196 lines
6.9 KiB
JavaScript
196 lines
6.9 KiB
JavaScript
import { isNodePattern, throwError } from "@jimp/utils";
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/**
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* Rotates an image counter-clockwise by multiple of 90 degrees. NB: 'this' must be a Jimp object.
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*
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* This function is based on matrix rotation. Check this to get an initial idea how it works: https://stackoverflow.com/a/8664879/10561909
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*
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* @param {number} deg the number of degrees to rotate the image by, it should be a multiple of 90
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*/
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function matrixRotate(deg) {
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if (Math.abs(deg) % 90 !== 0) {
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throw new Error("Unsupported matrix rotation degree");
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}
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deg %= 360;
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if (Math.abs(deg) === 0) {
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// no rotation for 0, 360, -360, 720, -720, ...
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return;
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}
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const w = this.bitmap.width;
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const h = this.bitmap.height;
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// decide which rotation angle to use
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let angle;
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switch (deg) {
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// 90 degree & -270 degree are same
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case 90:
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case -270:
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angle = 90;
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break;
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case 180:
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case -180:
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angle = 180;
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break;
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case 270:
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case -90:
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angle = -90;
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break;
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default:
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throw new Error("Unsupported matrix rotation degree");
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}
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// After this switch block, angle will be 90, 180 or -90
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// calculate the new width and height
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const nW = angle === 180 ? w : h;
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const nH = angle === 180 ? h : w;
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const dstBuffer = Buffer.alloc(this.bitmap.data.length);
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// function to translate the x, y coordinate to the index of the pixel in the buffer
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function createIdxTranslationFunction(w, h) {
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return function (x, y) {
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return y * w + x << 2;
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};
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}
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const srcIdxFunction = createIdxTranslationFunction(w, h);
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const dstIdxFunction = createIdxTranslationFunction(nW, nH);
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for (let x = 0; x < w; x++) {
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for (let y = 0; y < h; y++) {
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const srcIdx = srcIdxFunction(x, y);
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const pixelRGBA = this.bitmap.data.readUInt32BE(srcIdx);
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let dstIdx;
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switch (angle) {
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case 90:
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dstIdx = dstIdxFunction(y, w - x - 1);
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break;
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case -90:
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dstIdx = dstIdxFunction(h - y - 1, x);
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break;
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case 180:
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dstIdx = dstIdxFunction(w - x - 1, h - y - 1);
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break;
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default:
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throw new Error("Unsupported matrix rotation angle");
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}
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dstBuffer.writeUInt32BE(pixelRGBA, dstIdx);
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}
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}
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this.bitmap.data = dstBuffer;
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this.bitmap.width = nW;
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this.bitmap.height = nH;
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}
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/**
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* Rotates an image counter-clockwise by an arbitrary number of degrees. NB: 'this' must be a Jimp object.
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* @param {number} deg the number of degrees to rotate the image by
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* @param {string|boolean} mode (optional) resize mode or a boolean, if false then the width and height of the image will not be changed
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*/
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function advancedRotate(deg, mode) {
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deg %= 360;
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const rad = deg * Math.PI / 180;
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const cosine = Math.cos(rad);
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const sine = Math.sin(rad);
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// the final width and height will change if resize == true
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let w = this.bitmap.width;
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let h = this.bitmap.height;
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if (mode === true || typeof mode === "string") {
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// resize the image to it maximum dimension and blit the existing image
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// onto the center so that when it is rotated the image is kept in bounds
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// http://stackoverflow.com/questions/3231176/how-to-get-size-of-a-rotated-rectangle
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// Plus 1 border pixel to ensure to show all rotated result for some cases.
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w = Math.ceil(Math.abs(this.bitmap.width * cosine) + Math.abs(this.bitmap.height * sine)) + 1;
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h = Math.ceil(Math.abs(this.bitmap.width * sine) + Math.abs(this.bitmap.height * cosine)) + 1;
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// Ensure destination to have even size to a better result.
