fix: resolve transform core tools, add tests

2026-08-24 18:51:11 +05:00
parent 8745812a5f
commit ebc3c33c12
3 changed files with 95 additions and 61 deletions
@@ -67,14 +67,19 @@ describe('rotateFreeImage', () => {
 });

 describe('skewImage', () => {
-	it('наклон X=45° сдвигает верхний правый угол', () => {
-		const img = makeImage(2, 2, [
-			[255, 0, 0, 255], [0, 255, 0, 255],
-			[0, 0, 255, 255], [128, 128, 128, 255]
-		]);
+	it('наклон X=45° расширяет холст до w+h−1 и сдвигает строки вправо', () => {
+		const img = makeImage(2, 2, new Array(4).fill([255, 0, 0, 255]));
 		const out = skewImage(img, 45, 0);
-		expect(out.width).toBeGreaterThan(2);
-		expect(out.data[3]).toBe(255);
+		expect(out.width).toBe(3);
+		expect(out.height).toBe(2);
+		let opaque = 0;
+		for (let i = 3; i < out.data.length; i += 4) {
+			if (out.data[i] === 255) {
+				opaque++;
+				expect([out.data[i - 3], out.data[i - 2], out.data[i - 1]]).toEqual([255, 0, 0]);
+			}
+		}
+		expect(opaque).toBe(4);
 	});

 	it('углы 0° — тождественное преобразование', () => {
@@ -87,3 +92,25 @@ describe('skewImage', () => {
 		expect([...out.data]).toEqual([...img.data]);
 	});
 });
+
+describe('transformImage — заливка фона', () => {
+	it('сдвиг с белым фоном заполняет освободившийся край', () => {
+		const img = makeImage(2, 2, [
+			[255, 0, 0, 255], [0, 255, 0, 255],
+			[0, 0, 255, 255], [128, 128, 128, 255]
+		]);
+		const out = transformImage(img, [1, 0, 0, 1, -1, 0], 2, 2, '#ffffff');
+		expect(out.width).toBe(2);
+		expect(out.height).toBe(2);
+		for (let y = 0; y < 2; y++) {
+			const di = (y * 2) * 4;
+			expect([...out.data.slice(di, di + 4)]).toEqual([255, 255, 255, 255]);
+		}
+	});
+
+	it('без фона освободившийся край остаётся прозрачным', () => {
+		const img = makeImage(2, 2, new Array(4).fill([10, 20, 30, 255]));
+		const out = transformImage(img, [1, 0, 0, 1, -1, 0], 2, 2);
+		expect(out.data[3]).toBe(0);
+	});
+});
@@ -1,3 +1,4 @@
+import { parseHex } from './alpha';
 import { clonePixelImage, createPixelImage, type PixelImage } from './types';
 import { sampleBilinear } from './geometry';

@@ -15,61 +16,75 @@ export function invertAffine([a, b, c, d, e, f]: AffineMatrix): AffineMatrix {
 	return [ia, ib, ic, id, -(ia * e + ic * f), -(ib * e + id * f)];
 }

-function mulAffine(m1: AffineMatrix, m2: AffineMatrix): AffineMatrix {
-	return [
-		m1[0] * m2[0] + m1[2] * m2[1],
-		m1[1] * m2[0] + m1[3] * m2[1],
-		m1[0] * m2[2] + m1[2] * m2[3],
-		m1[1] * m2[2] + m1[3] * m2[3],
-		m1[0] * m2[4] + m1[2] * m2[5] + m1[4],
-		m1[1] * m2[4] + m1[3] * m2[5] + m1[5]
-	];
-}
+const EPS = 1e-9;

 export function transformImage(
 	img: PixelImage,
 	dstToSrc: AffineMatrix,
 	outWidth: number,
-	outHeight: number
+	outHeight: number,
+	bgHex?: string
 ): PixelImage {
-	const [a, b, c, d, e, f] = invertAffine(dstToSrc);
+	const [a, b, c, d, e, f] = dstToSrc;
 	const out = createPixelImage(outWidth, outHeight);
+	const bg = bgHex ? parseHex(bgHex) : null;
 	for (let y = 0; y < outHeight; y++) {
 		for (let x = 0; x < outWidth; x++) {
 			const sx = a * x + c * y + e;
 			const sy = b * x + d * y + f;
 			const di = (y * outWidth + x) * 4;
-			if (sx < -1 || sy < -1 || sx > img.width || sy > img.height) continue;
+			if (sx < -EPS || sy < -EPS || sx > img.width - 1 + EPS || sy > img.height - 1 + EPS) {
+				if (bg) {
+					out.data[di] = bg[0];
+					out.data[di + 1] = bg[1];
+					out.data[di + 2] = bg[2];
+					out.data[di + 3] = 255;
+				}
+				continue;
+			}
 			const [r, g, bl, al] = sampleBilinear(img, sx, sy);
-			out.data[di] = r;
-			out.data[di + 1] = g;
-			out.data[di + 2] = bl;
-			out.data[di + 3] = al;
+			if (bg) {
+				const sa = al / 255;
+				out.data[di] = r * sa + bg[0] * (1 - sa);
+				out.data[di + 1] = g * sa + bg[1] * (1 - sa);
+				out.data[di + 2] = bl * sa + bg[2] * (1 - sa);
+				out.data[di + 3] = 255;
+			} else {
+				out.data[di] = r;
+				out.data[di + 1] = g;
+				out.data[di + 2] = bl;
+				out.data[di + 3] = al;
+			}
 		}
 	}
 	return out;
 }

