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-rw-r--r--apps/web/src/lib/masks/__tests__/snap.test.ts235
-rw-r--r--apps/web/src/lib/masks/definitions/box-like.ts270
-rw-r--r--apps/web/src/lib/masks/definitions/ellipse.ts72
-rw-r--r--apps/web/src/lib/masks/definitions/index.ts39
-rw-r--r--apps/web/src/lib/masks/definitions/rectangle.ts94
-rw-r--r--apps/web/src/lib/masks/definitions/split.ts347
-rw-r--r--apps/web/src/lib/masks/geometry.ts112
-rw-r--r--apps/web/src/lib/masks/handle-positions.ts382
-rw-r--r--apps/web/src/lib/masks/index.ts18
-rw-r--r--apps/web/src/lib/masks/param-update.ts59
-rw-r--r--apps/web/src/lib/masks/registry.ts70
-rw-r--r--apps/web/src/lib/masks/shaders/jfa-distance.frag.glsl36
-rw-r--r--apps/web/src/lib/masks/snap.ts335
-rw-r--r--apps/web/src/lib/masks/types.ts115
-rw-r--r--apps/web/src/lib/masks/utils.ts64
15 files changed, 2248 insertions, 0 deletions
diff --git a/apps/web/src/lib/masks/__tests__/snap.test.ts b/apps/web/src/lib/masks/__tests__/snap.test.ts
new file mode 100644
index 00000000..3ec96344
--- /dev/null
+++ b/apps/web/src/lib/masks/__tests__/snap.test.ts
@@ -0,0 +1,235 @@
+import { describe, expect, test } from "bun:test";
+import { getSplitMaskStrokeSegment } from "@/lib/masks/definitions/split";
+import { getMaskSnapGeometry } from "@/lib/masks/geometry";
+import { snapMaskInteraction } from "@/lib/masks/snap";
+import type { ElementBounds } from "@/lib/preview/element-bounds";
+import type { RectangleMaskParams, SplitMaskParams } from "@/lib/masks/types";
+
+const bounds: ElementBounds = {
+ cx: 200,
+ cy: 150,
+ width: 200,
+ height: 100,
+ rotation: 0,
+};
+
+const canvasSize = {
+ width: 400,
+ height: 300,
+};
+
+const snapThreshold = {
+ x: 8,
+ y: 8,
+};
+
+function buildSplitParams(
+ overrides: Partial<SplitMaskParams> = {},
+): SplitMaskParams {
+ return {
+ feather: 0,
+ inverted: false,
+ strokeColor: "#ffffff",
+ strokeWidth: 0,
+ centerX: 0,
+ centerY: 0,
+ rotation: 0,
+ ...overrides,
+ };
+}
+
+function buildRectangleParams(
+ overrides: Partial<RectangleMaskParams> = {},
+): RectangleMaskParams {
+ return {
+ feather: 0,
+ inverted: false,
+ strokeColor: "#ffffff",
+ strokeWidth: 0,
+ centerX: 0,
+ centerY: 0,
+ width: 0.4,
+ height: 0.2,
+ rotation: 0,
+ scale: 1,
+ ...overrides,
+ };
+}
+
+function sortSegment(
+ segment: [{ x: number; y: number }, { x: number; y: number }],
+): [{ x: number; y: number }, { x: number; y: number }] {
+ return [...segment].sort((a, b) => (a.x === b.x ? a.y - b.y : a.x - b.x)) as [
+ { x: number; y: number },
+ { x: number; y: number },
+ ];
+}
+
+describe("mask geometry", () => {
+ test("resolves split mask center from centerX and centerY", () => {
+ expect(
+ getMaskSnapGeometry({
+ params: buildSplitParams({
+ centerX: 0.25,
+ centerY: -0.5,
+ rotation: 45,
+ }),
+ bounds,
+ }),
+ ).toEqual({
+ position: { x: 50, y: -50 },
+ size: { width: 0, height: 0 },
+ rotation: 45,
+ });
+ });
+
+ test("resolves box mask center and size from centerX and centerY", () => {
+ expect(
+ getMaskSnapGeometry({
+ params: buildRectangleParams({
+ centerX: -0.25,
+ centerY: 0.5,
+ width: 0.5,
+ height: 0.6,
+ rotation: 30,
+ }),
+ bounds,
+ }),
+ ).toEqual({
+ position: { x: -50, y: 50 },
+ size: { width: 100, height: 60 },
+ rotation: 30,
+ });
+ });
+
+ test("returns a vertical split stroke segment for rotation 0", () => {
+ const segment = getSplitMaskStrokeSegment({
+ resolvedParams: buildSplitParams(),
+ width: bounds.width,
+ height: bounds.height,
+ });
+
+ expect(segment).not.toBeNull();
+ if (!segment) {
+ throw new Error("Expected split stroke segment for rotation 0");
+ }
+ expect(sortSegment(segment)).toEqual([
+ { x: bounds.width / 2, y: 0 },
+ { x: bounds.width / 2, y: bounds.height },
+ ]);
+ });
+
+ test("returns a horizontal split stroke segment for rotation 90", () => {
+ const segment = getSplitMaskStrokeSegment({
+ resolvedParams: buildSplitParams({ rotation: 90 }),
+ width: bounds.width,
+ height: bounds.height,
+ });
+
+ expect(segment).not.toBeNull();
+ if (!segment) {
+ throw new Error("Expected split stroke segment for rotation 90");
+ }
+ expect(sortSegment(segment)).toEqual([
+ { x: 0, y: bounds.height / 2 },
+ { x: bounds.width, y: bounds.height / 2 },
+ ]);
+ });
+});
+
+describe("mask snapping", () => {
+ test("snaps split mask movement using the shared position pipeline", () => {
+ const result = snapMaskInteraction({
+ handleId: "position",
+ startParams: buildSplitParams({
+ centerX: 0.03,
+ centerY: -0.04,
+ }),
+ proposedParams: buildSplitParams({
+ centerX: 0.03,
+ centerY: -0.04,
+ }),
+ bounds,
+ canvasSize,
+ snapThreshold,
+ });
+
+ expect(result.params.centerX).toBe(0);
+ expect(result.params.centerY).toBe(0);
+ expect(result.activeLines).toEqual([
+ { type: "vertical", position: 0 },
+ { type: "horizontal", position: 0 },
+ ]);
+ });
+
+ test("snaps box mask movement against element center and edges", () => {
+ const result = snapMaskInteraction({
+ handleId: "position",
+ startParams: buildRectangleParams(),
+ proposedParams: buildRectangleParams({
+ centerX: 0.29,
+ centerY: 0.03,
+ }),
+ bounds,
+ canvasSize,
+ snapThreshold,
+ });
+
+ expect(result.params.centerX).toBeCloseTo(0.3);
+ expect(result.params.centerY).toBe(0);
+ expect(result.activeLines).toEqual([
+ { type: "vertical", position: 100 },
+ { type: "horizontal", position: 0 },
+ ]);
+ });
+
+ test("snaps mask rotation through the shared rotation path", () => {
+ const result = snapMaskInteraction({
+ handleId: "rotation",
+ startParams: buildRectangleParams(),
+ proposedParams: buildRectangleParams({
+ rotation: 88,
+ }),
+ bounds,
+ canvasSize,
+ snapThreshold,
+ });
+
+ expect(result.params.rotation).toBe(90);
+ expect(result.activeLines).toEqual([]);
+ });
+
+ test("snaps edge resize for box masks", () => {
+ const result = snapMaskInteraction({
+ handleId: "right",
+ startParams: buildRectangleParams(),
+ proposedParams: buildRectangleParams({
+ width: 0.98,
+ }),
+ bounds,
+ canvasSize,
+ snapThreshold,
+ });
+
+ expect(result.params.width).toBe(1);
+ expect(result.activeLines).toEqual([{ type: "vertical", position: 100 }]);
+ });
+
+ test("snaps corner resize for box masks", () => {
+ const result = snapMaskInteraction({
+ handleId: "bottom-right",
+ startParams: buildRectangleParams(),
+ proposedParams: buildRectangleParams({
+ width: 0.99,
+ height: 0.495,
+ }),
+ bounds,
+ canvasSize,
+ snapThreshold,
+ });
+
+ expect(result.params.width).toBe(1);
+ expect(result.params.height).toBe(0.5);
+ expect(result.activeLines).toEqual([{ type: "vertical", position: 100 }]);