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if (w % 2 !== 0) {
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w++;
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}
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if (h % 2 !== 0) {
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h++;
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}
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const c = this.cloneQuiet();
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this.scanQuiet(0, 0, this.bitmap.width, this.bitmap.height, function (x, y, idx) {
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this.bitmap.data.writeUInt32BE(this._background, idx);
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});
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const max = Math.max(w, h, this.bitmap.width, this.bitmap.height);
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this.resize(max, max, mode);
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this.blit(c, this.bitmap.width / 2 - c.bitmap.width / 2, this.bitmap.height / 2 - c.bitmap.height / 2);
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}
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const bW = this.bitmap.width;
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const bH = this.bitmap.height;
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const dstBuffer = Buffer.alloc(this.bitmap.data.length);
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function createTranslationFunction(deltaX, deltaY) {
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return function (x, y) {
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return {
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x: x + deltaX,
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y: y + deltaY
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};
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};
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}
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const translate2Cartesian = createTranslationFunction(-(bW / 2), -(bH / 2));
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const translate2Screen = createTranslationFunction(bW / 2 + 0.5, bH / 2 + 0.5);
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for (let y = 1; y <= bH; y++) {
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for (let x = 1; x <= bW; x++) {
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const cartesian = translate2Cartesian(x, y);
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const source = translate2Screen(cosine * cartesian.x - sine * cartesian.y, cosine * cartesian.y + sine * cartesian.x);
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const dstIdx = bW * (y - 1) + x - 1 << 2;
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if (source.x >= 0 && source.x < bW && source.y >= 0 && source.y < bH) {
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const srcIdx = (bW * (source.y | 0) + source.x | 0) << 2;
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const pixelRGBA = this.bitmap.data.readUInt32BE(srcIdx);
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dstBuffer.writeUInt32BE(pixelRGBA, dstIdx);
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} else {
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// reset off-image pixels
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dstBuffer.writeUInt32BE(this._background, dstIdx);
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}
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}
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}
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this.bitmap.data = dstBuffer;
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if (mode === true || typeof mode === "string") {
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// now crop the image to the final size
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const x = bW / 2 - w / 2;
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const y = bH / 2 - h / 2;
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this.crop(x, y, w, h);
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}
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}
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export default (() => ({
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/**
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* Rotates the image counter-clockwise by a number of degrees. By default the width and height of the image will be resized appropriately.
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* @param {number} deg the number of degrees to rotate the image by
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* @param {string|boolean} mode (optional) resize mode or a boolean, if false then the width and height of the image will not be changed
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* @param {function(Error, Jimp)} cb (optional) a callback for when complete
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* @returns {Jimp} this for chaining of methods
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*/
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rotate(deg, mode, cb) {
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// enable overloading
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if (typeof mode === "undefined" || mode === null) {
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// e.g. image.resize(120);
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// e.g. image.resize(120, null, cb);
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// e.g. image.resize(120, undefined, cb);
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mode = true;
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}
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if (typeof mode === "function" && typeof cb === "undefined") {
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// e.g. image.resize(120, cb);
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cb = mode;
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mode = true;
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}
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if (typeof deg !== "number") {
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return throwError.call(this, "deg must be a number", cb);
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}
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if (typeof mode !== "boolean" && typeof mode !== "string") {
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return throwError.call(this, "mode must be a boolean or a string", cb);
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}
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// use matrixRotate if the angle is a multiple of 90 degrees (eg: 180 or -90) and resize is allowed or not needed.
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const matrixRotateAllowed = deg % 90 === 0 && (mode || this.bitmap.width === this.bitmap.height || deg % 180 === 0);
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if (matrixRotateAllowed) {
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matrixRotate.call(this, deg);
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} else {
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advancedRotate.call(this, deg, mode, cb);
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}
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if (isNodePattern(cb)) {
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cb.call(this, null, this);
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}
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return this;
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}
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}));
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//# sourceMappingURL=index.js.map
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