-function transformCorners(
-	img: PixelImage,
-	m: AffineMatrix
-): { minX: number; minY: number; outW: number; outH: number } {
-	const pts = [
-		[0, 0],
-		[img.width, 0],
-		[0, img.height],
-		[img.width, img.height]
-	].map(([x, y]) => [m[0] * x + m[2] * y + m[4], m[1] * x + m[3] * y + m[5]]);
-	const xs = pts.map((p) => p[0]);
-	const ys = pts.map((p) => p[1]);
-	const minX = Math.min(...xs);
-	const minY = Math.min(...ys);
-	return {
-		minX,
-		minY,
-		outW: Math.ceil(Math.max(...xs) - minX),
-		outH: Math.ceil(Math.max(...ys) - minY)
-	};
+function centeredTransform(img: PixelImage, forward: AffineMatrix): PixelImage {
+	const inv = invertAffine(forward);
+
+	let minX = Infinity;
+	let maxX = -Infinity;
+	let minY = Infinity;
+	let maxY = -Infinity;
+	for (const [px, py] of [
+		[0.5, 0.5],
+		[img.width - 0.5, 0.5],
+		[0.5, img.height - 0.5],
+		[img.width - 0.5, img.height - 0.5]
+	]) {
+		const qx = forward[0] * px + forward[2] * py + forward[4];
+		const qy = forward[1] * px + forward[3] * py + forward[5];
+		minX = Math.min(minX, qx);
+		maxX = Math.max(maxX, qx);
+		minY = Math.min(minY, qy);
+		maxY = Math.max(maxY, qy);
+	}
+	const outW = Math.round(maxX - minX) + 1;
+	const outH = Math.round(maxY - minY) + 1;
+	const tx = inv[0] * minX + inv[2] * minY - 0.5;
+	const ty = inv[1] * minX + inv[3] * minY - 0.5;
+	return transformImage(img, [inv[0], inv[1], inv[2], inv[3], tx, ty], outW, outH);
 }

 export function skewImage(img: PixelImage, degX: number, degY: number): PixelImage {
@@ -78,25 +93,16 @@ export function skewImage(img: PixelImage, degX: number, degY: number): PixelIma
 	if (!Number.isFinite(kx) || !Number.isFinite(ky)) {
 		throw new Error('Углы наклона не могут быть 90° или -90°');
 	}
-	const forward: AffineMatrix = [1, ky, kx, 1, 0, 0];
-	const bounds = transformCorners(img, forward);
-	const toOrigin: AffineMatrix = [1, 0, 0, 1, -bounds.minX, -bounds.minY];
-	return transformImage(img, mulAffine(invertAffine(forward), invertAffine(toOrigin)), bounds.outW, bounds.outH);
+	return centeredTransform(img, [1, ky, kx, 1, 0, 0]);
 }

 export function rotateFreeImage(img: PixelImage, degrees: number): PixelImage {
 	const rad = (degrees * Math.PI) / 180;
-	const cos = Math.cos(rad);
-	const sin = Math.sin(rad);
-	const forward: AffineMatrix = [cos, sin, -sin, cos, 0, 0];
-	const bounds = transformCorners(img, forward);
-	const toOrigin: AffineMatrix = [1, 0, 0, 1, -bounds.minX, -bounds.minY];
-	return transformImage(
-		img,
-		mulAffine(invertAffine(forward), invertAffine(toOrigin)),
-		bounds.outW,
-		bounds.outH
-	);
+	let cos = Math.cos(rad);
+	let sin = Math.sin(rad);
+	if (Math.abs(sin) < 1e-12) sin = 0;
+	if (Math.abs(cos) < 1e-12) cos = 0;
+	return centeredTransform(img, [cos, sin, -sin, cos, 0, 0]);
 }

 export function zoomImage(img: PixelImage, scalePercent: number): PixelImage {
@@ -914,7 +914,8 @@ export const TOOLS: ToolEntry[] = [
 				img,
 				[1, 0, 0, 1, -Math.trunc(num(p, 'offsetX')), -Math.trunc(num(p, 'offsetY'))],
 				img.width,
-				img.height
+				img.height,
+				str(p, 'color')
 			)
 	},
 	{
@@ -959,7 +960,7 @@ export const TOOLS: ToolEntry[] = [
 	{
 		id: 'temperature-png',
 		title: 'Температура PNG',
-		description: 'Отрицательные значения делают изображение теплее (оранжевее), положительные — холоднее (синеватее).',
+		description: 'Положительные значения делают изображение теплее (оранжевее), отрицательные — холоднее (синеватее).',
 		category: 'color',
 		params: [
 			{ id: 'percent', label: 'Температура', type: 'slider', min: -100, max: 100, step: 1, default: 0 }