JavaScript Freehand Drawing Tools

1import {
2    AnnotationHoverModifier,
3    ECursorStyle,
4    EObservableArrayChangedAction,
5    EXyDirection,
6    MouseWheelZoomModifier,
7    NumberRange,
8    ZoomExtentsModifier,
9} from "scichart";
10import {
11    EAnnotationVisibilityMode,
12    ESnapMode,
13    FreehandDrawingAnnotation,
14    FreehandDrawingModifier,
15    IFreehandDrawingAnnotationOptions,
16} from "scichart-financial-tools";
17import { createFinancialChart, TRADING_ANNOTATION_COLORS } from "../_shared/tradingAnnotationExampleUtils";
18
19export type TFreehandVariant = "editableOutline" | "nonEditableLine" | "thickHighlight" | "locked";
20
21const generateHandDrawnTrendline = () => {
22    const startX = 1705104000; // 2024-01-13 00:00 UTC
23    const endX = 1705276800; // 2024-01-15 00:00 UTC
24    const startY = 65000;
25    const endY = 67500;
26    const count = 110;
27    let seed = 1337;
28    const rand = () => {
29        seed = (seed * 9301 + 49297) % 233280;
30        return seed / 233280;
31    };
32    const points: { x: number; y: number }[] = [];
33    for (let i = 0; i < count; i++) {
34        const t = i / (count - 1);
35        const drift = Math.sin(t * Math.PI * 1.6 + 0.4) * 18;
36        const yJitter = (rand() - 0.5) * 16;
37        const xJitter = (rand() - 0.5) * ((endX - startX) / count) * 0.35;
38        points.push({
39            x: startX + (endX - startX) * t + xJitter,
40            y: startY + (endY - startY) * t + drift + yJitter,
41        });
42    }
43    return points;
44};
45
46const handDrawnTrendlinePoints = generateHandDrawnTrendline();
47
48type TInitialFreehandAnnotation = {
49    points: { x: number; y: number }[];
50    stroke: string;
51    strokeThickness: number;
52};
53
54const initialFreehandAnnotations: TInitialFreehandAnnotation[] = [
55    {
56        points: [
57            { x: 1705074424.9760892, y: 65731.6718827903 },
58            { x: 1705075600.6684432, y: 65642.12282942746 },
59            { x: 1705087445.885085, y: 65307.71857034999 },
60            { x: 1705085666.0820355, y: 65356.5315837517 },
61            { x: 1705081130.604812, y: 65410.78777490682 },
62            { x: 1705070214.7892404, y: 65438.14998565657 },
63            { x: 1705086971.8905394, y: 65356.648641337786 },
64            { x: 1705090526.8496335, y: 65388.83947751397 },
65            { x: 1705094908.9756804, y: 65460.77136416947 },
66            { x: 1705091521.3087788, y: 65449.416778318235 },
67        ],
68        stroke: "#F97066",
69        strokeThickness: 4,
70    },
71    {
72        points: [
73            { x: 1705025064.4852417, y: 66127.82401853298 },
74            { x: 1705025394.4226215, y: 65871.17526101925 },
75            { x: 1705024855.3700008, y: 65954.7251130947 },
76            { x: 1705029753.3136415, y: 65982.08732384446 },
77            { x: 1705035097.3697963, y: 65992.00795426602 },
78            { x: 1705040343.8388386, y: 65986.09654616822 },
79            { x: 1705044791.0229604, y: 65964.20677756841 },
80            { x: 1705045278.9585223, y: 65933.80106958018 },
81            { x: 1705043201.74713, y: 65906.67297400262 },
82            { x: 1705035543.48231, y: 65873.80905670639 },
83            { x: 1705027936.3345492, y: 65859.3231804271 },
84            { x: 1705022132.2248645, y: 65859.11832965145 },
85        ],
86        stroke: "#F97066",
87        strokeThickness: 4,
88    },
89    {
90        points: [
91            { x: 1705060251.609766, y: 65972.86903893946 },
92            { x: 1705060688.4282691, y: 65910.50660994725 },
93            { x: 1705065716.4880598, y: 65861.5180101664 },
94            { x: 1705069043.7438917, y: 65854.55308379373 },
95            { x: 1705070656.2547488, y: 65860.55228508111 },
96            { x: 1705072877.523307, y: 65910.76998951596 },
97            { x: 1705073388.6938958, y: 65974.47858074827 },
98            { x: 1705080935.4305873, y: 65866.11252042063 },
99        ],
100        stroke: "#F97066",
101        strokeThickness: 4,
102    },
103    {
104        points: [
105            { x: 1705091646.7779233, y: 65990.3691480607 },
106            { x: 1705091860.5401695, y: 65928.09451225805 },
107            { x: 1705094035.338674, y: 65896.19632004711 },
108            { x: 1705100819.966488, y: 65890.43123393191 },
109            { x: 1705104123.987293, y: 65914.89626942581 },
110            { x: 1705104742.0390048, y: 65990.60326323289 },
111            { x: 1705105169.5634973, y: 65837.34561863774 },
112            { x: 1705103979.9301271, y: 65712.03547272283 },
113            { x: 1705100095.033653, y: 65693.04287937887 },
114            { x: 1705092195.1245549, y: 65700.32971411331 },
115            { x: 1705088156.876904, y: 65734.97875959748 },