+ });
+});
diff --git a/apps/web/src/lib/masks/definitions/box-like.ts b/apps/web/src/lib/masks/definitions/box-like.ts
new file mode 100644
index 00000000..0436151e
--- /dev/null
+++ b/apps/web/src/lib/masks/definitions/box-like.ts
@@ -0,0 +1,270 @@
+import {
+ DEFAULT_SHAPE_MASK_SHORT_SIDE_RATIO,
+ MIN_MASK_DIMENSION,
+} from "@/constants/mask-constants";
+import { computeFeatherUpdate } from "../param-update";
+import type {
+ BaseMaskParams,
+ MaskDefaultContext,
+ MaskParamUpdateArgs,
+ RectangleMaskParams,
+} from "@/lib/masks/types";
+import type {
+ NumberParamDefinition,
+ ParamDefinition,
+ ParamValues,
+} from "@/lib/params";
+
+const PERCENTAGE_DISPLAY: Pick<
+ NumberParamDefinition,
+ "displayMultiplier" | "step"
+> = {
+ displayMultiplier: 100,
+ step: 1,
+};
+
+export const BOX_LIKE_MASK_PARAMS: ParamDefinition<
+ keyof RectangleMaskParams & string
+>[] = [
+ {
+ key: "centerX",
+ label: "X",
+ type: "number",
+ default: 0,
+ min: -100,
+ max: 100,
+ ...PERCENTAGE_DISPLAY,
+ },
+ {
+ key: "centerY",
+ label: "Y",
+ type: "number",
+ default: 0,
+ min: -100,
+ max: 100,
+ ...PERCENTAGE_DISPLAY,
+ },
+ {
+ key: "width",
+ label: "Width",
+ type: "number",
+ default: 0.6,
+ min: 1,
+ ...PERCENTAGE_DISPLAY,
+ },
+ {
+ key: "height",
+ label: "Height",
+ type: "number",
+ default: 0.6,
+ min: 1,
+ ...PERCENTAGE_DISPLAY,
+ },
+ {
+ key: "rotation",
+ label: "Rotation",
+ type: "number",
+ default: 0,
+ min: 0,
+ max: 360,
+ step: 1,
+ },
+ {
+ key: "scale",
+ label: "Scale",
+ type: "number",
+ default: 1,
+ min: 1,
+ max: 500,
+ ...PERCENTAGE_DISPLAY,
+ },
+ {
+ key: "strokeAlign",
+ label: "Stroke Align",
+ type: "select",
+ default: "center",
+ options: [
+ { value: "inside", label: "Inside" },
+ { value: "center", label: "Center" },
+ { value: "outside", label: "Outside" },
+ ],
+ },
+];
+
+export function getDefaultBaseMaskParams(): BaseMaskParams {
+ return {
+ feather: 0,
+ inverted: false,
+ strokeColor: "#ffffff",
+ strokeWidth: 0,
+ strokeAlign: "center",
+ };
+}
+
+export function getStrokeOffset({
+ strokeAlign,
+ strokeWidth,
+}: Pick<BaseMaskParams, "strokeAlign" | "strokeWidth">): number {
+ if (strokeAlign === "inside") {
+ return -(strokeWidth / 2);
+ }
+
+ if (strokeAlign === "outside") {
+ return strokeWidth / 2;
+ }
+
+ return 0;
+}
+
+export function getDefaultSquareMaskParams({
+ elementSize,
+}: MaskDefaultContext): RectangleMaskParams {
+ const absWidth = Math.abs(elementSize?.width ?? 0);
+ const absHeight = Math.abs(elementSize?.height ?? 0);
+ const shortSide = Math.min(absWidth, absHeight);
+ const squareSide =
+ shortSide > 0 ? shortSide * DEFAULT_SHAPE_MASK_SHORT_SIDE_RATIO : 0;
+ const width =
+ absWidth > 0 ? squareSide / absWidth : DEFAULT_SHAPE_MASK_SHORT_SIDE_RATIO;
+ const height =
+ absHeight > 0
+ ? squareSide / absHeight
+ : DEFAULT_SHAPE_MASK_SHORT_SIDE_RATIO;
+
+ return {
+ ...getDefaultBaseMaskParams(),
+ centerX: 0,
+ centerY: 0,
+ width,
+ height,
+ rotation: 0,
+ scale: 1,
+ };
+}
+
+export function getBoxLikeGeometry({
+ params,
+ width,
+ height,
+}: {
+ params: RectangleMaskParams;
+ width: number;
+ height: number;
+}) {
+ return {
+ centerX: width / 2 + params.centerX * width,
+ centerY: height / 2 + params.centerY * height,
+ maskWidth: Math.max(params.width, MIN_MASK_DIMENSION) * width,
+ maskHeight: Math.max(params.height, MIN_MASK_DIMENSION) * height,
+ rotationRad: (params.rotation * Math.PI) / 180,
+ };
+}
+
+export function computeBoxMaskParamUpdate({
+ handleId,
+ startParams,
+ deltaX,
+ deltaY,
+ bounds,
+}: MaskParamUpdateArgs<RectangleMaskParams>): ParamValues {
+ if (handleId === "position") {
+ return {
+ centerX: startParams.centerX + deltaX / bounds.width,
+ centerY: startParams.centerY + deltaY / bounds.height,
+ };
+ }
+
+ if (handleId === "rotation") {
+ const currentAngle = (Math.atan2(deltaY, deltaX) * 180) / Math.PI;
+ const newRotation = (startParams.rotation + currentAngle) % 360;
+ return { rotation: newRotation < 0 ? newRotation + 360 : newRotation };
+ }
+
+ if (handleId === "feather") {
+ const angleRad = (startParams.rotation * Math.PI) / 180;
+ return computeFeatherUpdate({
+ startFeather: startParams.feather,
+ deltaX,
+ deltaY,
+ directionX: -Math.sin(angleRad),
+ directionY: Math.cos(angleRad),
+ });
+ }
+
+ const halfWidth = startParams.width * bounds.width;
+ const halfHeight = startParams.height * bounds.height;
+
+ if (handleId === "right" || handleId === "left") {
+ const sign = handleId === "right" ? 1 : -1;
+ return {
+ width: Math.max(
+ MIN_MASK_DIMENSION,
+ startParams.width + (sign * deltaX * 2) / bounds.width,
+ ),
+ };
+ }
+
+ if (handleId === "bottom" || handleId === "top") {
+ const sign = handleId === "bottom" ? 1 : -1;
+ return {
+ height: Math.max(
+ MIN_MASK_DIMENSION,
+ startParams.height + (sign * deltaY * 2) / bounds.height,
+ ),
+ };
+ }
+
+ if (
+ handleId === "top-left" ||
+ handleId === "top-right" ||
+ handleId === "bottom-left" ||
+ handleId === "bottom-right"
+ ) {
+ const signX = handleId.includes("right") ? 1 : -1;
+ const signY = handleId.includes("bottom") ? 1 : -1;
+ const distance = Math.sqrt(
+ (signX * deltaX + halfWidth) ** 2 + (signY * deltaY + halfHeight) ** 2,
+ );
+ const originalDistance = Math.sqrt(halfWidth ** 2 + halfHeight ** 2);
+ const scale = originalDistance > 0 ? distance / originalDistance : 1;
+ return {
+ width: Math.max(MIN_MASK_DIMENSION, startParams.width * scale),
+ height: Math.max(MIN_MASK_DIMENSION, startParams.height * scale),
+ };
+ }
+
+ if (handleId === "scale") {
+ const distance = Math.sqrt(deltaX ** 2 + deltaY ** 2);
+ const originalDistance = Math.sqrt(halfWidth ** 2 + halfHeight ** 2);
+ const scale = originalDistance > 0 ? 1 + distance / originalDistance : 1;
+ return {
+ scale: Math.max(MIN_MASK_DIMENSION, startParams.scale * scale),
+ };
+ }
+
+ return {};
+}
+
+export function rotatePoint({
+ x,
+ y,
+ centerX,
+ centerY,
+ rotationRad,
+}: {
+ x: number;
+ y: number;
+ centerX: number;
+ centerY: number;
+ rotationRad: number;
+}) {
+ const dx = x - centerX;
+ const dy = y - centerY;
+ const cos = Math.cos(rotationRad);
+ const sin = Math.sin(rotationRad);
+
+ return {
+ x: centerX + dx * cos - dy * sin,
+ y: centerY + dx * sin + dy * cos,
+ };
+}
diff --git a/apps/web/src/lib/masks/definitions/ellipse.ts b/apps/web/src/lib/masks/definitions/ellipse.ts
new file mode 100644
index 00000000..45d0a7c0
--- /dev/null
+++ b/apps/web/src/lib/masks/definitions/ellipse.ts
@@ -0,0 +1,72 @@
+import type { MaskDefinition, RectangleMaskParams } from "@/lib/masks/types";
