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https://github.com/excalidraw/excalidraw.git
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Segments detection
This commit is contained in:
Mathias Krafft
parent
9cf17321f1
commit
89a733120f
3 changed files with 321 additions and 133 deletions
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@ -1,136 +1,267 @@
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import type {
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ExcalidrawArrowElement,
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ExcalidrawDiamondElement,
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ExcalidrawElement,
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ExcalidrawEllipseElement,
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ExcalidrawFreeDrawElement,
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ExcalidrawLinearElement,
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ExcalidrawRectangleElement,
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} from "../excalidraw/element/types";
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import type { BoundingBox } from "../excalidraw/element/bounds";
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import { getCommonBoundingBox } from "../excalidraw/element/bounds";
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import { newElement } from "../excalidraw/element";
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// @ts-ignore
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import shapeit from "@amaplex-software/shapeit";
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type Shape =
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| ExcalidrawRectangleElement["type"]
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| ExcalidrawEllipseElement["type"]
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| ExcalidrawDiamondElement["type"]
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// | ExcalidrawArrowElement["type"]
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// | ExcalidrawLinearElement["type"]
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| ExcalidrawFreeDrawElement["type"];
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interface ShapeRecognitionResult {
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type: Shape;
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confidence: number;
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boundingBox: BoundingBox;
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ExcalidrawArrowElement,
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ExcalidrawDiamondElement,
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ExcalidrawElement,
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ExcalidrawEllipseElement,
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ExcalidrawFreeDrawElement,
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ExcalidrawLinearElement,
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ExcalidrawRectangleElement,
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} from "../excalidraw/element/types";
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import type { BoundingBox, Bounds } from "../excalidraw/element/bounds";
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import { getCenterForBounds, getCommonBoundingBox } from "../excalidraw/element/bounds";
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import { newArrowElement, newElement, newLinearElement } from "../excalidraw/element";
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import { angleBetween, GlobalPoint, LocalPoint, perpendicularDistance, pointDistance } from "@excalidraw/math";
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import { ROUNDNESS } from "@excalidraw/excalidraw/constants";
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type Shape =
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| ExcalidrawRectangleElement["type"]
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| ExcalidrawEllipseElement["type"]
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| ExcalidrawDiamondElement["type"]
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| ExcalidrawArrowElement["type"]
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| ExcalidrawLinearElement["type"]
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| ExcalidrawFreeDrawElement["type"];
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interface ShapeRecognitionResult {
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type: Shape;
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simplified: readonly LocalPoint[];
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boundingBox: BoundingBox;
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}
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interface ShapeRecognitionOptions {
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closedDistThreshPercent: number; // Max distance between stroke start/end to consider shape closed
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cornerAngleThresh: number; // Angle (in degrees) below which a corner is considered "sharp" (for arrow detection)
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rdpTolerancePercent: number; // RDP simplification tolerance (percentage of bounding box diagonal)
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rectAngleThresh: number; // Angle (in degrees) to check for rectangle corners
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rectOrientationThresh: number; // Angle difference (in degrees) to nearest 0/90 orientation to call it rectangle
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}
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const DEFAULT_OPTIONS: ShapeRecognitionOptions = {
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closedDistThreshPercent: 10, // distance between start/end < % of bounding box diagonal
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cornerAngleThresh: 60, // <60° considered a sharp corner (possible arrow tip)
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rdpTolerancePercent: 10, // percentage of bounding box diagonal
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rectAngleThresh: 20, // <20° considered a sharp corner (rectangle)
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rectOrientationThresh: 10, //
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};
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/**
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* Recognizes common shapes from free-draw input
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* @param element The freedraw element to analyze
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* @returns Information about the recognized shape, or null if no shape is recognized
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*/
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export const recognizeShape = (
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element: ExcalidrawFreeDrawElement,
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opts: Partial<ShapeRecognitionOptions> = {},
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): ShapeRecognitionResult => {
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const options = { ...DEFAULT_OPTIONS, ...opts };
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const boundingBox = getCommonBoundingBox([element]);;
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// We need at least a few points to recognize a shape
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if (!element.points || element.points.length < 3) {
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return { type: "freedraw", simplified: element.points, boundingBox };
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}
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/**
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* Recognizes common shapes from free-draw input
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* @param element The freedraw element to analyze