116            { x: 1705088291.6400592, y: 65779.40211352061 },
117            { x: 1705102172.2450452, y: 65854.20191103544 },
118            { x: 1705112846.4163384, y: 65896.78160797758 },
119        ],
120        stroke: "#F97066",
121        strokeThickness: 4,
122    },
123    {
124        points: [
125            { x: 1705271913.4095333, y: 68272.31899579709 },
126            { x: 1705254473.1984477, y: 68281.71286708124 },
127            { x: 1705243325.0326085, y: 68256.80886563948 },
128            { x: 1705241071.2350128, y: 68237.43583514073 },
129            { x: 1705240253.362071, y: 68204.68897543059 },
130            { x: 1705263358.2726805, y: 68162.25560047108 },
131            { x: 1705266676.2345016, y: 68137.556449805 },
132            { x: 1705266866.7617211, y: 68104.31209535395 },
133            { x: 1705263558.0939107, y: 68079.99338184268 },
134            { x: 1705255137.720213, y: 68056.46480703754 },
135            { x: 1705245188.4817545, y: 68058.92301634554 },
136            { x: 1705237929.859395, y: 68076.89135581115 },
137        ],
138        stroke: "#4EC385",
139        strokeThickness: 4,
140    },
141    {
142        points: [
143            { x: 1705282146.115318, y: 68129.39168317485 },
144            { x: 1705292318.4100335, y: 68129.39168317485 },
145            { x: 1705293675.335596, y: 68157.39771064813 },
146            { x: 1705293670.6885908, y: 68187.07180872327 },
147            { x: 1705292443.8791778, y: 68194.03673509593 },
148            { x: 1705280305.9011989, y: 68194.82687380207 },
149            { x: 1705275919.1281466, y: 68183.64787432998 },
150            { x: 1705274227.6181984, y: 68106.59471828281 },
151            { x: 1705277666.402159, y: 68075.6037223641 },
152            { x: 1705283721.4501324, y: 68055.26496678006 },
153            { x: 1705292304.4690173, y: 68053.74321816083 },
154            { x: 1705297546.2910542, y: 68064.07355013373 },
155        ],
156        stroke: "#4EC385",
157        strokeThickness: 4,
158    },
159    {
160        points: [
161            { x: 1705314953.9731023, y: 68304.74394714547 },
162            { x: 1705314517.1545992, y: 68072.50169633258 },
163        ],
164        stroke: "#4EC385",
165        strokeThickness: 4,
166    },
167    {
168        points: [
169            { x: 1705332956.4718356, y: 68300.50060964952 },
170            { x: 1705332956.4718356, y: 68178.23396097307 },
171            { x: 1705330897.8484647, y: 68051.95808997288 },
172        ],
173        stroke: "#4EC385",
174        strokeThickness: 4,
175    },
176    {
177        points: [
178            { x: 1705294609.3836718, y: 67929.01836017639 },
179            { x: 1705294474.6205165, y: 67825.6272472578 },
180            { x: 1705285682.4863908, y: 67528.6814157308 },
181            { x: 1705283005.8113081, y: 67676.43735377946 },
182            { x: 1705285306.0789573, y: 67543.25508519965 },
183            { x: 1705300334.4942653, y: 67679.27600024227 },
184        ],
185        stroke: "#4EC385",
186        strokeThickness: 4,
187    },
188];
189
190const variantOptions = (variant: TFreehandVariant, background: string): IFreehandDrawingAnnotationOptions => {
191    const base: IFreehandDrawingAnnotationOptions = {
192        isEditable: true,
193        strokeThickness: 4,
194        showBoxOutline: false,
195        boxOutlineStrokeDashArray: [6, 4],
196        snapMode: ESnapMode.None,
197        annotationsGripsRadius: 4,
198        gripSvgTemplate: (annotation: any, x: number, y: number) => {
199            const ann = annotation as FreehandDrawingAnnotation;
200            return `<circle cx="${x}" cy="${y}" r="${ann.annotationsGripsRadius}" fill="${background}" stroke="${ann.annotationsGripsStroke}" stroke-width="${ann.strokeThickness}" />`;
201        },
202    };
203
204    switch (variant) {
205        case "editableOutline":
206            return {
207                ...base,
208                stroke: TRADING_ANNOTATION_COLORS.freehand,
209                annotationsGripsStroke: TRADING_ANNOTATION_COLORS.freehand,
210                allowMove: true,
211                showBoxOutlineOnlyWhenSelected: false,
212            };
213        case "locked":
214            return {
215                ...base,
216                stroke: TRADING_ANNOTATION_COLORS.lockedFreehand,
217                annotationsGripsStroke: TRADING_ANNOTATION_COLORS.lockedFreehand,
218                keepAspectRatioOnResize: true,
219                forcedAspectRatio: 1,
220                showBoxOutlineOnlyWhenSelected: false,
221            };
222        case "nonEditableLine":
223            return {
224                ...base,
225                isEditable: false,
226                isSelected: false,
227                stroke: TRADING_ANNOTATION_COLORS.foreground,