+import {
+ BOX_LIKE_MASK_PARAMS,
+ computeBoxMaskParamUpdate,
+ getBoxLikeGeometry,
+ getDefaultSquareMaskParams,
+ getStrokeOffset,
+} from "./box-like";
+
+export const ellipseMaskDefinition: MaskDefinition<RectangleMaskParams> = {
+ type: "ellipse",
+ name: "Ellipse",
+ overlayShape: "box",
+ buildOverlayPath({ width, height }) {
+ const rx = Math.max((width - 1) / 2, 0);
+ const ry = Math.max((height - 1) / 2, 0);
+ const cx = width / 2;
+ const cy = height / 2;
+ return `M ${cx},${cy - ry} A ${rx},${ry} 0 1,1 ${cx},${cy + ry} A ${rx},${ry} 0 1,1 ${cx},${cy - ry} Z`;
+ },
+ features: {
+ hasPosition: true,
+ hasRotation: true,
+ sizeMode: "width-height",
+ },
+ params: BOX_LIKE_MASK_PARAMS,
+ buildDefault(context) {
+ return {
+ type: "ellipse",
+ params: getDefaultSquareMaskParams(context),
+ };
+ },
+ computeParamUpdate: computeBoxMaskParamUpdate,
+ renderer: {
+ buildPath({ resolvedParams, width, height }) {
+ const params = resolvedParams as RectangleMaskParams;
+ const { centerX, centerY, maskWidth, maskHeight, rotationRad } =
+ getBoxLikeGeometry({ params, width, height });
+ const path = new Path2D();
+ path.ellipse(
+ centerX,
+ centerY,
+ maskWidth / 2,
+ maskHeight / 2,
+ rotationRad,
+ 0,
+ Math.PI * 2,
+ );
+ return path;
+ },
+ buildStrokePath({ resolvedParams, width, height }) {
+ const params = resolvedParams as RectangleMaskParams;
+ const { centerX, centerY, maskWidth, maskHeight, rotationRad } =
+ getBoxLikeGeometry({ params, width, height });
+ const offset = getStrokeOffset({
+ strokeAlign: params.strokeAlign,
+ strokeWidth: params.strokeWidth,
+ });
+ const path = new Path2D();
+ path.ellipse(
+ centerX,
+ centerY,
+ Math.max(1, maskWidth / 2 + offset),
+ Math.max(1, maskHeight / 2 + offset),
+ rotationRad,
+ 0,
+ Math.PI * 2,
+ );
+ return path;
+ },
+ },
+};
diff --git a/apps/web/src/lib/masks/definitions/index.ts b/apps/web/src/lib/masks/definitions/index.ts
new file mode 100644
index 00000000..c2affe30
--- /dev/null
+++ b/apps/web/src/lib/masks/definitions/index.ts
@@ -0,0 +1,39 @@
+import type { BaseMaskParams, MaskDefinition } from "@/lib/masks/types";
+import { masksRegistry, type MaskIconProps } from "../registry";
+import { ellipseMaskDefinition } from "./ellipse";
+import { rectangleMaskDefinition } from "./rectangle";
+import { splitMaskDefinition } from "./split";
+import {
+ PanelRightDashedIcon,
+ SquareIcon,
+ CircleIcon,
+} from "@hugeicons/core-free-icons";
+
+function registerDefaultMask<TParams extends BaseMaskParams>({
+ definition,
+ icon,
+}: {
+ definition: MaskDefinition<TParams>;
+ icon: MaskIconProps;
+}) {
+ if (masksRegistry.has(definition.type)) {
+ return;
+ }
+
+ masksRegistry.registerMask({ definition, icon });
+}
+
+export function registerDefaultMasks(): void {
+ registerDefaultMask({
+ definition: splitMaskDefinition,
+ icon: { icon: PanelRightDashedIcon, strokeWidth: 1 },
+ });
+ registerDefaultMask({
+ definition: rectangleMaskDefinition,
+ icon: { icon: SquareIcon },
+ });
+ registerDefaultMask({
+ definition: ellipseMaskDefinition,
+ icon: { icon: CircleIcon },
+ });
+}
diff --git a/apps/web/src/lib/masks/definitions/rectangle.ts b/apps/web/src/lib/masks/definitions/rectangle.ts
new file mode 100644
index 00000000..5b7f84a9
--- /dev/null
+++ b/apps/web/src/lib/masks/definitions/rectangle.ts
@@ -0,0 +1,94 @@
+import type { MaskDefinition, RectangleMaskParams } from "@/lib/masks/types";
+import {
+ BOX_LIKE_MASK_PARAMS,
+ computeBoxMaskParamUpdate,
+ getBoxLikeGeometry,
+ getDefaultSquareMaskParams,
+ getStrokeOffset,
+ rotatePoint,
+} from "./box-like";
+
+function buildRectanglePath({
+ centerX,
+ centerY,
+ halfWidth,
+ halfHeight,
+ rotationRad,
+}: {
+ centerX: number;
+ centerY: number;
+ halfWidth: number;
+ halfHeight: number;
+ rotationRad: number;
+}): Path2D {
+ const corners = [
+ { x: centerX - halfWidth, y: centerY - halfHeight },
+ { x: centerX + halfWidth, y: centerY - halfHeight },
+ { x: centerX + halfWidth, y: centerY + halfHeight },
+ { x: centerX - halfWidth, y: centerY + halfHeight },
+ ].map((point) =>
+ rotatePoint({
+ ...point,
+ centerX,
+ centerY,
+ rotationRad,
+ }),
+ );
+
+ const path = new Path2D();
+ path.moveTo(corners[0].x, corners[0].y);
+ for (const corner of corners.slice(1)) {
+ path.lineTo(corner.x, corner.y);
+ }
+ path.closePath();
+ return path;
+}
+
+export const rectangleMaskDefinition: MaskDefinition<RectangleMaskParams> = {
+ type: "rectangle",
+ name: "Rectangle",
+ overlayShape: "box",
+ features: {
+ hasPosition: true,
+ hasRotation: true,
+ sizeMode: "width-height",
+ },
+ params: BOX_LIKE_MASK_PARAMS,
+ buildDefault(context) {
+ return {
+ type: "rectangle",
+ params: getDefaultSquareMaskParams(context),
+ };
+ },
+ computeParamUpdate: computeBoxMaskParamUpdate,
+ renderer: {
+ buildPath({ resolvedParams, width, height }) {
+ const params = resolvedParams as RectangleMaskParams;
+ const { centerX, centerY, maskWidth, maskHeight, rotationRad } =
+ getBoxLikeGeometry({ params, width, height });
+ return buildRectanglePath({
+ centerX,
+ centerY,
+ halfWidth: maskWidth / 2,
+ halfHeight: maskHeight / 2,
+ rotationRad,
+ });
+ },
+ buildStrokePath({ resolvedParams, width, height }) {
+ const params = resolvedParams as RectangleMaskParams;
+ const { centerX, centerY, maskWidth, maskHeight, rotationRad } =
+ getBoxLikeGeometry({ params, width, height });
+ const offset = getStrokeOffset({
+ strokeAlign: params.strokeAlign,
+ strokeWidth: params.strokeWidth,
+ });
+ return buildRectanglePath({
+ centerX,
+ centerY,
+ halfWidth: Math.max(1, maskWidth / 2 + offset),
+ halfHeight: Math.max(1, maskHeight / 2 + offset),
+ rotationRad,
+ });
+ },
+ },
+};
diff --git a/apps/web/src/lib/masks/definitions/split.ts b/apps/web/src/lib/masks/definitions/split.ts
new file mode 100644
index 00000000..43f02db1
--- /dev/null
+++ b/apps/web/src/lib/masks/definitions/split.ts
@@ -0,0 +1,347 @@
+import { computeFeatherUpdate } from "../param-update";
+import type { ParamValues } from "@/lib/params";
+import type {
+ MaskDefinition,
+ MaskParamUpdateArgs,
+ SplitMaskParams,
+} from "@/lib/masks/types";
+import { halfPlaneSign, lineEdgeIntersection } from "../utils";
+
+// cos(π/2) returns ~6e-17 in JS, not 0. Values below this threshold are snapped
+// to exactly 0 to prevent opposite-sign float noise on canvas corners that lie
+// exactly on the split line, which produces spurious midpoint vertices.
+const NORMAL_SNAP_EPSILON = 1e-10;
+
+// Guards against collinear vertices from float noise at canvas edges.