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* @returns Information about the recognized shape, or null if no shape is recognized
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*/
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export const recognizeShape = (
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element: ExcalidrawFreeDrawElement,
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): ShapeRecognitionResult => {
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const boundingBox = getCommonBoundingBox([element]);
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// We need at least a few points to recognize a shape
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if (!element.points || element.points.length < 3) {
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return { type: "freedraw", confidence: 1, boundingBox };
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const tolerance = pointDistance(
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[boundingBox.minX, boundingBox.minY] as LocalPoint,
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[boundingBox.maxX, boundingBox.maxY] as LocalPoint,
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) * options.rdpTolerancePercent / 100;
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const simplified = simplifyRDP(element.points, tolerance);
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console.log("Simplified points:", simplified);
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// Check if the original points form a closed shape
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const start = element.points[0], end = element.points[element.points.length - 1];
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const closedDist = pointDistance(start, end);
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const diag = Math.hypot(boundingBox.width, boundingBox.height); // diagonal of bounding box
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const isClosed = closedDist < Math.max(10, diag * options.closedDistThreshPercent / 100); // e.g., threshold: 10px or % of size
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console.log("Closed shape:", isClosed);
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let bestShape: Shape = 'freedraw'; // TODO: Should this even be possible in this mode?
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const boundingBoxCenter = getCenterForBounds([
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boundingBox.minX,
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boundingBox.minY,
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boundingBox.maxX,
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boundingBox.maxY,
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] as Bounds);
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// **Line** (open shape with low deviation from a straight line)
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if (!isClosed && simplified.length == 2) {
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bestShape = 'line';
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}
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// **Arrow** (open shape with a sharp angle indicating an arrowhead)
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if (!isClosed && simplified.length == 5) {
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// The last two segments will make an arrowhead
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console.log("Simplified points:", simplified);
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const arrow_start = simplified[2], arrow_tip = simplified[3], arrow_end = simplified[4];
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const tipAngle = angleBetween(arrow_tip, arrow_start, arrow_end); // angle at the second-last point (potential arrow tip)
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// Lengths of the last two segments
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const seg1Len = pointDistance(arrow_start, arrow_tip);
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const seg2Len = pointDistance(arrow_tip, arrow_end);
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// Length of the rest of the stroke (approx arrow shaft length)
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const shaftLen = pointDistance(simplified[0], simplified[1])
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// Heuristic checks for arrowhead: sharp angle and short segments relative to shaft
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console.log("Arrow tip angle:", tipAngle);
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if (tipAngle > 30 && tipAngle < 150 && seg1Len < shaftLen * 0.8 && seg2Len < shaftLen * 0.8) {
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bestShape = 'arrow';
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}
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console.log("Recognizing shape from points:", element.points);
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const shapethat = shapeit.new({
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atlas: {},
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output: {},
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thresholds: {},
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});
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const shape = shapethat(element.points);
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console.log("Shape recognized:", shape);
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const mappedShape = (name: string): Shape => {
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switch (name) {
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case "rectangle":
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return "rectangle";
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case "square":
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return "rectangle";
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case "circle":
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return "ellipse";
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case "open polygon":
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return "diamond";
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default:
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return "freedraw";
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}
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// **Rectangle or Diamond** (closed shape with 4 corners - RDP might include last point
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if (isClosed && (simplified.length == 4 || simplified.length == 5)) {
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const vertices = simplified.slice(); // copy
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if (simplified.length === 5) {
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vertices.pop(); // remove last point if RDP included it
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}
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// Compute angles at each corner
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console.log("Vertices:", vertices);
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var angles = []
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for (let i = 0; i < vertices.length; i++) {
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angles.push(angleBetween(vertices[i], vertices[(i + 1) % vertices.length], vertices[(i + 2) % vertices.length]));
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}
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console.log("Angles:", angles);
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console.log("Angles sum:", angles.reduce((a, b) => a + b, 0));
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// All angles are sharp enough, so we can check for rectangle/diamond
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if (angles.every(a => (a > options.rectAngleThresh && a < 180 - options.rectAngleThresh))) {
