc / wDst;
const xMin = Math.floor(x);
const xMax = Math.min(Math.ceil(x), wSrc - 1);
const y = i * hSrc / hDst;
const yMin = Math.floor(y);
const yMax = Math.min(Math.ceil(y), hSrc - 1);
assign(posDst, 0, x, xMin, xMax, y, yMin, yMax);
assign(posDst, 1, x, xMin, xMax, y, yMin, yMax);
assign(posDst, 2, x, xMin, xMax, y, yMin, yMax);
assign(posDst, 3, x, xMin, xMax, y, yMin, yMax);
}
}
},
_interpolate2D(src, dst, options, interpolate) {
const bufSrc = src.data;
const bufDst = dst.data;
const wSrc = src.width;
const hSrc = src.height;
const wDst = dst.width;
const hDst = dst.height;
// when dst smaller than src/2, interpolate first to a multiple between 0.5 and 1.0 src, then sum squares
const wM = Math.max(1, Math.floor(wSrc / wDst));
const wDst2 = wDst * wM;
const hM = Math.max(1, Math.floor(hSrc / hDst));
const hDst2 = hDst * hM;
// ===========================================================
// Pass 1 - interpolate rows
// buf1 has width of dst2 and height of src
const buf1 = Buffer.alloc(wDst2 * hSrc * 4);
for (let i = 0; i < hSrc; i++) {
for (let j = 0; j < wDst2; j++) {
// i in src coords, j in dst coords
// calculate x in src coords
// this interpolation requires 4 sample points and the two inner ones must be real
// the outer points can be fudged for the edges.
// therefore (wSrc-1)/wDst2
const x = j * (wSrc - 1) / wDst2;
const xPos = Math.floor(x);
const t = x - xPos;
const srcPos = (i * wSrc + xPos) * 4;
const buf1Pos = (i * wDst2 + j) * 4;
for (let k = 0; k < 4; k++) {
const kPos = srcPos + k;
const x0 = xPos > 0 ? bufSrc[kPos - 4] : 2 * bufSrc[kPos] - bufSrc[kPos + 4];
const x1 = bufSrc[kPos];
const x2 = bufSrc[kPos + 4];
const x3 = xPos < wSrc - 2 ? bufSrc[kPos + 8] : 2 * bufSrc[kPos + 4] - bufSrc[kPos];
buf1[buf1Pos + k] = interpolate(x0, x1, x2, x3, t);
}
}
}
// this._writeFile(wDst2, hSrc, buf1, "out/buf1.jpg");
// ===========================================================
// Pass 2 - interpolate columns
// buf2 has width and height of dst2
const buf2 = Buffer.alloc(wDst2 * hDst2 * 4);
for (let i = 0; i < hDst2; i++) {
for (let j = 0; j < wDst2; j++) {
// i&j in dst2 coords
// calculate y in buf1 coords
// this interpolation requires 4 sample points and the two inner ones must be real
// the outer points can be fudged for the edges.
// therefore (hSrc-1)/hDst2
const y = i * (hSrc - 1) / hDst2;
const yPos = Math.floor(y);
const t = y - yPos;
const buf1Pos = (yPos * wDst2 + j) * 4;
const buf2Pos = (i * wDst2 + j) * 4;
for (let k = 0; k < 4; k++) {
const kPos = buf1Pos + k;
const y0 = yPos > 0 ? buf1[kPos - wDst2 * 4] : 2 * buf1[kPos] - buf1[kPos + wDst2 * 4];
const y1 = buf1[kPos];
const y2 = buf1[kPos + wDst2 * 4];
const y3 = yPos < hSrc - 2 ? buf1[kPos + wDst2 * 8] : 2 * buf1[kPos + wDst2 * 4] - buf1[kPos];
buf2[buf2Pos + k] = interpolate(y0, y1, y2, y3, t);
}
}
}
// this._writeFile(wDst2, hDst2, buf2, "out/buf2.jpg");
// ===========================================================
// Pass 3 - scale to dst
const m = wM * hM;
if (m > 1) {
for (let i = 0; i < hDst; i++) {
for (let j = 0; j < wDst; j++) {
// i&j in dst bounded coords
let r = 0;
let g = 0;
let b = 0;
let a = 0;
let realColors = 0;
for (let y = 0; y < hM; y++) {
const yPos = i * hM + y;
for (let x = 0; x < wM; x++) {
const xPos = j * wM + x;
const xyPos = (yPos * wDst2 + xPos) * 4;
const pixelAlpha = buf2[xyPos + 3];
if (pixelAlpha) {
r += buf2[xyPos];
g += buf2[xyPos + 1];
b += buf2[xyPos + 2];
realColors++;
}
a += pixelAlpha;
}
}
const pos = (i * wDst + j) * 4;
bufDst[pos] = realColors ? Math.round(r / realColors) : 0;
bufDst[pos + 1] = realColors ? Math.round(g / realColors) : 0;
bufDst[pos + 2] = realColors ? Math.round(b / realColors) : 0;
bufDst[pos + 3] = Math.round(a / m);
}
}
} else {
// replace dst buffer with buf2
dst.data = buf2;
}
},
bicubicInterpolation(src, dst, options) {
const interpolateCubic = function (x0, x1, x2, x3, t) {
const a0 = x3 - x2 - x0 + x1;
const a1 = x0 - x1 - a0;
const a2 = x2 - x0;
const a3 = x1;
return Math.max(0, Math.min(255, a0 * (t * t * t) + a1 * (t * t) + a2 * t + a3));
};
return this._interpolate2D(src, dst, options, interpolateCubic);
},
hermiteInterpolation(src, dst, options) {
const interpolateHermite = function (x0, x1, x2, x3, t) {
const c0 = x1;
const c1 = 0.5 * (x2 - x0);
const c2 = x0 - 2.5 * x1 + 2 * x2 - 0.5 * x3;
const c3 = 0.5 * (x3 - x0) + 1.5 * (x1 - x2);
return Math.max(0, Math.min(255, Math.round(((c3 * t + c2) * t + c1) * t + c0)));
};
return this._interpolate2D(src, dst, options, interpolateHermite);
},
bezierInterpolation(src, dst, options) {
// between 2 points y(n), y(n+1), use next points out, y(n-1), y(n+2)
// to predict control points (a & b) to be placed at n+0.5
// ya(n) = y(n) + (y(n+1)-y(n-1))/4
// yb(n) = y(n+1) - (y(n+2)-y(n))/4
// then use std bezier to interpolate [n,n+1)
// y(n+t) = y(n)*(1-t)^3 + 3 * ya(n)*(1-t)^2*t + 3 * yb(n)*(1-t)*t^2 + y(n+1)*t^3
// note the 3* factor for the two control points
// for edge cases, can choose:
// y(-1) = y(0) - 2*(y(1)-y(0))
// y(w) = y(w-1) + 2*(y(w-1)-y(w-2))
// but can go with y(-1) = y(0) and y(w) = y(w-1)
const interpolateBezier = function (x0, x1, x2, x3, t) {
// x1, x2 are the knots, use x0 and x3 to calculate control points
const cp1 = x1 + (x2 - x0) / 4;
const cp2 = x2 - (x3 - x1) / 4;
const nt = 1 - t;
const c0 = x1 * nt * nt * nt;
const c1 = 3 * cp1 * nt * nt * t;
const c2 = 3 * cp2 * nt * t * t;
const c3 = x2 * t * t * t;
return Math.max(0, Math.min(255, Math.round(c0 + c1 + c2 + c3)));
};
return this._interpolate2D(src, dst, options, interpolateBezier);
}
};
export default operations;
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