228                strokeThickness: 2,
229                showBoxOutline: false,
230                gripVisibility: EAnnotationVisibilityMode.OnInteraction,
231                allowMove: false,
232                showBoxOutlineOnlyWhenSelected: false,
233            };
234        case "thickHighlight":
235            return {
236                ...base,
237                stroke: TRADING_ANNOTATION_COLORS.warning,
238                fill: `${TRADING_ANNOTATION_COLORS.warning}33`,
239                annotationsGripsStroke: TRADING_ANNOTATION_COLORS.warning,
240                strokeThickness: 4,
241                showBoxOutlineOnlyWhenSelected: false,
242            };
243    }
244};
245
246export const drawExample = async (rootElement: string | HTMLDivElement) => {
247    const { sciChartSurface, xAxis } = await createFinancialChart(rootElement, {
248        volatility: 0.0023,
249        title: "BTC / USDT - Freehand Drawing",
250        startDate: new Date("2024-01-01T00:00:00Z"),
251        dataSeed: 2024,
252    });
253
254    // Jan 20 2024 00:00 UTC
255    xAxis.visibleRange = new NumberRange(xAxis.visibleRange.min, 1705708800);
256
257    const freehandDrawingModifier = new FreehandDrawingModifier({
258        isDrawing: false,
259        keepDrawingAfterComplete: true,
260        pointSamplingDistancePx: 1.2,
261        simplifyTolerancePx: 0.8,
262        maxPoints: 6000,
263    });
264
265    sciChartSurface.chartModifiers.add(
266        new MouseWheelZoomModifier({ xyDirection: EXyDirection.XDirection }),
267        new ZoomExtentsModifier({ xyDirection: EXyDirection.XDirection }),
268        new AnnotationHoverModifier({
269            enableHover: true,
270            enableCursor: true,
271            idleCursor: ECursorStyle.Crosshair,
272        }),
273        freehandDrawingModifier
274    );
275
276    sciChartSurface.annotations.add(
277        ...initialFreehandAnnotations.map(
278            (data) =>
279                new FreehandDrawingAnnotation({
280                    points: data.points,
281                    stroke: data.stroke,
282                    strokeThickness: data.strokeThickness,
283                    isEditable: true,
284                    isSelected: false,
285                    allowMove: true,
286                    showBoxOutline: false,
287                    opacity: 0.9,
288                    gripVisibility: EAnnotationVisibilityMode.OnInteraction,
289                })
290        ),
291        new FreehandDrawingAnnotation({
292            points: handDrawnTrendlinePoints,
293            isEditable: true,
294            isSelected: false,
295            allowMove: true,
296            showBoxOutline: false,
297            stroke: "#686c70",
298            annotationsGripsStroke: "#9AA0A6",
299            strokeThickness: 7,
300            opacity: 0.9,
301            gripVisibility: EAnnotationVisibilityMode.OnInteraction,
302        })
303    );
304
305    return {
306        sciChartSurface,
307        startDrawing: (variant: TFreehandVariant, color?: string) => {
308            const options = variantOptions(variant, sciChartSurface.background);
309            if (color) {
310                options.stroke = color;
311                options.annotationsGripsStroke = color;
312            }
313            freehandDrawingModifier.startDrawing(options);
314        },
315        stopDrawing: () => freehandDrawingModifier.stopDrawing(true),
316        clear: () => sciChartSurface.annotations.clear(true),
317        removeLast: () => {
318            const annotations = sciChartSurface.annotations;
319            if (annotations.size() > 0) {
320                annotations.removeAt(annotations.size() - 1, true);
321            }
322        },
323        exportAnnotations: () =>
324            sciChartSurface.annotations
325                .asArray()
326                .filter((a): a is FreehandDrawingAnnotation => a instanceof FreehandDrawingAnnotation)
327                .map((a) => ({
328                    points: a.points.map((p) => ({ x: p.x, y: p.y })),
329                    stroke: a.stroke,
330                    strokeThickness: a.strokeThickness,
331                })),
332        setKeepDrawingAfterComplete: (enabled: boolean) => {
333            (freehandDrawingModifier as any).keepDrawingAfterCompleteProperty = enabled;
334        },
335        setSampling: (pointSamplingDistancePx: number, simplifyTolerancePx: number, maxPoints: number) => {
336            freehandDrawingModifier.pointSamplingDistancePx = pointSamplingDistancePx;
337            (freehandDrawingModifier as any).simplifyTolerancePxProperty = simplifyTolerancePx;
338            (freehandDrawingModifier as any).maxPointsProperty = maxPoints;
339        },
340    };
341};
342