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// Determine orientation by checking the slope of each segment
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interface Segment { length: number; angleDeg: number; }
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const segments: Segment[] = [];
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for (let i = 0; i < 4; i++) {
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const p1 = simplified[i];
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const p2 = simplified[(i + 1) % (simplified.length)];
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const dx = p2[0] - p1[0];
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const dy = p2[1] - p1[1];
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const length = Math.hypot(dx, dy);
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// angle of segment in degrees from horizontal
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let segAngle = (Math.atan2(dy, dx) * 180) / Math.PI;
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if (segAngle < 0) segAngle += 360;
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if (segAngle > 180) segAngle -= 180; // use [0,180] range for undirected line
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segments.push({ length, angleDeg: segAngle });
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}
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// Check for axis-aligned orientation
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const hasAxisAlignedSide = segments.some(seg => {
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const angle = seg.angleDeg;
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const distToHoriz = Math.min(Math.abs(angle - 0), Math.abs(angle - 180));
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const distToVert = Math.abs(angle - 90);
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return (distToHoriz < options.rectOrientationThresh) || (distToVert < options.rectOrientationThresh);
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});
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if (hasAxisAlignedSide) {
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bestShape = "rectangle";
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} else {
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// Not near axis-aligned, likely a rotated shape -> diamond
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bestShape = "diamond";
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}
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};
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const recognizedShape: ShapeRecognitionResult = {
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type: mappedShape(shape.name),
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confidence: 0.8,
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boundingBox,
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};
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return recognizedShape;
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};
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/**
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* Creates a new element based on the recognized shape from a freedraw element
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* @param freedrawElement The original freedraw element
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* @param recognizedShape The recognized shape information
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* @returns A new element of the recognized shape type
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*/
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export const createElementFromRecognizedShape = (
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freedrawElement: ExcalidrawFreeDrawElement,
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recognizedShape: ShapeRecognitionResult,
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): ExcalidrawElement => {
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if (!recognizedShape.type || recognizedShape.type === "freedraw") {
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return freedrawElement;
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}
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// if (recognizedShape.type === "rectangle") {
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return newElement({
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...freedrawElement,
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type: recognizedShape.type,
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x: recognizedShape.boundingBox.minX,
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y: recognizedShape.boundingBox.minY,
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width: recognizedShape.boundingBox.width!,
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height: recognizedShape.boundingBox.height!,
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});
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};
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/**
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* Determines if shape recognition should be applied based on app state
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* @param element The freedraw element to potentially snap
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* @param minConfidence The minimum confidence level required to apply snapping
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* @returns Whether to apply shape snapping
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*/
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export const shouldApplyShapeSnapping = (
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recognizedShape: ShapeRecognitionResult,
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minConfidence: number = 0.75,
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): boolean => {
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return (
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!!recognizedShape.type && (recognizedShape.confidence || 0) >= minConfidence
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);
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};
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/**
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* Converts a freedraw element to the detected shape
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*/
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export const convertToShape = (
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freeDrawElement: ExcalidrawFreeDrawElement,
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): ExcalidrawElement => {
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const recognizedShape = recognizeShape(freeDrawElement);
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if (shouldApplyShapeSnapping(recognizedShape)) {
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return createElementFromRecognizedShape(freeDrawElement, recognizedShape);
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} else {
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const aspectRatio = boundingBox.width && boundingBox.height ? Math.min(boundingBox.width, boundingBox.height) / Math.max(boundingBox.width, boundingBox.height) : 1;
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// If aspect ratio ~1 (nearly square) and simplified has few corners, good for circle
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if (aspectRatio > 0.8) {
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// Measure radius variance
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const cx = boundingBoxCenter[0];
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const cy = boundingBoxCenter[1];
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let totalDist = 0, maxDist = 0, minDist = Infinity;
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for (const p of simplified) {