+const MIN_POLYGON_AREA_PX = 0.5;
+const INTERSECTION_EPSILON = 1e-6;
+
+function polygonArea({ vertices }: { vertices: [number, number][] }): number {
+ let area = 0;
+ for (let i = 0; i < vertices.length; i++) {
+ const [x1, y1] = vertices[i];
+ const [x2, y2] = vertices[(i + 1) % vertices.length];
+ area += x1 * y2 - x2 * y1;
+ }
+ return Math.abs(area) * 0.5;
+}
+
+function splitLineGeometry({
+ centerX,
+ centerY,
+ rotation,
+ width,
+ height,
+}: {
+ centerX: number;
+ centerY: number;
+ rotation: number;
+ width: number;
+ height: number;
+}): { normalX: number; normalY: number; lineX: number; lineY: number } {
+ const angleRad = (rotation * Math.PI) / 180;
+ const normalX =
+ Math.abs(Math.cos(angleRad)) < NORMAL_SNAP_EPSILON ? 0 : Math.cos(angleRad);
+ const normalY =
+ Math.abs(Math.sin(angleRad)) < NORMAL_SNAP_EPSILON ? 0 : Math.sin(angleRad);
+ const lineX = width / 2 + centerX * width;
+ const lineY = height / 2 + centerY * height;
+ return { normalX, normalY, lineX, lineY };
+}
+
+function pointsEqual(
+ a: { x: number; y: number },
+ b: { x: number; y: number },
+): boolean {
+ return (
+ Math.abs(a.x - b.x) <= INTERSECTION_EPSILON &&
+ Math.abs(a.y - b.y) <= INTERSECTION_EPSILON
+ );
+}
+
+export function getSplitMaskStrokeSegment({
+ resolvedParams,
+ width,
+ height,
+}: {
+ resolvedParams: unknown;
+ width: number;
+ height: number;
+}): [{ x: number; y: number }, { x: number; y: number }] | null {
+ const { centerX, centerY, rotation } = resolvedParams as SplitMaskParams;
+ const { normalX, normalY, lineX, lineY } = splitLineGeometry({
+ centerX,
+ centerY,
+ rotation,
+ width,
+ height,
+ });
+
+ const edges: [number, number, number, number][] = [
+ [0, 0, width, 0],
+ [width, 0, width, height],
+ [width, height, 0, height],
+ [0, height, 0, 0],
+ ];
+ const intersections: { x: number; y: number }[] = [];
+
+ for (const [x1, y1, x2, y2] of edges) {
+ const hit = lineEdgeIntersection({
+ lineX,
+ lineY,
+ normalX,
+ normalY,
+ x1,
+ y1,
+ x2,
+ y2,
+ });
+
+ if (!hit || intersections.some((point) => pointsEqual(point, hit))) {
+ continue;
+ }
+
+ intersections.push(hit);
+ }
+
+ if (intersections.length !== 2) {
+ return null;
+ }
+
+ return [intersections[0], intersections[1]];
+}
+
+function computeSplitMaskParamUpdate({
+ handleId,
+ startParams,
+ deltaX,
+ deltaY,
+ startCanvasX,
+ startCanvasY,
+ bounds,
+ canvasSize,
+}: MaskParamUpdateArgs<SplitMaskParams>): ParamValues {
+ if (handleId === "position") {
+ const rawX = startParams.centerX + deltaX / bounds.width;
+ const rawY = startParams.centerY + deltaY / bounds.height;
+
+ const minX = -bounds.cx / bounds.width;
+ const maxX = (canvasSize.width - bounds.cx) / bounds.width;
+ const minY = -bounds.cy / bounds.height;
+ const maxY = (canvasSize.height - bounds.cy) / bounds.height;
+
+ return {
+ centerX: Math.max(minX, Math.min(maxX, rawX)),
+ centerY: Math.max(minY, Math.min(maxY, rawY)),
+ };
+ }
+
+ if (handleId === "feather") {
+ const angleRad = (startParams.rotation * Math.PI) / 180;
+ return computeFeatherUpdate({
+ startFeather: startParams.feather,
+ deltaX,
+ deltaY,
+ directionX: -Math.cos(angleRad),
+ directionY: -Math.sin(angleRad),
+ });
+ }
+
+ if (handleId === "rotation") {
+ const pivotX = bounds.cx + startParams.centerX * bounds.width;
+ const pivotY = bounds.cy + startParams.centerY * bounds.height;
+ const startAngle =
+ (Math.atan2(startCanvasY - pivotY, startCanvasX - pivotX) * 180) /
+ Math.PI;
+ const currentAngle =
+ (Math.atan2(
+ startCanvasY + deltaY - pivotY,
+ startCanvasX + deltaX - pivotX,
+ ) *
+ 180) /
+ Math.PI;
+
+ let deltaAngle = currentAngle - startAngle;
+ if (deltaAngle > 180) deltaAngle -= 360;
+ if (deltaAngle < -180) deltaAngle += 360;
+
+ return {
+ rotation: (((startParams.rotation + deltaAngle) % 360) + 360) % 360,
+ };
+ }
+
+ return {};
+}
+
+export const splitMaskDefinition: MaskDefinition<SplitMaskParams> = {
+ type: "split",
+ name: "Split",
+ overlayShape: "line",
+ features: {
+ hasPosition: true,
+ hasRotation: true,
+ sizeMode: "none",
+ },
+ buildDefault() {
+ return {
+ type: "split",
+ params: {
+ feather: 0,
+ inverted: false,
+ strokeColor: "#ffffff",
+ strokeWidth: 0,
+ strokeAlign: "center",
+ centerX: 0,
+ centerY: 0,
+ rotation: 0,
+ },
+ };
+ },
+ computeParamUpdate: computeSplitMaskParamUpdate,
+ params: [
+ {
+ key: "centerX",
+ label: "X",
+ type: "number",
+ default: 0,
+ min: -100,
+ max: 100,
+ step: 1,
+ displayMultiplier: 100,
+ },
+ {
+ key: "centerY",
+ label: "Y",
+ type: "number",
+ default: 0,
+ min: -100,
+ max: 100,
+ step: 1,
+ displayMultiplier: 100,
+ },
+ {
+ key: "rotation",
+ label: "Rotation",
+ type: "number",
+ default: 0,
+ min: 0,
+ max: 360,
+ step: 1,
+ },
+ ],
+ renderer: {
+ renderMask({ resolvedParams, ctx, width, height, feather }) {
+ const { centerX, centerY, rotation } = resolvedParams as SplitMaskParams;
+ const { normalX, normalY, lineX, lineY } = splitLineGeometry({
+ centerX,
+ centerY,
+ rotation,
+ width,
+ height,
+ });
+
+ // Analytical gradient avoids JFA's two-sided distance artifact near canvas edges.
+ const featherHalf = feather / 2;
+ const gradient = ctx.createLinearGradient(
+ lineX - normalX * featherHalf,
+ lineY - normalY * featherHalf,
+ lineX + normalX * featherHalf,
+ lineY + normalY * featherHalf,
+ );
+ gradient.addColorStop(0, "rgba(255,255,255,0)");
+ gradient.addColorStop(1, "white");
+
+ ctx.fillStyle = gradient;
+ ctx.fillRect(0, 0, width, height);
+ },
+
+ buildPath({ resolvedParams, width, height }) {
+ const { centerX, centerY, rotation } = resolvedParams as SplitMaskParams;
+ const { normalX, normalY, lineX, lineY } = splitLineGeometry({
+ centerX,
+ centerY,
+ rotation,
+ width,
+ height,
+ });
+
+ const edges: [number, number, number, number][] = [
+ [0, 0, width, 0],
+ [width, 0, width, height],
+ [width, height, 0, height],
+ [0, height, 0, 0],
+ ];
+
+ const isInsideHalfPlane = (x: number, y: number) =>
+ halfPlaneSign({ lineX, lineY, normalX, normalY, x, y }) >= 0;
+
+ const vertices: [number, number][] = [];
+ for (const [x1, y1, x2, y2] of edges) {
+ const isVertex1Inside = isInsideHalfPlane(x1, y1);
+ const isVertex2Inside = isInsideHalfPlane(x2, y2);
+
+ if (isVertex1Inside && isVertex2Inside) {
+ vertices.push([x2, y2]);
+ } else if (isVertex1Inside && !isVertex2Inside) {
+ const hit = lineEdgeIntersection({
+ lineX,
+ lineY,
+ normalX,
+ normalY,
+ x1,
+ y1,
+ x2,
+ y2,
+ });
+ if (hit) vertices.push([hit.x, hit.y]);
+ } else if (!isVertex1Inside && isVertex2Inside) {
+ const hit = lineEdgeIntersection({
+ lineX,
+ lineY,
+ normalX,
+ normalY,
+ x1,
+ y1,
+ x2,
+ y2,
+ });
+ if (hit) {
+ vertices.push([hit.x, hit.y]);
+ vertices.push([x2, y2]);
+ }
+ }
+ }
+
+ if (
+ vertices.length < 3 ||
+ polygonArea({ vertices }) < MIN_POLYGON_AREA_PX
+ ) {
+ return new Path2D();
+ }
+
+ const path = new Path2D();
+ path.moveTo(vertices[0][0], vertices[0][1]);
+ for (let i = 1; i < vertices.length; i++) {
+ path.lineTo(vertices[i][0], vertices[i][1]);
+ }
+ path.closePath();
+ return path;
+ },
+ buildStrokePath({ resolvedParams, width, height }) {
+ const segment = getSplitMaskStrokeSegment({
+ resolvedParams,
+ width,
+ height,
