move bar annotations to a separate model

src/index.ts

@@ -2,6 +2,7 @@ import { ChartwerkPod, VueChartwerkPodMixin, TimeFormat, AxisFormat } from '@cha
 
 import { BarConfig } from './models/bar_options';
 import { BarSeries } from './models/bar_series';
+import { BarAnnotation } from './models/bar_annotation';
 
 import { BarSerie, BarOptions, RowValues } from './types';
 import { findClosest } from './utils';
@@ -88,27 +89,17 @@ export class ChartwerkBarPod extends ChartwerkPod<BarSerie, BarOptions> {
         const series = _.filter(this.series.visibleSeries, serie => _.includes(d.serieTarget, serie.target));
         const matchedKeys = _.map(series, serie => serie.matchedKey); // here matchedKeys should be equal
         const key = matchedKeys[0];
-
-        const lastRect = _.last(container.selectAll('rect')?.nodes());
         const annotation = _.find(this.options.barOptions.annotations, a => a.key === key);
-        if(!lastRect || !key || !annotation) {
+        if(!key || !annotation) {
           return;
         }
-
-        const rectSelection = d3.select(lastRect);
-        // render triangle
-        container.append('path')
-          .attr('d', () => {
-            const x = Math.ceil(_.toNumber(rectSelection.attr('x')));
-            const y = Math.ceil(_.toNumber(rectSelection.attr('y')));
-            const options = { max: this.options.barOptions.maxAnnotationSize, min: this.options.barOptions.minAnnotationSize };
-            return this.getTrianglePath(x, y, this.barWidth, options);
-          })
-          .attr('fill', annotation.color)
-          .on('mouseover', this.redirectEventToOverlay.bind(this))
-          .on('mousemove', this.redirectEventToOverlay.bind(this))
-          .on('mouseout', this.redirectEventToOverlay.bind(this))
-          .on('mousedown', () => { d3.event.stopPropagation(); });
+        const annotationOptions = {
+          size: this.barWidth,
+          max: this.options.barOptions.maxAnnotationSize,
+          min: this.options.barOptions.minAnnotationSize,
+          color: annotation.color,
+        };
+        new BarAnnotation(this.overlay, container, annotationOptions);
       });
   }
 
@@ -116,33 +107,6 @@ export class ChartwerkBarPod extends ChartwerkPod<BarSerie, BarOptions> {
     this.overlay?.node().dispatchEvent(new MouseEvent(d3.event.type, d3.event));
   }
 
-  getTrianglePath(x: number, y: number, length: number, options?: { max: number, min: number }): string {
-    // (x, y) - top left corner of bar
-    const minTriangleSize = options?.min || 6;
-    const maxTriagleSize = options?.max || 10;
-    const yOffset = 4; // offset between triangle and bar
-    const centerX = x + length / 2;
-    const correctedLength = _.clamp(length, minTriangleSize, maxTriagleSize);
-
-    const topY = Math.max(y - correctedLength - yOffset, 4);
-    const topLeftCorner = {
-      x: centerX - correctedLength / 2,
-      y: topY,
-    };
-    const topRightCorner = {
-      x: centerX + correctedLength / 2,
-      y: topY,
-    };
-    const bottomMiddleCorner = {
-      x: centerX,
-      y: topY + correctedLength,
-    };
-
-    return `M ${topLeftCorner.x} ${topLeftCorner.y}
-      L ${topRightCorner.x} ${topRightCorner.y}
-      L ${bottomMiddleCorner.x} ${bottomMiddleCorner.y} z`;
-  }
-
   getBarOpacity(rowValues: RowValues): number {
     if(this.options.barOptions.opacityFormatter === undefined) {
       return 1;

src/models/bar_annotation.ts

@@ -0,0 +1,71 @@
+import * as d3 from 'd3';
+import * as _ from 'lodash';
+
+
+const DEFAULT_ANNOTATION_MIN_SIZE = 6; //px
+const DEFAULT_ANNOTATION_MAX_SIZE = 10; //px
+const DEFAULT_ANNOTATION_OFFSET_Y = 4; //offset between triangle and bar in px
+const DEFAULT_ANNOTATION_COLOR = 'red';
+
+export class BarAnnotation {
+  position: { x: number, y: number };
+
+  constructor(
+    protected overlay: d3.Selection<SVGRectElement, unknown, null, undefined>, // overlay from core. It should be global
+    protected groupContainer: d3.Selection<SVGGElement, unknown, null, undefined>, // group - bars as one item
+    protected annotationOptions: { size: number, max?: number, min?: number, offset?: number, color?: string },
+  ) {
+    this.position = this.getGroupLastRectPosition();
+    this.renderAnnotation();
+  }
+
+  protected renderAnnotation(): void {
+    this.groupContainer.append('path')
+      .attr('d', () => this.getTrianglePath())
+      .attr('fill', this.annotationOptions.color || DEFAULT_ANNOTATION_COLOR)
+      .on('mouseover', this.redirectEventToOverlay.bind(this))
+      .on('mousemove', this.redirectEventToOverlay.bind(this))
+      .on('mouseout', this.redirectEventToOverlay.bind(this))
+      .on('mousedown', () => { d3.event.stopPropagation(); });
+  }
+
+  getGroupLastRectPosition(): { x: number, y: number } {
+    const lastRect = _.last(this.groupContainer.selectAll('rect')?.nodes());
+    const barSelection = d3.select(lastRect);
+    return {
+      x: Math.ceil(_.toNumber(barSelection.attr('x'))),
+      y: Math.ceil(_.toNumber(barSelection.attr('y'))),
+    }
+  }
+
+  protected getTrianglePath(): string {
+    // (x, y) - top left corner of bar
+    const minTriangleSize = this.annotationOptions?.min || DEFAULT_ANNOTATION_MIN_SIZE;
+    const maxTriagleSize = this.annotationOptions?.max || DEFAULT_ANNOTATION_MAX_SIZE;
+    const yOffset = this.annotationOptions?.offset || DEFAULT_ANNOTATION_OFFSET_Y;
+    const centerX = this.position.x + this.annotationOptions.size / 2;
+    const correctedLength = _.clamp(this.annotationOptions.size, minTriangleSize, maxTriagleSize);
+
+    const topY = Math.max(this.position.y - correctedLength - yOffset, 4);
+    const topLeftCorner = {
+      x: centerX - correctedLength / 2,
+      y: topY,
+    };
+    const topRightCorner = {
+      x: centerX + correctedLength / 2,
+      y: topY,
+    };
+    const bottomMiddleCorner = {
+      x: centerX,
+      y: topY + correctedLength,
+    };
+
+    return `M ${topLeftCorner.x} ${topLeftCorner.y}
+      L ${topRightCorner.x} ${topRightCorner.y}
+      L ${bottomMiddleCorner.x} ${bottomMiddleCorner.y} z`;
+  }
+
+  redirectEventToOverlay(): void {
+    this.overlay?.node().dispatchEvent(new MouseEvent(d3.event.type, d3.event));
+  }
+}