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const d = Math.hypot(p[0] - cx, p[1] - cy);
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totalDist += d;
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maxDist = Math.max(maxDist, d);
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minDist = Math.min(minDist, d);
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}
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const avgDist = totalDist / simplified.length;
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const radiusVar = (maxDist - minDist) / (avgDist || 1);
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// If variance in radius is small, shape is round
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if (radiusVar < 0.3) {
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bestShape = 'ellipse';
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}
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}
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// Add more shape conversions as needed
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return freeDrawElement;
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};
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}
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return {
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type: bestShape,
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simplified,
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boundingBox
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} as ShapeRecognitionResult;
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};
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/**
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* Simplify a polyline using Ramer-Douglas-Peucker algorithm.
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* @param points Array of points [x,y] representing the stroke.
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* @param epsilon Tolerance for simplification (higher = more simplification).
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* @returns Simplified list of points.
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*/
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function simplifyRDP(points: readonly LocalPoint[], epsilon: number): readonly LocalPoint[] {
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if (points.length < 3) return points;
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// Find the point with the maximum distance from the line between first and last
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const first = points[0], last = points[points.length - 1];
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let index = -1;
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let maxDist = 0;
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for (let i = 1; i < points.length - 1; i++) {
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// Perpendicular distance from points[i] to line (first-last)
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const dist = perpendicularDistance(points[i], first, last);
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if (dist > maxDist) {
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maxDist = dist;
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index = i;
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}
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}
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// If max distance is greater than epsilon, recursively simplify
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if (maxDist > epsilon && index !== -1) {
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const left = simplifyRDP(points.slice(0, index + 1), epsilon);
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const right = simplifyRDP(points.slice(index), epsilon);
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// Concatenate results (omit duplicate point at junction)
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return left.slice(0, -1).concat(right);
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} else {
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// Not enough deviation, return straight line (keep only endpoints)
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return [first, last];
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}
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}
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/**
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* Converts a freedraw element to the detected shape
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*/
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export const convertToShape = (
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freeDrawElement: ExcalidrawFreeDrawElement,
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): ExcalidrawElement => {
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const recognizedShape = recognizeShape(freeDrawElement);
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switch (recognizedShape.type) {
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case "rectangle": case "diamond": case "ellipse": {
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return newElement({
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...freeDrawElement,
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roundness: { type: ROUNDNESS.PROPORTIONAL_RADIUS },
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type: recognizedShape.type,
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x: recognizedShape.boundingBox.minX,
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y: recognizedShape.boundingBox.minY,
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width: recognizedShape.boundingBox.width!,
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height: recognizedShape.boundingBox.height!,
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});
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}
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case "arrow": {
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return newArrowElement({
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...freeDrawElement,
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type: recognizedShape.type,
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endArrowhead: "arrow", // TODO: Get correct state
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points: [
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recognizedShape.simplified[0],
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recognizedShape.simplified[recognizedShape.simplified.length - 2]
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],
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roundness: { type: ROUNDNESS.PROPORTIONAL_RADIUS }
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});
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}
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case "line": {
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return newLinearElement({
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...freeDrawElement,
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type: recognizedShape.type,
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points: [
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recognizedShape.simplified[0],
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recognizedShape.simplified[recognizedShape.simplified.length - 1]
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],
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roundness: { type: ROUNDNESS.PROPORTIONAL_RADIUS }
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});
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}
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default: return freeDrawElement
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}
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};
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