+ });
+ const path = new Path2D();
+
+ if (!segment) {
+ return path;
+ }
+
+ path.moveTo(segment[0].x, segment[0].y);
+ path.lineTo(segment[1].x, segment[1].y);
+ return path;
+ },
+ },
+};
diff --git a/apps/web/src/lib/masks/geometry.ts b/apps/web/src/lib/masks/geometry.ts
new file mode 100644
index 00000000..c6d386f8
--- /dev/null
+++ b/apps/web/src/lib/masks/geometry.ts
@@ -0,0 +1,112 @@
+import type { ElementBounds } from "@/lib/preview/element-bounds";
+import type { SnapLine } from "@/lib/preview/preview-snap";
+import { MIN_MASK_DIMENSION } from "@/constants/mask-constants";
+import type { ParamValues } from "@/lib/params";
+import type { RectangleMaskParams } from "@/lib/masks/types";
+
+export function hasCenterParams(params: ParamValues): params is ParamValues & {
+ centerX: number;
+ centerY: number;
+} {
+ return (
+ typeof params.centerX === "number" && typeof params.centerY === "number"
+ );
+}
+
+export function isRectangleMaskParams(
+ params: ParamValues,
+): params is RectangleMaskParams {
+ return (
+ hasCenterParams(params) &&
+ typeof params.width === "number" &&
+ typeof params.height === "number" &&
+ typeof params.rotation === "number" &&
+ typeof params.scale === "number"
+ );
+}
+
+export function getMaskLocalCenter({
+ params,
+ bounds,
+}: {
+ params: ParamValues;
+ bounds: ElementBounds;
+}): { x: number; y: number } | null {
+ if (!hasCenterParams(params)) return null;
+
+ return {
+ x: params.centerX * bounds.width,
+ y: params.centerY * bounds.height,
+ };
+}
+
+export function setMaskLocalCenter({
+ center,
+ bounds,
+}: {
+ center: { x: number; y: number };
+ bounds: ElementBounds;
+}): Pick<ParamValues, "centerX" | "centerY"> {
+ return {
+ centerX: bounds.width === 0 ? 0 : center.x / bounds.width,
+ centerY: bounds.height === 0 ? 0 : center.y / bounds.height,
+ };
+}
+
+export function getMaskSnapGeometry({
+ params,
+ bounds,
+}: {
+ params: ParamValues;
+ bounds: ElementBounds;
+}): {
+ position: { x: number; y: number };
+ size: { width: number; height: number };
+ rotation: number;
+} | null {
+ const position = getMaskLocalCenter({ params, bounds });
+ if (!position) return null;
+
+ if (isRectangleMaskParams(params)) {
+ return {
+ position,
+ size: {
+ width: Math.max(params.width, MIN_MASK_DIMENSION) * bounds.width,
+ height: Math.max(params.height, MIN_MASK_DIMENSION) * bounds.height,
+ },
+ rotation: params.rotation,
+ };
+ }
+
+ return {
+ position,
+ size: { width: 0, height: 0 },
+ rotation: typeof params.rotation === "number" ? params.rotation : 0,
+ };
+}
+
+export function toGlobalMaskSnapLines({
+ lines,
+ bounds,
+ canvasSize,
+}: {
+ lines: SnapLine[];
+ bounds: ElementBounds;
+ canvasSize: { width: number; height: number };
+}): SnapLine[] {
+ const centerX = bounds.cx - canvasSize.width / 2;
+ const centerY = bounds.cy - canvasSize.height / 2;
+
+ return lines.map((line) =>
+ line.type === "vertical"
+ ? {
+ type: "vertical" as const,
+ position: centerX + line.position,
+ }
+ : {
+ type: "horizontal" as const,
+ position: centerY + line.position,
+ },
+ );
+}
+
diff --git a/apps/web/src/lib/masks/handle-positions.ts b/apps/web/src/lib/masks/handle-positions.ts
new file mode 100644
index 00000000..753b17ce
--- /dev/null
+++ b/apps/web/src/lib/masks/handle-positions.ts
@@ -0,0 +1,382 @@
+import { FEATHER_HANDLE_SCALE } from "@/constants/mask-constants";
+import type { ElementBounds } from "@/lib/preview/element-bounds";
+import type {
+ MaskFeatures,
+ MaskHandlePosition,
+ MaskLinePoints,
+ MaskOverlayShape,
+} from "@/lib/masks/types";
+import type { ParamValues } from "@/lib/params";
+
+const LINE_HANDLE_OFFSET_SCREEN_PX = 20;
+const BOX_HANDLE_OFFSET_SCREEN_PX = 20;
+const LINE_EXTENT_MULTIPLIER = 50;
+
+const CURSOR = {
+ rotate: "cursor-crosshair",
+ resizeDiagonal: "cursor-nwse-resize",
+ resizeHorizontal: "cursor-ew-resize",
+ resizeVertical: "cursor-ns-resize",
+} as const;
+
+function getNumParam({
+ params,
+ key,
+ fallback,
+}: {
+ params: ParamValues;
+ key: string;
+ fallback: number;
+}): number {
+ const value = params[key];
+ return typeof value === "number" && !Number.isNaN(value) ? value : fallback;
+}
+
+/**
+ * The renderer defines the split line as:
+ * - normal direction: (cos(rotation), sin(rotation))
+ * - line direction (parallel to cut): (-sin(rotation), cos(rotation))
+ * - reference point: (centerX * width, centerY * height) from element centre
+ *
+ * So rotation=0 → normal points right → line runs vertically.
+ */
+export function getLineMaskLinePoints({
+ centerX,
+ centerY,
+ rotation,
+ bounds,
+}: {
+ centerX: number;
+ centerY: number;
+ rotation: number;
+ bounds: ElementBounds;
+}): MaskLinePoints {
+ const angleRad = (rotation * Math.PI) / 180;
+ const normalX = Math.cos(angleRad);
+ const normalY = Math.sin(angleRad);
+ const lineDirX = -normalY;
+ const lineDirY = normalX;
+
+ const cx = bounds.cx + centerX * bounds.width;
+ const cy = bounds.cy + centerY * bounds.height;
+
+ const extent = Math.max(bounds.width, bounds.height) * LINE_EXTENT_MULTIPLIER;
+
+ return {
+ start: {
+ x: cx - lineDirX * extent,
+ y: cy - lineDirY * extent,
+ },
+ end: {
+ x: cx + lineDirX * extent,
+ y: cy + lineDirY * extent,
+ },
+ };
+}
+
+export function getLineMaskHandlePositions({
+ centerX,
+ centerY,
+ rotation,
+ feather,
+ bounds,
+ displayScale,
+}: {
+ centerX: number;
+ centerY: number;
+ rotation: number;
+ feather: number;
+ bounds: ElementBounds;
+ displayScale: number;
+}): MaskHandlePosition[] {
+ const angleRad = (rotation * Math.PI) / 180;
+ const normalX = Math.cos(angleRad);
+ const normalY = Math.sin(angleRad);
+
+ const cx = bounds.cx + centerX * bounds.width;
+ const cy = bounds.cy + centerY * bounds.height;
+
+ const iconOffsetCanvas = LINE_HANDLE_OFFSET_SCREEN_PX / displayScale;
+ const featherOffset = iconOffsetCanvas + feather * FEATHER_HANDLE_SCALE;
+
+ return [
+ {
+ id: "rotation",
+ x: cx + normalX * iconOffsetCanvas,
+ y: cy + normalY * iconOffsetCanvas,
+ cursor: CURSOR.rotate,
+ },
+ {
+ id: "feather",
+ x: cx - normalX * featherOffset,
+ y: cy - normalY * featherOffset,
+ cursor: CURSOR.resizeHorizontal,
+ },
+ ];
+}
+
+function rotatePoint({
+ localX,
+ localY,
+ cx,
+ cy,
+ angleRad,
+}: {
+ localX: number;
+ localY: number;
+ cx: number;
+ cy: number;
+ angleRad: number;
+}): { x: number; y: number } {
+ const cos = Math.cos(angleRad);
+ const sin = Math.sin(angleRad);
+ return {
+ x: cx + localX * cos - localY * sin,
+ y: cy + localX * sin + localY * cos,
+ };
+}
+
+export function getBoxMaskHandlePositions({
+ centerX,
+ centerY,
+ width,
+ height,
+ rotation,
+ feather,
+ sizeMode,
+ bounds,
+ displayScale,
+}: {
+ centerX: number;
+ centerY: number;
+ width: number;
+ height: number;
+ rotation: number;
+ feather: number;
+ sizeMode: MaskFeatures["sizeMode"];
+ bounds: ElementBounds;
+ displayScale: number;
+}): MaskHandlePosition[] {
+ const cx = bounds.cx + centerX * bounds.width;
+ const cy = bounds.cy + centerY * bounds.height;
+ const angleRad = (rotation * Math.PI) / 180;
+ const halfWidth = (width * bounds.width) / 2;
+ const halfHeight = (height * bounds.height) / 2;
+
+ const handles: MaskHandlePosition[] = [];
+ const handleOffsetCanvas = BOX_HANDLE_OFFSET_SCREEN_PX / displayScale;
+
+ const rotHandle = rotatePoint({
+ localX: 0,
+ localY: -halfHeight - handleOffsetCanvas,
+ cx,
+ cy,
+ angleRad,
+ });
+ handles.push({
+ id: "rotation",
+ x: rotHandle.x,
+ y: rotHandle.y,
+ cursor: CURSOR.rotate,
+ });
+
+ const featherHandle = rotatePoint({
+ localX: 0,
+ localY: halfHeight + handleOffsetCanvas + feather * FEATHER_HANDLE_SCALE,
+ cx,
+ cy,
+ angleRad,
+ });
+ handles.push({
+ id: "feather",
+ x: featherHandle.x,
+ y: featherHandle.y,
+ cursor: CURSOR.resizeVertical,
+ });
+
+ if (sizeMode === "width-height") {
+ const corners = [
+ { localX: -halfWidth, localY: -halfHeight, id: "top-left" },
+ { localX: halfWidth, localY: -halfHeight, id: "top-right" },
+ { localX: halfWidth, localY: halfHeight, id: "bottom-right" },
+ { localX: -halfWidth, localY: halfHeight, id: "bottom-left" },
+ ];
+ for (const { localX, localY, id } of corners) {
+ const point = rotatePoint({ localX, localY, cx, cy, angleRad });
+ handles.push({
+ id,
+ x: point.x,
+ y: point.y,
+ cursor: CURSOR.resizeDiagonal,
+ });
+ }
+ const right = rotatePoint({
+ localX: halfWidth,
+ localY: 0,
+ cx,
+ cy,
+ angleRad,
+ });
+ const left = rotatePoint({
+ localX: -halfWidth,
+ localY: 0,
+ cx,
+ cy,
+ angleRad,
+ });
+ const bottom = rotatePoint({
+ localX: 0,
+ localY: halfHeight,
+ cx,
+ cy,
+ angleRad,
+ });
+ handles.push({
+ id: "left",
+ x: left.x,
+ y: left.y,
+ cursor: CURSOR.resizeHorizontal,
+ });
+ handles.push({
+ id: "right",
+ x: right.x,
+ y: right.y,
+ cursor: CURSOR.resizeHorizontal,
+ });
+ handles.push({
+ id: "bottom",
+ x: bottom.x,
+ y: bottom.y,
+ cursor: CURSOR.resizeVertical,
+ });
+ } else if (sizeMode === "height-only") {
+ const top = rotatePoint({
+ localX: 0,
+ localY: -halfHeight,
+ cx,
+ cy,
+ angleRad,
+ });
+ const bottom = rotatePoint({
+ localX: 0,
+ localY: halfHeight,
+ cx,
+ cy,
+ angleRad,
+ });
+ handles.push({
+ id: "top",
+ x: top.x,
+ y: top.y,
+ cursor: CURSOR.resizeVertical,
+ });
+ handles.push({
+ id: "bottom",
+ x: bottom.x,
+ y: bottom.y,
+ cursor: CURSOR.resizeVertical,
+ });
+ } else if (sizeMode === "width-only") {
+ const left = rotatePoint({
+ localX: -halfWidth,
+ localY: 0,
+ cx,
+ cy,
+ angleRad,
+ });
+ const right = rotatePoint({
+ localX: halfWidth,
+ localY: 0,
+ cx,
+ cy,
+ angleRad,
+ });
+ handles.push({
+ id: "left",
+ x: left.x,
+ y: left.y,
+ cursor: CURSOR.resizeHorizontal,
+ });
+ handles.push({
+ id: "right",
+ x: right.x,
+ y: right.y,
+ cursor: CURSOR.resizeHorizontal,
+ });
+ } else if (sizeMode === "uniform") {
+ const point = rotatePoint({
+ localX: halfWidth,
+ localY: halfHeight,
+ cx,
+ cy,
+ angleRad,
+ });
+ handles.push({
+ id: "scale",
+ x: point.x,
+ y: point.y,
+ cursor: CURSOR.resizeDiagonal,
+ });
+ }
+
+ return handles;
+}
+
+type MaskHandleResolver = (args: {
+ features: MaskFeatures;
+ params: ParamValues;
+ bounds: ElementBounds;
+ displayScale: number;
+}) => MaskHandlePosition[];
+
+const rectangleHandles: MaskHandleResolver = ({
+ features,
+ params,
+ bounds,
+ displayScale,
+}) =>
+ getBoxMaskHandlePositions({
+ centerX: getNumParam({ params, key: "centerX", fallback: 0 }),
+ centerY: getNumParam({ params, key: "centerY", fallback: 0 }),
+ width: getNumParam({ params, key: "width", fallback: 1 }),
+ height: getNumParam({ params, key: "height", fallback: 1 }),
+ rotation: getNumParam({ params, key: "rotation", fallback: 0 }),
+ feather: getNumParam({ params, key: "feather", fallback: 0 }),
+ sizeMode: features.sizeMode,
+ bounds,
+ displayScale,
+ });
+
+const HANDLE_RESOLVERS: Record<MaskOverlayShape, MaskHandleResolver> = {
+ line: ({ params, bounds, displayScale }) =>
+ getLineMaskHandlePositions({
+ centerX: getNumParam({ params, key: "centerX", fallback: 0 }),
+ centerY: getNumParam({ params, key: "centerY", fallback: 0 }),
+ rotation: getNumParam({ params, key: "rotation", fallback: 0 }),
+ feather: getNumParam({ params, key: "feather", fallback: 0 }),
+ bounds,
+ displayScale,
+ }),
+ box: rectangleHandles,
+};
+
+export function getMaskHandlePositions({
+ overlayShape,
+ features,
+ params,
+ bounds,
+ displayScale,
+}: {
+ overlayShape: MaskOverlayShape;
+ features: MaskFeatures;
+ params: ParamValues;
+ bounds: ElementBounds;
+ displayScale: number;
+}): MaskHandlePosition[] {
+ return HANDLE_RESOLVERS[overlayShape]({
+ features,
+ params,
+ bounds,
+ displayScale,
+ });
+}
diff --git a/apps/web/src/lib/masks/index.ts b/apps/web/src/lib/masks/index.ts
new file mode 100644
index 00000000..bc9f20b0
--- /dev/null
+++ b/apps/web/src/lib/masks/index.ts
@@ -0,0 +1,18 @@
+import type { Mask, MaskDefaultContext, MaskType } from "@/lib/masks/types";
+import { masksRegistry } from "./registry";
+import { generateUUID } from "@/utils/id";
+
+export { masksRegistry } from "./registry";
+export { registerDefaultMasks } from "./definitions";
+
+export function buildDefaultMaskInstance({
+ maskType,
+ elementSize,
+}: {
+ maskType: MaskType;
+ elementSize?: { width: number; height: number };
+}): Mask {
+ const definition = masksRegistry.get(maskType);
+ const context: MaskDefaultContext = { elementSize };
+ return { ...definition.buildDefault(context), id: generateUUID() } as Mask;
+}
diff --git a/apps/web/src/lib/masks/param-update.ts b/apps/web/src/lib/masks/param-update.ts
new file mode 100644
index 00000000..967a4be0
--- /dev/null
+++ b/apps/web/src/lib/masks/param-update.ts
@@ -0,0 +1,59 @@
+import { FEATHER_HANDLE_SCALE, MAX_FEATHER } from "@/constants/mask-constants";
+import { masksRegistry } from "@/lib/masks";
+import type { ParamValues } from "@/lib/params";
+import type {
+ BaseMaskParams,
+ MaskParamUpdateArgs,
+ MaskType,
+} from "@/lib/masks/types";
+
+function compactMaskParamValues({
+ params,
+}: {
+ params: Partial<ParamValues>;
+}): ParamValues {
+ const nextParams: ParamValues = {};
+ for (const [key, value] of Object.entries(params)) {
+ if (value !== undefined) {
+ nextParams[key] = value;
+ }
+ }
+ return nextParams;
+}
+
+export function computeFeatherUpdate({
+ startFeather,
+ deltaX,
+ deltaY,
+ directionX,
+ directionY,
+}: {
+ startFeather: number;
+ deltaX: number;
+ deltaY: number;
+ directionX: number;
+ directionY: number;
+}): ParamValues {
+ const projection = deltaX * directionX + deltaY * directionY;
+ return {
+ feather: Math.max(
+ 0,
+ Math.min(
+ MAX_FEATHER,
+ Math.round(startFeather + projection / FEATHER_HANDLE_SCALE),
+ ),
+ ),
+ };
+}
+
+export function computeMaskParamUpdate({
+ maskType,
+ ...args
+}: {
+ maskType: MaskType;
+} & MaskParamUpdateArgs<BaseMaskParams & ParamValues>): ParamValues {
+ const definition = masksRegistry.get(maskType);
+ return compactMaskParamValues({
+ params: definition.computeParamUpdate(args),
+ });
+}
diff --git a/apps/web/src/lib/masks/registry.ts b/apps/web/src/lib/masks/registry.ts
new file mode 100644
index 00000000..5a98cb41
--- /dev/null
+++ b/apps/web/src/lib/masks/registry.ts
@@ -0,0 +1,70 @@
+import { MAX_FEATHER } from "@/constants/mask-constants";
+import type { ParamDefinition } from "@/lib/params";
+import type { BaseMaskParams, MaskDefinition, MaskType } from "@/lib/masks/types";
+import type { HugeiconsIconProps } from "@hugeicons/react";
+import { DefinitionRegistry } from "@/lib/registry";
+
+export type MaskIconProps = {
+ icon: HugeiconsIconProps["icon"];
+ strokeWidth?: number;
+};
+
+const BASE_MASK_PARAM_DEFINITIONS: ParamDefinition<
+ keyof BaseMaskParams & string
+>[] = [
+ {
+ key: "feather",
+ label: "Feather",
+ type: "number",
+ default: 0,
+ min: 0,
+ max: MAX_FEATHER,
+ step: 1,
+ unit: "percent",
+ },
+ {
+ key: "strokeWidth",
+ label: "Stroke width",
+ type: "number",
+ default: 0,
+ min: 0,
+ max: 100,
+ step: 1,
+ },
+ {
+ key: "strokeColor",
+ label: "Stroke color",
+ type: "color",
+ default: "#ffffff",
+ },
+];
+
+export type RegisteredMaskDefinition = MaskDefinition<BaseMaskParams> & {
+ icon: MaskIconProps;
+};
+
+export class MasksRegistry extends DefinitionRegistry<
+ MaskType,
+ RegisteredMaskDefinition
+> {
+ constructor() {
+ super("mask");
+ }
+
+ registerMask<TParams extends BaseMaskParams>({
+ definition,
+ icon,
+ }: {
+ definition: MaskDefinition<TParams>;
+ icon: MaskIconProps;
+ }): void {
+ const withBaseParams: RegisteredMaskDefinition = {
+ ...definition,
+ params: [...definition.params, ...BASE_MASK_PARAM_DEFINITIONS],
+ icon,
+ };
+ this.register(definition.type, withBaseParams);
+ }
+}
+
+export const masksRegistry = new MasksRegistry();
diff --git a/apps/web/src/lib/masks/shaders/jfa-distance.frag.glsl b/apps/web/src/lib/masks/shaders/jfa-distance.frag.glsl
new file mode 100644
index 00000000..4ba2c5a1
--- /dev/null
+++ b/apps/web/src/lib/masks/shaders/jfa-distance.frag.glsl
@@ -0,0 +1,36 @@
+precision mediump float;
+
+uniform sampler2D u_texture;
+uniform sampler2D u_jfa_outside;
+uniform vec2 u_resolution;
+uniform float u_feather_half;
+
+varying vec2 v_texCoord;
+
+vec2 decodeSeed(vec4 encoded) {
+ float x = floor(encoded.r * 255.0 + 0.5) * 256.0 + floor(encoded.g * 255.0 + 0.5);
+ float y = floor(encoded.b * 255.0 + 0.5) * 256.0 + floor(encoded.a * 255.0 + 0.5);
+ return vec2(x, y);
+}
+
+bool isNoSeed(vec4 encoded) {
+ return encoded.r > 0.99 && encoded.g > 0.99 && encoded.b > 0.99 && encoded.a > 0.99;
+}
+
+void main() {
+ vec2 pixelCoord = floor(v_texCoord * u_resolution);
+
+ vec4 insideEncoded = texture2D(u_texture, v_texCoord);
+ vec4 outsideEncoded = texture2D(u_jfa_outside, v_texCoord);
+
+ bool hasInside = !isNoSeed(insideEncoded);
+ bool hasOutside = !isNoSeed(outsideEncoded);
+
+ float distToInside = hasInside ? distance(pixelCoord, decodeSeed(insideEncoded)) : 1e5;
+ float distToOutside = hasOutside ? distance(pixelCoord, decodeSeed(outsideEncoded)) : 1e5;
+
+ float signedDist = distToOutside - distToInside;
+ float alpha = smoothstep(-u_feather_half, u_feather_half, signedDist);
+
+ gl_FragColor = vec4(alpha, alpha, alpha, alpha);
+}
diff --git a/apps/web/src/lib/masks/snap.ts b/apps/web/src/lib/masks/snap.ts
new file mode 100644
index 00000000..83cc0e99
--- /dev/null
+++ b/apps/web/src/lib/masks/snap.ts
@@ -0,0 +1,335 @@
+import type { ElementBounds } from "@/lib/preview/element-bounds";
+import { MIN_MASK_DIMENSION } from "@/constants/mask-constants";
+import {
+ snapPosition,
+ snapRotation,
+ snapScale,
+ snapScaleAxes,
+ type ScaleEdgePreference,
+ type SnapLine,
+} from "@/lib/preview/preview-snap";
+import type { ParamValues } from "@/lib/params";
+import {
+ isRectangleMaskParams,
+ getMaskSnapGeometry,
+ setMaskLocalCenter,
+ toGlobalMaskSnapLines,
+} from "./geometry";
+
+type MaskSnapResult = {
+ params: ParamValues;
+ activeLines: SnapLine[];
+};
+
+const CORNER_SIZE_HANDLES = new Set([
+ "top-left",
+ "top-right",
+ "bottom-left",
+ "bottom-right",
+]);
+
+function getClampedRatio({
+ next,
+ base,
+}: {
+ next: number;
+ base: number;
+}): number {
+ return (
+ Math.max(next, MIN_MASK_DIMENSION) / Math.max(base, MIN_MASK_DIMENSION)
+ );
+}
+
+function getPreferredEdges({
+ handleId,
+}: {
+ handleId: string;
+}): ScaleEdgePreference | undefined {
+ const preferredEdges = {
+ left:
+ handleId === "left" ||
+ handleId === "top-left" ||
+ handleId === "bottom-left",
+ right:
+ handleId === "right" ||
+ handleId === "top-right" ||
+ handleId === "bottom-right",
+ top:
+ handleId === "top" || handleId === "top-left" || handleId === "top-right",
+ bottom:
+ handleId === "bottom" ||
+ handleId === "bottom-left" ||
+ handleId === "bottom-right",
+ } satisfies ScaleEdgePreference;
+
+ return Object.values(preferredEdges).some(Boolean)
+ ? preferredEdges
+ : undefined;
+}
+
+function snapMaskPosition({
+ proposedParams,
+ bounds,
+ canvasSize,
+ snapThreshold,
+}: {
+ proposedParams: ParamValues;
+ bounds: ElementBounds;
+ canvasSize: { width: number; height: number };
+ snapThreshold: { x: number; y: number };
+}): MaskSnapResult {
+ const geometry = getMaskSnapGeometry({
+ params: proposedParams,
+ bounds,
+ });
+ if (!geometry) {
+ return { params: proposedParams, activeLines: [] };
+ }
+
+ const { snappedPosition, activeLines } = snapPosition({
+ proposedPosition: geometry.position,
+ canvasSize: bounds,
+ elementSize: geometry.size,
+ rotation: geometry.rotation,
+ snapThreshold,
+ });
+
+ return {
+ params: {
+ ...proposedParams,
+ ...setMaskLocalCenter({
+ center: snappedPosition,
+ bounds,
+ }),
+ },
+ activeLines: toGlobalMaskSnapLines({
+ lines: activeLines,
+ bounds,
+ canvasSize,
+ }),
+ };
+}
+
+function snapMaskRotation({
+ proposedParams,
+}: {
+ proposedParams: ParamValues;
+}): MaskSnapResult {
+ if (typeof proposedParams.rotation !== "number") {
+ return { params: proposedParams, activeLines: [] };
+ }
+
+ const { snappedRotation } = snapRotation({
+ proposedRotation: proposedParams.rotation,
+ });
+
+ return {
+ params: {
+ ...proposedParams,
+ rotation: snappedRotation,
+ },
+ activeLines: [],
+ };
+}
+
+function snapBoxMaskSize({
+ handleId,
+ startParams,
+ proposedParams,
+ bounds,
+ canvasSize,
+ snapThreshold,
+}: {
+ handleId: string;
+ startParams: ParamValues;
+ proposedParams: ParamValues;
+ bounds: ElementBounds;
+ canvasSize: { width: number; height: number };
+ snapThreshold: { x: number; y: number };
+}): MaskSnapResult {
+ if (
+ !isRectangleMaskParams(startParams) ||
+ !isRectangleMaskParams(proposedParams)
+ ) {
+ return { params: proposedParams, activeLines: [] };
+ }
+
+ const geometry = getMaskSnapGeometry({
+ params: proposedParams,
+ bounds,
+ });
+ if (!geometry) {
+ return { params: proposedParams, activeLines: [] };
+ }
+
+ const localCanvasSize = bounds;
+ const baseWidth =
+ Math.max(startParams.width, MIN_MASK_DIMENSION) * bounds.width;
+ const baseHeight =
+ Math.max(startParams.height, MIN_MASK_DIMENSION) * bounds.height;
+ const preferredEdges = getPreferredEdges({ handleId });
+
+ if (handleId === "right" || handleId === "left") {
+ const proposedScaleX = getClampedRatio({
+ next: proposedParams.width,
+ base: startParams.width,
+ });
+ const { x } = snapScaleAxes({
+ proposedScaleX,
+ proposedScaleY: 1,
+ position: geometry.position,
+ baseWidth,
+ baseHeight,
+ rotation: proposedParams.rotation,
+ canvasSize: localCanvasSize,
+ snapThreshold,
+ preferredEdges,
+ });
+
+ return {
+ params: {
+ ...proposedParams,
+ width: Math.max(MIN_MASK_DIMENSION, startParams.width * x.snappedScale),
+ },
+ activeLines: toGlobalMaskSnapLines({
+ lines: x.activeLines,
+ bounds,
+ canvasSize,
+ }),
+ };
+ }
+
+ if (handleId === "top" || handleId === "bottom") {
+ const proposedScaleY = getClampedRatio({
+ next: proposedParams.height,
+ base: startParams.height,
+ });
+ const { y } = snapScaleAxes({
+ proposedScaleX: 1,
+ proposedScaleY,
+ position: geometry.position,
+ baseWidth,
+ baseHeight,
+ rotation: proposedParams.rotation,
+ canvasSize: localCanvasSize,
+ snapThreshold,
+ preferredEdges,
+ });
+
+ return {
+ params: {
+ ...proposedParams,
+ height: Math.max(
+ MIN_MASK_DIMENSION,
+ startParams.height * y.snappedScale,
+ ),
+ },
+ activeLines: toGlobalMaskSnapLines({
+ lines: y.activeLines,
+ bounds,
+ canvasSize,
+ }),
+ };
+ }
+
+ if (handleId === "scale") {
+ const baseScale = Math.max(startParams.scale, MIN_MASK_DIMENSION);
+ const proposedScale = getClampedRatio({
+ next: proposedParams.scale,
+ base: startParams.scale,
+ });
+ const { snappedScale, activeLines } = snapScale({
+ proposedScale,
+ position: geometry.position,
+ baseWidth: baseWidth * baseScale,
+ baseHeight: baseHeight * baseScale,
+ rotation: proposedParams.rotation,
+ canvasSize: localCanvasSize,
+ snapThreshold,
+ preferredEdges,
+ });
+
+ return {
+ params: {
+ ...proposedParams,
+ scale: Math.max(MIN_MASK_DIMENSION, startParams.scale * snappedScale),
+ },
+ activeLines: toGlobalMaskSnapLines({
+ lines: activeLines,
+ bounds,
+ canvasSize,
+ }),
+ };
+ }
+
+ if (CORNER_SIZE_HANDLES.has(handleId)) {
+ const proposedScale = getClampedRatio({
+ next: proposedParams.width,
+ base: startParams.width,
+ });
+ const { snappedScale, activeLines } = snapScale({
+ proposedScale,
+ position: geometry.position,
+ baseWidth,
+ baseHeight,
+ rotation: proposedParams.rotation,
+ canvasSize: localCanvasSize,
+ snapThreshold,
+ preferredEdges,
+ });
+
+ return {
+ params: {
+ ...proposedParams,
+ width: Math.max(MIN_MASK_DIMENSION, startParams.width * snappedScale),
+ height: Math.max(MIN_MASK_DIMENSION, startParams.height * snappedScale),
+ },
+ activeLines: toGlobalMaskSnapLines({
+ lines: activeLines,
+ bounds,
+ canvasSize,
+ }),
+ };
+ }
+
+ return { params: proposedParams, activeLines: [] };
+}
+
+export function snapMaskInteraction({
+ handleId,
+ startParams,
+ proposedParams,
+ bounds,
+ canvasSize,
+ snapThreshold,
+}: {
+ handleId: string;
+ startParams: ParamValues;
+ proposedParams: ParamValues;
+ bounds: ElementBounds;
+ canvasSize: { width: number; height: number };
+ snapThreshold: { x: number; y: number };
+}): MaskSnapResult {
+ if (handleId === "position") {
+ return snapMaskPosition({
+ proposedParams,
+ bounds,
+ canvasSize,
+ snapThreshold,
+ });
+ }
+
+ if (handleId === "rotation") {
+ return snapMaskRotation({ proposedParams });
+ }
+
+ return snapBoxMaskSize({
+ handleId,
+ startParams,
+ proposedParams,
+ bounds,
+ canvasSize,
+ snapThreshold,
+ });
+}
+
diff --git a/apps/web/src/lib/masks/types.ts b/apps/web/src/lib/masks/types.ts
new file mode 100644
index 00000000..569ff0ff
--- /dev/null
+++ b/apps/web/src/lib/masks/types.ts
@@ -0,0 +1,115 @@
+import type { ElementBounds } from "@/lib/preview/element-bounds";
+import type { ParamDefinition, ParamValues } from "@/lib/params";
+
+export type MaskType = "split" | "rectangle" | "ellipse";
+
+export interface BaseMaskParams extends ParamValues {
+ feather: number;
+ inverted: boolean;
+ strokeColor: string;
+ strokeWidth: number;
+ strokeAlign: "inside" | "center" | "outside";
+}
+
+export interface SplitMaskParams extends BaseMaskParams {
+ centerX: number;
+ centerY: number;
+ rotation: number;
+}
+
+export interface RectangleMaskParams extends BaseMaskParams {
+ centerX: number;
+ centerY: number;
+ width: number;
+ height: number;
+ rotation: number;
+ scale: number;
+}
+
+export interface SplitMask {
+ id: string;
+ type: "split";
+ params: SplitMaskParams;
+}
+
+export interface RectangleMask {
+ id: string;
+ type: "rectangle";
+ params: RectangleMaskParams;
+}
+
+export interface EllipseMask {
+ id: string;
+ type: "ellipse";
+ params: RectangleMaskParams;
+}
+
+export type Mask = SplitMask | RectangleMask | EllipseMask;
+
+export interface MaskRenderer {
+ buildPath(params: {
+ resolvedParams: unknown;
+ width: number;
+ height: number;
+ }): Path2D;
+ buildStrokePath?: (params: {
+ resolvedParams: unknown;
+ width: number;
+ height: number;
+ }) => Path2D;
+ /** Renders the feathered mask directly onto ctx, bypassing JFA. */
+ renderMask?: (params: {
+ resolvedParams: unknown;
+ ctx: CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D;
+ width: number;
+ height: number;
+ feather: number;
+ }) => void;
+}
+
+export type MaskOverlayShape = "line" | "box";
+
+export interface MaskFeatures {
+ hasPosition: boolean;
+ hasRotation: boolean;
+ sizeMode: "none" | "uniform" | "width-height" | "height-only" | "width-only";
+}
+
+export interface MaskHandlePosition {
+ id: string;
+ x: number;
+ y: number;
+ cursor: string;
+}
+
+export interface MaskLinePoints {
+ start: { x: number; y: number };
+ end: { x: number; y: number };
+}
+
+export interface MaskDefaultContext {
+ elementSize?: { width: number; height: number };
+}
+
+export interface MaskParamUpdateArgs<TParams extends BaseMaskParams = BaseMaskParams> {
+ handleId: string;
+ startParams: TParams;
+ deltaX: number;
+ deltaY: number;
+ startCanvasX: number;
+ startCanvasY: number;
+ bounds: ElementBounds;
+ canvasSize: { width: number; height: number };
+}
+
+export interface MaskDefinition<TParams extends BaseMaskParams = BaseMaskParams> {
+ type: MaskType;
+ name: string;
+ overlayShape: MaskOverlayShape;
+ features: MaskFeatures;
+ params: ParamDefinition<keyof TParams & string>[];
+ renderer: MaskRenderer;
+ buildOverlayPath?: (params: { width: number; height: number }) => string;
+ buildDefault(context: MaskDefaultContext): Omit<Mask, "id">;
+ computeParamUpdate(args: MaskParamUpdateArgs<TParams>): ParamValues;
+}
diff --git a/apps/web/src/lib/masks/utils.ts b/apps/web/src/lib/masks/utils.ts
new file mode 100644
index 00000000..a9110237
--- /dev/null
+++ b/apps/web/src/lib/masks/utils.ts
@@ -0,0 +1,64 @@
+const LINE_PARALLEL_EPSILON = 1e-10;
+
+export function lineEdgeIntersection({
+ lineX,
+ lineY,
+ normalX,
+ normalY,
+ x1,
+ y1,
+ x2,
+ y2,
+}: {
+ lineX: number;
+ lineY: number;
+ normalX: number;
+ normalY: number;
+ x1: number;
+ y1: number;
+ x2: number;
+ y2: number;
+}): { x: number; y: number } | null {
+ const distance1 = halfPlaneSign({
+ lineX,
+ lineY,
+ normalX,
+ normalY,
+ x: x1,
+ y: y1,
+ });
+ const distance2 = halfPlaneSign({
+ lineX,
+ lineY,
+ normalX,
+ normalY,
+ x: x2,
+ y: y2,
+ });
+ const denom = distance1 - distance2;
+ if (Math.abs(denom) < LINE_PARALLEL_EPSILON) return null;
+ const t = distance1 / denom;
+ if (t < 0 || t > 1) return null;
+ return {
+ x: x1 + (x2 - x1) * t,
+ y: y1 + (y2 - y1) * t,
+ };
+}
+
+export function halfPlaneSign({
+ lineX,
+ lineY,
+ normalX,
+ normalY,
+ x,
+ y,
+}: {
+ lineX: number;
+ lineY: number;
+ normalX: number;
+ normalY: number;
+ x: number;
+ y: number;
+}): number {
+ return (x - lineX) * normalX + (y - lineY) * normalY;
+}
generated by cgit v1.3.1 (git 2.54.0) at 2026-10-17 09:43:02 +0000